[PATCH 0/7] ocxl: Implement Power9 as_notify/wait for OpenCAPI

[PATCH 0/7] ocxl: Implement Power9 as_notify/wait for OpenCAPI

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The Power 9 as_notify/wait feature provides a lower latency way to
signal a thread that work is complete. This series enables the use of
this feature from OpenCAPI adapters, as well as addressing a potential
starvation issue when allocating thread IDs.

Alastair D'Silva (7):
  powerpc: Add TIDR CPU feature for Power9
  powerpc: Use TIDR CPU feature to control TIDR allocation
  powerpc: use task_pid_nr() for TID allocation
  ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action
  ocxl: Expose the thread_id needed for wait on p9
  ocxl: Add an IOCTL so userspace knows which platform the kernel
    requires
  ocxl: Document new OCXL IOCTLs

 Documentation/accelerators/ocxl.rst   | 10 ++++
 arch/powerpc/include/asm/cputable.h   |  3 +-
 arch/powerpc/include/asm/pnv-ocxl.h   |  2 +-
 arch/powerpc/include/asm/switch_to.h  |  1 -
 arch/powerpc/kernel/dt_cpu_ftrs.c     |  1 +
 arch/powerpc/kernel/process.c         | 99 +----------------------------------
 arch/powerpc/platforms/powernv/ocxl.c |  4 +-
 drivers/misc/ocxl/context.c           |  5 +-
 drivers/misc/ocxl/file.c              | 78 +++++++++++++++++++++++++++
 drivers/misc/ocxl/link.c              | 38 +++++++++++++-
 drivers/misc/ocxl/ocxl_internal.h     |  1 +
 include/misc/ocxl.h                   |  9 ++++
 include/uapi/misc/ocxl.h              | 14 +++++
 13 files changed, 161 insertions(+), 104 deletions(-)

-- 
2.14.3

[PATCH 0/7] ocxl: Implement Power9 as_notify/wait for OpenCAPI

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The Power 9 as_notify/wait feature provides a lower latency way to
signal a thread that work is complete. This series enables the use of
this feature from OpenCAPI adapters, as well as addressing a potential
starvation issue when allocating thread IDs.

Alastair D'Silva (7):
  powerpc: Add TIDR CPU feature for Power9
  powerpc: Use TIDR CPU feature to control TIDR allocation
  powerpc: use task_pid_nr() for TID allocation
  ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action
  ocxl: Expose the thread_id needed for wait on p9
  ocxl: Add an IOCTL so userspace knows which platform the kernel
    requires
  ocxl: Document new OCXL IOCTLs

 Documentation/accelerators/ocxl.rst   | 10 ++++
 arch/powerpc/include/asm/cputable.h   |  3 +-
 arch/powerpc/include/asm/pnv-ocxl.h   |  2 +-
 arch/powerpc/include/asm/switch_to.h  |  1 -
 arch/powerpc/kernel/dt_cpu_ftrs.c     |  1 +
 arch/powerpc/kernel/process.c         | 99 +----------------------------------
 arch/powerpc/platforms/powernv/ocxl.c |  4 +-
 drivers/misc/ocxl/context.c           |  5 +-
 drivers/misc/ocxl/file.c              | 78 +++++++++++++++++++++++++++
 drivers/misc/ocxl/link.c              | 38 +++++++++++++-
 drivers/misc/ocxl/ocxl_internal.h     |  1 +
 include/misc/ocxl.h                   |  9 ++++
 include/uapi/misc/ocxl.h              | 14 +++++
 13 files changed, 161 insertions(+), 104 deletions(-)

-- 
2.14.3

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[PATCH 1/7] powerpc: Add TIDR CPU feature for Power9

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

This patch adds a CPU feature bit to show whether the CPU has
the TIDR register available, enabling as_notify/wait in userspace.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/cputable.h  | 3 ++-
 arch/powerpc/include/asm/switch_to.h | 1 -
 arch/powerpc/kernel/dt_cpu_ftrs.c    | 1 +
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index 4e332f3531c5..54c4cbbe57b4 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -215,6 +215,7 @@ static inline void cpu_feature_keys_init(void) { }
 #define CPU_FTR_P9_TM_HV_ASSIST		LONG_ASM_CONST(0x0000100000000000)
 #define CPU_FTR_P9_TM_XER_SO_BUG	LONG_ASM_CONST(0x0000200000000000)
 #define CPU_FTR_P9_TLBIE_BUG		LONG_ASM_CONST(0x0000400000000000)
+#define CPU_FTR_P9_TIDR			LONG_ASM_CONST(0x0000800000000000)
 
 #ifndef __ASSEMBLY__
 
@@ -462,7 +463,7 @@ static inline void cpu_feature_keys_init(void) { }
 	    CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
 	    CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S | \
 	    CPU_FTR_TM_COMP | CPU_FTR_ARCH_300 | CPU_FTR_PKEY | \
-	    CPU_FTR_P9_TLBIE_BUG)
+	    CPU_FTR_P9_TLBIE_BUG | CPU_FTR_P9_TIDR)
 #define CPU_FTRS_POWER9_DD1 ((CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD1) & \
 			     (~CPU_FTR_SAO))
 #define CPU_FTRS_POWER9_DD2_0 CPU_FTRS_POWER9
diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index be8c9fa23983..5b03d8a82409 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -94,6 +94,5 @@ static inline void clear_task_ebb(struct task_struct *t)
 extern int set_thread_uses_vas(void);
 
 extern int set_thread_tidr(struct task_struct *t);
-extern void clear_thread_tidr(struct task_struct *t);
 
 #endif /* _ASM_POWERPC_SWITCH_TO_H */
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
index 11a3a4fed3fb..10f8b7f55637 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -722,6 +722,7 @@ static __init void cpufeatures_cpu_quirks(void)
 	if ((version & 0xffff0000) == 0x004e0000) {
 		cur_cpu_spec->cpu_features &= ~(CPU_FTR_DAWR);
 		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TLBIE_BUG;
+		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TIDR;
 	}
 }
 
-- 
2.14.3

[PATCH 1/7] powerpc: Add TIDR CPU feature for Power9

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

This patch adds a CPU feature bit to show whether the CPU has
the TIDR register available, enabling as_notify/wait in userspace.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/cputable.h  | 3 ++-
 arch/powerpc/include/asm/switch_to.h | 1 -
 arch/powerpc/kernel/dt_cpu_ftrs.c    | 1 +
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index 4e332f3531c5..54c4cbbe57b4 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -215,6 +215,7 @@ static inline void cpu_feature_keys_init(void) { }
 #define CPU_FTR_P9_TM_HV_ASSIST		LONG_ASM_CONST(0x0000100000000000)
 #define CPU_FTR_P9_TM_XER_SO_BUG	LONG_ASM_CONST(0x0000200000000000)
 #define CPU_FTR_P9_TLBIE_BUG		LONG_ASM_CONST(0x0000400000000000)
+#define CPU_FTR_P9_TIDR			LONG_ASM_CONST(0x0000800000000000)
 
 #ifndef __ASSEMBLY__
 
@@ -462,7 +463,7 @@ static inline void cpu_feature_keys_init(void) { }
 	    CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
 	    CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S | \
 	    CPU_FTR_TM_COMP | CPU_FTR_ARCH_300 | CPU_FTR_PKEY | \
-	    CPU_FTR_P9_TLBIE_BUG)
+	    CPU_FTR_P9_TLBIE_BUG | CPU_FTR_P9_TIDR)
 #define CPU_FTRS_POWER9_DD1 ((CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD1) & \
 			     (~CPU_FTR_SAO))
 #define CPU_FTRS_POWER9_DD2_0 CPU_FTRS_POWER9
diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index be8c9fa23983..5b03d8a82409 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -94,6 +94,5 @@ static inline void clear_task_ebb(struct task_struct *t)
 extern int set_thread_uses_vas(void);
 
 extern int set_thread_tidr(struct task_struct *t);
-extern void clear_thread_tidr(struct task_struct *t);
 
 #endif /* _ASM_POWERPC_SWITCH_TO_H */
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
index 11a3a4fed3fb..10f8b7f55637 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -722,6 +722,7 @@ static __init void cpufeatures_cpu_quirks(void)
 	if ((version & 0xffff0000) == 0x004e0000) {
 		cur_cpu_spec->cpu_features &= ~(CPU_FTR_DAWR);
 		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TLBIE_BUG;
+		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TIDR;
 	}
 }
 
-- 
2.14.3

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Re: [PATCH 1/7] powerpc: Add TIDR CPU feature for Power9

[Andrew Donnellan]

On 17/04/18 12:09, Alastair D'Silva wrote:
> diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
> index be8c9fa23983..5b03d8a82409 100644
> --- a/arch/powerpc/include/asm/switch_to.h
> +++ b/arch/powerpc/include/asm/switch_to.h
> @@ -94,6 +94,5 @@ static inline void clear_task_ebb(struct task_struct *t)
>   extern int set_thread_uses_vas(void);
>   
>   extern int set_thread_tidr(struct task_struct *t);
> -extern void clear_thread_tidr(struct task_struct *t);

This hunk looks like it really belongs in patch 3.

Apart from that, I'm not really familiar with the CPU features code but 
nothing seems overly wrong...

Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

Re: [PATCH 1/7] powerpc: Add TIDR CPU feature for Power9

[Andrew Donnellan]

On 17/04/18 12:09, Alastair D'Silva wrote:
> diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
> index be8c9fa23983..5b03d8a82409 100644
> --- a/arch/powerpc/include/asm/switch_to.h
> +++ b/arch/powerpc/include/asm/switch_to.h
> @@ -94,6 +94,5 @@ static inline void clear_task_ebb(struct task_struct *t)
>   extern int set_thread_uses_vas(void);
>   
>   extern int set_thread_tidr(struct task_struct *t);
> -extern void clear_thread_tidr(struct task_struct *t);

This hunk looks like it really belongs in patch 3.

Apart from that, I'm not really familiar with the CPU features code but 
nothing seems overly wrong...

Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

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[PATCH 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

Switch the use of TIDR on it's CPU feature, rather than assuming it
is available based on architecture.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/kernel/process.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 1237f13fed51..a3e0a3e06d5a 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1570,7 +1570,7 @@ void clear_thread_tidr(struct task_struct *t)
 	if (!t->thread.tidr)
 		return;
 
-	if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
+	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
 		WARN_ON_ONCE(1);
 		return;
 	}
@@ -1593,7 +1593,7 @@ int set_thread_tidr(struct task_struct *t)
 {
 	int rc;
 
-	if (!cpu_has_feature(CPU_FTR_ARCH_300))
+	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
 		return -EINVAL;
 
 	if (t != current)
-- 
2.14.3

[PATCH 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

Switch the use of TIDR on it's CPU feature, rather than assuming it
is available based on architecture.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/kernel/process.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 1237f13fed51..a3e0a3e06d5a 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1570,7 +1570,7 @@ void clear_thread_tidr(struct task_struct *t)
 	if (!t->thread.tidr)
 		return;
 
-	if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
+	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
 		WARN_ON_ONCE(1);
 		return;
 	}
@@ -1593,7 +1593,7 @@ int set_thread_tidr(struct task_struct *t)
 {
 	int rc;
 
-	if (!cpu_has_feature(CPU_FTR_ARCH_300))
+	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
 		return -EINVAL;
 
 	if (t != current)
-- 
2.14.3

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Re: [PATCH 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

[Andrew Donnellan]

On 17/04/18 12:09, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> Switch the use of TIDR on it's CPU feature, rather than assuming it
> is available based on architecture.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>

There's a use of TIDR in restore_sprs() that's behind the ARCH_300 flag 
as well, ideally it should never trigger in the !P9_TIDR case, but you 
might want to update that too for clarity?

> ---
>   arch/powerpc/kernel/process.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 1237f13fed51..a3e0a3e06d5a 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -1570,7 +1570,7 @@ void clear_thread_tidr(struct task_struct *t)
>   	if (!t->thread.tidr)
>   		return;
>   
> -	if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
> +	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
>   		WARN_ON_ONCE(1);
>   		return;
>   	}
> @@ -1593,7 +1593,7 @@ int set_thread_tidr(struct task_struct *t)
>   {
>   	int rc;
>   
> -	if (!cpu_has_feature(CPU_FTR_ARCH_300))
> +	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
>   		return -EINVAL;
>   
>   	if (t != current)
> 

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

Re: [PATCH 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

[Andrew Donnellan]

On 17/04/18 12:09, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> Switch the use of TIDR on it's CPU feature, rather than assuming it
> is available based on architecture.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>

There's a use of TIDR in restore_sprs() that's behind the ARCH_300 flag 
as well, ideally it should never trigger in the !P9_TIDR case, but you 
might want to update that too for clarity?

> ---
>   arch/powerpc/kernel/process.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 1237f13fed51..a3e0a3e06d5a 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -1570,7 +1570,7 @@ void clear_thread_tidr(struct task_struct *t)
>   	if (!t->thread.tidr)
>   		return;
>   
> -	if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
> +	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
>   		WARN_ON_ONCE(1);
>   		return;
>   	}
> @@ -1593,7 +1593,7 @@ int set_thread_tidr(struct task_struct *t)
>   {
>   	int rc;
>   
> -	if (!cpu_has_feature(CPU_FTR_ARCH_300))
> +	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
>   		return -EINVAL;
>   
>   	if (t != current)
> 

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

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Re: [PATCH 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

[Alastair D'Silva]

On Tue, 2018-04-17 at 14:21 +1000, Andrew Donnellan wrote:
> On 17/04/18 12:09, Alastair D'Silva wrote:
> > From: Alastair D'Silva <alastair@d-silva.org>
> > 
> > Switch the use of TIDR on it's CPU feature, rather than assuming it
> > is available based on architecture.
> > 
> > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> 
> There's a use of TIDR in restore_sprs() that's behind the ARCH_300
> flag 
> as well, ideally it should never trigger in the !P9_TIDR case, but
> you 
> might want to update that too for clarity?
> 

Thanks for the review, I'll include your suggestions in the next set.

-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819

Re: [PATCH 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

[Alastair D'Silva]

On Tue, 2018-04-17 at 14:21 +1000, Andrew Donnellan wrote:
> On 17/04/18 12:09, Alastair D'Silva wrote:
> > From: Alastair D'Silva <alastair@d-silva.org>
> > 
> > Switch the use of TIDR on it's CPU feature, rather than assuming it
> > is available based on architecture.
> > 
> > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> 
> There's a use of TIDR in restore_sprs() that's behind the ARCH_300
> flag 
> as well, ideally it should never trigger in the !P9_TIDR case, but
> you 
> might want to update that too for clarity?
> 

Thanks for the review, I'll include your suggestions in the next set.

-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819

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[PATCH 3/7] powerpc: use task_pid_nr() for TID allocation

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The current implementation of TID allocation, using a global IDR, may
result in an errant process starving the system of available TIDs.
Instead, use task_pid_nr(), as mentioned by the original author. The
scenario described which prevented it's use is not applicable, as
set_thread_tidr can only be called after the task struct has been
populated.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/kernel/process.c | 97 +------------------------------------------
 1 file changed, 1 insertion(+), 96 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index a3e0a3e06d5a..56ff7eb5ff79 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1496,103 +1496,12 @@ int set_thread_uses_vas(void)
 }
 
 #ifdef CONFIG_PPC64
-static DEFINE_SPINLOCK(vas_thread_id_lock);
-static DEFINE_IDA(vas_thread_ida);
-
-/*
- * We need to assign a unique thread id to each thread in a process.
- *
- * This thread id, referred to as TIDR, and separate from the Linux's tgid,
- * is intended to be used to direct an ASB_Notify from the hardware to the
- * thread, when a suitable event occurs in the system.
- *
- * One such event is a "paste" instruction in the context of Fast Thread
- * Wakeup (aka Core-to-core wake up in the Virtual Accelerator Switchboard
- * (VAS) in POWER9.
- *
- * To get a unique TIDR per process we could simply reuse task_pid_nr() but
- * the problem is that task_pid_nr() is not yet available copy_thread() is
- * called. Fixing that would require changing more intrusive arch-neutral
- * code in code path in copy_process()?.
- *
- * Further, to assign unique TIDRs within each process, we need an atomic
- * field (or an IDR) in task_struct, which again intrudes into the arch-
- * neutral code. So try to assign globally unique TIDRs for now.
- *
- * NOTE: TIDR 0 indicates that the thread does not need a TIDR value.
- *	 For now, only threads that expect to be notified by the VAS
- *	 hardware need a TIDR value and we assign values > 0 for those.
- */
-#define MAX_THREAD_CONTEXT	((1 << 16) - 1)
-static int assign_thread_tidr(void)
-{
-	int index;
-	int err;
-	unsigned long flags;
-
-again:
-	if (!ida_pre_get(&vas_thread_ida, GFP_KERNEL))
-		return -ENOMEM;
-
-	spin_lock_irqsave(&vas_thread_id_lock, flags);
-	err = ida_get_new_above(&vas_thread_ida, 1, &index);
-	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-
-	if (err == -EAGAIN)
-		goto again;
-	else if (err)
-		return err;
-
-	if (index > MAX_THREAD_CONTEXT) {
-		spin_lock_irqsave(&vas_thread_id_lock, flags);
-		ida_remove(&vas_thread_ida, index);
-		spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-		return -ENOMEM;
-	}
-
-	return index;
-}
-
-static void free_thread_tidr(int id)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&vas_thread_id_lock, flags);
-	ida_remove(&vas_thread_ida, id);
-	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-}
-
-/*
- * Clear any TIDR value assigned to this thread.
- */
-void clear_thread_tidr(struct task_struct *t)
-{
-	if (!t->thread.tidr)
-		return;
-
-	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
-		WARN_ON_ONCE(1);
-		return;
-	}
-
-	mtspr(SPRN_TIDR, 0);
-	free_thread_tidr(t->thread.tidr);
-	t->thread.tidr = 0;
-}
-
-void arch_release_task_struct(struct task_struct *t)
-{
-	clear_thread_tidr(t);
-}
-
 /*
  * Assign a unique TIDR (thread id) for task @t and set it in the thread
  * structure. For now, we only support setting TIDR for 'current' task.
  */
 int set_thread_tidr(struct task_struct *t)
 {
-	int rc;
-
 	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
 		return -EINVAL;
 
@@ -1602,11 +1511,7 @@ int set_thread_tidr(struct task_struct *t)
 	if (t->thread.tidr)
 		return 0;
 
-	rc = assign_thread_tidr();
-	if (rc < 0)
-		return rc;
-
-	t->thread.tidr = rc;
+	t->thread.tidr = (u16)task_pid_nr(t);
 	mtspr(SPRN_TIDR, t->thread.tidr);
 
 	return 0;
-- 
2.14.3

[PATCH 3/7] powerpc: use task_pid_nr() for TID allocation

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The current implementation of TID allocation, using a global IDR, may
result in an errant process starving the system of available TIDs.
Instead, use task_pid_nr(), as mentioned by the original author. The
scenario described which prevented it's use is not applicable, as
set_thread_tidr can only be called after the task struct has been
populated.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/kernel/process.c | 97 +------------------------------------------
 1 file changed, 1 insertion(+), 96 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index a3e0a3e06d5a..56ff7eb5ff79 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1496,103 +1496,12 @@ int set_thread_uses_vas(void)
 }
 
 #ifdef CONFIG_PPC64
-static DEFINE_SPINLOCK(vas_thread_id_lock);
-static DEFINE_IDA(vas_thread_ida);
-
-/*
- * We need to assign a unique thread id to each thread in a process.
- *
- * This thread id, referred to as TIDR, and separate from the Linux's tgid,
- * is intended to be used to direct an ASB_Notify from the hardware to the
- * thread, when a suitable event occurs in the system.
- *
- * One such event is a "paste" instruction in the context of Fast Thread
- * Wakeup (aka Core-to-core wake up in the Virtual Accelerator Switchboard
- * (VAS) in POWER9.
- *
- * To get a unique TIDR per process we could simply reuse task_pid_nr() but
- * the problem is that task_pid_nr() is not yet available copy_thread() is
- * called. Fixing that would require changing more intrusive arch-neutral
- * code in code path in copy_process()?.
- *
- * Further, to assign unique TIDRs within each process, we need an atomic
- * field (or an IDR) in task_struct, which again intrudes into the arch-
- * neutral code. So try to assign globally unique TIDRs for now.
- *
- * NOTE: TIDR 0 indicates that the thread does not need a TIDR value.
- *	 For now, only threads that expect to be notified by the VAS
- *	 hardware need a TIDR value and we assign values > 0 for those.
- */
-#define MAX_THREAD_CONTEXT	((1 << 16) - 1)
-static int assign_thread_tidr(void)
-{
-	int index;
-	int err;
-	unsigned long flags;
-
-again:
-	if (!ida_pre_get(&vas_thread_ida, GFP_KERNEL))
-		return -ENOMEM;
-
-	spin_lock_irqsave(&vas_thread_id_lock, flags);
-	err = ida_get_new_above(&vas_thread_ida, 1, &index);
-	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-
-	if (err == -EAGAIN)
-		goto again;
-	else if (err)
-		return err;
-
-	if (index > MAX_THREAD_CONTEXT) {
-		spin_lock_irqsave(&vas_thread_id_lock, flags);
-		ida_remove(&vas_thread_ida, index);
-		spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-		return -ENOMEM;
-	}
-
-	return index;
-}
-
-static void free_thread_tidr(int id)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&vas_thread_id_lock, flags);
-	ida_remove(&vas_thread_ida, id);
-	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-}
-
-/*
- * Clear any TIDR value assigned to this thread.
- */
-void clear_thread_tidr(struct task_struct *t)
-{
-	if (!t->thread.tidr)
-		return;
-
-	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
-		WARN_ON_ONCE(1);
-		return;
-	}
-
-	mtspr(SPRN_TIDR, 0);
-	free_thread_tidr(t->thread.tidr);
-	t->thread.tidr = 0;
-}
-
-void arch_release_task_struct(struct task_struct *t)
-{
-	clear_thread_tidr(t);
-}
-
 /*
  * Assign a unique TIDR (thread id) for task @t and set it in the thread
  * structure. For now, we only support setting TIDR for 'current' task.
  */
 int set_thread_tidr(struct task_struct *t)
 {
-	int rc;
-
 	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
 		return -EINVAL;
 
@@ -1602,11 +1511,7 @@ int set_thread_tidr(struct task_struct *t)
 	if (t->thread.tidr)
 		return 0;
 
-	rc = assign_thread_tidr();
-	if (rc < 0)
-		return rc;
-
-	t->thread.tidr = rc;
+	t->thread.tidr = (u16)task_pid_nr(t);
 	mtspr(SPRN_TIDR, t->thread.tidr);
 
 	return 0;
-- 
2.14.3

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[PATCH 4/7] ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The function removes the process element from NPU cache.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/pnv-ocxl.h   | 2 +-
 arch/powerpc/platforms/powernv/ocxl.c | 4 ++--
 drivers/misc/ocxl/link.c              | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/pnv-ocxl.h b/arch/powerpc/include/asm/pnv-ocxl.h
index f6945d3bc971..208b5503f4ed 100644
--- a/arch/powerpc/include/asm/pnv-ocxl.h
+++ b/arch/powerpc/include/asm/pnv-ocxl.h
@@ -28,7 +28,7 @@ extern int pnv_ocxl_map_xsl_regs(struct pci_dev *dev, void __iomem **dsisr,
 extern int pnv_ocxl_spa_setup(struct pci_dev *dev, void *spa_mem, int PE_mask,
 			void **platform_data);
 extern void pnv_ocxl_spa_release(void *platform_data);
-extern int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle);
+extern int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle);
 
 extern int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr);
 extern void pnv_ocxl_free_xive_irq(u32 irq);
diff --git a/arch/powerpc/platforms/powernv/ocxl.c b/arch/powerpc/platforms/powernv/ocxl.c
index fa9b53af3c7b..8c65aacda9c8 100644
--- a/arch/powerpc/platforms/powernv/ocxl.c
+++ b/arch/powerpc/platforms/powernv/ocxl.c
@@ -475,7 +475,7 @@ void pnv_ocxl_spa_release(void *platform_data)
 }
 EXPORT_SYMBOL_GPL(pnv_ocxl_spa_release);
 
-int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
+int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle)
 {
 	struct spa_data *data = (struct spa_data *) platform_data;
 	int rc;
@@ -483,7 +483,7 @@ int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
 	rc = opal_npu_spa_clear_cache(data->phb_opal_id, data->bdfn, pe_handle);
 	return rc;
 }
-EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe);
+EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe_from_cache);
 
 int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr)
 {
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index f30790582dc0..656e8610eec2 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -599,7 +599,7 @@ int ocxl_link_remove_pe(void *link_handle, int pasid)
 	 * On powerpc, the entry needs to be cleared from the context
 	 * cache of the NPU.
 	 */
-	rc = pnv_ocxl_spa_remove_pe(link->platform_data, pe_handle);
+	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
 	WARN_ON(rc);
 
 	pe_data = radix_tree_delete(&spa->pe_tree, pe_handle);
-- 
2.14.3

[PATCH 4/7] ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The function removes the process element from NPU cache.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/pnv-ocxl.h   | 2 +-
 arch/powerpc/platforms/powernv/ocxl.c | 4 ++--
 drivers/misc/ocxl/link.c              | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/pnv-ocxl.h b/arch/powerpc/include/asm/pnv-ocxl.h
index f6945d3bc971..208b5503f4ed 100644
--- a/arch/powerpc/include/asm/pnv-ocxl.h
+++ b/arch/powerpc/include/asm/pnv-ocxl.h
@@ -28,7 +28,7 @@ extern int pnv_ocxl_map_xsl_regs(struct pci_dev *dev, void __iomem **dsisr,
 extern int pnv_ocxl_spa_setup(struct pci_dev *dev, void *spa_mem, int PE_mask,
 			void **platform_data);
 extern void pnv_ocxl_spa_release(void *platform_data);
-extern int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle);
+extern int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle);
 
 extern int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr);
 extern void pnv_ocxl_free_xive_irq(u32 irq);
diff --git a/arch/powerpc/platforms/powernv/ocxl.c b/arch/powerpc/platforms/powernv/ocxl.c
index fa9b53af3c7b..8c65aacda9c8 100644
--- a/arch/powerpc/platforms/powernv/ocxl.c
+++ b/arch/powerpc/platforms/powernv/ocxl.c
@@ -475,7 +475,7 @@ void pnv_ocxl_spa_release(void *platform_data)
 }
 EXPORT_SYMBOL_GPL(pnv_ocxl_spa_release);
 
-int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
+int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle)
 {
 	struct spa_data *data = (struct spa_data *) platform_data;
 	int rc;
@@ -483,7 +483,7 @@ int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
 	rc = opal_npu_spa_clear_cache(data->phb_opal_id, data->bdfn, pe_handle);
 	return rc;
 }
-EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe);
+EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe_from_cache);
 
 int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr)
 {
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index f30790582dc0..656e8610eec2 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -599,7 +599,7 @@ int ocxl_link_remove_pe(void *link_handle, int pasid)
 	 * On powerpc, the entry needs to be cleared from the context
 	 * cache of the NPU.
 	 */
-	rc = pnv_ocxl_spa_remove_pe(link->platform_data, pe_handle);
+	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
 	WARN_ON(rc);
 
 	pe_data = radix_tree_delete(&spa->pe_tree, pe_handle);
-- 
2.14.3

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Re: [PATCH 4/7] ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action

[Andrew Donnellan]

On 17/04/18 12:09, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> The function removes the process element from NPU cache.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>


Hmm, personally I'd suggest pnv_ocxl_spa_clear_cache() because it's just 
a wrapper around the OPAL call of a similar name.

But I don't feel strongly about this at all, so:

Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>


-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

Re: [PATCH 4/7] ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action

[Andrew Donnellan]

On 17/04/18 12:09, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> The function removes the process element from NPU cache.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>


Hmm, personally I'd suggest pnv_ocxl_spa_clear_cache() because it's just 
a wrapper around the OPAL call of a similar name.

But I don't feel strongly about this at all, so:

Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>


-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

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[PATCH 5/7] ocxl: Expose the thread_id needed for wait on p9

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

In order to successfully issue as_notify, an AFU needs to know the TID
to notify, which in turn means that this information should be
available in userspace so it can be communicated to the AFU.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/misc/ocxl/context.c       |  5 +++-
 drivers/misc/ocxl/file.c          | 53 +++++++++++++++++++++++++++++++++++++++
 drivers/misc/ocxl/link.c          | 36 ++++++++++++++++++++++++++
 drivers/misc/ocxl/ocxl_internal.h |  1 +
 include/misc/ocxl.h               |  9 +++++++
 include/uapi/misc/ocxl.h          | 10 ++++++++
 6 files changed, 113 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
index 909e8807824a..95f74623113e 100644
--- a/drivers/misc/ocxl/context.c
+++ b/drivers/misc/ocxl/context.c
@@ -34,6 +34,8 @@ int ocxl_context_init(struct ocxl_context *ctx, struct ocxl_afu *afu,
 	mutex_init(&ctx->xsl_error_lock);
 	mutex_init(&ctx->irq_lock);
 	idr_init(&ctx->irq_idr);
+	ctx->tidr = 0;
+
 	/*
 	 * Keep a reference on the AFU to make sure it's valid for the
 	 * duration of the life of the context
@@ -65,6 +67,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 {
 	int rc;
 
+	// Locks both status & tidr
 	mutex_lock(&ctx->status_mutex);
 	if (ctx->status != OPENED) {
 		rc = -EIO;
@@ -72,7 +75,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 	}
 
 	rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid,
-			current->mm->context.id, 0, amr, current->mm,
+			current->mm->context.id, ctx->tidr, amr, current->mm,
 			xsl_fault_error, ctx);
 	if (rc)
 		goto out;
diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index 038509e5d031..eb409a469f21 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -5,6 +5,8 @@
 #include <linux/sched/signal.h>
 #include <linux/uaccess.h>
 #include <uapi/misc/ocxl.h>
+#include <asm/reg.h>
+#include <asm/switch_to.h>
 #include "ocxl_internal.h"
 
 
@@ -123,11 +125,55 @@ static long afu_ioctl_get_metadata(struct ocxl_context *ctx,
 	return 0;
 }
 
+#ifdef CONFIG_PPC64
+static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
+		struct ocxl_ioctl_p9_wait __user *uarg)
+{
+	struct ocxl_ioctl_p9_wait arg;
+
+	memset(&arg, 0, sizeof(arg));
+
+	if (cpu_has_feature(CPU_FTR_P9_TIDR)) {
+		enum ocxl_context_status status;
+
+		// Locks both status & tidr
+		mutex_lock(&ctx->status_mutex);
+		if (!ctx->tidr) {
+			if (set_thread_tidr(current))
+				return -ENOENT;
+
+			ctx->tidr = current->thread.tidr;
+		}
+
+		status = ctx->status;
+		mutex_unlock(&ctx->status_mutex);
+
+		if (status == ATTACHED) {
+			int rc;
+			struct link *link = ctx->afu->fn->link;
+
+			rc = ocxl_link_update_pe(link, ctx->pasid, ctx->tidr);
+			if (rc)
+				return rc;
+		}
+
+		arg.thread_id = ctx->tidr;
+	} else
+		return -ENOENT;
+
+	if (copy_to_user(uarg, &arg, sizeof(arg)))
+		return -EFAULT;
+
+	return 0;
+}
+#endif
+
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
 			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
 			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
 			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
 			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
+			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
 			"UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -186,6 +232,13 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 				(struct ocxl_ioctl_metadata __user *) args);
 		break;
 
+#ifdef CONFIG_PPC64
+	case OCXL_IOCTL_ENABLE_P9_WAIT:
+		rc = afu_ioctl_enable_p9_wait(ctx,
+				(struct ocxl_ioctl_p9_wait __user *) args);
+		break;
+#endif
+
 	default:
 		rc = -EINVAL;
 	}
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index 656e8610eec2..88876ae8f330 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -544,6 +544,42 @@ int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
 }
 EXPORT_SYMBOL_GPL(ocxl_link_add_pe);
 
+int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid)
+{
+	struct link *link = (struct link *) link_handle;
+	struct spa *spa = link->spa;
+	struct ocxl_process_element *pe;
+	int pe_handle, rc;
+
+	if (pasid > SPA_PASID_MAX)
+		return -EINVAL;
+
+	pe_handle = pasid & SPA_PE_MASK;
+	pe = spa->spa_mem + pe_handle;
+
+	mutex_lock(&spa->spa_lock);
+
+	pe->tid = tid;
+
+	/*
+	 * The barrier makes sure the PE is updated
+	 * before we clear the NPU context cache below, so that the
+	 * old PE cannot be reloaded erroneously.
+	 */
+	mb();
+
+	/*
+	 * hook to platform code
+	 * On powerpc, the entry needs to be cleared from the context
+	 * cache of the NPU.
+	 */
+	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
+	WARN_ON(rc);
+
+	mutex_unlock(&spa->spa_lock);
+	return rc;
+}
+
 int ocxl_link_remove_pe(void *link_handle, int pasid)
 {
 	struct link *link = (struct link *) link_handle;
diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
index 5d421824afd9..6c6d4e61888e 100644
--- a/drivers/misc/ocxl/ocxl_internal.h
+++ b/drivers/misc/ocxl/ocxl_internal.h
@@ -77,6 +77,7 @@ struct ocxl_context {
 	struct ocxl_xsl_error xsl_error;
 	struct mutex irq_lock;
 	struct idr irq_idr;
+	__u16 tidr; // Thread ID used for P9 wait implementation
 };
 
 struct ocxl_process_element {
diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
index 51ccf76db293..9ff6ddc28e22 100644
--- a/include/misc/ocxl.h
+++ b/include/misc/ocxl.h
@@ -188,6 +188,15 @@ extern int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
 		void (*xsl_err_cb)(void *data, u64 addr, u64 dsisr),
 		void *xsl_err_data);
 
+/**
+ * Update values within a Process Element
+ *
+ * link_handle: the link handle associated with the process element
+ * pasid: the PASID for the AFU context
+ * tid: the new thread id for the process element
+ */
+extern int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid);
+
 /*
  * Remove a Process Element from the Shared Process Area for a link
  */
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 0af83d80fb3e..8d2748e69c84 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -48,6 +48,15 @@ struct ocxl_ioctl_metadata {
 	__u64 reserved[13]; // Total of 16*u64
 };
 
+struct ocxl_ioctl_p9_wait {
+	__u16 thread_id; // The thread ID required to wake this thread
+	__u16 reserved1;
+	__u32 reserved2;
+	__u64 reserved3[3];
+};
+
+};
+
 struct ocxl_ioctl_irq_fd {
 	__u64 irq_offset;
 	__s32 eventfd;
@@ -62,5 +71,6 @@ struct ocxl_ioctl_irq_fd {
 #define OCXL_IOCTL_IRQ_FREE	_IOW(OCXL_MAGIC, 0x12, __u64)
 #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
+#define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.3

[PATCH 5/7] ocxl: Expose the thread_id needed for wait on p9

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

In order to successfully issue as_notify, an AFU needs to know the TID
to notify, which in turn means that this information should be
available in userspace so it can be communicated to the AFU.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/misc/ocxl/context.c       |  5 +++-
 drivers/misc/ocxl/file.c          | 53 +++++++++++++++++++++++++++++++++++++++
 drivers/misc/ocxl/link.c          | 36 ++++++++++++++++++++++++++
 drivers/misc/ocxl/ocxl_internal.h |  1 +
 include/misc/ocxl.h               |  9 +++++++
 include/uapi/misc/ocxl.h          | 10 ++++++++
 6 files changed, 113 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
index 909e8807824a..95f74623113e 100644
--- a/drivers/misc/ocxl/context.c
+++ b/drivers/misc/ocxl/context.c
@@ -34,6 +34,8 @@ int ocxl_context_init(struct ocxl_context *ctx, struct ocxl_afu *afu,
 	mutex_init(&ctx->xsl_error_lock);
 	mutex_init(&ctx->irq_lock);
 	idr_init(&ctx->irq_idr);
+	ctx->tidr = 0;
+
 	/*
 	 * Keep a reference on the AFU to make sure it's valid for the
 	 * duration of the life of the context
@@ -65,6 +67,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 {
 	int rc;
 
+	// Locks both status & tidr
 	mutex_lock(&ctx->status_mutex);
 	if (ctx->status != OPENED) {
 		rc = -EIO;
@@ -72,7 +75,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 	}
 
 	rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid,
-			current->mm->context.id, 0, amr, current->mm,
+			current->mm->context.id, ctx->tidr, amr, current->mm,
 			xsl_fault_error, ctx);
 	if (rc)
 		goto out;
diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index 038509e5d031..eb409a469f21 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -5,6 +5,8 @@
 #include <linux/sched/signal.h>
 #include <linux/uaccess.h>
 #include <uapi/misc/ocxl.h>
+#include <asm/reg.h>
+#include <asm/switch_to.h>
 #include "ocxl_internal.h"
 
 
@@ -123,11 +125,55 @@ static long afu_ioctl_get_metadata(struct ocxl_context *ctx,
 	return 0;
 }
 
+#ifdef CONFIG_PPC64
+static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
+		struct ocxl_ioctl_p9_wait __user *uarg)
+{
+	struct ocxl_ioctl_p9_wait arg;
+
+	memset(&arg, 0, sizeof(arg));
+
+	if (cpu_has_feature(CPU_FTR_P9_TIDR)) {
+		enum ocxl_context_status status;
+
+		// Locks both status & tidr
+		mutex_lock(&ctx->status_mutex);
+		if (!ctx->tidr) {
+			if (set_thread_tidr(current))
+				return -ENOENT;
+
+			ctx->tidr = current->thread.tidr;
+		}
+
+		status = ctx->status;
+		mutex_unlock(&ctx->status_mutex);
+
+		if (status == ATTACHED) {
+			int rc;
+			struct link *link = ctx->afu->fn->link;
+
+			rc = ocxl_link_update_pe(link, ctx->pasid, ctx->tidr);
+			if (rc)
+				return rc;
+		}
+
+		arg.thread_id = ctx->tidr;
+	} else
+		return -ENOENT;
+
+	if (copy_to_user(uarg, &arg, sizeof(arg)))
+		return -EFAULT;
+
+	return 0;
+}
+#endif
+
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
 			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
 			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
 			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
 			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
+			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
 			"UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -186,6 +232,13 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 				(struct ocxl_ioctl_metadata __user *) args);
 		break;
 
+#ifdef CONFIG_PPC64
+	case OCXL_IOCTL_ENABLE_P9_WAIT:
+		rc = afu_ioctl_enable_p9_wait(ctx,
+				(struct ocxl_ioctl_p9_wait __user *) args);
+		break;
+#endif
+
 	default:
 		rc = -EINVAL;
 	}
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index 656e8610eec2..88876ae8f330 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -544,6 +544,42 @@ int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
 }
 EXPORT_SYMBOL_GPL(ocxl_link_add_pe);
 
+int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid)
+{
+	struct link *link = (struct link *) link_handle;
+	struct spa *spa = link->spa;
+	struct ocxl_process_element *pe;
+	int pe_handle, rc;
+
+	if (pasid > SPA_PASID_MAX)
+		return -EINVAL;
+
+	pe_handle = pasid & SPA_PE_MASK;
+	pe = spa->spa_mem + pe_handle;
+
+	mutex_lock(&spa->spa_lock);
+
+	pe->tid = tid;
+
+	/*
+	 * The barrier makes sure the PE is updated
+	 * before we clear the NPU context cache below, so that the
+	 * old PE cannot be reloaded erroneously.
+	 */
+	mb();
+
+	/*
+	 * hook to platform code
+	 * On powerpc, the entry needs to be cleared from the context
+	 * cache of the NPU.
+	 */
+	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
+	WARN_ON(rc);
+
+	mutex_unlock(&spa->spa_lock);
+	return rc;
+}
+
 int ocxl_link_remove_pe(void *link_handle, int pasid)
 {
 	struct link *link = (struct link *) link_handle;
diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
index 5d421824afd9..6c6d4e61888e 100644
--- a/drivers/misc/ocxl/ocxl_internal.h
+++ b/drivers/misc/ocxl/ocxl_internal.h
@@ -77,6 +77,7 @@ struct ocxl_context {
 	struct ocxl_xsl_error xsl_error;
 	struct mutex irq_lock;
 	struct idr irq_idr;
+	__u16 tidr; // Thread ID used for P9 wait implementation
 };
 
 struct ocxl_process_element {
diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
index 51ccf76db293..9ff6ddc28e22 100644
--- a/include/misc/ocxl.h
+++ b/include/misc/ocxl.h
@@ -188,6 +188,15 @@ extern int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
 		void (*xsl_err_cb)(void *data, u64 addr, u64 dsisr),
 		void *xsl_err_data);
 
+/**
+ * Update values within a Process Element
+ *
+ * link_handle: the link handle associated with the process element
+ * pasid: the PASID for the AFU context
+ * tid: the new thread id for the process element
+ */
+extern int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid);
+
 /*
  * Remove a Process Element from the Shared Process Area for a link
  */
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 0af83d80fb3e..8d2748e69c84 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -48,6 +48,15 @@ struct ocxl_ioctl_metadata {
 	__u64 reserved[13]; // Total of 16*u64
 };
 
+struct ocxl_ioctl_p9_wait {
+	__u16 thread_id; // The thread ID required to wake this thread
+	__u16 reserved1;
+	__u32 reserved2;
+	__u64 reserved3[3];
+};
+
+};
+
 struct ocxl_ioctl_irq_fd {
 	__u64 irq_offset;
 	__s32 eventfd;
@@ -62,5 +71,6 @@ struct ocxl_ioctl_irq_fd {
 #define OCXL_IOCTL_IRQ_FREE	_IOW(OCXL_MAGIC, 0x12, __u64)
 #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
+#define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.3

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[PATCH 6/7] ocxl: Add an IOCTL so userspace knows which platform the kernel requires

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

In order for a userspace AFU driver to call the Power9 specific
OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
make that call.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/misc/ocxl/file.c | 25 +++++++++++++++++++++++++
 include/uapi/misc/ocxl.h |  4 ++++
 2 files changed, 29 insertions(+)

diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index eb409a469f21..5a9f4f85aafd 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -168,12 +168,32 @@ static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
 }
 #endif
 
+
+static long afu_ioctl_get_platform(struct ocxl_context *ctx,
+		struct ocxl_ioctl_platform __user *uarg)
+{
+	struct ocxl_ioctl_platform arg;
+
+	memset(&arg, 0, sizeof(arg));
+
+#ifdef CONFIG_PPC64
+	if (cpu_has_feature(CPU_FTR_P9_TIDR))
+		arg.flags[0] |= OCXL_IOCTL_PLATFORM_FLAGS0_P9_WAIT;
+#endif
+
+	if (copy_to_user(uarg, &arg, sizeof(arg)))
+		return -EFAULT;
+
+	return 0;
+}
+
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
 			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
 			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
 			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
 			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
 			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
+			x == OCXL_IOCTL_GET_PLATFORM ? "GET_PLATFORM" :	\
 			"UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -239,6 +259,11 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 		break;
 #endif
 
+	case OCXL_IOCTL_GET_PLATFORM:
+		rc = afu_ioctl_get_platform(ctx,
+				(struct ocxl_ioctl_platform __user *) args);
+		break;
+
 	default:
 		rc = -EINVAL;
 	}
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 8d2748e69c84..7bdd3efcf294 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -55,6 +55,9 @@ struct ocxl_ioctl_p9_wait {
 	__u64 reserved3[3];
 };
 
+#define OCXL_IOCTL_PLATFORM_FLAGS0_P9_WAIT	0x01
+struct ocxl_ioctl_platform {
+	__u64 flags[4];
 };
 
 struct ocxl_ioctl_irq_fd {
@@ -72,5 +75,6 @@ struct ocxl_ioctl_irq_fd {
 #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
 #define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
+#define OCXL_IOCTL_GET_PLATFORM _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_platform)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.3

[PATCH 6/7] ocxl: Add an IOCTL so userspace knows which platform the kernel requires

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

In order for a userspace AFU driver to call the Power9 specific
OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
make that call.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/misc/ocxl/file.c | 25 +++++++++++++++++++++++++
 include/uapi/misc/ocxl.h |  4 ++++
 2 files changed, 29 insertions(+)

diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index eb409a469f21..5a9f4f85aafd 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -168,12 +168,32 @@ static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
 }
 #endif
 
+
+static long afu_ioctl_get_platform(struct ocxl_context *ctx,
+		struct ocxl_ioctl_platform __user *uarg)
+{
+	struct ocxl_ioctl_platform arg;
+
+	memset(&arg, 0, sizeof(arg));
+
+#ifdef CONFIG_PPC64
+	if (cpu_has_feature(CPU_FTR_P9_TIDR))
+		arg.flags[0] |= OCXL_IOCTL_PLATFORM_FLAGS0_P9_WAIT;
+#endif
+
+	if (copy_to_user(uarg, &arg, sizeof(arg)))
+		return -EFAULT;
+
+	return 0;
+}
+
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
 			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
 			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
 			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
 			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
 			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
+			x == OCXL_IOCTL_GET_PLATFORM ? "GET_PLATFORM" :	\
 			"UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -239,6 +259,11 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 		break;
 #endif
 
+	case OCXL_IOCTL_GET_PLATFORM:
+		rc = afu_ioctl_get_platform(ctx,
+				(struct ocxl_ioctl_platform __user *) args);
+		break;
+
 	default:
 		rc = -EINVAL;
 	}
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 8d2748e69c84..7bdd3efcf294 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -55,6 +55,9 @@ struct ocxl_ioctl_p9_wait {
 	__u64 reserved3[3];
 };
 
+#define OCXL_IOCTL_PLATFORM_FLAGS0_P9_WAIT	0x01
+struct ocxl_ioctl_platform {
+	__u64 flags[4];
 };
 
 struct ocxl_ioctl_irq_fd {
@@ -72,5 +75,6 @@ struct ocxl_ioctl_irq_fd {
 #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
 #define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
+#define OCXL_IOCTL_GET_PLATFORM _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_platform)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.3

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[PATCH 7/7] ocxl: Document new OCXL IOCTLs

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 Documentation/accelerators/ocxl.rst | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
index ddcc58d01cfb..144595a80a1c 100644
--- a/Documentation/accelerators/ocxl.rst
+++ b/Documentation/accelerators/ocxl.rst
@@ -157,6 +157,16 @@ OCXL_IOCTL_GET_METADATA:
   Obtains configuration information from the card, such at the size of
   MMIO areas, the AFU version, and the PASID for the current context.
 
+OCXL_IOCTL_ENABLE_P9_WAIT:
+
+  Allows the AFU to wake a userspace thread executing 'wait'. Returns
+  information to userspace to allow it to configure the AFU.
+
+OCXL_IOCTL_GET_PLATFORM:
+
+  Notifies userspace as to the platform the kernel believes we are on,
+  which may differ from what userspace believes. Also reports on which CPU
+  features which are usable from userspace.
 
 mmap
 ----
-- 
2.14.3

[PATCH 7/7] ocxl: Document new OCXL IOCTLs

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 Documentation/accelerators/ocxl.rst | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
index ddcc58d01cfb..144595a80a1c 100644
--- a/Documentation/accelerators/ocxl.rst
+++ b/Documentation/accelerators/ocxl.rst
@@ -157,6 +157,16 @@ OCXL_IOCTL_GET_METADATA:
   Obtains configuration information from the card, such at the size of
   MMIO areas, the AFU version, and the PASID for the current context.
 
+OCXL_IOCTL_ENABLE_P9_WAIT:
+
+  Allows the AFU to wake a userspace thread executing 'wait'. Returns
+  information to userspace to allow it to configure the AFU.
+
+OCXL_IOCTL_GET_PLATFORM:
+
+  Notifies userspace as to the platform the kernel believes we are on,
+  which may differ from what userspace believes. Also reports on which CPU
+  features which are usable from userspace.
 
 mmap
 ----
-- 
2.14.3

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Re: [PATCH 7/7] ocxl: Document new OCXL IOCTLs

[Andrew Donnellan]

On 17/04/18 12:09, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---
>   Documentation/accelerators/ocxl.rst | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
> index ddcc58d01cfb..144595a80a1c 100644
> --- a/Documentation/accelerators/ocxl.rst
> +++ b/Documentation/accelerators/ocxl.rst
> @@ -157,6 +157,16 @@ OCXL_IOCTL_GET_METADATA:
>     Obtains configuration information from the card, such at the size of
>     MMIO areas, the AFU version, and the PASID for the current context.
>   
> +OCXL_IOCTL_ENABLE_P9_WAIT:
> +
> +  Allows the AFU to wake a userspace thread executing 'wait'. Returns
> +  information to userspace to allow it to configure the AFU.

Note that this is only available on POWER9.

> +
> +OCXL_IOCTL_GET_PLATFORM:
> +
> +  Notifies userspace as to the platform the kernel believes we are on,
> +  which may differ from what userspace believes. Also reports on which CPU
> +  features which are usable from userspace.

The first sentence here doesn't seem to relate to anything that 
GET_PLATFORM actually does - afaict you're just passing flags which I 
suppose imply what the correct platform is, but really they're just 
feature flags?

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

Re: [PATCH 7/7] ocxl: Document new OCXL IOCTLs

[Andrew Donnellan]

On 17/04/18 12:09, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---
>   Documentation/accelerators/ocxl.rst | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
> index ddcc58d01cfb..144595a80a1c 100644
> --- a/Documentation/accelerators/ocxl.rst
> +++ b/Documentation/accelerators/ocxl.rst
> @@ -157,6 +157,16 @@ OCXL_IOCTL_GET_METADATA:
>     Obtains configuration information from the card, such at the size of
>     MMIO areas, the AFU version, and the PASID for the current context.
>   
> +OCXL_IOCTL_ENABLE_P9_WAIT:
> +
> +  Allows the AFU to wake a userspace thread executing 'wait'. Returns
> +  information to userspace to allow it to configure the AFU.

Note that this is only available on POWER9.

> +
> +OCXL_IOCTL_GET_PLATFORM:
> +
> +  Notifies userspace as to the platform the kernel believes we are on,
> +  which may differ from what userspace believes. Also reports on which CPU
> +  features which are usable from userspace.

The first sentence here doesn't seem to relate to anything that 
GET_PLATFORM actually does - afaict you're just passing flags which I 
suppose imply what the correct platform is, but really they're just 
feature flags?

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

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[PATCH v2 0/7] ocxl: Implement Power9 as_notify/wait for OpenCAPI

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The Power 9 as_notify/wait feature provides a lower latency way to
signal a thread that work is complete. This series enables the use of
this feature from OpenCAPI adapters, as well as addressing a potential
starvation issue when allocating thread IDs.

Changelog:
v2:
  Rename get_platform IOCTL to get_features
  Move stray edit from patch 1 to patch 3

Alastair D'Silva (7):
  powerpc: Add TIDR CPU feature for Power9
  powerpc: Use TIDR CPU feature to control TIDR allocation
  powerpc: use task_pid_nr() for TID allocation
  ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action
  ocxl: Expose the thread_id needed for wait on p9
  ocxl: Add an IOCTL so userspace knows what CPU features are available
  ocxl: Document new OCXL IOCTLs

 Documentation/accelerators/ocxl.rst   |  10 ++++
 arch/powerpc/include/asm/cputable.h   |   3 +-
 arch/powerpc/include/asm/pnv-ocxl.h   |   2 +-
 arch/powerpc/include/asm/switch_to.h  |   1 -
 arch/powerpc/kernel/dt_cpu_ftrs.c     |   1 +
 arch/powerpc/kernel/process.c         | 101 +---------------------------------
 arch/powerpc/platforms/powernv/ocxl.c |   4 +-
 drivers/misc/ocxl/context.c           |   5 +-
 drivers/misc/ocxl/file.c              |  78 ++++++++++++++++++++++++++
 drivers/misc/ocxl/link.c              |  38 ++++++++++++-
 drivers/misc/ocxl/ocxl_internal.h     |   1 +
 include/misc/ocxl.h                   |   9 +++
 include/uapi/misc/ocxl.h              |  14 +++++
 13 files changed, 162 insertions(+), 105 deletions(-)

-- 
2.14.3

[PATCH v2 0/7] ocxl: Implement Power9 as_notify/wait for OpenCAPI

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The Power 9 as_notify/wait feature provides a lower latency way to
signal a thread that work is complete. This series enables the use of
this feature from OpenCAPI adapters, as well as addressing a potential
starvation issue when allocating thread IDs.

Changelog:
v2:
  Rename get_platform IOCTL to get_features
  Move stray edit from patch 1 to patch 3

Alastair D'Silva (7):
  powerpc: Add TIDR CPU feature for Power9
  powerpc: Use TIDR CPU feature to control TIDR allocation
  powerpc: use task_pid_nr() for TID allocation
  ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action
  ocxl: Expose the thread_id needed for wait on p9
  ocxl: Add an IOCTL so userspace knows what CPU features are available
  ocxl: Document new OCXL IOCTLs

 Documentation/accelerators/ocxl.rst   |  10 ++++
 arch/powerpc/include/asm/cputable.h   |   3 +-
 arch/powerpc/include/asm/pnv-ocxl.h   |   2 +-
 arch/powerpc/include/asm/switch_to.h  |   1 -
 arch/powerpc/kernel/dt_cpu_ftrs.c     |   1 +
 arch/powerpc/kernel/process.c         | 101 +---------------------------------
 arch/powerpc/platforms/powernv/ocxl.c |   4 +-
 drivers/misc/ocxl/context.c           |   5 +-
 drivers/misc/ocxl/file.c              |  78 ++++++++++++++++++++++++++
 drivers/misc/ocxl/link.c              |  38 ++++++++++++-
 drivers/misc/ocxl/ocxl_internal.h     |   1 +
 include/misc/ocxl.h                   |   9 +++
 include/uapi/misc/ocxl.h              |  14 +++++
 13 files changed, 162 insertions(+), 105 deletions(-)

-- 
2.14.3

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[PATCH v2 1/7] powerpc: Add TIDR CPU feature for Power9

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

This patch adds a CPU feature bit to show whether the CPU has
the TIDR register available, enabling as_notify/wait in userspace.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/cputable.h | 3 ++-
 arch/powerpc/kernel/dt_cpu_ftrs.c   | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index 4e332f3531c5..54c4cbbe57b4 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -215,6 +215,7 @@ static inline void cpu_feature_keys_init(void) { }
 #define CPU_FTR_P9_TM_HV_ASSIST		LONG_ASM_CONST(0x0000100000000000)
 #define CPU_FTR_P9_TM_XER_SO_BUG	LONG_ASM_CONST(0x0000200000000000)
 #define CPU_FTR_P9_TLBIE_BUG		LONG_ASM_CONST(0x0000400000000000)
+#define CPU_FTR_P9_TIDR			LONG_ASM_CONST(0x0000800000000000)
 
 #ifndef __ASSEMBLY__
 
@@ -462,7 +463,7 @@ static inline void cpu_feature_keys_init(void) { }
 	    CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
 	    CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S | \
 	    CPU_FTR_TM_COMP | CPU_FTR_ARCH_300 | CPU_FTR_PKEY | \
-	    CPU_FTR_P9_TLBIE_BUG)
+	    CPU_FTR_P9_TLBIE_BUG | CPU_FTR_P9_TIDR)
 #define CPU_FTRS_POWER9_DD1 ((CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD1) & \
 			     (~CPU_FTR_SAO))
 #define CPU_FTRS_POWER9_DD2_0 CPU_FTRS_POWER9
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
index 11a3a4fed3fb..10f8b7f55637 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -722,6 +722,7 @@ static __init void cpufeatures_cpu_quirks(void)
 	if ((version & 0xffff0000) == 0x004e0000) {
 		cur_cpu_spec->cpu_features &= ~(CPU_FTR_DAWR);
 		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TLBIE_BUG;
+		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TIDR;
 	}
 }
 
-- 
2.14.3

[PATCH v2 1/7] powerpc: Add TIDR CPU feature for Power9

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

This patch adds a CPU feature bit to show whether the CPU has
the TIDR register available, enabling as_notify/wait in userspace.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/cputable.h | 3 ++-
 arch/powerpc/kernel/dt_cpu_ftrs.c   | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index 4e332f3531c5..54c4cbbe57b4 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -215,6 +215,7 @@ static inline void cpu_feature_keys_init(void) { }
 #define CPU_FTR_P9_TM_HV_ASSIST		LONG_ASM_CONST(0x0000100000000000)
 #define CPU_FTR_P9_TM_XER_SO_BUG	LONG_ASM_CONST(0x0000200000000000)
 #define CPU_FTR_P9_TLBIE_BUG		LONG_ASM_CONST(0x0000400000000000)
+#define CPU_FTR_P9_TIDR			LONG_ASM_CONST(0x0000800000000000)
 
 #ifndef __ASSEMBLY__
 
@@ -462,7 +463,7 @@ static inline void cpu_feature_keys_init(void) { }
 	    CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
 	    CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S | \
 	    CPU_FTR_TM_COMP | CPU_FTR_ARCH_300 | CPU_FTR_PKEY | \
-	    CPU_FTR_P9_TLBIE_BUG)
+	    CPU_FTR_P9_TLBIE_BUG | CPU_FTR_P9_TIDR)
 #define CPU_FTRS_POWER9_DD1 ((CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD1) & \
 			     (~CPU_FTR_SAO))
 #define CPU_FTRS_POWER9_DD2_0 CPU_FTRS_POWER9
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
index 11a3a4fed3fb..10f8b7f55637 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -722,6 +722,7 @@ static __init void cpufeatures_cpu_quirks(void)
 	if ((version & 0xffff0000) == 0x004e0000) {
 		cur_cpu_spec->cpu_features &= ~(CPU_FTR_DAWR);
 		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TLBIE_BUG;
+		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TIDR;
 	}
 }
 
-- 
2.14.3

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Re: [PATCH v2 1/7] powerpc: Add TIDR CPU feature for Power9

[Andrew Donnellan]

On 18/04/18 11:08, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> This patch adds a CPU feature bit to show whether the CPU has
> the TIDR register available, enabling as_notify/wait in userspace.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>

Per my previous email:

Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>


-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

Re: [PATCH v2 1/7] powerpc: Add TIDR CPU feature for Power9

[Andrew Donnellan]

On 18/04/18 11:08, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> This patch adds a CPU feature bit to show whether the CPU has
> the TIDR register available, enabling as_notify/wait in userspace.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>

Per my previous email:

Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>


-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

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Re: [PATCH v2 1/7] powerpc: Add TIDR CPU feature for Power9

[Frederic Barrat]

Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> This patch adds a CPU feature bit to show whether the CPU has
> the TIDR register available, enabling as_notify/wait in userspace.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---
>   arch/powerpc/include/asm/cputable.h | 3 ++-
>   arch/powerpc/kernel/dt_cpu_ftrs.c   | 1 +
>   2 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
> index 4e332f3531c5..54c4cbbe57b4 100644
> --- a/arch/powerpc/include/asm/cputable.h
> +++ b/arch/powerpc/include/asm/cputable.h
> @@ -215,6 +215,7 @@ static inline void cpu_feature_keys_init(void) { }
>   #define CPU_FTR_P9_TM_HV_ASSIST		LONG_ASM_CONST(0x0000100000000000)
>   #define CPU_FTR_P9_TM_XER_SO_BUG	LONG_ASM_CONST(0x0000200000000000)
>   #define CPU_FTR_P9_TLBIE_BUG		LONG_ASM_CONST(0x0000400000000000)
> +#define CPU_FTR_P9_TIDR			LONG_ASM_CONST(0x0000800000000000)
> 
>   #ifndef __ASSEMBLY__
> 
> @@ -462,7 +463,7 @@ static inline void cpu_feature_keys_init(void) { }
>   	    CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
>   	    CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S | \
>   	    CPU_FTR_TM_COMP | CPU_FTR_ARCH_300 | CPU_FTR_PKEY | \
> -	    CPU_FTR_P9_TLBIE_BUG)
> +	    CPU_FTR_P9_TLBIE_BUG | CPU_FTR_P9_TIDR)
>   #define CPU_FTRS_POWER9_DD1 ((CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD1) & \
>   			     (~CPU_FTR_SAO))
>   #define CPU_FTRS_POWER9_DD2_0 CPU_FTRS_POWER9
> diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
> index 11a3a4fed3fb..10f8b7f55637 100644
> --- a/arch/powerpc/kernel/dt_cpu_ftrs.c
> +++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
> @@ -722,6 +722,7 @@ static __init void cpufeatures_cpu_quirks(void)
>   	if ((version & 0xffff0000) == 0x004e0000) {
>   		cur_cpu_spec->cpu_features &= ~(CPU_FTR_DAWR);
>   		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TLBIE_BUG; > +		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TIDR;


Isn't it redundant with adding the flag to CPU_FTRS_POWER9?

   Fred


>   	}
>   }
> 

Re: [PATCH v2 1/7] powerpc: Add TIDR CPU feature for Power9

[Frederic Barrat]

Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> This patch adds a CPU feature bit to show whether the CPU has
> the TIDR register available, enabling as_notify/wait in userspace.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---
>   arch/powerpc/include/asm/cputable.h | 3 ++-
>   arch/powerpc/kernel/dt_cpu_ftrs.c   | 1 +
>   2 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
> index 4e332f3531c5..54c4cbbe57b4 100644
> --- a/arch/powerpc/include/asm/cputable.h
> +++ b/arch/powerpc/include/asm/cputable.h
> @@ -215,6 +215,7 @@ static inline void cpu_feature_keys_init(void) { }
>   #define CPU_FTR_P9_TM_HV_ASSIST		LONG_ASM_CONST(0x0000100000000000)
>   #define CPU_FTR_P9_TM_XER_SO_BUG	LONG_ASM_CONST(0x0000200000000000)
>   #define CPU_FTR_P9_TLBIE_BUG		LONG_ASM_CONST(0x0000400000000000)
> +#define CPU_FTR_P9_TIDR			LONG_ASM_CONST(0x0000800000000000)
> 
>   #ifndef __ASSEMBLY__
> 
> @@ -462,7 +463,7 @@ static inline void cpu_feature_keys_init(void) { }
>   	    CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
>   	    CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S | \
>   	    CPU_FTR_TM_COMP | CPU_FTR_ARCH_300 | CPU_FTR_PKEY | \
> -	    CPU_FTR_P9_TLBIE_BUG)
> +	    CPU_FTR_P9_TLBIE_BUG | CPU_FTR_P9_TIDR)
>   #define CPU_FTRS_POWER9_DD1 ((CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD1) & \
>   			     (~CPU_FTR_SAO))
>   #define CPU_FTRS_POWER9_DD2_0 CPU_FTRS_POWER9
> diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
> index 11a3a4fed3fb..10f8b7f55637 100644
> --- a/arch/powerpc/kernel/dt_cpu_ftrs.c
> +++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
> @@ -722,6 +722,7 @@ static __init void cpufeatures_cpu_quirks(void)
>   	if ((version & 0xffff0000) == 0x004e0000) {
>   		cur_cpu_spec->cpu_features &= ~(CPU_FTR_DAWR);
>   		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TLBIE_BUG; > +		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TIDR;


Isn't it redundant with adding the flag to CPU_FTRS_POWER9?

   Fred


>   	}
>   }
> 

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Re: [PATCH v2 1/7] powerpc: Add TIDR CPU feature for Power9

[Alastair D'Silva]

On Mon, 2018-05-07 at 19:17 +0200, Frederic Barrat wrote:
> 
> Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> > From: Alastair D'Silva <alastair@d-silva.org>
> > 
> > This patch adds a CPU feature bit to show whether the CPU has
> > the TIDR register available, enabling as_notify/wait in userspace.
> > 
> > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > ---
> >   arch/powerpc/include/asm/cputable.h | 3 ++-
> >   arch/powerpc/kernel/dt_cpu_ftrs.c   | 1 +
> >   2 files changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/powerpc/include/asm/cputable.h
> > b/arch/powerpc/include/asm/cputable.h
> > index 4e332f3531c5..54c4cbbe57b4 100644
> > --- a/arch/powerpc/include/asm/cputable.h
> > +++ b/arch/powerpc/include/asm/cputable.h
> > @@ -215,6 +215,7 @@ static inline void cpu_feature_keys_init(void)
> > { }
> >   #define CPU_FTR_P9_TM_HV_ASSIST		LONG_ASM_CONST(0x0
> > 000100000000000)
> >   #define CPU_FTR_P9_TM_XER_SO_BUG	LONG_ASM_CONST(0x00002000
> > 00000000)
> >   #define CPU_FTR_P9_TLBIE_BUG		LONG_ASM_CONST(0x0000
> > 400000000000)
> > +#define CPU_FTR_P9_TIDR			LONG_ASM_CONST(0x00
> > 00800000000000)
> > 
> >   #ifndef __ASSEMBLY__
> > 
> > @@ -462,7 +463,7 @@ static inline void cpu_feature_keys_init(void)
> > { }
> >   	    CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
> >   	    CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S |
> > \
> >   	    CPU_FTR_TM_COMP | CPU_FTR_ARCH_300 | CPU_FTR_PKEY | \
> > -	    CPU_FTR_P9_TLBIE_BUG)
> > +	    CPU_FTR_P9_TLBIE_BUG | CPU_FTR_P9_TIDR)
> >   #define CPU_FTRS_POWER9_DD1 ((CPU_FTRS_POWER9 |
> > CPU_FTR_POWER9_DD1) & \
> >   			     (~CPU_FTR_SAO))
> >   #define CPU_FTRS_POWER9_DD2_0 CPU_FTRS_POWER9
> > diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c
> > b/arch/powerpc/kernel/dt_cpu_ftrs.c
> > index 11a3a4fed3fb..10f8b7f55637 100644
> > --- a/arch/powerpc/kernel/dt_cpu_ftrs.c
> > +++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
> > @@ -722,6 +722,7 @@ static __init void cpufeatures_cpu_quirks(void)
> >   	if ((version & 0xffff0000) == 0x004e0000) {
> >   		cur_cpu_spec->cpu_features &= ~(CPU_FTR_DAWR);
> >   		cur_cpu_spec->cpu_features |=
> > CPU_FTR_P9_TLBIE_BUG; > +		cur_cpu_spec->cpu_features 
> > |= CPU_FTR_P9_TIDR;
> 
> 
> Isn't it redundant with adding the flag to CPU_FTRS_POWER9?
> 
>    Fred
> 

No, cpu_features is populated from device tree, not from
CPU_FTRS_POWER9. Since TIDR will not be explicitly requested in the
device tree, we need to handle it in quirks.

-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819

Re: [PATCH v2 1/7] powerpc: Add TIDR CPU feature for Power9

[Alastair D'Silva]

On Mon, 2018-05-07 at 19:17 +0200, Frederic Barrat wrote:
> 
> Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> > From: Alastair D'Silva <alastair@d-silva.org>
> > 
> > This patch adds a CPU feature bit to show whether the CPU has
> > the TIDR register available, enabling as_notify/wait in userspace.
> > 
> > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > ---
> >   arch/powerpc/include/asm/cputable.h | 3 ++-
> >   arch/powerpc/kernel/dt_cpu_ftrs.c   | 1 +
> >   2 files changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/powerpc/include/asm/cputable.h
> > b/arch/powerpc/include/asm/cputable.h
> > index 4e332f3531c5..54c4cbbe57b4 100644
> > --- a/arch/powerpc/include/asm/cputable.h
> > +++ b/arch/powerpc/include/asm/cputable.h
> > @@ -215,6 +215,7 @@ static inline void cpu_feature_keys_init(void)
> > { }
> >   #define CPU_FTR_P9_TM_HV_ASSIST		LONG_ASM_CONST(0x0
> > 000100000000000)
> >   #define CPU_FTR_P9_TM_XER_SO_BUG	LONG_ASM_CONST(0x00002000
> > 00000000)
> >   #define CPU_FTR_P9_TLBIE_BUG		LONG_ASM_CONST(0x0000
> > 400000000000)
> > +#define CPU_FTR_P9_TIDR			LONG_ASM_CONST(0x00
> > 00800000000000)
> > 
> >   #ifndef __ASSEMBLY__
> > 
> > @@ -462,7 +463,7 @@ static inline void cpu_feature_keys_init(void)
> > { }
> >   	    CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
> >   	    CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S |
> > \
> >   	    CPU_FTR_TM_COMP | CPU_FTR_ARCH_300 | CPU_FTR_PKEY | \
> > -	    CPU_FTR_P9_TLBIE_BUG)
> > +	    CPU_FTR_P9_TLBIE_BUG | CPU_FTR_P9_TIDR)
> >   #define CPU_FTRS_POWER9_DD1 ((CPU_FTRS_POWER9 |
> > CPU_FTR_POWER9_DD1) & \
> >   			     (~CPU_FTR_SAO))
> >   #define CPU_FTRS_POWER9_DD2_0 CPU_FTRS_POWER9
> > diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c
> > b/arch/powerpc/kernel/dt_cpu_ftrs.c
> > index 11a3a4fed3fb..10f8b7f55637 100644
> > --- a/arch/powerpc/kernel/dt_cpu_ftrs.c
> > +++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
> > @@ -722,6 +722,7 @@ static __init void cpufeatures_cpu_quirks(void)
> >   	if ((version & 0xffff0000) == 0x004e0000) {
> >   		cur_cpu_spec->cpu_features &= ~(CPU_FTR_DAWR);
> >   		cur_cpu_spec->cpu_features |=
> > CPU_FTR_P9_TLBIE_BUG; > +		cur_cpu_spec->cpu_features 
> > |= CPU_FTR_P9_TIDR;
> 
> 
> Isn't it redundant with adding the flag to CPU_FTRS_POWER9?
> 
>    Fred
> 

No, cpu_features is populated from device tree, not from
CPU_FTRS_POWER9. Since TIDR will not be explicitly requested in the
device tree, we need to handle it in quirks.

-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819

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[PATCH v2 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

Switch the use of TIDR on it's CPU feature, rather than assuming it
is available based on architecture.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/kernel/process.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 1237f13fed51..3b00da47699b 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1154,7 +1154,7 @@ static inline void restore_sprs(struct thread_struct *old_thread,
 			mtspr(SPRN_TAR, new_thread->tar);
 	}
 
-	if (cpu_has_feature(CPU_FTR_ARCH_300) &&
+	if (cpu_has_feature(CPU_FTR_P9_TIDR) &&
 	    old_thread->tidr != new_thread->tidr)
 		mtspr(SPRN_TIDR, new_thread->tidr);
 #endif
@@ -1570,7 +1570,7 @@ void clear_thread_tidr(struct task_struct *t)
 	if (!t->thread.tidr)
 		return;
 
-	if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
+	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
 		WARN_ON_ONCE(1);
 		return;
 	}
@@ -1593,7 +1593,7 @@ int set_thread_tidr(struct task_struct *t)
 {
 	int rc;
 
-	if (!cpu_has_feature(CPU_FTR_ARCH_300))
+	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
 		return -EINVAL;
 
 	if (t != current)
-- 
2.14.3

[PATCH v2 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

Switch the use of TIDR on it's CPU feature, rather than assuming it
is available based on architecture.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/kernel/process.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 1237f13fed51..3b00da47699b 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1154,7 +1154,7 @@ static inline void restore_sprs(struct thread_struct *old_thread,
 			mtspr(SPRN_TAR, new_thread->tar);
 	}
 
-	if (cpu_has_feature(CPU_FTR_ARCH_300) &&
+	if (cpu_has_feature(CPU_FTR_P9_TIDR) &&
 	    old_thread->tidr != new_thread->tidr)
 		mtspr(SPRN_TIDR, new_thread->tidr);
 #endif
@@ -1570,7 +1570,7 @@ void clear_thread_tidr(struct task_struct *t)
 	if (!t->thread.tidr)
 		return;
 
-	if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
+	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
 		WARN_ON_ONCE(1);
 		return;
 	}
@@ -1593,7 +1593,7 @@ int set_thread_tidr(struct task_struct *t)
 {
 	int rc;
 
-	if (!cpu_has_feature(CPU_FTR_ARCH_300))
+	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
 		return -EINVAL;
 
 	if (t != current)
-- 
2.14.3

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Re: [PATCH v2 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

[Andrew Donnellan]

On 18/04/18 11:08, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> Switch the use of TIDR on it's CPU feature, rather than assuming it
> is available based on architecture.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>

Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

Re: [PATCH v2 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

[Andrew Donnellan]

On 18/04/18 11:08, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> Switch the use of TIDR on it's CPU feature, rather than assuming it
> is available based on architecture.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>

Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

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Re: [PATCH v2 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

[Frederic Barrat]

Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> Switch the use of TIDR on it's CPU feature, rather than assuming it
> is available based on architecture.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---

Reviewed-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>


>   arch/powerpc/kernel/process.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 1237f13fed51..3b00da47699b 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -1154,7 +1154,7 @@ static inline void restore_sprs(struct thread_struct *old_thread,
>   			mtspr(SPRN_TAR, new_thread->tar);
>   	}
> 
> -	if (cpu_has_feature(CPU_FTR_ARCH_300) &&
> +	if (cpu_has_feature(CPU_FTR_P9_TIDR) &&
>   	    old_thread->tidr != new_thread->tidr)
>   		mtspr(SPRN_TIDR, new_thread->tidr);
>   #endif
> @@ -1570,7 +1570,7 @@ void clear_thread_tidr(struct task_struct *t)
>   	if (!t->thread.tidr)
>   		return;
> 
> -	if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
> +	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
>   		WARN_ON_ONCE(1);
>   		return;
>   	}
> @@ -1593,7 +1593,7 @@ int set_thread_tidr(struct task_struct *t)
>   {
>   	int rc;
> 
> -	if (!cpu_has_feature(CPU_FTR_ARCH_300))
> +	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
>   		return -EINVAL;
> 
>   	if (t != current)
> 

Re: [PATCH v2 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

[Frederic Barrat]

Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> Switch the use of TIDR on it's CPU feature, rather than assuming it
> is available based on architecture.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---

Reviewed-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>


>   arch/powerpc/kernel/process.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 1237f13fed51..3b00da47699b 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -1154,7 +1154,7 @@ static inline void restore_sprs(struct thread_struct *old_thread,
>   			mtspr(SPRN_TAR, new_thread->tar);
>   	}
> 
> -	if (cpu_has_feature(CPU_FTR_ARCH_300) &&
> +	if (cpu_has_feature(CPU_FTR_P9_TIDR) &&
>   	    old_thread->tidr != new_thread->tidr)
>   		mtspr(SPRN_TIDR, new_thread->tidr);
>   #endif
> @@ -1570,7 +1570,7 @@ void clear_thread_tidr(struct task_struct *t)
>   	if (!t->thread.tidr)
>   		return;
> 
> -	if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
> +	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
>   		WARN_ON_ONCE(1);
>   		return;
>   	}
> @@ -1593,7 +1593,7 @@ int set_thread_tidr(struct task_struct *t)
>   {
>   	int rc;
> 
> -	if (!cpu_has_feature(CPU_FTR_ARCH_300))
> +	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
>   		return -EINVAL;
> 
>   	if (t != current)
> 

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[PATCH v2 3/7] powerpc: use task_pid_nr() for TID allocation

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The current implementation of TID allocation, using a global IDR, may
result in an errant process starving the system of available TIDs.
Instead, use task_pid_nr(), as mentioned by the original author. The
scenario described which prevented it's use is not applicable, as
set_thread_tidr can only be called after the task struct has been
populated.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/switch_to.h |  1 -
 arch/powerpc/kernel/process.c        | 97 +-----------------------------------
 2 files changed, 1 insertion(+), 97 deletions(-)

diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index be8c9fa23983..5b03d8a82409 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -94,6 +94,5 @@ static inline void clear_task_ebb(struct task_struct *t)
 extern int set_thread_uses_vas(void);
 
 extern int set_thread_tidr(struct task_struct *t);
-extern void clear_thread_tidr(struct task_struct *t);
 
 #endif /* _ASM_POWERPC_SWITCH_TO_H */
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 3b00da47699b..87f047fd2762 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1496,103 +1496,12 @@ int set_thread_uses_vas(void)
 }
 
 #ifdef CONFIG_PPC64
-static DEFINE_SPINLOCK(vas_thread_id_lock);
-static DEFINE_IDA(vas_thread_ida);
-
-/*
- * We need to assign a unique thread id to each thread in a process.
- *
- * This thread id, referred to as TIDR, and separate from the Linux's tgid,
- * is intended to be used to direct an ASB_Notify from the hardware to the
- * thread, when a suitable event occurs in the system.
- *
- * One such event is a "paste" instruction in the context of Fast Thread
- * Wakeup (aka Core-to-core wake up in the Virtual Accelerator Switchboard
- * (VAS) in POWER9.
- *
- * To get a unique TIDR per process we could simply reuse task_pid_nr() but
- * the problem is that task_pid_nr() is not yet available copy_thread() is
- * called. Fixing that would require changing more intrusive arch-neutral
- * code in code path in copy_process()?.
- *
- * Further, to assign unique TIDRs within each process, we need an atomic
- * field (or an IDR) in task_struct, which again intrudes into the arch-
- * neutral code. So try to assign globally unique TIDRs for now.
- *
- * NOTE: TIDR 0 indicates that the thread does not need a TIDR value.
- *	 For now, only threads that expect to be notified by the VAS
- *	 hardware need a TIDR value and we assign values > 0 for those.
- */
-#define MAX_THREAD_CONTEXT	((1 << 16) - 1)
-static int assign_thread_tidr(void)
-{
-	int index;
-	int err;
-	unsigned long flags;
-
-again:
-	if (!ida_pre_get(&vas_thread_ida, GFP_KERNEL))
-		return -ENOMEM;
-
-	spin_lock_irqsave(&vas_thread_id_lock, flags);
-	err = ida_get_new_above(&vas_thread_ida, 1, &index);
-	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-
-	if (err == -EAGAIN)
-		goto again;
-	else if (err)
-		return err;
-
-	if (index > MAX_THREAD_CONTEXT) {
-		spin_lock_irqsave(&vas_thread_id_lock, flags);
-		ida_remove(&vas_thread_ida, index);
-		spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-		return -ENOMEM;
-	}
-
-	return index;
-}
-
-static void free_thread_tidr(int id)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&vas_thread_id_lock, flags);
-	ida_remove(&vas_thread_ida, id);
-	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-}
-
-/*
- * Clear any TIDR value assigned to this thread.
- */
-void clear_thread_tidr(struct task_struct *t)
-{
-	if (!t->thread.tidr)
-		return;
-
-	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
-		WARN_ON_ONCE(1);
-		return;
-	}
-
-	mtspr(SPRN_TIDR, 0);
-	free_thread_tidr(t->thread.tidr);
-	t->thread.tidr = 0;
-}
-
-void arch_release_task_struct(struct task_struct *t)
-{
-	clear_thread_tidr(t);
-}
-
 /*
  * Assign a unique TIDR (thread id) for task @t and set it in the thread
  * structure. For now, we only support setting TIDR for 'current' task.
  */
 int set_thread_tidr(struct task_struct *t)
 {
-	int rc;
-
 	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
 		return -EINVAL;
 
@@ -1602,11 +1511,7 @@ int set_thread_tidr(struct task_struct *t)
 	if (t->thread.tidr)
 		return 0;
 
-	rc = assign_thread_tidr();
-	if (rc < 0)
-		return rc;
-
-	t->thread.tidr = rc;
+	t->thread.tidr = (u16)task_pid_nr(t);
 	mtspr(SPRN_TIDR, t->thread.tidr);
 
 	return 0;
-- 
2.14.3

[PATCH v2 3/7] powerpc: use task_pid_nr() for TID allocation

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The current implementation of TID allocation, using a global IDR, may
result in an errant process starving the system of available TIDs.
Instead, use task_pid_nr(), as mentioned by the original author. The
scenario described which prevented it's use is not applicable, as
set_thread_tidr can only be called after the task struct has been
populated.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/switch_to.h |  1 -
 arch/powerpc/kernel/process.c        | 97 +-----------------------------------
 2 files changed, 1 insertion(+), 97 deletions(-)

diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index be8c9fa23983..5b03d8a82409 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -94,6 +94,5 @@ static inline void clear_task_ebb(struct task_struct *t)
 extern int set_thread_uses_vas(void);
 
 extern int set_thread_tidr(struct task_struct *t);
-extern void clear_thread_tidr(struct task_struct *t);
 
 #endif /* _ASM_POWERPC_SWITCH_TO_H */
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 3b00da47699b..87f047fd2762 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1496,103 +1496,12 @@ int set_thread_uses_vas(void)
 }
 
 #ifdef CONFIG_PPC64
-static DEFINE_SPINLOCK(vas_thread_id_lock);
-static DEFINE_IDA(vas_thread_ida);
-
-/*
- * We need to assign a unique thread id to each thread in a process.
- *
- * This thread id, referred to as TIDR, and separate from the Linux's tgid,
- * is intended to be used to direct an ASB_Notify from the hardware to the
- * thread, when a suitable event occurs in the system.
- *
- * One such event is a "paste" instruction in the context of Fast Thread
- * Wakeup (aka Core-to-core wake up in the Virtual Accelerator Switchboard
- * (VAS) in POWER9.
- *
- * To get a unique TIDR per process we could simply reuse task_pid_nr() but
- * the problem is that task_pid_nr() is not yet available copy_thread() is
- * called. Fixing that would require changing more intrusive arch-neutral
- * code in code path in copy_process()?.
- *
- * Further, to assign unique TIDRs within each process, we need an atomic
- * field (or an IDR) in task_struct, which again intrudes into the arch-
- * neutral code. So try to assign globally unique TIDRs for now.
- *
- * NOTE: TIDR 0 indicates that the thread does not need a TIDR value.
- *	 For now, only threads that expect to be notified by the VAS
- *	 hardware need a TIDR value and we assign values > 0 for those.
- */
-#define MAX_THREAD_CONTEXT	((1 << 16) - 1)
-static int assign_thread_tidr(void)
-{
-	int index;
-	int err;
-	unsigned long flags;
-
-again:
-	if (!ida_pre_get(&vas_thread_ida, GFP_KERNEL))
-		return -ENOMEM;
-
-	spin_lock_irqsave(&vas_thread_id_lock, flags);
-	err = ida_get_new_above(&vas_thread_ida, 1, &index);
-	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-
-	if (err == -EAGAIN)
-		goto again;
-	else if (err)
-		return err;
-
-	if (index > MAX_THREAD_CONTEXT) {
-		spin_lock_irqsave(&vas_thread_id_lock, flags);
-		ida_remove(&vas_thread_ida, index);
-		spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-		return -ENOMEM;
-	}
-
-	return index;
-}
-
-static void free_thread_tidr(int id)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&vas_thread_id_lock, flags);
-	ida_remove(&vas_thread_ida, id);
-	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-}
-
-/*
- * Clear any TIDR value assigned to this thread.
- */
-void clear_thread_tidr(struct task_struct *t)
-{
-	if (!t->thread.tidr)
-		return;
-
-	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
-		WARN_ON_ONCE(1);
-		return;
-	}
-
-	mtspr(SPRN_TIDR, 0);
-	free_thread_tidr(t->thread.tidr);
-	t->thread.tidr = 0;
-}
-
-void arch_release_task_struct(struct task_struct *t)
-{
-	clear_thread_tidr(t);
-}
-
 /*
  * Assign a unique TIDR (thread id) for task @t and set it in the thread
  * structure. For now, we only support setting TIDR for 'current' task.
  */
 int set_thread_tidr(struct task_struct *t)
 {
-	int rc;
-
 	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
 		return -EINVAL;
 
@@ -1602,11 +1511,7 @@ int set_thread_tidr(struct task_struct *t)
 	if (t->thread.tidr)
 		return 0;
 
-	rc = assign_thread_tidr();
-	if (rc < 0)
-		return rc;
-
-	t->thread.tidr = rc;
+	t->thread.tidr = (u16)task_pid_nr(t);
 	mtspr(SPRN_TIDR, t->thread.tidr);
 
 	return 0;
-- 
2.14.3

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Re: [PATCH v2 3/7] powerpc: use task_pid_nr() for TID allocation

[Andrew Donnellan]

[+ Sukadev, Christophe]

On 18/04/18 11:08, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> The current implementation of TID allocation, using a global IDR, may
> result in an errant process starving the system of available TIDs.
> Instead, use task_pid_nr(), as mentioned by the original author. The
> scenario described which prevented it's use is not applicable, as
> set_thread_tidr can only be called after the task struct has been
> populated.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>

So it's too late in the evening for me to completely get my head around 
what's going on here enough to give my Reviewed-by:, but my current 
thinking is:

- In the first version of the patch to add TIDR support 
(https://patchwork.ozlabs.org/patch/799494/), it was originally proposed 
to call assign_thread_id() (as it was then called) from copy_thread()

- The comment block documents the reason why we can't use task_pid_nr() 
but assumes that we're trying to assign a TIDR from within copy_thread()

- The final patch that was accepted 
(https://patchwork.ozlabs.org/patch/835552/, 
ec233ede4c8654894610ea54f4dae7adc954ac62) instead sets the TIDR to 0 
from copy_thread(), so the original reasoning regarding not using 
task_pid_nr() within copy_thread() is no longer applicable.

Sukadev: does this sound right?


Andrew


> ---
>   arch/powerpc/include/asm/switch_to.h |  1 -
>   arch/powerpc/kernel/process.c        | 97 +-----------------------------------
>   2 files changed, 1 insertion(+), 97 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
> index be8c9fa23983..5b03d8a82409 100644
> --- a/arch/powerpc/include/asm/switch_to.h
> +++ b/arch/powerpc/include/asm/switch_to.h
> @@ -94,6 +94,5 @@ static inline void clear_task_ebb(struct task_struct *t)
>   extern int set_thread_uses_vas(void);
>   
>   extern int set_thread_tidr(struct task_struct *t);
> -extern void clear_thread_tidr(struct task_struct *t);
>   
>   #endif /* _ASM_POWERPC_SWITCH_TO_H */
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 3b00da47699b..87f047fd2762 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -1496,103 +1496,12 @@ int set_thread_uses_vas(void)
>   }
>   
>   #ifdef CONFIG_PPC64
> -static DEFINE_SPINLOCK(vas_thread_id_lock);
> -static DEFINE_IDA(vas_thread_ida);
> -
> -/*
> - * We need to assign a unique thread id to each thread in a process.
> - *
> - * This thread id, referred to as TIDR, and separate from the Linux's tgid,
> - * is intended to be used to direct an ASB_Notify from the hardware to the
> - * thread, when a suitable event occurs in the system.
> - *
> - * One such event is a "paste" instruction in the context of Fast Thread
> - * Wakeup (aka Core-to-core wake up in the Virtual Accelerator Switchboard
> - * (VAS) in POWER9.
> - *
> - * To get a unique TIDR per process we could simply reuse task_pid_nr() but
> - * the problem is that task_pid_nr() is not yet available copy_thread() is
> - * called. Fixing that would require changing more intrusive arch-neutral
> - * code in code path in copy_process()?.
> - *
> - * Further, to assign unique TIDRs within each process, we need an atomic
> - * field (or an IDR) in task_struct, which again intrudes into the arch-
> - * neutral code. So try to assign globally unique TIDRs for now.
> - *
> - * NOTE: TIDR 0 indicates that the thread does not need a TIDR value.
> - *	 For now, only threads that expect to be notified by the VAS
> - *	 hardware need a TIDR value and we assign values > 0 for those.
> - */
> -#define MAX_THREAD_CONTEXT	((1 << 16) - 1)
> -static int assign_thread_tidr(void)
> -{
> -	int index;
> -	int err;
> -	unsigned long flags;
> -
> -again:
> -	if (!ida_pre_get(&vas_thread_ida, GFP_KERNEL))
> -		return -ENOMEM;
> -
> -	spin_lock_irqsave(&vas_thread_id_lock, flags);
> -	err = ida_get_new_above(&vas_thread_ida, 1, &index);
> -	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
> -
> -	if (err == -EAGAIN)
> -		goto again;
> -	else if (err)
> -		return err;
> -
> -	if (index > MAX_THREAD_CONTEXT) {
> -		spin_lock_irqsave(&vas_thread_id_lock, flags);
> -		ida_remove(&vas_thread_ida, index);
> -		spin_unlock_irqrestore(&vas_thread_id_lock, flags);
> -		return -ENOMEM;
> -	}
> -
> -	return index;
> -}
> -
> -static void free_thread_tidr(int id)
> -{
> -	unsigned long flags;
> -
> -	spin_lock_irqsave(&vas_thread_id_lock, flags);
> -	ida_remove(&vas_thread_ida, id);
> -	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
> -}
> -
> -/*
> - * Clear any TIDR value assigned to this thread.
> - */
> -void clear_thread_tidr(struct task_struct *t)
> -{
> -	if (!t->thread.tidr)
> -		return;
> -
> -	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
> -		WARN_ON_ONCE(1);
> -		return;
> -	}
> -
> -	mtspr(SPRN_TIDR, 0);
> -	free_thread_tidr(t->thread.tidr);
> -	t->thread.tidr = 0;
> -}
> -
> -void arch_release_task_struct(struct task_struct *t)
> -{
> -	clear_thread_tidr(t);
> -}
> -
>   /*
>    * Assign a unique TIDR (thread id) for task @t and set it in the thread
>    * structure. For now, we only support setting TIDR for 'current' task.
>    */
>   int set_thread_tidr(struct task_struct *t)
>   {
> -	int rc;
> -
>   	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
>   		return -EINVAL;
>   
> @@ -1602,11 +1511,7 @@ int set_thread_tidr(struct task_struct *t)
>   	if (t->thread.tidr)
>   		return 0;
>   
> -	rc = assign_thread_tidr();
> -	if (rc < 0)
> -		return rc;
> -
> -	t->thread.tidr = rc;
> +	t->thread.tidr = (u16)task_pid_nr(t);
>   	mtspr(SPRN_TIDR, t->thread.tidr);
>   
>   	return 0;
> 

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

Re: [PATCH v2 3/7] powerpc: use task_pid_nr() for TID allocation

[Andrew Donnellan]

[+ Sukadev, Christophe]

On 18/04/18 11:08, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> The current implementation of TID allocation, using a global IDR, may
> result in an errant process starving the system of available TIDs.
> Instead, use task_pid_nr(), as mentioned by the original author. The
> scenario described which prevented it's use is not applicable, as
> set_thread_tidr can only be called after the task struct has been
> populated.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>

So it's too late in the evening for me to completely get my head around 
what's going on here enough to give my Reviewed-by:, but my current 
thinking is:

- In the first version of the patch to add TIDR support 
(https://patchwork.ozlabs.org/patch/799494/), it was originally proposed 
to call assign_thread_id() (as it was then called) from copy_thread()

- The comment block documents the reason why we can't use task_pid_nr() 
but assumes that we're trying to assign a TIDR from within copy_thread()

- The final patch that was accepted 
(https://patchwork.ozlabs.org/patch/835552/, 
ec233ede4c8654894610ea54f4dae7adc954ac62) instead sets the TIDR to 0 
from copy_thread(), so the original reasoning regarding not using 
task_pid_nr() within copy_thread() is no longer applicable.

Sukadev: does this sound right?


Andrew


> ---
>   arch/powerpc/include/asm/switch_to.h |  1 -
>   arch/powerpc/kernel/process.c        | 97 +-----------------------------------
>   2 files changed, 1 insertion(+), 97 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
> index be8c9fa23983..5b03d8a82409 100644
> --- a/arch/powerpc/include/asm/switch_to.h
> +++ b/arch/powerpc/include/asm/switch_to.h
> @@ -94,6 +94,5 @@ static inline void clear_task_ebb(struct task_struct *t)
>   extern int set_thread_uses_vas(void);
>   
>   extern int set_thread_tidr(struct task_struct *t);
> -extern void clear_thread_tidr(struct task_struct *t);
>   
>   #endif /* _ASM_POWERPC_SWITCH_TO_H */
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 3b00da47699b..87f047fd2762 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -1496,103 +1496,12 @@ int set_thread_uses_vas(void)
>   }
>   
>   #ifdef CONFIG_PPC64
> -static DEFINE_SPINLOCK(vas_thread_id_lock);
> -static DEFINE_IDA(vas_thread_ida);
> -
> -/*
> - * We need to assign a unique thread id to each thread in a process.
> - *
> - * This thread id, referred to as TIDR, and separate from the Linux's tgid,
> - * is intended to be used to direct an ASB_Notify from the hardware to the
> - * thread, when a suitable event occurs in the system.
> - *
> - * One such event is a "paste" instruction in the context of Fast Thread
> - * Wakeup (aka Core-to-core wake up in the Virtual Accelerator Switchboard
> - * (VAS) in POWER9.
> - *
> - * To get a unique TIDR per process we could simply reuse task_pid_nr() but
> - * the problem is that task_pid_nr() is not yet available copy_thread() is
> - * called. Fixing that would require changing more intrusive arch-neutral
> - * code in code path in copy_process()?.
> - *
> - * Further, to assign unique TIDRs within each process, we need an atomic
> - * field (or an IDR) in task_struct, which again intrudes into the arch-
> - * neutral code. So try to assign globally unique TIDRs for now.
> - *
> - * NOTE: TIDR 0 indicates that the thread does not need a TIDR value.
> - *	 For now, only threads that expect to be notified by the VAS
> - *	 hardware need a TIDR value and we assign values > 0 for those.
> - */
> -#define MAX_THREAD_CONTEXT	((1 << 16) - 1)
> -static int assign_thread_tidr(void)
> -{
> -	int index;
> -	int err;
> -	unsigned long flags;
> -
> -again:
> -	if (!ida_pre_get(&vas_thread_ida, GFP_KERNEL))
> -		return -ENOMEM;
> -
> -	spin_lock_irqsave(&vas_thread_id_lock, flags);
> -	err = ida_get_new_above(&vas_thread_ida, 1, &index);
> -	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
> -
> -	if (err == -EAGAIN)
> -		goto again;
> -	else if (err)
> -		return err;
> -
> -	if (index > MAX_THREAD_CONTEXT) {
> -		spin_lock_irqsave(&vas_thread_id_lock, flags);
> -		ida_remove(&vas_thread_ida, index);
> -		spin_unlock_irqrestore(&vas_thread_id_lock, flags);
> -		return -ENOMEM;
> -	}
> -
> -	return index;
> -}
> -
> -static void free_thread_tidr(int id)
> -{
> -	unsigned long flags;
> -
> -	spin_lock_irqsave(&vas_thread_id_lock, flags);
> -	ida_remove(&vas_thread_ida, id);
> -	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
> -}
> -
> -/*
> - * Clear any TIDR value assigned to this thread.
> - */
> -void clear_thread_tidr(struct task_struct *t)
> -{
> -	if (!t->thread.tidr)
> -		return;
> -
> -	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
> -		WARN_ON_ONCE(1);
> -		return;
> -	}
> -
> -	mtspr(SPRN_TIDR, 0);
> -	free_thread_tidr(t->thread.tidr);
> -	t->thread.tidr = 0;
> -}
> -
> -void arch_release_task_struct(struct task_struct *t)
> -{
> -	clear_thread_tidr(t);
> -}
> -
>   /*
>    * Assign a unique TIDR (thread id) for task @t and set it in the thread
>    * structure. For now, we only support setting TIDR for 'current' task.
>    */
>   int set_thread_tidr(struct task_struct *t)
>   {
> -	int rc;
> -
>   	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
>   		return -EINVAL;
>   
> @@ -1602,11 +1511,7 @@ int set_thread_tidr(struct task_struct *t)
>   	if (t->thread.tidr)
>   		return 0;
>   
> -	rc = assign_thread_tidr();
> -	if (rc < 0)
> -		return rc;
> -
> -	t->thread.tidr = rc;
> +	t->thread.tidr = (u16)task_pid_nr(t);
>   	mtspr(SPRN_TIDR, t->thread.tidr);
>   
>   	return 0;
> 

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

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Re: [PATCH v2 3/7] powerpc: use task_pid_nr() for TID allocation

[Sukadev Bhattiprolu]

Andrew Donnellan [andrew.donnellan@au1.ibm.com] wrote:
> [+ Sukadev, Christophe]
> 
> On 18/04/18 11:08, Alastair D'Silva wrote:
> > From: Alastair D'Silva <alastair@d-silva.org>
> > 
> > The current implementation of TID allocation, using a global IDR, may
> > result in an errant process starving the system of available TIDs.
> > Instead, use task_pid_nr(), as mentioned by the original author. The
> > scenario described which prevented it's use is not applicable, as
> > set_thread_tidr can only be called after the task struct has been
> > populated.
> > 
> > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> 
> So it's too late in the evening for me to completely get my head around
> what's going on here enough to give my Reviewed-by:, but my current thinking
> is:
> 
> - In the first version of the patch to add TIDR support
> (https://patchwork.ozlabs.org/patch/799494/), it was originally proposed to
> call assign_thread_id() (as it was then called) from copy_thread()
> 
> - The comment block documents the reason why we can't use task_pid_nr() but
> assumes that we're trying to assign a TIDR from within copy_thread()
> 
> - The final patch that was accepted
> (https://patchwork.ozlabs.org/patch/835552/,
> ec233ede4c8654894610ea54f4dae7adc954ac62) instead sets the TIDR to 0 from
> copy_thread(), so the original reasoning regarding not using task_pid_nr()
> within copy_thread() is no longer applicable.
> 
> Sukadev: does this sound right?

Yes. Like with PIDR, was trying to assign TIDR initially to all threads.
But since only a subset of threads need/use TIDR, we can assign the
value later (when set_thread_tidr() is called). So we should be able to
use task_pid_nr() then.

Sukadev

Re: [PATCH v2 3/7] powerpc: use task_pid_nr() for TID allocation

[Sukadev Bhattiprolu]

Andrew Donnellan [andrew.donnellan@au1.ibm.com] wrote:
> [+ Sukadev, Christophe]
> 
> On 18/04/18 11:08, Alastair D'Silva wrote:
> > From: Alastair D'Silva <alastair@d-silva.org>
> > 
> > The current implementation of TID allocation, using a global IDR, may
> > result in an errant process starving the system of available TIDs.
> > Instead, use task_pid_nr(), as mentioned by the original author. The
> > scenario described which prevented it's use is not applicable, as
> > set_thread_tidr can only be called after the task struct has been
> > populated.
> > 
> > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> 
> So it's too late in the evening for me to completely get my head around
> what's going on here enough to give my Reviewed-by:, but my current thinking
> is:
> 
> - In the first version of the patch to add TIDR support
> (https://patchwork.ozlabs.org/patch/799494/), it was originally proposed to
> call assign_thread_id() (as it was then called) from copy_thread()
> 
> - The comment block documents the reason why we can't use task_pid_nr() but
> assumes that we're trying to assign a TIDR from within copy_thread()
> 
> - The final patch that was accepted
> (https://patchwork.ozlabs.org/patch/835552/,
> ec233ede4c8654894610ea54f4dae7adc954ac62) instead sets the TIDR to 0 from
> copy_thread(), so the original reasoning regarding not using task_pid_nr()
> within copy_thread() is no longer applicable.
> 
> Sukadev: does this sound right?

Yes. Like with PIDR, was trying to assign TIDR initially to all threads.
But since only a subset of threads need/use TIDR, we can assign the
value later (when set_thread_tidr() is called). So we should be able to
use task_pid_nr() then.

Sukadev

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Re: [PATCH v2 3/7] powerpc: use task_pid_nr() for TID allocation

[Andrew Donnellan]

On 25/04/18 07:12, Sukadev Bhattiprolu wrote:
> Yes. Like with PIDR, was trying to assign TIDR initially to all threads.
> But since only a subset of threads need/use TIDR, we can assign the
> value later (when set_thread_tidr() is called). So we should be able to
> use task_pid_nr() then.

OK. Alastair has also confirmed with me that truncating the pid to a u16 
should be safe, so therefore:

Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>


-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

Re: [PATCH v2 3/7] powerpc: use task_pid_nr() for TID allocation

[Andrew Donnellan]

On 25/04/18 07:12, Sukadev Bhattiprolu wrote:
> Yes. Like with PIDR, was trying to assign TIDR initially to all threads.
> But since only a subset of threads need/use TIDR, we can assign the
> value later (when set_thread_tidr() is called). So we should be able to
> use task_pid_nr() then.

OK. Alastair has also confirmed with me that truncating the pid to a u16 
should be safe, so therefore:

Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>


-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

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Re: [PATCH v2 3/7] powerpc: use task_pid_nr() for TID allocation

[Frederic Barrat]

Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> The current implementation of TID allocation, using a global IDR, may
> result in an errant process starving the system of available TIDs.
> Instead, use task_pid_nr(), as mentioned by the original author. The
> scenario described which prevented it's use is not applicable, as
> set_thread_tidr can only be called after the task struct has been
> populated.


Here is how I understand what's going to happen if 2 threads are using 
the same TIDR value, which is possible with this patch (if unlikely):

1. waking up the wrong thread is not really a problem, as threads have 
to handle spurious wake up from the 'wait' instruction anyway, and must 
be using some other condition to know when to loop around the 'wait' 
instruction.

2. missing the right thread: if the wrong thread is on a CPU, and a 
wake_host_thread/as_notify is sent, the core will see a matching thread 
and will accept the command. The (open)capi adapter won't send an 
interrupt. The wrong thread is awaken, which is not a problem as 
discussed above. As the right thread to notify is not running, no harm 
is done either: as soon as the thread runs, it's supposed to check its 
condition (which will be met) or call 'wait', but 'wait' immediately 
returns when called the first time after a thread is scheduled.

So I believe we are ok. But I think it requires a huge comment with the 
above (at the minimum) :-)

With a comment:
Reviewed-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>

   Fred



> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---
>   arch/powerpc/include/asm/switch_to.h |  1 -
>   arch/powerpc/kernel/process.c        | 97 +-----------------------------------
>   2 files changed, 1 insertion(+), 97 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
> index be8c9fa23983..5b03d8a82409 100644
> --- a/arch/powerpc/include/asm/switch_to.h
> +++ b/arch/powerpc/include/asm/switch_to.h
> @@ -94,6 +94,5 @@ static inline void clear_task_ebb(struct task_struct *t)
>   extern int set_thread_uses_vas(void);
> 
>   extern int set_thread_tidr(struct task_struct *t);
> -extern void clear_thread_tidr(struct task_struct *t);
> 
>   #endif /* _ASM_POWERPC_SWITCH_TO_H */
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 3b00da47699b..87f047fd2762 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -1496,103 +1496,12 @@ int set_thread_uses_vas(void)
>   }
> 
>   #ifdef CONFIG_PPC64
> -static DEFINE_SPINLOCK(vas_thread_id_lock);
> -static DEFINE_IDA(vas_thread_ida);
> -
> -/*
> - * We need to assign a unique thread id to each thread in a process.
> - *
> - * This thread id, referred to as TIDR, and separate from the Linux's tgid,
> - * is intended to be used to direct an ASB_Notify from the hardware to the
> - * thread, when a suitable event occurs in the system.
> - *
> - * One such event is a "paste" instruction in the context of Fast Thread
> - * Wakeup (aka Core-to-core wake up in the Virtual Accelerator Switchboard
> - * (VAS) in POWER9.
> - *
> - * To get a unique TIDR per process we could simply reuse task_pid_nr() but
> - * the problem is that task_pid_nr() is not yet available copy_thread() is
> - * called. Fixing that would require changing more intrusive arch-neutral
> - * code in code path in copy_process()?.
> - *
> - * Further, to assign unique TIDRs within each process, we need an atomic
> - * field (or an IDR) in task_struct, which again intrudes into the arch-
> - * neutral code. So try to assign globally unique TIDRs for now.
> - *
> - * NOTE: TIDR 0 indicates that the thread does not need a TIDR value.
> - *	 For now, only threads that expect to be notified by the VAS
> - *	 hardware need a TIDR value and we assign values > 0 for those.
> - */
> -#define MAX_THREAD_CONTEXT	((1 << 16) - 1)
> -static int assign_thread_tidr(void)
> -{
> -	int index;
> -	int err;
> -	unsigned long flags;
> -
> -again:
> -	if (!ida_pre_get(&vas_thread_ida, GFP_KERNEL))
> -		return -ENOMEM;
> -
> -	spin_lock_irqsave(&vas_thread_id_lock, flags);
> -	err = ida_get_new_above(&vas_thread_ida, 1, &index);
> -	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
> -
> -	if (err == -EAGAIN)
> -		goto again;
> -	else if (err)
> -		return err;
> -
> -	if (index > MAX_THREAD_CONTEXT) {
> -		spin_lock_irqsave(&vas_thread_id_lock, flags);
> -		ida_remove(&vas_thread_ida, index);
> -		spin_unlock_irqrestore(&vas_thread_id_lock, flags);
> -		return -ENOMEM;
> -	}
> -
> -	return index;
> -}
> -
> -static void free_thread_tidr(int id)
> -{
> -	unsigned long flags;
> -
> -	spin_lock_irqsave(&vas_thread_id_lock, flags);
> -	ida_remove(&vas_thread_ida, id);
> -	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
> -}
> -
> -/*
> - * Clear any TIDR value assigned to this thread.
> - */
> -void clear_thread_tidr(struct task_struct *t)
> -{
> -	if (!t->thread.tidr)
> -		return;
> -
> -	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
> -		WARN_ON_ONCE(1);
> -		return;
> -	}
> -
> -	mtspr(SPRN_TIDR, 0);
> -	free_thread_tidr(t->thread.tidr);
> -	t->thread.tidr = 0;
> -}
> -
> -void arch_release_task_struct(struct task_struct *t)
> -{
> -	clear_thread_tidr(t);
> -}
> -
>   /*
>    * Assign a unique TIDR (thread id) for task @t and set it in the thread
>    * structure. For now, we only support setting TIDR for 'current' task.
>    */
>   int set_thread_tidr(struct task_struct *t)
>   {
> -	int rc;
> -
>   	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
>   		return -EINVAL;
> 
> @@ -1602,11 +1511,7 @@ int set_thread_tidr(struct task_struct *t)
>   	if (t->thread.tidr)
>   		return 0;
> 
> -	rc = assign_thread_tidr();
> -	if (rc < 0)
> -		return rc;
> -
> -	t->thread.tidr = rc;
> +	t->thread.tidr = (u16)task_pid_nr(t);
>   	mtspr(SPRN_TIDR, t->thread.tidr);
> 
>   	return 0;
> 

Re: [PATCH v2 3/7] powerpc: use task_pid_nr() for TID allocation

[Frederic Barrat]

Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> The current implementation of TID allocation, using a global IDR, may
> result in an errant process starving the system of available TIDs.
> Instead, use task_pid_nr(), as mentioned by the original author. The
> scenario described which prevented it's use is not applicable, as
> set_thread_tidr can only be called after the task struct has been
> populated.


Here is how I understand what's going to happen if 2 threads are using 
the same TIDR value, which is possible with this patch (if unlikely):

1. waking up the wrong thread is not really a problem, as threads have 
to handle spurious wake up from the 'wait' instruction anyway, and must 
be using some other condition to know when to loop around the 'wait' 
instruction.

2. missing the right thread: if the wrong thread is on a CPU, and a 
wake_host_thread/as_notify is sent, the core will see a matching thread 
and will accept the command. The (open)capi adapter won't send an 
interrupt. The wrong thread is awaken, which is not a problem as 
discussed above. As the right thread to notify is not running, no harm 
is done either: as soon as the thread runs, it's supposed to check its 
condition (which will be met) or call 'wait', but 'wait' immediately 
returns when called the first time after a thread is scheduled.

So I believe we are ok. But I think it requires a huge comment with the 
above (at the minimum) :-)

With a comment:
Reviewed-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>

   Fred



> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---
>   arch/powerpc/include/asm/switch_to.h |  1 -
>   arch/powerpc/kernel/process.c        | 97 +-----------------------------------
>   2 files changed, 1 insertion(+), 97 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
> index be8c9fa23983..5b03d8a82409 100644
> --- a/arch/powerpc/include/asm/switch_to.h
> +++ b/arch/powerpc/include/asm/switch_to.h
> @@ -94,6 +94,5 @@ static inline void clear_task_ebb(struct task_struct *t)
>   extern int set_thread_uses_vas(void);
> 
>   extern int set_thread_tidr(struct task_struct *t);
> -extern void clear_thread_tidr(struct task_struct *t);
> 
>   #endif /* _ASM_POWERPC_SWITCH_TO_H */
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 3b00da47699b..87f047fd2762 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -1496,103 +1496,12 @@ int set_thread_uses_vas(void)
>   }
> 
>   #ifdef CONFIG_PPC64
> -static DEFINE_SPINLOCK(vas_thread_id_lock);
> -static DEFINE_IDA(vas_thread_ida);
> -
> -/*
> - * We need to assign a unique thread id to each thread in a process.
> - *
> - * This thread id, referred to as TIDR, and separate from the Linux's tgid,
> - * is intended to be used to direct an ASB_Notify from the hardware to the
> - * thread, when a suitable event occurs in the system.
> - *
> - * One such event is a "paste" instruction in the context of Fast Thread
> - * Wakeup (aka Core-to-core wake up in the Virtual Accelerator Switchboard
> - * (VAS) in POWER9.
> - *
> - * To get a unique TIDR per process we could simply reuse task_pid_nr() but
> - * the problem is that task_pid_nr() is not yet available copy_thread() is
> - * called. Fixing that would require changing more intrusive arch-neutral
> - * code in code path in copy_process()?.
> - *
> - * Further, to assign unique TIDRs within each process, we need an atomic
> - * field (or an IDR) in task_struct, which again intrudes into the arch-
> - * neutral code. So try to assign globally unique TIDRs for now.
> - *
> - * NOTE: TIDR 0 indicates that the thread does not need a TIDR value.
> - *	 For now, only threads that expect to be notified by the VAS
> - *	 hardware need a TIDR value and we assign values > 0 for those.
> - */
> -#define MAX_THREAD_CONTEXT	((1 << 16) - 1)
> -static int assign_thread_tidr(void)
> -{
> -	int index;
> -	int err;
> -	unsigned long flags;
> -
> -again:
> -	if (!ida_pre_get(&vas_thread_ida, GFP_KERNEL))
> -		return -ENOMEM;
> -
> -	spin_lock_irqsave(&vas_thread_id_lock, flags);
> -	err = ida_get_new_above(&vas_thread_ida, 1, &index);
> -	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
> -
> -	if (err == -EAGAIN)
> -		goto again;
> -	else if (err)
> -		return err;
> -
> -	if (index > MAX_THREAD_CONTEXT) {
> -		spin_lock_irqsave(&vas_thread_id_lock, flags);
> -		ida_remove(&vas_thread_ida, index);
> -		spin_unlock_irqrestore(&vas_thread_id_lock, flags);
> -		return -ENOMEM;
> -	}
> -
> -	return index;
> -}
> -
> -static void free_thread_tidr(int id)
> -{
> -	unsigned long flags;
> -
> -	spin_lock_irqsave(&vas_thread_id_lock, flags);
> -	ida_remove(&vas_thread_ida, id);
> -	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
> -}
> -
> -/*
> - * Clear any TIDR value assigned to this thread.
> - */
> -void clear_thread_tidr(struct task_struct *t)
> -{
> -	if (!t->thread.tidr)
> -		return;
> -
> -	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
> -		WARN_ON_ONCE(1);
> -		return;
> -	}
> -
> -	mtspr(SPRN_TIDR, 0);
> -	free_thread_tidr(t->thread.tidr);
> -	t->thread.tidr = 0;
> -}
> -
> -void arch_release_task_struct(struct task_struct *t)
> -{
> -	clear_thread_tidr(t);
> -}
> -
>   /*
>    * Assign a unique TIDR (thread id) for task @t and set it in the thread
>    * structure. For now, we only support setting TIDR for 'current' task.
>    */
>   int set_thread_tidr(struct task_struct *t)
>   {
> -	int rc;
> -
>   	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
>   		return -EINVAL;
> 
> @@ -1602,11 +1511,7 @@ int set_thread_tidr(struct task_struct *t)
>   	if (t->thread.tidr)
>   		return 0;
> 
> -	rc = assign_thread_tidr();
> -	if (rc < 0)
> -		return rc;
> -
> -	t->thread.tidr = rc;
> +	t->thread.tidr = (u16)task_pid_nr(t);
>   	mtspr(SPRN_TIDR, t->thread.tidr);
> 
>   	return 0;
> 

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Re: [PATCH v2 3/7] powerpc: use task_pid_nr() for TID allocation

[Alastair D'Silva]

On Mon, 2018-05-07 at 19:37 +0200, Frederic Barrat wrote:
> 
> Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> > From: Alastair D'Silva <alastair@d-silva.org>
> > 
> > The current implementation of TID allocation, using a global IDR,
> > may
> > result in an errant process starving the system of available TIDs.
> > Instead, use task_pid_nr(), as mentioned by the original author.
> > The
> > scenario described which prevented it's use is not applicable, as
> > set_thread_tidr can only be called after the task struct has been
> > populated.
> 
> 
> Here is how I understand what's going to happen if 2 threads are
> using 
> the same TIDR value, which is possible with this patch (if unlikely):
> 
> 1. waking up the wrong thread is not really a problem, as threads
> have 
> to handle spurious wake up from the 'wait' instruction anyway, and
> must 
> be using some other condition to know when to loop around the 'wait' 
> instruction.
> 
> 2. missing the right thread: if the wrong thread is on a CPU, and a 
> wake_host_thread/as_notify is sent, the core will see a matching
> thread 
> and will accept the command. The (open)capi adapter won't send an 
> interrupt. The wrong thread is awaken, which is not a problem as 
> discussed above. As the right thread to notify is not running, no
> harm 
> is done either: as soon as the thread runs, it's supposed to check
> its 
> condition (which will be met) or call 'wait', but 'wait' immediately 
> returns when called the first time after a thread is scheduled.
> 
> So I believe we are ok. But I think it requires a huge comment with
> the 
> above (at the minimum) :-)
> 
> With a comment:
> Reviewed-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
> 
>    Fred
> 

Good point, I'll add this in the next revision.


-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australiamob: 0423 762 819

Re: [PATCH v2 3/7] powerpc: use task_pid_nr() for TID allocation

[Alastair D'Silva]

On Mon, 2018-05-07 at 19:37 +0200, Frederic Barrat wrote:
> 
> Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> > From: Alastair D'Silva <alastair@d-silva.org>
> > 
> > The current implementation of TID allocation, using a global IDR,
> > may
> > result in an errant process starving the system of available TIDs.
> > Instead, use task_pid_nr(), as mentioned by the original author.
> > The
> > scenario described which prevented it's use is not applicable, as
> > set_thread_tidr can only be called after the task struct has been
> > populated.
> 
> 
> Here is how I understand what's going to happen if 2 threads are
> using 
> the same TIDR value, which is possible with this patch (if unlikely):
> 
> 1. waking up the wrong thread is not really a problem, as threads
> have 
> to handle spurious wake up from the 'wait' instruction anyway, and
> must 
> be using some other condition to know when to loop around the 'wait' 
> instruction.
> 
> 2. missing the right thread: if the wrong thread is on a CPU, and a 
> wake_host_thread/as_notify is sent, the core will see a matching
> thread 
> and will accept the command. The (open)capi adapter won't send an 
> interrupt. The wrong thread is awaken, which is not a problem as 
> discussed above. As the right thread to notify is not running, no
> harm 
> is done either: as soon as the thread runs, it's supposed to check
> its 
> condition (which will be met) or call 'wait', but 'wait' immediately 
> returns when called the first time after a thread is scheduled.
> 
> So I believe we are ok. But I think it requires a huge comment with
> the 
> above (at the minimum) :-)
> 
> With a comment:
> Reviewed-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
> 
>    Fred
> 

Good point, I'll add this in the next revision.


-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australiamob: 0423 762 819

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[PATCH v2 4/7] ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The function removes the process element from NPU cache.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/pnv-ocxl.h   | 2 +-
 arch/powerpc/platforms/powernv/ocxl.c | 4 ++--
 drivers/misc/ocxl/link.c              | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/pnv-ocxl.h b/arch/powerpc/include/asm/pnv-ocxl.h
index f6945d3bc971..208b5503f4ed 100644
--- a/arch/powerpc/include/asm/pnv-ocxl.h
+++ b/arch/powerpc/include/asm/pnv-ocxl.h
@@ -28,7 +28,7 @@ extern int pnv_ocxl_map_xsl_regs(struct pci_dev *dev, void __iomem **dsisr,
 extern int pnv_ocxl_spa_setup(struct pci_dev *dev, void *spa_mem, int PE_mask,
 			void **platform_data);
 extern void pnv_ocxl_spa_release(void *platform_data);
-extern int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle);
+extern int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle);
 
 extern int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr);
 extern void pnv_ocxl_free_xive_irq(u32 irq);
diff --git a/arch/powerpc/platforms/powernv/ocxl.c b/arch/powerpc/platforms/powernv/ocxl.c
index fa9b53af3c7b..8c65aacda9c8 100644
--- a/arch/powerpc/platforms/powernv/ocxl.c
+++ b/arch/powerpc/platforms/powernv/ocxl.c
@@ -475,7 +475,7 @@ void pnv_ocxl_spa_release(void *platform_data)
 }
 EXPORT_SYMBOL_GPL(pnv_ocxl_spa_release);
 
-int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
+int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle)
 {
 	struct spa_data *data = (struct spa_data *) platform_data;
 	int rc;
@@ -483,7 +483,7 @@ int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
 	rc = opal_npu_spa_clear_cache(data->phb_opal_id, data->bdfn, pe_handle);
 	return rc;
 }
-EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe);
+EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe_from_cache);
 
 int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr)
 {
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index f30790582dc0..656e8610eec2 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -599,7 +599,7 @@ int ocxl_link_remove_pe(void *link_handle, int pasid)
 	 * On powerpc, the entry needs to be cleared from the context
 	 * cache of the NPU.
 	 */
-	rc = pnv_ocxl_spa_remove_pe(link->platform_data, pe_handle);
+	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
 	WARN_ON(rc);
 
 	pe_data = radix_tree_delete(&spa->pe_tree, pe_handle);
-- 
2.14.3

[PATCH v2 4/7] ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The function removes the process element from NPU cache.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/pnv-ocxl.h   | 2 +-
 arch/powerpc/platforms/powernv/ocxl.c | 4 ++--
 drivers/misc/ocxl/link.c              | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/pnv-ocxl.h b/arch/powerpc/include/asm/pnv-ocxl.h
index f6945d3bc971..208b5503f4ed 100644
--- a/arch/powerpc/include/asm/pnv-ocxl.h
+++ b/arch/powerpc/include/asm/pnv-ocxl.h
@@ -28,7 +28,7 @@ extern int pnv_ocxl_map_xsl_regs(struct pci_dev *dev, void __iomem **dsisr,
 extern int pnv_ocxl_spa_setup(struct pci_dev *dev, void *spa_mem, int PE_mask,
 			void **platform_data);
 extern void pnv_ocxl_spa_release(void *platform_data);
-extern int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle);
+extern int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle);
 
 extern int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr);
 extern void pnv_ocxl_free_xive_irq(u32 irq);
diff --git a/arch/powerpc/platforms/powernv/ocxl.c b/arch/powerpc/platforms/powernv/ocxl.c
index fa9b53af3c7b..8c65aacda9c8 100644
--- a/arch/powerpc/platforms/powernv/ocxl.c
+++ b/arch/powerpc/platforms/powernv/ocxl.c
@@ -475,7 +475,7 @@ void pnv_ocxl_spa_release(void *platform_data)
 }
 EXPORT_SYMBOL_GPL(pnv_ocxl_spa_release);
 
-int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
+int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle)
 {
 	struct spa_data *data = (struct spa_data *) platform_data;
 	int rc;
@@ -483,7 +483,7 @@ int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
 	rc = opal_npu_spa_clear_cache(data->phb_opal_id, data->bdfn, pe_handle);
 	return rc;
 }
-EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe);
+EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe_from_cache);
 
 int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr)
 {
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index f30790582dc0..656e8610eec2 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -599,7 +599,7 @@ int ocxl_link_remove_pe(void *link_handle, int pasid)
 	 * On powerpc, the entry needs to be cleared from the context
 	 * cache of the NPU.
 	 */
-	rc = pnv_ocxl_spa_remove_pe(link->platform_data, pe_handle);
+	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
 	WARN_ON(rc);
 
 	pe_data = radix_tree_delete(&spa->pe_tree, pe_handle);
-- 
2.14.3

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Re: [PATCH v2 4/7] ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action

[Frederic Barrat]

Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> The function removes the process element from NPU cache.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---

Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>


>   arch/powerpc/include/asm/pnv-ocxl.h   | 2 +-
>   arch/powerpc/platforms/powernv/ocxl.c | 4 ++--
>   drivers/misc/ocxl/link.c              | 2 +-
>   3 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/pnv-ocxl.h b/arch/powerpc/include/asm/pnv-ocxl.h
> index f6945d3bc971..208b5503f4ed 100644
> --- a/arch/powerpc/include/asm/pnv-ocxl.h
> +++ b/arch/powerpc/include/asm/pnv-ocxl.h
> @@ -28,7 +28,7 @@ extern int pnv_ocxl_map_xsl_regs(struct pci_dev *dev, void __iomem **dsisr,
>   extern int pnv_ocxl_spa_setup(struct pci_dev *dev, void *spa_mem, int PE_mask,
>   			void **platform_data);
>   extern void pnv_ocxl_spa_release(void *platform_data);
> -extern int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle);
> +extern int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle);
> 
>   extern int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr);
>   extern void pnv_ocxl_free_xive_irq(u32 irq);
> diff --git a/arch/powerpc/platforms/powernv/ocxl.c b/arch/powerpc/platforms/powernv/ocxl.c
> index fa9b53af3c7b..8c65aacda9c8 100644
> --- a/arch/powerpc/platforms/powernv/ocxl.c
> +++ b/arch/powerpc/platforms/powernv/ocxl.c
> @@ -475,7 +475,7 @@ void pnv_ocxl_spa_release(void *platform_data)
>   }
>   EXPORT_SYMBOL_GPL(pnv_ocxl_spa_release);
> 
> -int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
> +int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle)
>   {
>   	struct spa_data *data = (struct spa_data *) platform_data;
>   	int rc;
> @@ -483,7 +483,7 @@ int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
>   	rc = opal_npu_spa_clear_cache(data->phb_opal_id, data->bdfn, pe_handle);
>   	return rc;
>   }
> -EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe);
> +EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe_from_cache);
> 
>   int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr)
>   {
> diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
> index f30790582dc0..656e8610eec2 100644
> --- a/drivers/misc/ocxl/link.c
> +++ b/drivers/misc/ocxl/link.c
> @@ -599,7 +599,7 @@ int ocxl_link_remove_pe(void *link_handle, int pasid)
>   	 * On powerpc, the entry needs to be cleared from the context
>   	 * cache of the NPU.
>   	 */
> -	rc = pnv_ocxl_spa_remove_pe(link->platform_data, pe_handle);
> +	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
>   	WARN_ON(rc);
> 
>   	pe_data = radix_tree_delete(&spa->pe_tree, pe_handle);
> 

Re: [PATCH v2 4/7] ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action

[Frederic Barrat]

Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> The function removes the process element from NPU cache.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---

Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>


>   arch/powerpc/include/asm/pnv-ocxl.h   | 2 +-
>   arch/powerpc/platforms/powernv/ocxl.c | 4 ++--
>   drivers/misc/ocxl/link.c              | 2 +-
>   3 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/pnv-ocxl.h b/arch/powerpc/include/asm/pnv-ocxl.h
> index f6945d3bc971..208b5503f4ed 100644
> --- a/arch/powerpc/include/asm/pnv-ocxl.h
> +++ b/arch/powerpc/include/asm/pnv-ocxl.h
> @@ -28,7 +28,7 @@ extern int pnv_ocxl_map_xsl_regs(struct pci_dev *dev, void __iomem **dsisr,
>   extern int pnv_ocxl_spa_setup(struct pci_dev *dev, void *spa_mem, int PE_mask,
>   			void **platform_data);
>   extern void pnv_ocxl_spa_release(void *platform_data);
> -extern int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle);
> +extern int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle);
> 
>   extern int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr);
>   extern void pnv_ocxl_free_xive_irq(u32 irq);
> diff --git a/arch/powerpc/platforms/powernv/ocxl.c b/arch/powerpc/platforms/powernv/ocxl.c
> index fa9b53af3c7b..8c65aacda9c8 100644
> --- a/arch/powerpc/platforms/powernv/ocxl.c
> +++ b/arch/powerpc/platforms/powernv/ocxl.c
> @@ -475,7 +475,7 @@ void pnv_ocxl_spa_release(void *platform_data)
>   }
>   EXPORT_SYMBOL_GPL(pnv_ocxl_spa_release);
> 
> -int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
> +int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle)
>   {
>   	struct spa_data *data = (struct spa_data *) platform_data;
>   	int rc;
> @@ -483,7 +483,7 @@ int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
>   	rc = opal_npu_spa_clear_cache(data->phb_opal_id, data->bdfn, pe_handle);
>   	return rc;
>   }
> -EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe);
> +EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe_from_cache);
> 
>   int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr)
>   {
> diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
> index f30790582dc0..656e8610eec2 100644
> --- a/drivers/misc/ocxl/link.c
> +++ b/drivers/misc/ocxl/link.c
> @@ -599,7 +599,7 @@ int ocxl_link_remove_pe(void *link_handle, int pasid)
>   	 * On powerpc, the entry needs to be cleared from the context
>   	 * cache of the NPU.
>   	 */
> -	rc = pnv_ocxl_spa_remove_pe(link->platform_data, pe_handle);
> +	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
>   	WARN_ON(rc);
> 
>   	pe_data = radix_tree_delete(&spa->pe_tree, pe_handle);
> 

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[PATCH v2 5/7] ocxl: Expose the thread_id needed for wait on p9

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

In order to successfully issue as_notify, an AFU needs to know the TID
to notify, which in turn means that this information should be
available in userspace so it can be communicated to the AFU.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/misc/ocxl/context.c       |  5 +++-
 drivers/misc/ocxl/file.c          | 53 +++++++++++++++++++++++++++++++++++++++
 drivers/misc/ocxl/link.c          | 36 ++++++++++++++++++++++++++
 drivers/misc/ocxl/ocxl_internal.h |  1 +
 include/misc/ocxl.h               |  9 +++++++
 include/uapi/misc/ocxl.h          | 10 ++++++++
 6 files changed, 113 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
index 909e8807824a..95f74623113e 100644
--- a/drivers/misc/ocxl/context.c
+++ b/drivers/misc/ocxl/context.c
@@ -34,6 +34,8 @@ int ocxl_context_init(struct ocxl_context *ctx, struct ocxl_afu *afu,
 	mutex_init(&ctx->xsl_error_lock);
 	mutex_init(&ctx->irq_lock);
 	idr_init(&ctx->irq_idr);
+	ctx->tidr = 0;
+
 	/*
 	 * Keep a reference on the AFU to make sure it's valid for the
 	 * duration of the life of the context
@@ -65,6 +67,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 {
 	int rc;
 
+	// Locks both status & tidr
 	mutex_lock(&ctx->status_mutex);
 	if (ctx->status != OPENED) {
 		rc = -EIO;
@@ -72,7 +75,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 	}
 
 	rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid,
-			current->mm->context.id, 0, amr, current->mm,
+			current->mm->context.id, ctx->tidr, amr, current->mm,
 			xsl_fault_error, ctx);
 	if (rc)
 		goto out;
diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index 038509e5d031..eb409a469f21 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -5,6 +5,8 @@
 #include <linux/sched/signal.h>
 #include <linux/uaccess.h>
 #include <uapi/misc/ocxl.h>
+#include <asm/reg.h>
+#include <asm/switch_to.h>
 #include "ocxl_internal.h"
 
 
@@ -123,11 +125,55 @@ static long afu_ioctl_get_metadata(struct ocxl_context *ctx,
 	return 0;
 }
 
+#ifdef CONFIG_PPC64
+static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
+		struct ocxl_ioctl_p9_wait __user *uarg)
+{
+	struct ocxl_ioctl_p9_wait arg;
+
+	memset(&arg, 0, sizeof(arg));
+
+	if (cpu_has_feature(CPU_FTR_P9_TIDR)) {
+		enum ocxl_context_status status;
+
+		// Locks both status & tidr
+		mutex_lock(&ctx->status_mutex);
+		if (!ctx->tidr) {
+			if (set_thread_tidr(current))
+				return -ENOENT;
+
+			ctx->tidr = current->thread.tidr;
+		}
+
+		status = ctx->status;
+		mutex_unlock(&ctx->status_mutex);
+
+		if (status == ATTACHED) {
+			int rc;
+			struct link *link = ctx->afu->fn->link;
+
+			rc = ocxl_link_update_pe(link, ctx->pasid, ctx->tidr);
+			if (rc)
+				return rc;
+		}
+
+		arg.thread_id = ctx->tidr;
+	} else
+		return -ENOENT;
+
+	if (copy_to_user(uarg, &arg, sizeof(arg)))
+		return -EFAULT;
+
+	return 0;
+}
+#endif
+
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
 			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
 			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
 			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
 			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
+			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
 			"UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -186,6 +232,13 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 				(struct ocxl_ioctl_metadata __user *) args);
 		break;
 
+#ifdef CONFIG_PPC64
+	case OCXL_IOCTL_ENABLE_P9_WAIT:
+		rc = afu_ioctl_enable_p9_wait(ctx,
+				(struct ocxl_ioctl_p9_wait __user *) args);
+		break;
+#endif
+
 	default:
 		rc = -EINVAL;
 	}
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index 656e8610eec2..88876ae8f330 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -544,6 +544,42 @@ int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
 }
 EXPORT_SYMBOL_GPL(ocxl_link_add_pe);
 
+int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid)
+{
+	struct link *link = (struct link *) link_handle;
+	struct spa *spa = link->spa;
+	struct ocxl_process_element *pe;
+	int pe_handle, rc;
+
+	if (pasid > SPA_PASID_MAX)
+		return -EINVAL;
+
+	pe_handle = pasid & SPA_PE_MASK;
+	pe = spa->spa_mem + pe_handle;
+
+	mutex_lock(&spa->spa_lock);
+
+	pe->tid = tid;
+
+	/*
+	 * The barrier makes sure the PE is updated
+	 * before we clear the NPU context cache below, so that the
+	 * old PE cannot be reloaded erroneously.
+	 */
+	mb();
+
+	/*
+	 * hook to platform code
+	 * On powerpc, the entry needs to be cleared from the context
+	 * cache of the NPU.
+	 */
+	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
+	WARN_ON(rc);
+
+	mutex_unlock(&spa->spa_lock);
+	return rc;
+}
+
 int ocxl_link_remove_pe(void *link_handle, int pasid)
 {
 	struct link *link = (struct link *) link_handle;
diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
index 5d421824afd9..6c6d4e61888e 100644
--- a/drivers/misc/ocxl/ocxl_internal.h
+++ b/drivers/misc/ocxl/ocxl_internal.h
@@ -77,6 +77,7 @@ struct ocxl_context {
 	struct ocxl_xsl_error xsl_error;
 	struct mutex irq_lock;
 	struct idr irq_idr;
+	__u16 tidr; // Thread ID used for P9 wait implementation
 };
 
 struct ocxl_process_element {
diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
index 51ccf76db293..9ff6ddc28e22 100644
--- a/include/misc/ocxl.h
+++ b/include/misc/ocxl.h
@@ -188,6 +188,15 @@ extern int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
 		void (*xsl_err_cb)(void *data, u64 addr, u64 dsisr),
 		void *xsl_err_data);
 
+/**
+ * Update values within a Process Element
+ *
+ * link_handle: the link handle associated with the process element
+ * pasid: the PASID for the AFU context
+ * tid: the new thread id for the process element
+ */
+extern int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid);
+
 /*
  * Remove a Process Element from the Shared Process Area for a link
  */
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 0af83d80fb3e..8d2748e69c84 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -48,6 +48,15 @@ struct ocxl_ioctl_metadata {
 	__u64 reserved[13]; // Total of 16*u64
 };
 
+struct ocxl_ioctl_p9_wait {
+	__u16 thread_id; // The thread ID required to wake this thread
+	__u16 reserved1;
+	__u32 reserved2;
+	__u64 reserved3[3];
+};
+
+};
+
 struct ocxl_ioctl_irq_fd {
 	__u64 irq_offset;
 	__s32 eventfd;
@@ -62,5 +71,6 @@ struct ocxl_ioctl_irq_fd {
 #define OCXL_IOCTL_IRQ_FREE	_IOW(OCXL_MAGIC, 0x12, __u64)
 #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
+#define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.3

[PATCH v2 5/7] ocxl: Expose the thread_id needed for wait on p9

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

In order to successfully issue as_notify, an AFU needs to know the TID
to notify, which in turn means that this information should be
available in userspace so it can be communicated to the AFU.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/misc/ocxl/context.c       |  5 +++-
 drivers/misc/ocxl/file.c          | 53 +++++++++++++++++++++++++++++++++++++++
 drivers/misc/ocxl/link.c          | 36 ++++++++++++++++++++++++++
 drivers/misc/ocxl/ocxl_internal.h |  1 +
 include/misc/ocxl.h               |  9 +++++++
 include/uapi/misc/ocxl.h          | 10 ++++++++
 6 files changed, 113 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
index 909e8807824a..95f74623113e 100644
--- a/drivers/misc/ocxl/context.c
+++ b/drivers/misc/ocxl/context.c
@@ -34,6 +34,8 @@ int ocxl_context_init(struct ocxl_context *ctx, struct ocxl_afu *afu,
 	mutex_init(&ctx->xsl_error_lock);
 	mutex_init(&ctx->irq_lock);
 	idr_init(&ctx->irq_idr);
+	ctx->tidr = 0;
+
 	/*
 	 * Keep a reference on the AFU to make sure it's valid for the
 	 * duration of the life of the context
@@ -65,6 +67,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 {
 	int rc;
 
+	// Locks both status & tidr
 	mutex_lock(&ctx->status_mutex);
 	if (ctx->status != OPENED) {
 		rc = -EIO;
@@ -72,7 +75,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 	}
 
 	rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid,
-			current->mm->context.id, 0, amr, current->mm,
+			current->mm->context.id, ctx->tidr, amr, current->mm,
 			xsl_fault_error, ctx);
 	if (rc)
 		goto out;
diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index 038509e5d031..eb409a469f21 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -5,6 +5,8 @@
 #include <linux/sched/signal.h>
 #include <linux/uaccess.h>
 #include <uapi/misc/ocxl.h>
+#include <asm/reg.h>
+#include <asm/switch_to.h>
 #include "ocxl_internal.h"
 
 
@@ -123,11 +125,55 @@ static long afu_ioctl_get_metadata(struct ocxl_context *ctx,
 	return 0;
 }
 
+#ifdef CONFIG_PPC64
+static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
+		struct ocxl_ioctl_p9_wait __user *uarg)
+{
+	struct ocxl_ioctl_p9_wait arg;
+
+	memset(&arg, 0, sizeof(arg));
+
+	if (cpu_has_feature(CPU_FTR_P9_TIDR)) {
+		enum ocxl_context_status status;
+
+		// Locks both status & tidr
+		mutex_lock(&ctx->status_mutex);
+		if (!ctx->tidr) {
+			if (set_thread_tidr(current))
+				return -ENOENT;
+
+			ctx->tidr = current->thread.tidr;
+		}
+
+		status = ctx->status;
+		mutex_unlock(&ctx->status_mutex);
+
+		if (status == ATTACHED) {
+			int rc;
+			struct link *link = ctx->afu->fn->link;
+
+			rc = ocxl_link_update_pe(link, ctx->pasid, ctx->tidr);
+			if (rc)
+				return rc;
+		}
+
+		arg.thread_id = ctx->tidr;
+	} else
+		return -ENOENT;
+
+	if (copy_to_user(uarg, &arg, sizeof(arg)))
+		return -EFAULT;
+
+	return 0;
+}
+#endif
+
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
 			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
 			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
 			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
 			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
+			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
 			"UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -186,6 +232,13 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 				(struct ocxl_ioctl_metadata __user *) args);
 		break;
 
+#ifdef CONFIG_PPC64
+	case OCXL_IOCTL_ENABLE_P9_WAIT:
+		rc = afu_ioctl_enable_p9_wait(ctx,
+				(struct ocxl_ioctl_p9_wait __user *) args);
+		break;
+#endif
+
 	default:
 		rc = -EINVAL;
 	}
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index 656e8610eec2..88876ae8f330 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -544,6 +544,42 @@ int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
 }
 EXPORT_SYMBOL_GPL(ocxl_link_add_pe);
 
+int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid)
+{
+	struct link *link = (struct link *) link_handle;
+	struct spa *spa = link->spa;
+	struct ocxl_process_element *pe;
+	int pe_handle, rc;
+
+	if (pasid > SPA_PASID_MAX)
+		return -EINVAL;
+
+	pe_handle = pasid & SPA_PE_MASK;
+	pe = spa->spa_mem + pe_handle;
+
+	mutex_lock(&spa->spa_lock);
+
+	pe->tid = tid;
+
+	/*
+	 * The barrier makes sure the PE is updated
+	 * before we clear the NPU context cache below, so that the
+	 * old PE cannot be reloaded erroneously.
+	 */
+	mb();
+
+	/*
+	 * hook to platform code
+	 * On powerpc, the entry needs to be cleared from the context
+	 * cache of the NPU.
+	 */
+	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
+	WARN_ON(rc);
+
+	mutex_unlock(&spa->spa_lock);
+	return rc;
+}
+
 int ocxl_link_remove_pe(void *link_handle, int pasid)
 {
 	struct link *link = (struct link *) link_handle;
diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
index 5d421824afd9..6c6d4e61888e 100644
--- a/drivers/misc/ocxl/ocxl_internal.h
+++ b/drivers/misc/ocxl/ocxl_internal.h
@@ -77,6 +77,7 @@ struct ocxl_context {
 	struct ocxl_xsl_error xsl_error;
 	struct mutex irq_lock;
 	struct idr irq_idr;
+	__u16 tidr; // Thread ID used for P9 wait implementation
 };
 
 struct ocxl_process_element {
diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
index 51ccf76db293..9ff6ddc28e22 100644
--- a/include/misc/ocxl.h
+++ b/include/misc/ocxl.h
@@ -188,6 +188,15 @@ extern int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
 		void (*xsl_err_cb)(void *data, u64 addr, u64 dsisr),
 		void *xsl_err_data);
 
+/**
+ * Update values within a Process Element
+ *
+ * link_handle: the link handle associated with the process element
+ * pasid: the PASID for the AFU context
+ * tid: the new thread id for the process element
+ */
+extern int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid);
+
 /*
  * Remove a Process Element from the Shared Process Area for a link
  */
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 0af83d80fb3e..8d2748e69c84 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -48,6 +48,15 @@ struct ocxl_ioctl_metadata {
 	__u64 reserved[13]; // Total of 16*u64
 };
 
+struct ocxl_ioctl_p9_wait {
+	__u16 thread_id; // The thread ID required to wake this thread
+	__u16 reserved1;
+	__u32 reserved2;
+	__u64 reserved3[3];
+};
+
+};
+
 struct ocxl_ioctl_irq_fd {
 	__u64 irq_offset;
 	__s32 eventfd;
@@ -62,5 +71,6 @@ struct ocxl_ioctl_irq_fd {
 #define OCXL_IOCTL_IRQ_FREE	_IOW(OCXL_MAGIC, 0x12, __u64)
 #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
+#define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.3

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Re: [PATCH v2 5/7] ocxl: Expose the thread_id needed for wait on p9

[Andrew Donnellan]

On 18/04/18 11:08, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> In order to successfully issue as_notify, an AFU needs to know the TID
> to notify, which in turn means that this information should be
> available in userspace so it can be communicated to the AFU.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>

nitpicks below

Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

> ---
>   drivers/misc/ocxl/context.c       |  5 +++-
>   drivers/misc/ocxl/file.c          | 53 +++++++++++++++++++++++++++++++++++++++
>   drivers/misc/ocxl/link.c          | 36 ++++++++++++++++++++++++++
>   drivers/misc/ocxl/ocxl_internal.h |  1 +
>   include/misc/ocxl.h               |  9 +++++++
>   include/uapi/misc/ocxl.h          | 10 ++++++++
>   6 files changed, 113 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
> index 909e8807824a..95f74623113e 100644
> --- a/drivers/misc/ocxl/context.c
> +++ b/drivers/misc/ocxl/context.c
> @@ -34,6 +34,8 @@ int ocxl_context_init(struct ocxl_context *ctx, struct ocxl_afu *afu,
>   	mutex_init(&ctx->xsl_error_lock);
>   	mutex_init(&ctx->irq_lock);
>   	idr_init(&ctx->irq_idr);
> +	ctx->tidr = 0;
> +
>   	/*
>   	 * Keep a reference on the AFU to make sure it's valid for the
>   	 * duration of the life of the context
> @@ -65,6 +67,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
>   {
>   	int rc;
>   
> +	// Locks both status & tidr
>   	mutex_lock(&ctx->status_mutex);
>   	if (ctx->status != OPENED) {
>   		rc = -EIO;
> @@ -72,7 +75,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
>   	}
>   
>   	rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid,
> -			current->mm->context.id, 0, amr, current->mm,
> +			current->mm->context.id, ctx->tidr, amr, current->mm,
>   			xsl_fault_error, ctx);
>   	if (rc)
>   		goto out;
> diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
> index 038509e5d031..eb409a469f21 100644
> --- a/drivers/misc/ocxl/file.c
> +++ b/drivers/misc/ocxl/file.c
> @@ -5,6 +5,8 @@
>   #include <linux/sched/signal.h>
>   #include <linux/uaccess.h>
>   #include <uapi/misc/ocxl.h>
> +#include <asm/reg.h>
> +#include <asm/switch_to.h>
>   #include "ocxl_internal.h"
>   
>   
> @@ -123,11 +125,55 @@ static long afu_ioctl_get_metadata(struct ocxl_context *ctx,
>   	return 0;
>   }
>   
> +#ifdef CONFIG_PPC64
> +static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
> +		struct ocxl_ioctl_p9_wait __user *uarg)
> +{
> +	struct ocxl_ioctl_p9_wait arg;
> +
> +	memset(&arg, 0, sizeof(arg));
> +
> +	if (cpu_has_feature(CPU_FTR_P9_TIDR)) {
> +		enum ocxl_context_status status;
> +
> +		// Locks both status & tidr
> +		mutex_lock(&ctx->status_mutex);
> +		if (!ctx->tidr) {
> +			if (set_thread_tidr(current))
> +				return -ENOENT;
> +
> +			ctx->tidr = current->thread.tidr;
> +		}
> +
> +		status = ctx->status;
> +		mutex_unlock(&ctx->status_mutex);
> +
> +		if (status == ATTACHED) {
> +			int rc;
> +			struct link *link = ctx->afu->fn->link;

Declarations at the top

> +
> +			rc = ocxl_link_update_pe(link, ctx->pasid, ctx->tidr);
> +			if (rc)
> +				return rc;
> +		}
> +
> +		arg.thread_id = ctx->tidr;
> +	} else
> +		return -ENOENT;
> +
> +	if (copy_to_user(uarg, &arg, sizeof(arg)))
> +		return -EFAULT;
> +
> +	return 0;
> +}
> +#endif
> +
>   #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
>   			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
>   			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
>   			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
>   			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
> +			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
>   			"UNKNOWN")
>   
>   static long afu_ioctl(struct file *file, unsigned int cmd,
> @@ -186,6 +232,13 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
>   				(struct ocxl_ioctl_metadata __user *) args);
>   		break;
>   
> +#ifdef CONFIG_PPC64
> +	case OCXL_IOCTL_ENABLE_P9_WAIT:
> +		rc = afu_ioctl_enable_p9_wait(ctx,
> +				(struct ocxl_ioctl_p9_wait __user *) args);
> +		break;
> +#endif
> +
>   	default:
>   		rc = -EINVAL;
>   	}
> diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
> index 656e8610eec2..88876ae8f330 100644
> --- a/drivers/misc/ocxl/link.c
> +++ b/drivers/misc/ocxl/link.c
> @@ -544,6 +544,42 @@ int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
>   }
>   EXPORT_SYMBOL_GPL(ocxl_link_add_pe);
>   
> +int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid)
> +{
> +	struct link *link = (struct link *) link_handle;
> +	struct spa *spa = link->spa;
> +	struct ocxl_process_element *pe;
> +	int pe_handle, rc;
> +
> +	if (pasid > SPA_PASID_MAX)
> +		return -EINVAL;
> +
> +	pe_handle = pasid & SPA_PE_MASK;
> +	pe = spa->spa_mem + pe_handle;
> +
> +	mutex_lock(&spa->spa_lock);
> +
> +	pe->tid = tid;
> +
> +	/*
> +	 * The barrier makes sure the PE is updated
> +	 * before we clear the NPU context cache below, so that the
> +	 * old PE cannot be reloaded erroneously.
> +	 */
> +	mb();
> +
> +	/*
> +	 * hook to platform code
> +	 * On powerpc, the entry needs to be cleared from the context
> +	 * cache of the NPU.
> +	 */
> +	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
> +	WARN_ON(rc);
> +
> +	mutex_unlock(&spa->spa_lock);
> +	return rc;
> +}
> +
>   int ocxl_link_remove_pe(void *link_handle, int pasid)
>   {
>   	struct link *link = (struct link *) link_handle;
> diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
> index 5d421824afd9..6c6d4e61888e 100644
> --- a/drivers/misc/ocxl/ocxl_internal.h
> +++ b/drivers/misc/ocxl/ocxl_internal.h
> @@ -77,6 +77,7 @@ struct ocxl_context {
>   	struct ocxl_xsl_error xsl_error;
>   	struct mutex irq_lock;
>   	struct idr irq_idr;
> +	__u16 tidr; // Thread ID used for P9 wait implementation

What's the difference between u16 and __u16...

>   };
>   
>   struct ocxl_process_element {
> diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
> index 51ccf76db293..9ff6ddc28e22 100644
> --- a/include/misc/ocxl.h
> +++ b/include/misc/ocxl.h
> @@ -188,6 +188,15 @@ extern int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
>   		void (*xsl_err_cb)(void *data, u64 addr, u64 dsisr),
>   		void *xsl_err_data);
>   
> +/**
> + * Update values within a Process Element
> + *
> + * link_handle: the link handle associated with the process element
> + * pasid: the PASID for the AFU context
> + * tid: the new thread id for the process element
> + */
> +extern int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid);
> +
>   /*
>    * Remove a Process Element from the Shared Process Area for a link
>    */
> diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
> index 0af83d80fb3e..8d2748e69c84 100644
> --- a/include/uapi/misc/ocxl.h
> +++ b/include/uapi/misc/ocxl.h
> @@ -48,6 +48,15 @@ struct ocxl_ioctl_metadata {
>   	__u64 reserved[13]; // Total of 16*u64
>   };
>   
> +struct ocxl_ioctl_p9_wait {
> +	__u16 thread_id; // The thread ID required to wake this thread
> +	__u16 reserved1;
> +	__u32 reserved2;
> +	__u64 reserved3[3];
> +};
> +
> +};
> +
>   struct ocxl_ioctl_irq_fd {
>   	__u64 irq_offset;
>   	__s32 eventfd;
> @@ -62,5 +71,6 @@ struct ocxl_ioctl_irq_fd {
>   #define OCXL_IOCTL_IRQ_FREE	_IOW(OCXL_MAGIC, 0x12, __u64)
>   #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
>   #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
> +#define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
>   
>   #endif /* _UAPI_MISC_OCXL_H */
> 

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

Re: [PATCH v2 5/7] ocxl: Expose the thread_id needed for wait on p9

[Andrew Donnellan]

On 18/04/18 11:08, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> In order to successfully issue as_notify, an AFU needs to know the TID
> to notify, which in turn means that this information should be
> available in userspace so it can be communicated to the AFU.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>

nitpicks below

Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

> ---
>   drivers/misc/ocxl/context.c       |  5 +++-
>   drivers/misc/ocxl/file.c          | 53 +++++++++++++++++++++++++++++++++++++++
>   drivers/misc/ocxl/link.c          | 36 ++++++++++++++++++++++++++
>   drivers/misc/ocxl/ocxl_internal.h |  1 +
>   include/misc/ocxl.h               |  9 +++++++
>   include/uapi/misc/ocxl.h          | 10 ++++++++
>   6 files changed, 113 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
> index 909e8807824a..95f74623113e 100644
> --- a/drivers/misc/ocxl/context.c
> +++ b/drivers/misc/ocxl/context.c
> @@ -34,6 +34,8 @@ int ocxl_context_init(struct ocxl_context *ctx, struct ocxl_afu *afu,
>   	mutex_init(&ctx->xsl_error_lock);
>   	mutex_init(&ctx->irq_lock);
>   	idr_init(&ctx->irq_idr);
> +	ctx->tidr = 0;
> +
>   	/*
>   	 * Keep a reference on the AFU to make sure it's valid for the
>   	 * duration of the life of the context
> @@ -65,6 +67,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
>   {
>   	int rc;
>   
> +	// Locks both status & tidr
>   	mutex_lock(&ctx->status_mutex);
>   	if (ctx->status != OPENED) {
>   		rc = -EIO;
> @@ -72,7 +75,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
>   	}
>   
>   	rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid,
> -			current->mm->context.id, 0, amr, current->mm,
> +			current->mm->context.id, ctx->tidr, amr, current->mm,
>   			xsl_fault_error, ctx);
>   	if (rc)
>   		goto out;
> diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
> index 038509e5d031..eb409a469f21 100644
> --- a/drivers/misc/ocxl/file.c
> +++ b/drivers/misc/ocxl/file.c
> @@ -5,6 +5,8 @@
>   #include <linux/sched/signal.h>
>   #include <linux/uaccess.h>
>   #include <uapi/misc/ocxl.h>
> +#include <asm/reg.h>
> +#include <asm/switch_to.h>
>   #include "ocxl_internal.h"
>   
>   
> @@ -123,11 +125,55 @@ static long afu_ioctl_get_metadata(struct ocxl_context *ctx,
>   	return 0;
>   }
>   
> +#ifdef CONFIG_PPC64
> +static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
> +		struct ocxl_ioctl_p9_wait __user *uarg)
> +{
> +	struct ocxl_ioctl_p9_wait arg;
> +
> +	memset(&arg, 0, sizeof(arg));
> +
> +	if (cpu_has_feature(CPU_FTR_P9_TIDR)) {
> +		enum ocxl_context_status status;
> +
> +		// Locks both status & tidr
> +		mutex_lock(&ctx->status_mutex);
> +		if (!ctx->tidr) {
> +			if (set_thread_tidr(current))
> +				return -ENOENT;
> +
> +			ctx->tidr = current->thread.tidr;
> +		}
> +
> +		status = ctx->status;
> +		mutex_unlock(&ctx->status_mutex);
> +
> +		if (status == ATTACHED) {
> +			int rc;
> +			struct link *link = ctx->afu->fn->link;

Declarations at the top

> +
> +			rc = ocxl_link_update_pe(link, ctx->pasid, ctx->tidr);
> +			if (rc)
> +				return rc;
> +		}
> +
> +		arg.thread_id = ctx->tidr;
> +	} else
> +		return -ENOENT;
> +
> +	if (copy_to_user(uarg, &arg, sizeof(arg)))
> +		return -EFAULT;
> +
> +	return 0;
> +}
> +#endif
> +
>   #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
>   			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
>   			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
>   			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
>   			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
> +			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
>   			"UNKNOWN")
>   
>   static long afu_ioctl(struct file *file, unsigned int cmd,
> @@ -186,6 +232,13 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
>   				(struct ocxl_ioctl_metadata __user *) args);
>   		break;
>   
> +#ifdef CONFIG_PPC64
> +	case OCXL_IOCTL_ENABLE_P9_WAIT:
> +		rc = afu_ioctl_enable_p9_wait(ctx,
> +				(struct ocxl_ioctl_p9_wait __user *) args);
> +		break;
> +#endif
> +
>   	default:
>   		rc = -EINVAL;
>   	}
> diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
> index 656e8610eec2..88876ae8f330 100644
> --- a/drivers/misc/ocxl/link.c
> +++ b/drivers/misc/ocxl/link.c
> @@ -544,6 +544,42 @@ int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
>   }
>   EXPORT_SYMBOL_GPL(ocxl_link_add_pe);
>   
> +int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid)
> +{
> +	struct link *link = (struct link *) link_handle;
> +	struct spa *spa = link->spa;
> +	struct ocxl_process_element *pe;
> +	int pe_handle, rc;
> +
> +	if (pasid > SPA_PASID_MAX)
> +		return -EINVAL;
> +
> +	pe_handle = pasid & SPA_PE_MASK;
> +	pe = spa->spa_mem + pe_handle;
> +
> +	mutex_lock(&spa->spa_lock);
> +
> +	pe->tid = tid;
> +
> +	/*
> +	 * The barrier makes sure the PE is updated
> +	 * before we clear the NPU context cache below, so that the
> +	 * old PE cannot be reloaded erroneously.
> +	 */
> +	mb();
> +
> +	/*
> +	 * hook to platform code
> +	 * On powerpc, the entry needs to be cleared from the context
> +	 * cache of the NPU.
> +	 */
> +	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
> +	WARN_ON(rc);
> +
> +	mutex_unlock(&spa->spa_lock);
> +	return rc;
> +}
> +
>   int ocxl_link_remove_pe(void *link_handle, int pasid)
>   {
>   	struct link *link = (struct link *) link_handle;
> diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
> index 5d421824afd9..6c6d4e61888e 100644
> --- a/drivers/misc/ocxl/ocxl_internal.h
> +++ b/drivers/misc/ocxl/ocxl_internal.h
> @@ -77,6 +77,7 @@ struct ocxl_context {
>   	struct ocxl_xsl_error xsl_error;
>   	struct mutex irq_lock;
>   	struct idr irq_idr;
> +	__u16 tidr; // Thread ID used for P9 wait implementation

What's the difference between u16 and __u16...

>   };
>   
>   struct ocxl_process_element {
> diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
> index 51ccf76db293..9ff6ddc28e22 100644
> --- a/include/misc/ocxl.h
> +++ b/include/misc/ocxl.h
> @@ -188,6 +188,15 @@ extern int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
>   		void (*xsl_err_cb)(void *data, u64 addr, u64 dsisr),
>   		void *xsl_err_data);
>   
> +/**
> + * Update values within a Process Element
> + *
> + * link_handle: the link handle associated with the process element
> + * pasid: the PASID for the AFU context
> + * tid: the new thread id for the process element
> + */
> +extern int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid);
> +
>   /*
>    * Remove a Process Element from the Shared Process Area for a link
>    */
> diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
> index 0af83d80fb3e..8d2748e69c84 100644
> --- a/include/uapi/misc/ocxl.h
> +++ b/include/uapi/misc/ocxl.h
> @@ -48,6 +48,15 @@ struct ocxl_ioctl_metadata {
>   	__u64 reserved[13]; // Total of 16*u64
>   };
>   
> +struct ocxl_ioctl_p9_wait {
> +	__u16 thread_id; // The thread ID required to wake this thread
> +	__u16 reserved1;
> +	__u32 reserved2;
> +	__u64 reserved3[3];
> +};
> +
> +};
> +
>   struct ocxl_ioctl_irq_fd {
>   	__u64 irq_offset;
>   	__s32 eventfd;
> @@ -62,5 +71,6 @@ struct ocxl_ioctl_irq_fd {
>   #define OCXL_IOCTL_IRQ_FREE	_IOW(OCXL_MAGIC, 0x12, __u64)
>   #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
>   #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
> +#define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
>   
>   #endif /* _UAPI_MISC_OCXL_H */
> 

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

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Re: [PATCH v2 5/7] ocxl: Expose the thread_id needed for wait on p9

[Frederic Barrat]

Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> In order to successfully issue as_notify, an AFU needs to know the TID
> to notify, which in turn means that this information should be
> available in userspace so it can be communicated to the AFU.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---
>   drivers/misc/ocxl/context.c       |  5 +++-
>   drivers/misc/ocxl/file.c          | 53 +++++++++++++++++++++++++++++++++++++++
>   drivers/misc/ocxl/link.c          | 36 ++++++++++++++++++++++++++
>   drivers/misc/ocxl/ocxl_internal.h |  1 +
>   include/misc/ocxl.h               |  9 +++++++
>   include/uapi/misc/ocxl.h          | 10 ++++++++
>   6 files changed, 113 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
> index 909e8807824a..95f74623113e 100644
> --- a/drivers/misc/ocxl/context.c
> +++ b/drivers/misc/ocxl/context.c
> @@ -34,6 +34,8 @@ int ocxl_context_init(struct ocxl_context *ctx, struct ocxl_afu *afu,
>   	mutex_init(&ctx->xsl_error_lock);
>   	mutex_init(&ctx->irq_lock);
>   	idr_init(&ctx->irq_idr);
> +	ctx->tidr = 0;
> +
>   	/*
>   	 * Keep a reference on the AFU to make sure it's valid for the
>   	 * duration of the life of the context
> @@ -65,6 +67,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
>   {
>   	int rc;
> 
> +	// Locks both status & tidr
>   	mutex_lock(&ctx->status_mutex);
>   	if (ctx->status != OPENED) {
>   		rc = -EIO;
> @@ -72,7 +75,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
>   	}
> 
>   	rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid,
> -			current->mm->context.id, 0, amr, current->mm,
> +			current->mm->context.id, ctx->tidr, amr, current->mm,
>   			xsl_fault_error, ctx);
>   	if (rc)
>   		goto out;
> diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
> index 038509e5d031..eb409a469f21 100644
> --- a/drivers/misc/ocxl/file.c
> +++ b/drivers/misc/ocxl/file.c
> @@ -5,6 +5,8 @@
>   #include <linux/sched/signal.h>
>   #include <linux/uaccess.h>
>   #include <uapi/misc/ocxl.h>
> +#include <asm/reg.h>
> +#include <asm/switch_to.h>
>   #include "ocxl_internal.h"
> 
> 
> @@ -123,11 +125,55 @@ static long afu_ioctl_get_metadata(struct ocxl_context *ctx,
>   	return 0;
>   }
> 
> +#ifdef CONFIG_PPC64
> +static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
> +		struct ocxl_ioctl_p9_wait __user *uarg)
> +{
> +	struct ocxl_ioctl_p9_wait arg;
> +
> +	memset(&arg, 0, sizeof(arg));
> +
> +	if (cpu_has_feature(CPU_FTR_P9_TIDR)) {
> +		enum ocxl_context_status status;
> +
> +		// Locks both status & tidr
> +		mutex_lock(&ctx->status_mutex);
> +		if (!ctx->tidr) {
> +			if (set_thread_tidr(current))
> +				return -ENOENT;
> +
> +			ctx->tidr = current->thread.tidr;
> +		}


Now that we don't have the TIDR limit problem, I'm wondering if we 
cannot relax our rule a bit and have:
- first thread to enable will become the default thread and update the 
Process element
- any subsequent enable would just allocate the TIDR for the calling thread.

That way, more than one thread could be used for 'wait'.
Thoughts?

    Fred


> +
> +		status = ctx->status;
> +		mutex_unlock(&ctx->status_mutex);
> +
> +		if (status == ATTACHED) {
> +			int rc;
> +			struct link *link = ctx->afu->fn->link;
> +
> +			rc = ocxl_link_update_pe(link, ctx->pasid, ctx->tidr);
> +			if (rc)
> +				return rc;
> +		}
> +
> +		arg.thread_id = ctx->tidr;
> +	} else
> +		return -ENOENT;
> +
> +	if (copy_to_user(uarg, &arg, sizeof(arg)))
> +		return -EFAULT;
> +
> +	return 0;
> +}
> +#endif
> +
>   #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
>   			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
>   			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
>   			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
>   			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
> +			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
>   			"UNKNOWN")
> 
>   static long afu_ioctl(struct file *file, unsigned int cmd,
> @@ -186,6 +232,13 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
>   				(struct ocxl_ioctl_metadata __user *) args);
>   		break;
> 
> +#ifdef CONFIG_PPC64
> +	case OCXL_IOCTL_ENABLE_P9_WAIT:
> +		rc = afu_ioctl_enable_p9_wait(ctx,
> +				(struct ocxl_ioctl_p9_wait __user *) args);
> +		break;
> +#endif
> +
>   	default:
>   		rc = -EINVAL;
>   	}
> diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
> index 656e8610eec2..88876ae8f330 100644
> --- a/drivers/misc/ocxl/link.c
> +++ b/drivers/misc/ocxl/link.c
> @@ -544,6 +544,42 @@ int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
>   }
>   EXPORT_SYMBOL_GPL(ocxl_link_add_pe);
> 
> +int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid)
> +{
> +	struct link *link = (struct link *) link_handle;
> +	struct spa *spa = link->spa;
> +	struct ocxl_process_element *pe;
> +	int pe_handle, rc;
> +
> +	if (pasid > SPA_PASID_MAX)
> +		return -EINVAL;
> +
> +	pe_handle = pasid & SPA_PE_MASK;
> +	pe = spa->spa_mem + pe_handle;
> +
> +	mutex_lock(&spa->spa_lock);
> +
> +	pe->tid = tid;
> +
> +	/*
> +	 * The barrier makes sure the PE is updated
> +	 * before we clear the NPU context cache below, so that the
> +	 * old PE cannot be reloaded erroneously.
> +	 */
> +	mb();
> +
> +	/*
> +	 * hook to platform code
> +	 * On powerpc, the entry needs to be cleared from the context
> +	 * cache of the NPU.
> +	 */
> +	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
> +	WARN_ON(rc);
> +
> +	mutex_unlock(&spa->spa_lock);
> +	return rc;
> +}
> +
>   int ocxl_link_remove_pe(void *link_handle, int pasid)
>   {
>   	struct link *link = (struct link *) link_handle;
> diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
> index 5d421824afd9..6c6d4e61888e 100644
> --- a/drivers/misc/ocxl/ocxl_internal.h
> +++ b/drivers/misc/ocxl/ocxl_internal.h
> @@ -77,6 +77,7 @@ struct ocxl_context {
>   	struct ocxl_xsl_error xsl_error;
>   	struct mutex irq_lock;
>   	struct idr irq_idr;
> +	__u16 tidr; // Thread ID used for P9 wait implementation
>   };
> 
>   struct ocxl_process_element {
> diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
> index 51ccf76db293..9ff6ddc28e22 100644
> --- a/include/misc/ocxl.h
> +++ b/include/misc/ocxl.h
> @@ -188,6 +188,15 @@ extern int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
>   		void (*xsl_err_cb)(void *data, u64 addr, u64 dsisr),
>   		void *xsl_err_data);
> 
> +/**
> + * Update values within a Process Element
> + *
> + * link_handle: the link handle associated with the process element
> + * pasid: the PASID for the AFU context
> + * tid: the new thread id for the process element
> + */
> +extern int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid);
> +
>   /*
>    * Remove a Process Element from the Shared Process Area for a link
>    */
> diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
> index 0af83d80fb3e..8d2748e69c84 100644
> --- a/include/uapi/misc/ocxl.h
> +++ b/include/uapi/misc/ocxl.h
> @@ -48,6 +48,15 @@ struct ocxl_ioctl_metadata {
>   	__u64 reserved[13]; // Total of 16*u64
>   };
> 
> +struct ocxl_ioctl_p9_wait {
> +	__u16 thread_id; // The thread ID required to wake this thread
> +	__u16 reserved1;
> +	__u32 reserved2;
> +	__u64 reserved3[3];
> +};
> +
> +};
> +
>   struct ocxl_ioctl_irq_fd {
>   	__u64 irq_offset;
>   	__s32 eventfd;
> @@ -62,5 +71,6 @@ struct ocxl_ioctl_irq_fd {
>   #define OCXL_IOCTL_IRQ_FREE	_IOW(OCXL_MAGIC, 0x12, __u64)
>   #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
>   #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
> +#define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
> 
>   #endif /* _UAPI_MISC_OCXL_H */
> 

Re: [PATCH v2 5/7] ocxl: Expose the thread_id needed for wait on p9

[Frederic Barrat]

Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> In order to successfully issue as_notify, an AFU needs to know the TID
> to notify, which in turn means that this information should be
> available in userspace so it can be communicated to the AFU.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---
>   drivers/misc/ocxl/context.c       |  5 +++-
>   drivers/misc/ocxl/file.c          | 53 +++++++++++++++++++++++++++++++++++++++
>   drivers/misc/ocxl/link.c          | 36 ++++++++++++++++++++++++++
>   drivers/misc/ocxl/ocxl_internal.h |  1 +
>   include/misc/ocxl.h               |  9 +++++++
>   include/uapi/misc/ocxl.h          | 10 ++++++++
>   6 files changed, 113 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
> index 909e8807824a..95f74623113e 100644
> --- a/drivers/misc/ocxl/context.c
> +++ b/drivers/misc/ocxl/context.c
> @@ -34,6 +34,8 @@ int ocxl_context_init(struct ocxl_context *ctx, struct ocxl_afu *afu,
>   	mutex_init(&ctx->xsl_error_lock);
>   	mutex_init(&ctx->irq_lock);
>   	idr_init(&ctx->irq_idr);
> +	ctx->tidr = 0;
> +
>   	/*
>   	 * Keep a reference on the AFU to make sure it's valid for the
>   	 * duration of the life of the context
> @@ -65,6 +67,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
>   {
>   	int rc;
> 
> +	// Locks both status & tidr
>   	mutex_lock(&ctx->status_mutex);
>   	if (ctx->status != OPENED) {
>   		rc = -EIO;
> @@ -72,7 +75,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
>   	}
> 
>   	rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid,
> -			current->mm->context.id, 0, amr, current->mm,
> +			current->mm->context.id, ctx->tidr, amr, current->mm,
>   			xsl_fault_error, ctx);
>   	if (rc)
>   		goto out;
> diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
> index 038509e5d031..eb409a469f21 100644
> --- a/drivers/misc/ocxl/file.c
> +++ b/drivers/misc/ocxl/file.c
> @@ -5,6 +5,8 @@
>   #include <linux/sched/signal.h>
>   #include <linux/uaccess.h>
>   #include <uapi/misc/ocxl.h>
> +#include <asm/reg.h>
> +#include <asm/switch_to.h>
>   #include "ocxl_internal.h"
> 
> 
> @@ -123,11 +125,55 @@ static long afu_ioctl_get_metadata(struct ocxl_context *ctx,
>   	return 0;
>   }
> 
> +#ifdef CONFIG_PPC64
> +static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
> +		struct ocxl_ioctl_p9_wait __user *uarg)
> +{
> +	struct ocxl_ioctl_p9_wait arg;
> +
> +	memset(&arg, 0, sizeof(arg));
> +
> +	if (cpu_has_feature(CPU_FTR_P9_TIDR)) {
> +		enum ocxl_context_status status;
> +
> +		// Locks both status & tidr
> +		mutex_lock(&ctx->status_mutex);
> +		if (!ctx->tidr) {
> +			if (set_thread_tidr(current))
> +				return -ENOENT;
> +
> +			ctx->tidr = current->thread.tidr;
> +		}


Now that we don't have the TIDR limit problem, I'm wondering if we 
cannot relax our rule a bit and have:
- first thread to enable will become the default thread and update the 
Process element
- any subsequent enable would just allocate the TIDR for the calling thread.

That way, more than one thread could be used for 'wait'.
Thoughts?

    Fred


> +
> +		status = ctx->status;
> +		mutex_unlock(&ctx->status_mutex);
> +
> +		if (status == ATTACHED) {
> +			int rc;
> +			struct link *link = ctx->afu->fn->link;
> +
> +			rc = ocxl_link_update_pe(link, ctx->pasid, ctx->tidr);
> +			if (rc)
> +				return rc;
> +		}
> +
> +		arg.thread_id = ctx->tidr;
> +	} else
> +		return -ENOENT;
> +
> +	if (copy_to_user(uarg, &arg, sizeof(arg)))
> +		return -EFAULT;
> +
> +	return 0;
> +}
> +#endif
> +
>   #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
>   			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
>   			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
>   			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
>   			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
> +			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
>   			"UNKNOWN")
> 
>   static long afu_ioctl(struct file *file, unsigned int cmd,
> @@ -186,6 +232,13 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
>   				(struct ocxl_ioctl_metadata __user *) args);
>   		break;
> 
> +#ifdef CONFIG_PPC64
> +	case OCXL_IOCTL_ENABLE_P9_WAIT:
> +		rc = afu_ioctl_enable_p9_wait(ctx,
> +				(struct ocxl_ioctl_p9_wait __user *) args);
> +		break;
> +#endif
> +
>   	default:
>   		rc = -EINVAL;
>   	}
> diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
> index 656e8610eec2..88876ae8f330 100644
> --- a/drivers/misc/ocxl/link.c
> +++ b/drivers/misc/ocxl/link.c
> @@ -544,6 +544,42 @@ int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
>   }
>   EXPORT_SYMBOL_GPL(ocxl_link_add_pe);
> 
> +int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid)
> +{
> +	struct link *link = (struct link *) link_handle;
> +	struct spa *spa = link->spa;
> +	struct ocxl_process_element *pe;
> +	int pe_handle, rc;
> +
> +	if (pasid > SPA_PASID_MAX)
> +		return -EINVAL;
> +
> +	pe_handle = pasid & SPA_PE_MASK;
> +	pe = spa->spa_mem + pe_handle;
> +
> +	mutex_lock(&spa->spa_lock);
> +
> +	pe->tid = tid;
> +
> +	/*
> +	 * The barrier makes sure the PE is updated
> +	 * before we clear the NPU context cache below, so that the
> +	 * old PE cannot be reloaded erroneously.
> +	 */
> +	mb();
> +
> +	/*
> +	 * hook to platform code
> +	 * On powerpc, the entry needs to be cleared from the context
> +	 * cache of the NPU.
> +	 */
> +	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
> +	WARN_ON(rc);
> +
> +	mutex_unlock(&spa->spa_lock);
> +	return rc;
> +}
> +
>   int ocxl_link_remove_pe(void *link_handle, int pasid)
>   {
>   	struct link *link = (struct link *) link_handle;
> diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
> index 5d421824afd9..6c6d4e61888e 100644
> --- a/drivers/misc/ocxl/ocxl_internal.h
> +++ b/drivers/misc/ocxl/ocxl_internal.h
> @@ -77,6 +77,7 @@ struct ocxl_context {
>   	struct ocxl_xsl_error xsl_error;
>   	struct mutex irq_lock;
>   	struct idr irq_idr;
> +	__u16 tidr; // Thread ID used for P9 wait implementation
>   };
> 
>   struct ocxl_process_element {
> diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
> index 51ccf76db293..9ff6ddc28e22 100644
> --- a/include/misc/ocxl.h
> +++ b/include/misc/ocxl.h
> @@ -188,6 +188,15 @@ extern int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
>   		void (*xsl_err_cb)(void *data, u64 addr, u64 dsisr),
>   		void *xsl_err_data);
> 
> +/**
> + * Update values within a Process Element
> + *
> + * link_handle: the link handle associated with the process element
> + * pasid: the PASID for the AFU context
> + * tid: the new thread id for the process element
> + */
> +extern int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid);
> +
>   /*
>    * Remove a Process Element from the Shared Process Area for a link
>    */
> diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
> index 0af83d80fb3e..8d2748e69c84 100644
> --- a/include/uapi/misc/ocxl.h
> +++ b/include/uapi/misc/ocxl.h
> @@ -48,6 +48,15 @@ struct ocxl_ioctl_metadata {
>   	__u64 reserved[13]; // Total of 16*u64
>   };
> 
> +struct ocxl_ioctl_p9_wait {
> +	__u16 thread_id; // The thread ID required to wake this thread
> +	__u16 reserved1;
> +	__u32 reserved2;
> +	__u64 reserved3[3];
> +};
> +
> +};
> +
>   struct ocxl_ioctl_irq_fd {
>   	__u64 irq_offset;
>   	__s32 eventfd;
> @@ -62,5 +71,6 @@ struct ocxl_ioctl_irq_fd {
>   #define OCXL_IOCTL_IRQ_FREE	_IOW(OCXL_MAGIC, 0x12, __u64)
>   #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
>   #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
> +#define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
> 
>   #endif /* _UAPI_MISC_OCXL_H */
> 

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[PATCH v2 6/7] ocxl: Add an IOCTL so userspace knows what CPU features are available

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

In order for a userspace AFU driver to call the Power9 specific
OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
make that call.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 Documentation/accelerators/ocxl.rst |  1 -
 drivers/misc/ocxl/file.c            | 25 +++++++++++++++++++++++++
 include/uapi/misc/ocxl.h            |  4 ++++
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
index ddcc58d01cfb..7904adcc07fd 100644
--- a/Documentation/accelerators/ocxl.rst
+++ b/Documentation/accelerators/ocxl.rst
@@ -157,7 +157,6 @@ OCXL_IOCTL_GET_METADATA:
   Obtains configuration information from the card, such at the size of
   MMIO areas, the AFU version, and the PASID for the current context.
 
-
 mmap
 ----
 
diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index eb409a469f21..33ae46ce0a8a 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -168,12 +168,32 @@ static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
 }
 #endif
 
+
+static long afu_ioctl_get_features(struct ocxl_context *ctx,
+		struct ocxl_ioctl_features __user *uarg)
+{
+	struct ocxl_ioctl_features arg;
+
+	memset(&arg, 0, sizeof(arg));
+
+#ifdef CONFIG_PPC64
+	if (cpu_has_feature(CPU_FTR_P9_TIDR))
+		arg.flags[0] |= OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT;
+#endif
+
+	if (copy_to_user(uarg, &arg, sizeof(arg)))
+		return -EFAULT;
+
+	return 0;
+}
+
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
 			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
 			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
 			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
 			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
 			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
+			x == OCXL_IOCTL_GET_FEATURES ? "GET_FEATURES" :	\
 			"UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -239,6 +259,11 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 		break;
 #endif
 
+	case OCXL_IOCTL_GET_FEATURES:
+		rc = afu_ioctl_get_features(ctx,
+				(struct ocxl_ioctl_features __user *) args);
+		break;
+
 	default:
 		rc = -EINVAL;
 	}
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 8d2748e69c84..bb80f294b429 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -55,6 +55,9 @@ struct ocxl_ioctl_p9_wait {
 	__u64 reserved3[3];
 };
 
+#define OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT	0x01
+struct ocxl_ioctl_features {
+	__u64 flags[4];
 };
 
 struct ocxl_ioctl_irq_fd {
@@ -72,5 +75,6 @@ struct ocxl_ioctl_irq_fd {
 #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
 #define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
+#define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_platform)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.3

[PATCH v2 6/7] ocxl: Add an IOCTL so userspace knows what CPU features are available

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

In order for a userspace AFU driver to call the Power9 specific
OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
make that call.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 Documentation/accelerators/ocxl.rst |  1 -
 drivers/misc/ocxl/file.c            | 25 +++++++++++++++++++++++++
 include/uapi/misc/ocxl.h            |  4 ++++
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
index ddcc58d01cfb..7904adcc07fd 100644
--- a/Documentation/accelerators/ocxl.rst
+++ b/Documentation/accelerators/ocxl.rst
@@ -157,7 +157,6 @@ OCXL_IOCTL_GET_METADATA:
   Obtains configuration information from the card, such at the size of
   MMIO areas, the AFU version, and the PASID for the current context.
 
-
 mmap
 ----
 
diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index eb409a469f21..33ae46ce0a8a 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -168,12 +168,32 @@ static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
 }
 #endif
 
+
+static long afu_ioctl_get_features(struct ocxl_context *ctx,
+		struct ocxl_ioctl_features __user *uarg)
+{
+	struct ocxl_ioctl_features arg;
+
+	memset(&arg, 0, sizeof(arg));
+
+#ifdef CONFIG_PPC64
+	if (cpu_has_feature(CPU_FTR_P9_TIDR))
+		arg.flags[0] |= OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT;
+#endif
+
+	if (copy_to_user(uarg, &arg, sizeof(arg)))
+		return -EFAULT;
+
+	return 0;
+}
+
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
 			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
 			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
 			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
 			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
 			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
+			x == OCXL_IOCTL_GET_FEATURES ? "GET_FEATURES" :	\
 			"UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -239,6 +259,11 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 		break;
 #endif
 
+	case OCXL_IOCTL_GET_FEATURES:
+		rc = afu_ioctl_get_features(ctx,
+				(struct ocxl_ioctl_features __user *) args);
+		break;
+
 	default:
 		rc = -EINVAL;
 	}
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 8d2748e69c84..bb80f294b429 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -55,6 +55,9 @@ struct ocxl_ioctl_p9_wait {
 	__u64 reserved3[3];
 };
 
+#define OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT	0x01
+struct ocxl_ioctl_features {
+	__u64 flags[4];
 };
 
 struct ocxl_ioctl_irq_fd {
@@ -72,5 +75,6 @@ struct ocxl_ioctl_irq_fd {
 #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
 #define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
+#define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_platform)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.3

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Re: [PATCH v2 6/7] ocxl: Add an IOCTL so userspace knows what CPU features are available

[Andrew Donnellan]

On 18/04/18 11:08, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> In order for a userspace AFU driver to call the Power9 specific
> OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
> make that call.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>

Looks good to me

Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

> ---
>   Documentation/accelerators/ocxl.rst |  1 -
>   drivers/misc/ocxl/file.c            | 25 +++++++++++++++++++++++++
>   include/uapi/misc/ocxl.h            |  4 ++++
>   3 files changed, 29 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
> index ddcc58d01cfb..7904adcc07fd 100644
> --- a/Documentation/accelerators/ocxl.rst
> +++ b/Documentation/accelerators/ocxl.rst
> @@ -157,7 +157,6 @@ OCXL_IOCTL_GET_METADATA:
>     Obtains configuration information from the card, such at the size of
>     MMIO areas, the AFU version, and the PASID for the current context.
>   
> -

This is stray


-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

Re: [PATCH v2 6/7] ocxl: Add an IOCTL so userspace knows what CPU features are available

[Andrew Donnellan]

On 18/04/18 11:08, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> In order for a userspace AFU driver to call the Power9 specific
> OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
> make that call.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>

Looks good to me

Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

> ---
>   Documentation/accelerators/ocxl.rst |  1 -
>   drivers/misc/ocxl/file.c            | 25 +++++++++++++++++++++++++
>   include/uapi/misc/ocxl.h            |  4 ++++
>   3 files changed, 29 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
> index ddcc58d01cfb..7904adcc07fd 100644
> --- a/Documentation/accelerators/ocxl.rst
> +++ b/Documentation/accelerators/ocxl.rst
> @@ -157,7 +157,6 @@ OCXL_IOCTL_GET_METADATA:
>     Obtains configuration information from the card, such at the size of
>     MMIO areas, the AFU version, and the PASID for the current context.
>   
> -

This is stray


-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

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Re: [PATCH v2 6/7] ocxl: Add an IOCTL so userspace knows what CPU features are available

[Frederic Barrat]

Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> In order for a userspace AFU driver to call the Power9 specific
> OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
> make that call.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---
>   Documentation/accelerators/ocxl.rst |  1 -
>   drivers/misc/ocxl/file.c            | 25 +++++++++++++++++++++++++
>   include/uapi/misc/ocxl.h            |  4 ++++
>   3 files changed, 29 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
> index ddcc58d01cfb..7904adcc07fd 100644
> --- a/Documentation/accelerators/ocxl.rst
> +++ b/Documentation/accelerators/ocxl.rst
> @@ -157,7 +157,6 @@ OCXL_IOCTL_GET_METADATA:
>     Obtains configuration information from the card, such at the size of
>     MMIO areas, the AFU version, and the PASID for the current context.
> 
> -


Intended?

Other than that,
Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>



>   mmap
>   ----
> 
> diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
> index eb409a469f21..33ae46ce0a8a 100644
> --- a/drivers/misc/ocxl/file.c
> +++ b/drivers/misc/ocxl/file.c
> @@ -168,12 +168,32 @@ static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
>   }
>   #endif
> 
> +
> +static long afu_ioctl_get_features(struct ocxl_context *ctx,
> +		struct ocxl_ioctl_features __user *uarg)
> +{
> +	struct ocxl_ioctl_features arg;
> +
> +	memset(&arg, 0, sizeof(arg));
> +
> +#ifdef CONFIG_PPC64
> +	if (cpu_has_feature(CPU_FTR_P9_TIDR))
> +		arg.flags[0] |= OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT;
> +#endif
> +
> +	if (copy_to_user(uarg, &arg, sizeof(arg)))
> +		return -EFAULT;
> +
> +	return 0;
> +}
> +
>   #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
>   			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
>   			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
>   			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
>   			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
>   			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
> +			x == OCXL_IOCTL_GET_FEATURES ? "GET_FEATURES" :	\
>   			"UNKNOWN")
> 
>   static long afu_ioctl(struct file *file, unsigned int cmd,
> @@ -239,6 +259,11 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
>   		break;
>   #endif
> 
> +	case OCXL_IOCTL_GET_FEATURES:
> +		rc = afu_ioctl_get_features(ctx,
> +				(struct ocxl_ioctl_features __user *) args);
> +		break;
> +
>   	default:
>   		rc = -EINVAL;
>   	}
> diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
> index 8d2748e69c84..bb80f294b429 100644
> --- a/include/uapi/misc/ocxl.h
> +++ b/include/uapi/misc/ocxl.h
> @@ -55,6 +55,9 @@ struct ocxl_ioctl_p9_wait {
>   	__u64 reserved3[3];
>   };
> 
> +#define OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT	0x01
> +struct ocxl_ioctl_features {
> +	__u64 flags[4];
>   };
> 
>   struct ocxl_ioctl_irq_fd {
> @@ -72,5 +75,6 @@ struct ocxl_ioctl_irq_fd {
>   #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
>   #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
>   #define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
> +#define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_platform)
> 
>   #endif /* _UAPI_MISC_OCXL_H */
> 

Re: [PATCH v2 6/7] ocxl: Add an IOCTL so userspace knows what CPU features are available

[Frederic Barrat]

Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> In order for a userspace AFU driver to call the Power9 specific
> OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
> make that call.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---
>   Documentation/accelerators/ocxl.rst |  1 -
>   drivers/misc/ocxl/file.c            | 25 +++++++++++++++++++++++++
>   include/uapi/misc/ocxl.h            |  4 ++++
>   3 files changed, 29 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
> index ddcc58d01cfb..7904adcc07fd 100644
> --- a/Documentation/accelerators/ocxl.rst
> +++ b/Documentation/accelerators/ocxl.rst
> @@ -157,7 +157,6 @@ OCXL_IOCTL_GET_METADATA:
>     Obtains configuration information from the card, such at the size of
>     MMIO areas, the AFU version, and the PASID for the current context.
> 
> -


Intended?

Other than that,
Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>



>   mmap
>   ----
> 
> diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
> index eb409a469f21..33ae46ce0a8a 100644
> --- a/drivers/misc/ocxl/file.c
> +++ b/drivers/misc/ocxl/file.c
> @@ -168,12 +168,32 @@ static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
>   }
>   #endif
> 
> +
> +static long afu_ioctl_get_features(struct ocxl_context *ctx,
> +		struct ocxl_ioctl_features __user *uarg)
> +{
> +	struct ocxl_ioctl_features arg;
> +
> +	memset(&arg, 0, sizeof(arg));
> +
> +#ifdef CONFIG_PPC64
> +	if (cpu_has_feature(CPU_FTR_P9_TIDR))
> +		arg.flags[0] |= OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT;
> +#endif
> +
> +	if (copy_to_user(uarg, &arg, sizeof(arg)))
> +		return -EFAULT;
> +
> +	return 0;
> +}
> +
>   #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
>   			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
>   			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
>   			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
>   			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
>   			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
> +			x == OCXL_IOCTL_GET_FEATURES ? "GET_FEATURES" :	\
>   			"UNKNOWN")
> 
>   static long afu_ioctl(struct file *file, unsigned int cmd,
> @@ -239,6 +259,11 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
>   		break;
>   #endif
> 
> +	case OCXL_IOCTL_GET_FEATURES:
> +		rc = afu_ioctl_get_features(ctx,
> +				(struct ocxl_ioctl_features __user *) args);
> +		break;
> +
>   	default:
>   		rc = -EINVAL;
>   	}
> diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
> index 8d2748e69c84..bb80f294b429 100644
> --- a/include/uapi/misc/ocxl.h
> +++ b/include/uapi/misc/ocxl.h
> @@ -55,6 +55,9 @@ struct ocxl_ioctl_p9_wait {
>   	__u64 reserved3[3];
>   };
> 
> +#define OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT	0x01
> +struct ocxl_ioctl_features {
> +	__u64 flags[4];
>   };
> 
>   struct ocxl_ioctl_irq_fd {
> @@ -72,5 +75,6 @@ struct ocxl_ioctl_irq_fd {
>   #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
>   #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
>   #define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
> +#define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_platform)
> 
>   #endif /* _UAPI_MISC_OCXL_H */
> 

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Re: [PATCH v2 6/7] ocxl: Add an IOCTL so userspace knows what CPU features are available

[Alastair D'Silva]

On Mon, 2018-05-07 at 20:14 +0200, Frederic Barrat wrote:
> 
> Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> > From: Alastair D'Silva <alastair@d-silva.org>
> > 
> > In order for a userspace AFU driver to call the Power9 specific
> > OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
> > make that call.
> > 
> > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > ---
> >   Documentation/accelerators/ocxl.rst |  1 -
> >   drivers/misc/ocxl/file.c            | 25
> > +++++++++++++++++++++++++
> >   include/uapi/misc/ocxl.h            |  4 ++++
> >   3 files changed, 29 insertions(+), 1 deletion(-)
> > 
> > diff --git a/Documentation/accelerators/ocxl.rst
> > b/Documentation/accelerators/ocxl.rst
> > index ddcc58d01cfb..7904adcc07fd 100644
> > --- a/Documentation/accelerators/ocxl.rst
> > +++ b/Documentation/accelerators/ocxl.rst
> > @@ -157,7 +157,6 @@ OCXL_IOCTL_GET_METADATA:
> >     Obtains configuration information from the card, such at the
> > size of
> >     MMIO areas, the AFU version, and the PASID for the current
> > context.
> > 
> > -
> 
> 
> Intended?
> 
> Other than that,
> Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
> 

Nope, I'll fix that, thanks.

-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australiamob: 0423 762 819

Re: [PATCH v2 6/7] ocxl: Add an IOCTL so userspace knows what CPU features are available

[Alastair D'Silva]

On Mon, 2018-05-07 at 20:14 +0200, Frederic Barrat wrote:
> 
> Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> > From: Alastair D'Silva <alastair@d-silva.org>
> > 
> > In order for a userspace AFU driver to call the Power9 specific
> > OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
> > make that call.
> > 
> > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > ---
> >   Documentation/accelerators/ocxl.rst |  1 -
> >   drivers/misc/ocxl/file.c            | 25
> > +++++++++++++++++++++++++
> >   include/uapi/misc/ocxl.h            |  4 ++++
> >   3 files changed, 29 insertions(+), 1 deletion(-)
> > 
> > diff --git a/Documentation/accelerators/ocxl.rst
> > b/Documentation/accelerators/ocxl.rst
> > index ddcc58d01cfb..7904adcc07fd 100644
> > --- a/Documentation/accelerators/ocxl.rst
> > +++ b/Documentation/accelerators/ocxl.rst
> > @@ -157,7 +157,6 @@ OCXL_IOCTL_GET_METADATA:
> >     Obtains configuration information from the card, such at the
> > size of
> >     MMIO areas, the AFU version, and the PASID for the current
> > context.
> > 
> > -
> 
> 
> Intended?
> 
> Other than that,
> Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
> 

Nope, I'll fix that, thanks.

-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australiamob: 0423 762 819

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Re: [PATCH v2 6/7] ocxl: Add an IOCTL so userspace knows what CPU features are available

[Nicholas Piggin]

On Tue, 08 May 2018 10:41:55 +1000
"Alastair D'Silva" <alastair@au1.ibm.com> wrote:

> On Mon, 2018-05-07 at 20:14 +0200, Frederic Barrat wrote:
> > 
> > Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :  
> > > From: Alastair D'Silva <alastair@d-silva.org>
> > > 
> > > In order for a userspace AFU driver to call the Power9 specific
> > > OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
> > > make that call.
> > > 
> > > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > > ---
> > >   Documentation/accelerators/ocxl.rst |  1 -
> > >   drivers/misc/ocxl/file.c            | 25
> > > +++++++++++++++++++++++++
> > >   include/uapi/misc/ocxl.h            |  4 ++++
> > >   3 files changed, 29 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/Documentation/accelerators/ocxl.rst
> > > b/Documentation/accelerators/ocxl.rst
> > > index ddcc58d01cfb..7904adcc07fd 100644
> > > --- a/Documentation/accelerators/ocxl.rst
> > > +++ b/Documentation/accelerators/ocxl.rst
> > > @@ -157,7 +157,6 @@ OCXL_IOCTL_GET_METADATA:
> > >     Obtains configuration information from the card, such at the
> > > size of
> > >     MMIO areas, the AFU version, and the PASID for the current
> > > context.
> > > 
> > > -  
> > 
> > 
> > Intended?
> > 
> > Other than that,
> > Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
> >   
> 
> Nope, I'll fix that, thanks.
> 

Just to be clear, this is for OCXL features. I would just make that
explicit in the title (s/CPU/OCXL).

Thanks,
Nick

Re: [PATCH v2 6/7] ocxl: Add an IOCTL so userspace knows what CPU features are available

[Nicholas Piggin]

On Tue, 08 May 2018 10:41:55 +1000
"Alastair D'Silva" <alastair@au1.ibm.com> wrote:

> On Mon, 2018-05-07 at 20:14 +0200, Frederic Barrat wrote:
> > 
> > Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :  
> > > From: Alastair D'Silva <alastair@d-silva.org>
> > > 
> > > In order for a userspace AFU driver to call the Power9 specific
> > > OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
> > > make that call.
> > > 
> > > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > > ---
> > >   Documentation/accelerators/ocxl.rst |  1 -
> > >   drivers/misc/ocxl/file.c            | 25
> > > +++++++++++++++++++++++++
> > >   include/uapi/misc/ocxl.h            |  4 ++++
> > >   3 files changed, 29 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/Documentation/accelerators/ocxl.rst
> > > b/Documentation/accelerators/ocxl.rst
> > > index ddcc58d01cfb..7904adcc07fd 100644
> > > --- a/Documentation/accelerators/ocxl.rst
> > > +++ b/Documentation/accelerators/ocxl.rst
> > > @@ -157,7 +157,6 @@ OCXL_IOCTL_GET_METADATA:
> > >     Obtains configuration information from the card, such at the
> > > size of
> > >     MMIO areas, the AFU version, and the PASID for the current
> > > context.
> > > 
> > > -  
> > 
> > 
> > Intended?
> > 
> > Other than that,
> > Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
> >   
> 
> Nope, I'll fix that, thanks.
> 

Just to be clear, this is for OCXL features. I would just make that
explicit in the title (s/CPU/OCXL).

Thanks,
Nick
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Re: [PATCH v2 6/7] ocxl: Add an IOCTL so userspace knows what CPU features are available

[Alastair D'Silva]

On Tue, 2018-05-08 at 13:50 +1000, Nicholas Piggin wrote:
> On Tue, 08 May 2018 10:41:55 +1000
> "Alastair D'Silva" <alastair@au1.ibm.com> wrote:
> 
> > On Mon, 2018-05-07 at 20:14 +0200, Frederic Barrat wrote:
> > > 
> > > Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :  
> > > > From: Alastair D'Silva <alastair@d-silva.org>
> > > > 
> > > > In order for a userspace AFU driver to call the Power9 specific
> > > > OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can
> > > > actually
> > > > make that call.
> > > > 
> > > > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > > > ---
> > > >   Documentation/accelerators/ocxl.rst |  1 -
> > > >   drivers/misc/ocxl/file.c            | 25
> > > > +++++++++++++++++++++++++
> > > >   include/uapi/misc/ocxl.h            |  4 ++++
> > > >   3 files changed, 29 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/Documentation/accelerators/ocxl.rst
> > > > b/Documentation/accelerators/ocxl.rst
> > > > index ddcc58d01cfb..7904adcc07fd 100644
> > > > --- a/Documentation/accelerators/ocxl.rst
> > > > +++ b/Documentation/accelerators/ocxl.rst
> > > > @@ -157,7 +157,6 @@ OCXL_IOCTL_GET_METADATA:
> > > >     Obtains configuration information from the card, such at
> > > > the
> > > > size of
> > > >     MMIO areas, the AFU version, and the PASID for the current
> > > > context.
> > > > 
> > > > -  
> > > 
> > > 
> > > Intended?
> > > 
> > > Other than that,
> > > Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
> > >   
> > 
> > Nope, I'll fix that, thanks.
> > 
> 
> Just to be clear, this is for OCXL features. I would just make that
> explicit in the title (s/CPU/OCXL).
> 
> Thanks,
> Nick
> 

OK, sounds reasonable.

-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819

Re: [PATCH v2 6/7] ocxl: Add an IOCTL so userspace knows what CPU features are available

[Alastair D'Silva]

On Tue, 2018-05-08 at 13:50 +1000, Nicholas Piggin wrote:
> On Tue, 08 May 2018 10:41:55 +1000
> "Alastair D'Silva" <alastair@au1.ibm.com> wrote:
> 
> > On Mon, 2018-05-07 at 20:14 +0200, Frederic Barrat wrote:
> > > 
> > > Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :  
> > > > From: Alastair D'Silva <alastair@d-silva.org>
> > > > 
> > > > In order for a userspace AFU driver to call the Power9 specific
> > > > OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can
> > > > actually
> > > > make that call.
> > > > 
> > > > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > > > ---
> > > >   Documentation/accelerators/ocxl.rst |  1 -
> > > >   drivers/misc/ocxl/file.c            | 25
> > > > +++++++++++++++++++++++++
> > > >   include/uapi/misc/ocxl.h            |  4 ++++
> > > >   3 files changed, 29 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/Documentation/accelerators/ocxl.rst
> > > > b/Documentation/accelerators/ocxl.rst
> > > > index ddcc58d01cfb..7904adcc07fd 100644
> > > > --- a/Documentation/accelerators/ocxl.rst
> > > > +++ b/Documentation/accelerators/ocxl.rst
> > > > @@ -157,7 +157,6 @@ OCXL_IOCTL_GET_METADATA:
> > > >     Obtains configuration information from the card, such at
> > > > the
> > > > size of
> > > >     MMIO areas, the AFU version, and the PASID for the current
> > > > context.
> > > > 
> > > > -  
> > > 
> > > 
> > > Intended?
> > > 
> > > Other than that,
> > > Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
> > >   
> > 
> > Nope, I'll fix that, thanks.
> > 
> 
> Just to be clear, this is for OCXL features. I would just make that
> explicit in the title (s/CPU/OCXL).
> 
> Thanks,
> Nick
> 

OK, sounds reasonable.

-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819

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[PATCH v2 7/7] ocxl: Document new OCXL IOCTLs

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 Documentation/accelerators/ocxl.rst | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
index 7904adcc07fd..3b8d3b99795c 100644
--- a/Documentation/accelerators/ocxl.rst
+++ b/Documentation/accelerators/ocxl.rst
@@ -157,6 +157,17 @@ OCXL_IOCTL_GET_METADATA:
   Obtains configuration information from the card, such at the size of
   MMIO areas, the AFU version, and the PASID for the current context.
 
+OCXL_IOCTL_ENABLE_P9_WAIT:
+
+  Allows the AFU to wake a userspace thread executing 'wait'. Returns
+  information to userspace to allow it to configure the AFU. Note that
+  this is only available on Power 9.
+
+OCXL_IOCTL_GET_FEATURES:
+
+  Reports on which CPU features that affect OpenCAPI are usable from
+  userspace.
+
 mmap
 ----
 
-- 
2.14.3

[PATCH v2 7/7] ocxl: Document new OCXL IOCTLs

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 Documentation/accelerators/ocxl.rst | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
index 7904adcc07fd..3b8d3b99795c 100644
--- a/Documentation/accelerators/ocxl.rst
+++ b/Documentation/accelerators/ocxl.rst
@@ -157,6 +157,17 @@ OCXL_IOCTL_GET_METADATA:
   Obtains configuration information from the card, such at the size of
   MMIO areas, the AFU version, and the PASID for the current context.
 
+OCXL_IOCTL_ENABLE_P9_WAIT:
+
+  Allows the AFU to wake a userspace thread executing 'wait'. Returns
+  information to userspace to allow it to configure the AFU. Note that
+  this is only available on Power 9.
+
+OCXL_IOCTL_GET_FEATURES:
+
+  Reports on which CPU features that affect OpenCAPI are usable from
+  userspace.
+
 mmap
 ----
 
-- 
2.14.3

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Re: [PATCH v2 7/7] ocxl: Document new OCXL IOCTLs

[Andrew Donnellan]

On 18/04/18 11:08, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>

This looks better.

Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

> ---
>   Documentation/accelerators/ocxl.rst | 11 +++++++++++
>   1 file changed, 11 insertions(+)
> 
> diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
> index 7904adcc07fd..3b8d3b99795c 100644
> --- a/Documentation/accelerators/ocxl.rst
> +++ b/Documentation/accelerators/ocxl.rst
> @@ -157,6 +157,17 @@ OCXL_IOCTL_GET_METADATA:
>     Obtains configuration information from the card, such at the size of
>     MMIO areas, the AFU version, and the PASID for the current context.
>   
> +OCXL_IOCTL_ENABLE_P9_WAIT:
> +
> +  Allows the AFU to wake a userspace thread executing 'wait'. Returns
> +  information to userspace to allow it to configure the AFU. Note that
> +  this is only available on Power 9.

Nitpicking time, if you do a v3 you should stay on brand and call it 
POWER9. :D

> +
> +OCXL_IOCTL_GET_FEATURES:
> +
> +  Reports on which CPU features that affect OpenCAPI are usable from
> +  userspace.
> +
>   mmap
>   ----
>   
> 

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

Re: [PATCH v2 7/7] ocxl: Document new OCXL IOCTLs

[Andrew Donnellan]

On 18/04/18 11:08, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>

This looks better.

Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

> ---
>   Documentation/accelerators/ocxl.rst | 11 +++++++++++
>   1 file changed, 11 insertions(+)
> 
> diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
> index 7904adcc07fd..3b8d3b99795c 100644
> --- a/Documentation/accelerators/ocxl.rst
> +++ b/Documentation/accelerators/ocxl.rst
> @@ -157,6 +157,17 @@ OCXL_IOCTL_GET_METADATA:
>     Obtains configuration information from the card, such at the size of
>     MMIO areas, the AFU version, and the PASID for the current context.
>   
> +OCXL_IOCTL_ENABLE_P9_WAIT:
> +
> +  Allows the AFU to wake a userspace thread executing 'wait'. Returns
> +  information to userspace to allow it to configure the AFU. Note that
> +  this is only available on Power 9.

Nitpicking time, if you do a v3 you should stay on brand and call it 
POWER9. :D

> +
> +OCXL_IOCTL_GET_FEATURES:
> +
> +  Reports on which CPU features that affect OpenCAPI are usable from
> +  userspace.
> +
>   mmap
>   ----
>   
> 

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

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Re: [PATCH v2 7/7] ocxl: Document new OCXL IOCTLs

[Frederic Barrat]

Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---

Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>

   Fred


>   Documentation/accelerators/ocxl.rst | 11 +++++++++++
>   1 file changed, 11 insertions(+)
> 
> diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
> index 7904adcc07fd..3b8d3b99795c 100644
> --- a/Documentation/accelerators/ocxl.rst
> +++ b/Documentation/accelerators/ocxl.rst
> @@ -157,6 +157,17 @@ OCXL_IOCTL_GET_METADATA:
>     Obtains configuration information from the card, such at the size of
>     MMIO areas, the AFU version, and the PASID for the current context.
> 
> +OCXL_IOCTL_ENABLE_P9_WAIT:
> +
> +  Allows the AFU to wake a userspace thread executing 'wait'. Returns
> +  information to userspace to allow it to configure the AFU. Note that
> +  this is only available on Power 9.
> +
> +OCXL_IOCTL_GET_FEATURES:
> +
> +  Reports on which CPU features that affect OpenCAPI are usable from
> +  userspace.
> +
>   mmap
>   ----
> 

Re: [PATCH v2 7/7] ocxl: Document new OCXL IOCTLs

[Frederic Barrat]

Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---

Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>

   Fred


>   Documentation/accelerators/ocxl.rst | 11 +++++++++++
>   1 file changed, 11 insertions(+)
> 
> diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
> index 7904adcc07fd..3b8d3b99795c 100644
> --- a/Documentation/accelerators/ocxl.rst
> +++ b/Documentation/accelerators/ocxl.rst
> @@ -157,6 +157,17 @@ OCXL_IOCTL_GET_METADATA:
>     Obtains configuration information from the card, such at the size of
>     MMIO areas, the AFU version, and the PASID for the current context.
> 
> +OCXL_IOCTL_ENABLE_P9_WAIT:
> +
> +  Allows the AFU to wake a userspace thread executing 'wait'. Returns
> +  information to userspace to allow it to configure the AFU. Note that
> +  this is only available on Power 9.
> +
> +OCXL_IOCTL_GET_FEATURES:
> +
> +  Reports on which CPU features that affect OpenCAPI are usable from
> +  userspace.
> +
>   mmap
>   ----
> 

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[PATCH v3 0/7] ocxl: Implement Power9 as_notify/wait for OpenCAPI

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The Power 9 as_notify/wait feature provides a lower latency way to
signal a thread that work is complete. This series enables the use of
this feature from OpenCAPI adapters, as well as addressing a potential
starvation issue when allocating thread IDs.

Changelog:
v3:
  Fix references to POWER9
  Remove stray whitespace edit from docs
  Add more details to commit message for "use task_pid_nr()"
  Retitle patch 6 to indicate OCXL rather than CPU features
v2:
  Rename get_platform IOCTL to get_features
  Move stray edit from patch 1 to patch 3

Alastair D'Silva (7):
  powerpc: Add TIDR CPU feature for POWER9
  powerpc: Use TIDR CPU feature to control TIDR allocation
  powerpc: use task_pid_nr() for TID allocation
  ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action
  ocxl: Expose the thread_id needed for wait on POWER9
  ocxl: Add an IOCTL so userspace knows what OCXL features are available
  ocxl: Document new OCXL IOCTLs

 Documentation/accelerators/ocxl.rst   |  11 ++++
 arch/powerpc/include/asm/cputable.h   |   3 +-
 arch/powerpc/include/asm/pnv-ocxl.h   |   2 +-
 arch/powerpc/include/asm/switch_to.h  |   1 -
 arch/powerpc/kernel/dt_cpu_ftrs.c     |   1 +
 arch/powerpc/kernel/process.c         | 101 +---------------------------------
 arch/powerpc/platforms/powernv/ocxl.c |   4 +-
 drivers/misc/ocxl/context.c           |   5 +-
 drivers/misc/ocxl/file.c              |  78 ++++++++++++++++++++++++++
 drivers/misc/ocxl/link.c              |  38 ++++++++++++-
 drivers/misc/ocxl/ocxl_internal.h     |   1 +
 include/misc/ocxl.h                   |   9 +++
 include/uapi/misc/ocxl.h              |  14 +++++
 13 files changed, 163 insertions(+), 105 deletions(-)

-- 
2.14.3

[PATCH v3 0/7] ocxl: Implement Power9 as_notify/wait for OpenCAPI

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The Power 9 as_notify/wait feature provides a lower latency way to
signal a thread that work is complete. This series enables the use of
this feature from OpenCAPI adapters, as well as addressing a potential
starvation issue when allocating thread IDs.

Changelog:
v3:
  Fix references to POWER9
  Remove stray whitespace edit from docs
  Add more details to commit message for "use task_pid_nr()"
  Retitle patch 6 to indicate OCXL rather than CPU features
v2:
  Rename get_platform IOCTL to get_features
  Move stray edit from patch 1 to patch 3

Alastair D'Silva (7):
  powerpc: Add TIDR CPU feature for POWER9
  powerpc: Use TIDR CPU feature to control TIDR allocation
  powerpc: use task_pid_nr() for TID allocation
  ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action
  ocxl: Expose the thread_id needed for wait on POWER9
  ocxl: Add an IOCTL so userspace knows what OCXL features are available
  ocxl: Document new OCXL IOCTLs

 Documentation/accelerators/ocxl.rst   |  11 ++++
 arch/powerpc/include/asm/cputable.h   |   3 +-
 arch/powerpc/include/asm/pnv-ocxl.h   |   2 +-
 arch/powerpc/include/asm/switch_to.h  |   1 -
 arch/powerpc/kernel/dt_cpu_ftrs.c     |   1 +
 arch/powerpc/kernel/process.c         | 101 +---------------------------------
 arch/powerpc/platforms/powernv/ocxl.c |   4 +-
 drivers/misc/ocxl/context.c           |   5 +-
 drivers/misc/ocxl/file.c              |  78 ++++++++++++++++++++++++++
 drivers/misc/ocxl/link.c              |  38 ++++++++++++-
 drivers/misc/ocxl/ocxl_internal.h     |   1 +
 include/misc/ocxl.h                   |   9 +++
 include/uapi/misc/ocxl.h              |  14 +++++
 13 files changed, 163 insertions(+), 105 deletions(-)

-- 
2.14.3

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[PATCH v3 1/7] powerpc: Add TIDR CPU feature for POWER9

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

This patch adds a CPU feature bit to show whether the CPU has
the TIDR register available, enabling as_notify/wait in userspace.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/cputable.h | 3 ++-
 arch/powerpc/kernel/dt_cpu_ftrs.c   | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index 4e332f3531c5..54c4cbbe57b4 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -215,6 +215,7 @@ static inline void cpu_feature_keys_init(void) { }
 #define CPU_FTR_P9_TM_HV_ASSIST		LONG_ASM_CONST(0x0000100000000000)
 #define CPU_FTR_P9_TM_XER_SO_BUG	LONG_ASM_CONST(0x0000200000000000)
 #define CPU_FTR_P9_TLBIE_BUG		LONG_ASM_CONST(0x0000400000000000)
+#define CPU_FTR_P9_TIDR			LONG_ASM_CONST(0x0000800000000000)
 
 #ifndef __ASSEMBLY__
 
@@ -462,7 +463,7 @@ static inline void cpu_feature_keys_init(void) { }
 	    CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
 	    CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S | \
 	    CPU_FTR_TM_COMP | CPU_FTR_ARCH_300 | CPU_FTR_PKEY | \
-	    CPU_FTR_P9_TLBIE_BUG)
+	    CPU_FTR_P9_TLBIE_BUG | CPU_FTR_P9_TIDR)
 #define CPU_FTRS_POWER9_DD1 ((CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD1) & \
 			     (~CPU_FTR_SAO))
 #define CPU_FTRS_POWER9_DD2_0 CPU_FTRS_POWER9
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
index 11a3a4fed3fb..10f8b7f55637 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -722,6 +722,7 @@ static __init void cpufeatures_cpu_quirks(void)
 	if ((version & 0xffff0000) == 0x004e0000) {
 		cur_cpu_spec->cpu_features &= ~(CPU_FTR_DAWR);
 		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TLBIE_BUG;
+		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TIDR;
 	}
 }
 
-- 
2.14.3

[PATCH v3 1/7] powerpc: Add TIDR CPU feature for POWER9

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

This patch adds a CPU feature bit to show whether the CPU has
the TIDR register available, enabling as_notify/wait in userspace.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/cputable.h | 3 ++-
 arch/powerpc/kernel/dt_cpu_ftrs.c   | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index 4e332f3531c5..54c4cbbe57b4 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -215,6 +215,7 @@ static inline void cpu_feature_keys_init(void) { }
 #define CPU_FTR_P9_TM_HV_ASSIST		LONG_ASM_CONST(0x0000100000000000)
 #define CPU_FTR_P9_TM_XER_SO_BUG	LONG_ASM_CONST(0x0000200000000000)
 #define CPU_FTR_P9_TLBIE_BUG		LONG_ASM_CONST(0x0000400000000000)
+#define CPU_FTR_P9_TIDR			LONG_ASM_CONST(0x0000800000000000)
 
 #ifndef __ASSEMBLY__
 
@@ -462,7 +463,7 @@ static inline void cpu_feature_keys_init(void) { }
 	    CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
 	    CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S | \
 	    CPU_FTR_TM_COMP | CPU_FTR_ARCH_300 | CPU_FTR_PKEY | \
-	    CPU_FTR_P9_TLBIE_BUG)
+	    CPU_FTR_P9_TLBIE_BUG | CPU_FTR_P9_TIDR)
 #define CPU_FTRS_POWER9_DD1 ((CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD1) & \
 			     (~CPU_FTR_SAO))
 #define CPU_FTRS_POWER9_DD2_0 CPU_FTRS_POWER9
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
index 11a3a4fed3fb..10f8b7f55637 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -722,6 +722,7 @@ static __init void cpufeatures_cpu_quirks(void)
 	if ((version & 0xffff0000) == 0x004e0000) {
 		cur_cpu_spec->cpu_features &= ~(CPU_FTR_DAWR);
 		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TLBIE_BUG;
+		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TIDR;
 	}
 }
 
-- 
2.14.3

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[PATCH v3 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

Switch the use of TIDR on it's CPU feature, rather than assuming it
is available based on architecture.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/kernel/process.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 1237f13fed51..3b00da47699b 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1154,7 +1154,7 @@ static inline void restore_sprs(struct thread_struct *old_thread,
 			mtspr(SPRN_TAR, new_thread->tar);
 	}
 
-	if (cpu_has_feature(CPU_FTR_ARCH_300) &&
+	if (cpu_has_feature(CPU_FTR_P9_TIDR) &&
 	    old_thread->tidr != new_thread->tidr)
 		mtspr(SPRN_TIDR, new_thread->tidr);
 #endif
@@ -1570,7 +1570,7 @@ void clear_thread_tidr(struct task_struct *t)
 	if (!t->thread.tidr)
 		return;
 
-	if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
+	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
 		WARN_ON_ONCE(1);
 		return;
 	}
@@ -1593,7 +1593,7 @@ int set_thread_tidr(struct task_struct *t)
 {
 	int rc;
 
-	if (!cpu_has_feature(CPU_FTR_ARCH_300))
+	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
 		return -EINVAL;
 
 	if (t != current)
-- 
2.14.3

[PATCH v3 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

Switch the use of TIDR on it's CPU feature, rather than assuming it
is available based on architecture.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/kernel/process.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 1237f13fed51..3b00da47699b 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1154,7 +1154,7 @@ static inline void restore_sprs(struct thread_struct *old_thread,
 			mtspr(SPRN_TAR, new_thread->tar);
 	}
 
-	if (cpu_has_feature(CPU_FTR_ARCH_300) &&
+	if (cpu_has_feature(CPU_FTR_P9_TIDR) &&
 	    old_thread->tidr != new_thread->tidr)
 		mtspr(SPRN_TIDR, new_thread->tidr);
 #endif
@@ -1570,7 +1570,7 @@ void clear_thread_tidr(struct task_struct *t)
 	if (!t->thread.tidr)
 		return;
 
-	if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
+	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
 		WARN_ON_ONCE(1);
 		return;
 	}
@@ -1593,7 +1593,7 @@ int set_thread_tidr(struct task_struct *t)
 {
 	int rc;
 
-	if (!cpu_has_feature(CPU_FTR_ARCH_300))
+	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
 		return -EINVAL;
 
 	if (t != current)
-- 
2.14.3

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[PATCH v3 3/7] powerpc: use task_pid_nr() for TID allocation

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The current implementation of TID allocation, using a global IDR, may
result in an errant process starving the system of available TIDs.
Instead, use task_pid_nr(), as mentioned by the original author. The
scenario described which prevented it's use is not applicable, as
set_thread_tidr can only be called after the task struct has been
populated.

In the unlikely event that 2 threads share the TID and are waiting,
one of the following cases will happen:

1. The correct thread is running, the wrong thread is not
In this situation, the correct thread is woken and proceeds to pass it's
condition check.

2. Neither threads are running
In this situation, neither thread will be woken. When scheduled, the waiting
threads will execute either a wait, which will return immediately, followed
by a condition check, which will pass for the correct thread and fail
for the wrong thread, or they will execute the condition check immediately.

3. The wrong thread is running, the correct thread is not
The wrong thread will be woken, but will fail it's condition check and
re-execute wait. The correct thread, when scheduled, will execute either
it's condition check (which will pass), or wait, which returns immediately
when called the first time after the thread is scheduled, followed by it's
condition check (which will pass).

4. Both threads are running
Both threads will be woken. The wrong thread will fail it's condition check
and execute another wait, while the correct thread will pass it's condition
check.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/switch_to.h |  1 -
 arch/powerpc/kernel/process.c        | 97 +-----------------------------------
 2 files changed, 1 insertion(+), 97 deletions(-)

diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index be8c9fa23983..5b03d8a82409 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -94,6 +94,5 @@ static inline void clear_task_ebb(struct task_struct *t)
 extern int set_thread_uses_vas(void);
 
 extern int set_thread_tidr(struct task_struct *t);
-extern void clear_thread_tidr(struct task_struct *t);
 
 #endif /* _ASM_POWERPC_SWITCH_TO_H */
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 3b00da47699b..87f047fd2762 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1496,103 +1496,12 @@ int set_thread_uses_vas(void)
 }
 
 #ifdef CONFIG_PPC64
-static DEFINE_SPINLOCK(vas_thread_id_lock);
-static DEFINE_IDA(vas_thread_ida);
-
-/*
- * We need to assign a unique thread id to each thread in a process.
- *
- * This thread id, referred to as TIDR, and separate from the Linux's tgid,
- * is intended to be used to direct an ASB_Notify from the hardware to the
- * thread, when a suitable event occurs in the system.
- *
- * One such event is a "paste" instruction in the context of Fast Thread
- * Wakeup (aka Core-to-core wake up in the Virtual Accelerator Switchboard
- * (VAS) in POWER9.
- *
- * To get a unique TIDR per process we could simply reuse task_pid_nr() but
- * the problem is that task_pid_nr() is not yet available copy_thread() is
- * called. Fixing that would require changing more intrusive arch-neutral
- * code in code path in copy_process()?.
- *
- * Further, to assign unique TIDRs within each process, we need an atomic
- * field (or an IDR) in task_struct, which again intrudes into the arch-
- * neutral code. So try to assign globally unique TIDRs for now.
- *
- * NOTE: TIDR 0 indicates that the thread does not need a TIDR value.
- *	 For now, only threads that expect to be notified by the VAS
- *	 hardware need a TIDR value and we assign values > 0 for those.
- */
-#define MAX_THREAD_CONTEXT	((1 << 16) - 1)
-static int assign_thread_tidr(void)
-{
-	int index;
-	int err;
-	unsigned long flags;
-
-again:
-	if (!ida_pre_get(&vas_thread_ida, GFP_KERNEL))
-		return -ENOMEM;
-
-	spin_lock_irqsave(&vas_thread_id_lock, flags);
-	err = ida_get_new_above(&vas_thread_ida, 1, &index);
-	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-
-	if (err == -EAGAIN)
-		goto again;
-	else if (err)
-		return err;
-
-	if (index > MAX_THREAD_CONTEXT) {
-		spin_lock_irqsave(&vas_thread_id_lock, flags);
-		ida_remove(&vas_thread_ida, index);
-		spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-		return -ENOMEM;
-	}
-
-	return index;
-}
-
-static void free_thread_tidr(int id)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&vas_thread_id_lock, flags);
-	ida_remove(&vas_thread_ida, id);
-	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-}
-
-/*
- * Clear any TIDR value assigned to this thread.
- */
-void clear_thread_tidr(struct task_struct *t)
-{
-	if (!t->thread.tidr)
-		return;
-
-	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
-		WARN_ON_ONCE(1);
-		return;
-	}
-
-	mtspr(SPRN_TIDR, 0);
-	free_thread_tidr(t->thread.tidr);
-	t->thread.tidr = 0;
-}
-
-void arch_release_task_struct(struct task_struct *t)
-{
-	clear_thread_tidr(t);
-}
-
 /*
  * Assign a unique TIDR (thread id) for task @t and set it in the thread
  * structure. For now, we only support setting TIDR for 'current' task.
  */
 int set_thread_tidr(struct task_struct *t)
 {
-	int rc;
-
 	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
 		return -EINVAL;
 
@@ -1602,11 +1511,7 @@ int set_thread_tidr(struct task_struct *t)
 	if (t->thread.tidr)
 		return 0;
 
-	rc = assign_thread_tidr();
-	if (rc < 0)
-		return rc;
-
-	t->thread.tidr = rc;
+	t->thread.tidr = (u16)task_pid_nr(t);
 	mtspr(SPRN_TIDR, t->thread.tidr);
 
 	return 0;
-- 
2.14.3

[PATCH v3 3/7] powerpc: use task_pid_nr() for TID allocation

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The current implementation of TID allocation, using a global IDR, may
result in an errant process starving the system of available TIDs.
Instead, use task_pid_nr(), as mentioned by the original author. The
scenario described which prevented it's use is not applicable, as
set_thread_tidr can only be called after the task struct has been
populated.

In the unlikely event that 2 threads share the TID and are waiting,
one of the following cases will happen:

1. The correct thread is running, the wrong thread is not
In this situation, the correct thread is woken and proceeds to pass it's
condition check.

2. Neither threads are running
In this situation, neither thread will be woken. When scheduled, the waiting
threads will execute either a wait, which will return immediately, followed
by a condition check, which will pass for the correct thread and fail
for the wrong thread, or they will execute the condition check immediately.

3. The wrong thread is running, the correct thread is not
The wrong thread will be woken, but will fail it's condition check and
re-execute wait. The correct thread, when scheduled, will execute either
it's condition check (which will pass), or wait, which returns immediately
when called the first time after the thread is scheduled, followed by it's
condition check (which will pass).

4. Both threads are running
Both threads will be woken. The wrong thread will fail it's condition check
and execute another wait, while the correct thread will pass it's condition
check.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/switch_to.h |  1 -
 arch/powerpc/kernel/process.c        | 97 +-----------------------------------
 2 files changed, 1 insertion(+), 97 deletions(-)

diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index be8c9fa23983..5b03d8a82409 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -94,6 +94,5 @@ static inline void clear_task_ebb(struct task_struct *t)
 extern int set_thread_uses_vas(void);
 
 extern int set_thread_tidr(struct task_struct *t);
-extern void clear_thread_tidr(struct task_struct *t);
 
 #endif /* _ASM_POWERPC_SWITCH_TO_H */
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 3b00da47699b..87f047fd2762 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1496,103 +1496,12 @@ int set_thread_uses_vas(void)
 }
 
 #ifdef CONFIG_PPC64
-static DEFINE_SPINLOCK(vas_thread_id_lock);
-static DEFINE_IDA(vas_thread_ida);
-
-/*
- * We need to assign a unique thread id to each thread in a process.
- *
- * This thread id, referred to as TIDR, and separate from the Linux's tgid,
- * is intended to be used to direct an ASB_Notify from the hardware to the
- * thread, when a suitable event occurs in the system.
- *
- * One such event is a "paste" instruction in the context of Fast Thread
- * Wakeup (aka Core-to-core wake up in the Virtual Accelerator Switchboard
- * (VAS) in POWER9.
- *
- * To get a unique TIDR per process we could simply reuse task_pid_nr() but
- * the problem is that task_pid_nr() is not yet available copy_thread() is
- * called. Fixing that would require changing more intrusive arch-neutral
- * code in code path in copy_process()?.
- *
- * Further, to assign unique TIDRs within each process, we need an atomic
- * field (or an IDR) in task_struct, which again intrudes into the arch-
- * neutral code. So try to assign globally unique TIDRs for now.
- *
- * NOTE: TIDR 0 indicates that the thread does not need a TIDR value.
- *	 For now, only threads that expect to be notified by the VAS
- *	 hardware need a TIDR value and we assign values > 0 for those.
- */
-#define MAX_THREAD_CONTEXT	((1 << 16) - 1)
-static int assign_thread_tidr(void)
-{
-	int index;
-	int err;
-	unsigned long flags;
-
-again:
-	if (!ida_pre_get(&vas_thread_ida, GFP_KERNEL))
-		return -ENOMEM;
-
-	spin_lock_irqsave(&vas_thread_id_lock, flags);
-	err = ida_get_new_above(&vas_thread_ida, 1, &index);
-	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-
-	if (err == -EAGAIN)
-		goto again;
-	else if (err)
-		return err;
-
-	if (index > MAX_THREAD_CONTEXT) {
-		spin_lock_irqsave(&vas_thread_id_lock, flags);
-		ida_remove(&vas_thread_ida, index);
-		spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-		return -ENOMEM;
-	}
-
-	return index;
-}
-
-static void free_thread_tidr(int id)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&vas_thread_id_lock, flags);
-	ida_remove(&vas_thread_ida, id);
-	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-}
-
-/*
- * Clear any TIDR value assigned to this thread.
- */
-void clear_thread_tidr(struct task_struct *t)
-{
-	if (!t->thread.tidr)
-		return;
-
-	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
-		WARN_ON_ONCE(1);
-		return;
-	}
-
-	mtspr(SPRN_TIDR, 0);
-	free_thread_tidr(t->thread.tidr);
-	t->thread.tidr = 0;
-}
-
-void arch_release_task_struct(struct task_struct *t)
-{
-	clear_thread_tidr(t);
-}
-
 /*
  * Assign a unique TIDR (thread id) for task @t and set it in the thread
  * structure. For now, we only support setting TIDR for 'current' task.
  */
 int set_thread_tidr(struct task_struct *t)
 {
-	int rc;
-
 	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
 		return -EINVAL;
 
@@ -1602,11 +1511,7 @@ int set_thread_tidr(struct task_struct *t)
 	if (t->thread.tidr)
 		return 0;
 
-	rc = assign_thread_tidr();
-	if (rc < 0)
-		return rc;
-
-	t->thread.tidr = rc;
+	t->thread.tidr = (u16)task_pid_nr(t);
 	mtspr(SPRN_TIDR, t->thread.tidr);
 
 	return 0;
-- 
2.14.3

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[PATCH v3 4/7] ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The function removes the process element from NPU cache.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/pnv-ocxl.h   | 2 +-
 arch/powerpc/platforms/powernv/ocxl.c | 4 ++--
 drivers/misc/ocxl/link.c              | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/pnv-ocxl.h b/arch/powerpc/include/asm/pnv-ocxl.h
index f6945d3bc971..208b5503f4ed 100644
--- a/arch/powerpc/include/asm/pnv-ocxl.h
+++ b/arch/powerpc/include/asm/pnv-ocxl.h
@@ -28,7 +28,7 @@ extern int pnv_ocxl_map_xsl_regs(struct pci_dev *dev, void __iomem **dsisr,
 extern int pnv_ocxl_spa_setup(struct pci_dev *dev, void *spa_mem, int PE_mask,
 			void **platform_data);
 extern void pnv_ocxl_spa_release(void *platform_data);
-extern int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle);
+extern int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle);
 
 extern int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr);
 extern void pnv_ocxl_free_xive_irq(u32 irq);
diff --git a/arch/powerpc/platforms/powernv/ocxl.c b/arch/powerpc/platforms/powernv/ocxl.c
index fa9b53af3c7b..8c65aacda9c8 100644
--- a/arch/powerpc/platforms/powernv/ocxl.c
+++ b/arch/powerpc/platforms/powernv/ocxl.c
@@ -475,7 +475,7 @@ void pnv_ocxl_spa_release(void *platform_data)
 }
 EXPORT_SYMBOL_GPL(pnv_ocxl_spa_release);
 
-int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
+int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle)
 {
 	struct spa_data *data = (struct spa_data *) platform_data;
 	int rc;
@@ -483,7 +483,7 @@ int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
 	rc = opal_npu_spa_clear_cache(data->phb_opal_id, data->bdfn, pe_handle);
 	return rc;
 }
-EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe);
+EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe_from_cache);
 
 int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr)
 {
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index f30790582dc0..656e8610eec2 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -599,7 +599,7 @@ int ocxl_link_remove_pe(void *link_handle, int pasid)
 	 * On powerpc, the entry needs to be cleared from the context
 	 * cache of the NPU.
 	 */
-	rc = pnv_ocxl_spa_remove_pe(link->platform_data, pe_handle);
+	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
 	WARN_ON(rc);
 
 	pe_data = radix_tree_delete(&spa->pe_tree, pe_handle);
-- 
2.14.3

[PATCH v3 4/7] ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The function removes the process element from NPU cache.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/pnv-ocxl.h   | 2 +-
 arch/powerpc/platforms/powernv/ocxl.c | 4 ++--
 drivers/misc/ocxl/link.c              | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/pnv-ocxl.h b/arch/powerpc/include/asm/pnv-ocxl.h
index f6945d3bc971..208b5503f4ed 100644
--- a/arch/powerpc/include/asm/pnv-ocxl.h
+++ b/arch/powerpc/include/asm/pnv-ocxl.h
@@ -28,7 +28,7 @@ extern int pnv_ocxl_map_xsl_regs(struct pci_dev *dev, void __iomem **dsisr,
 extern int pnv_ocxl_spa_setup(struct pci_dev *dev, void *spa_mem, int PE_mask,
 			void **platform_data);
 extern void pnv_ocxl_spa_release(void *platform_data);
-extern int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle);
+extern int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle);
 
 extern int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr);
 extern void pnv_ocxl_free_xive_irq(u32 irq);
diff --git a/arch/powerpc/platforms/powernv/ocxl.c b/arch/powerpc/platforms/powernv/ocxl.c
index fa9b53af3c7b..8c65aacda9c8 100644
--- a/arch/powerpc/platforms/powernv/ocxl.c
+++ b/arch/powerpc/platforms/powernv/ocxl.c
@@ -475,7 +475,7 @@ void pnv_ocxl_spa_release(void *platform_data)
 }
 EXPORT_SYMBOL_GPL(pnv_ocxl_spa_release);
 
-int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
+int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle)
 {
 	struct spa_data *data = (struct spa_data *) platform_data;
 	int rc;
@@ -483,7 +483,7 @@ int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
 	rc = opal_npu_spa_clear_cache(data->phb_opal_id, data->bdfn, pe_handle);
 	return rc;
 }
-EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe);
+EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe_from_cache);
 
 int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr)
 {
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index f30790582dc0..656e8610eec2 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -599,7 +599,7 @@ int ocxl_link_remove_pe(void *link_handle, int pasid)
 	 * On powerpc, the entry needs to be cleared from the context
 	 * cache of the NPU.
 	 */
-	rc = pnv_ocxl_spa_remove_pe(link->platform_data, pe_handle);
+	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
 	WARN_ON(rc);
 
 	pe_data = radix_tree_delete(&spa->pe_tree, pe_handle);
-- 
2.14.3

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[PATCH v3 5/7] ocxl: Expose the thread_id needed for wait on POWER9

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

In order to successfully issue as_notify, an AFU needs to know the TID
to notify, which in turn means that this information should be
available in userspace so it can be communicated to the AFU.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/misc/ocxl/context.c       |  5 +++-
 drivers/misc/ocxl/file.c          | 53 +++++++++++++++++++++++++++++++++++++++
 drivers/misc/ocxl/link.c          | 36 ++++++++++++++++++++++++++
 drivers/misc/ocxl/ocxl_internal.h |  1 +
 include/misc/ocxl.h               |  9 +++++++
 include/uapi/misc/ocxl.h          | 10 ++++++++
 6 files changed, 113 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
index 909e8807824a..95f74623113e 100644
--- a/drivers/misc/ocxl/context.c
+++ b/drivers/misc/ocxl/context.c
@@ -34,6 +34,8 @@ int ocxl_context_init(struct ocxl_context *ctx, struct ocxl_afu *afu,
 	mutex_init(&ctx->xsl_error_lock);
 	mutex_init(&ctx->irq_lock);
 	idr_init(&ctx->irq_idr);
+	ctx->tidr = 0;
+
 	/*
 	 * Keep a reference on the AFU to make sure it's valid for the
 	 * duration of the life of the context
@@ -65,6 +67,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 {
 	int rc;
 
+	// Locks both status & tidr
 	mutex_lock(&ctx->status_mutex);
 	if (ctx->status != OPENED) {
 		rc = -EIO;
@@ -72,7 +75,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 	}
 
 	rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid,
-			current->mm->context.id, 0, amr, current->mm,
+			current->mm->context.id, ctx->tidr, amr, current->mm,
 			xsl_fault_error, ctx);
 	if (rc)
 		goto out;
diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index 038509e5d031..eb409a469f21 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -5,6 +5,8 @@
 #include <linux/sched/signal.h>
 #include <linux/uaccess.h>
 #include <uapi/misc/ocxl.h>
+#include <asm/reg.h>
+#include <asm/switch_to.h>
 #include "ocxl_internal.h"
 
 
@@ -123,11 +125,55 @@ static long afu_ioctl_get_metadata(struct ocxl_context *ctx,
 	return 0;
 }
 
+#ifdef CONFIG_PPC64
+static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
+		struct ocxl_ioctl_p9_wait __user *uarg)
+{
+	struct ocxl_ioctl_p9_wait arg;
+
+	memset(&arg, 0, sizeof(arg));
+
+	if (cpu_has_feature(CPU_FTR_P9_TIDR)) {
+		enum ocxl_context_status status;
+
+		// Locks both status & tidr
+		mutex_lock(&ctx->status_mutex);
+		if (!ctx->tidr) {
+			if (set_thread_tidr(current))
+				return -ENOENT;
+
+			ctx->tidr = current->thread.tidr;
+		}
+
+		status = ctx->status;
+		mutex_unlock(&ctx->status_mutex);
+
+		if (status == ATTACHED) {
+			int rc;
+			struct link *link = ctx->afu->fn->link;
+
+			rc = ocxl_link_update_pe(link, ctx->pasid, ctx->tidr);
+			if (rc)
+				return rc;
+		}
+
+		arg.thread_id = ctx->tidr;
+	} else
+		return -ENOENT;
+
+	if (copy_to_user(uarg, &arg, sizeof(arg)))
+		return -EFAULT;
+
+	return 0;
+}
+#endif
+
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
 			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
 			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
 			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
 			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
+			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
 			"UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -186,6 +232,13 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 				(struct ocxl_ioctl_metadata __user *) args);
 		break;
 
+#ifdef CONFIG_PPC64
+	case OCXL_IOCTL_ENABLE_P9_WAIT:
+		rc = afu_ioctl_enable_p9_wait(ctx,
+				(struct ocxl_ioctl_p9_wait __user *) args);
+		break;
+#endif
+
 	default:
 		rc = -EINVAL;
 	}
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index 656e8610eec2..88876ae8f330 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -544,6 +544,42 @@ int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
 }
 EXPORT_SYMBOL_GPL(ocxl_link_add_pe);
 
+int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid)
+{
+	struct link *link = (struct link *) link_handle;
+	struct spa *spa = link->spa;
+	struct ocxl_process_element *pe;
+	int pe_handle, rc;
+
+	if (pasid > SPA_PASID_MAX)
+		return -EINVAL;
+
+	pe_handle = pasid & SPA_PE_MASK;
+	pe = spa->spa_mem + pe_handle;
+
+	mutex_lock(&spa->spa_lock);
+
+	pe->tid = tid;
+
+	/*
+	 * The barrier makes sure the PE is updated
+	 * before we clear the NPU context cache below, so that the
+	 * old PE cannot be reloaded erroneously.
+	 */
+	mb();
+
+	/*
+	 * hook to platform code
+	 * On powerpc, the entry needs to be cleared from the context
+	 * cache of the NPU.
+	 */
+	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
+	WARN_ON(rc);
+
+	mutex_unlock(&spa->spa_lock);
+	return rc;
+}
+
 int ocxl_link_remove_pe(void *link_handle, int pasid)
 {
 	struct link *link = (struct link *) link_handle;
diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
index 5d421824afd9..a32f2151029f 100644
--- a/drivers/misc/ocxl/ocxl_internal.h
+++ b/drivers/misc/ocxl/ocxl_internal.h
@@ -77,6 +77,7 @@ struct ocxl_context {
 	struct ocxl_xsl_error xsl_error;
 	struct mutex irq_lock;
 	struct idr irq_idr;
+	u16 tidr; // Thread ID used for P9 wait implementation
 };
 
 struct ocxl_process_element {
diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
index 51ccf76db293..9ff6ddc28e22 100644
--- a/include/misc/ocxl.h
+++ b/include/misc/ocxl.h
@@ -188,6 +188,15 @@ extern int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
 		void (*xsl_err_cb)(void *data, u64 addr, u64 dsisr),
 		void *xsl_err_data);
 
+/**
+ * Update values within a Process Element
+ *
+ * link_handle: the link handle associated with the process element
+ * pasid: the PASID for the AFU context
+ * tid: the new thread id for the process element
+ */
+extern int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid);
+
 /*
  * Remove a Process Element from the Shared Process Area for a link
  */
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 0af83d80fb3e..8d2748e69c84 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -48,6 +48,15 @@ struct ocxl_ioctl_metadata {
 	__u64 reserved[13]; // Total of 16*u64
 };
 
+struct ocxl_ioctl_p9_wait {
+	__u16 thread_id; // The thread ID required to wake this thread
+	__u16 reserved1;
+	__u32 reserved2;
+	__u64 reserved3[3];
+};
+
+};
+
 struct ocxl_ioctl_irq_fd {
 	__u64 irq_offset;
 	__s32 eventfd;
@@ -62,5 +71,6 @@ struct ocxl_ioctl_irq_fd {
 #define OCXL_IOCTL_IRQ_FREE	_IOW(OCXL_MAGIC, 0x12, __u64)
 #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
+#define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.3

[PATCH v3 5/7] ocxl: Expose the thread_id needed for wait on POWER9

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

In order to successfully issue as_notify, an AFU needs to know the TID
to notify, which in turn means that this information should be
available in userspace so it can be communicated to the AFU.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/misc/ocxl/context.c       |  5 +++-
 drivers/misc/ocxl/file.c          | 53 +++++++++++++++++++++++++++++++++++++++
 drivers/misc/ocxl/link.c          | 36 ++++++++++++++++++++++++++
 drivers/misc/ocxl/ocxl_internal.h |  1 +
 include/misc/ocxl.h               |  9 +++++++
 include/uapi/misc/ocxl.h          | 10 ++++++++
 6 files changed, 113 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
index 909e8807824a..95f74623113e 100644
--- a/drivers/misc/ocxl/context.c
+++ b/drivers/misc/ocxl/context.c
@@ -34,6 +34,8 @@ int ocxl_context_init(struct ocxl_context *ctx, struct ocxl_afu *afu,
 	mutex_init(&ctx->xsl_error_lock);
 	mutex_init(&ctx->irq_lock);
 	idr_init(&ctx->irq_idr);
+	ctx->tidr = 0;
+
 	/*
 	 * Keep a reference on the AFU to make sure it's valid for the
 	 * duration of the life of the context
@@ -65,6 +67,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 {
 	int rc;
 
+	// Locks both status & tidr
 	mutex_lock(&ctx->status_mutex);
 	if (ctx->status != OPENED) {
 		rc = -EIO;
@@ -72,7 +75,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 	}
 
 	rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid,
-			current->mm->context.id, 0, amr, current->mm,
+			current->mm->context.id, ctx->tidr, amr, current->mm,
 			xsl_fault_error, ctx);
 	if (rc)
 		goto out;
diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index 038509e5d031..eb409a469f21 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -5,6 +5,8 @@
 #include <linux/sched/signal.h>
 #include <linux/uaccess.h>
 #include <uapi/misc/ocxl.h>
+#include <asm/reg.h>
+#include <asm/switch_to.h>
 #include "ocxl_internal.h"
 
 
@@ -123,11 +125,55 @@ static long afu_ioctl_get_metadata(struct ocxl_context *ctx,
 	return 0;
 }
 
+#ifdef CONFIG_PPC64
+static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
+		struct ocxl_ioctl_p9_wait __user *uarg)
+{
+	struct ocxl_ioctl_p9_wait arg;
+
+	memset(&arg, 0, sizeof(arg));
+
+	if (cpu_has_feature(CPU_FTR_P9_TIDR)) {
+		enum ocxl_context_status status;
+
+		// Locks both status & tidr
+		mutex_lock(&ctx->status_mutex);
+		if (!ctx->tidr) {
+			if (set_thread_tidr(current))
+				return -ENOENT;
+
+			ctx->tidr = current->thread.tidr;
+		}
+
+		status = ctx->status;
+		mutex_unlock(&ctx->status_mutex);
+
+		if (status == ATTACHED) {
+			int rc;
+			struct link *link = ctx->afu->fn->link;
+
+			rc = ocxl_link_update_pe(link, ctx->pasid, ctx->tidr);
+			if (rc)
+				return rc;
+		}
+
+		arg.thread_id = ctx->tidr;
+	} else
+		return -ENOENT;
+
+	if (copy_to_user(uarg, &arg, sizeof(arg)))
+		return -EFAULT;
+
+	return 0;
+}
+#endif
+
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
 			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
 			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
 			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
 			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
+			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
 			"UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -186,6 +232,13 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 				(struct ocxl_ioctl_metadata __user *) args);
 		break;
 
+#ifdef CONFIG_PPC64
+	case OCXL_IOCTL_ENABLE_P9_WAIT:
+		rc = afu_ioctl_enable_p9_wait(ctx,
+				(struct ocxl_ioctl_p9_wait __user *) args);
+		break;
+#endif
+
 	default:
 		rc = -EINVAL;
 	}
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index 656e8610eec2..88876ae8f330 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -544,6 +544,42 @@ int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
 }
 EXPORT_SYMBOL_GPL(ocxl_link_add_pe);
 
+int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid)
+{
+	struct link *link = (struct link *) link_handle;
+	struct spa *spa = link->spa;
+	struct ocxl_process_element *pe;
+	int pe_handle, rc;
+
+	if (pasid > SPA_PASID_MAX)
+		return -EINVAL;
+
+	pe_handle = pasid & SPA_PE_MASK;
+	pe = spa->spa_mem + pe_handle;
+
+	mutex_lock(&spa->spa_lock);
+
+	pe->tid = tid;
+
+	/*
+	 * The barrier makes sure the PE is updated
+	 * before we clear the NPU context cache below, so that the
+	 * old PE cannot be reloaded erroneously.
+	 */
+	mb();
+
+	/*
+	 * hook to platform code
+	 * On powerpc, the entry needs to be cleared from the context
+	 * cache of the NPU.
+	 */
+	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
+	WARN_ON(rc);
+
+	mutex_unlock(&spa->spa_lock);
+	return rc;
+}
+
 int ocxl_link_remove_pe(void *link_handle, int pasid)
 {
 	struct link *link = (struct link *) link_handle;
diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
index 5d421824afd9..a32f2151029f 100644
--- a/drivers/misc/ocxl/ocxl_internal.h
+++ b/drivers/misc/ocxl/ocxl_internal.h
@@ -77,6 +77,7 @@ struct ocxl_context {
 	struct ocxl_xsl_error xsl_error;
 	struct mutex irq_lock;
 	struct idr irq_idr;
+	u16 tidr; // Thread ID used for P9 wait implementation
 };
 
 struct ocxl_process_element {
diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
index 51ccf76db293..9ff6ddc28e22 100644
--- a/include/misc/ocxl.h
+++ b/include/misc/ocxl.h
@@ -188,6 +188,15 @@ extern int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
 		void (*xsl_err_cb)(void *data, u64 addr, u64 dsisr),
 		void *xsl_err_data);
 
+/**
+ * Update values within a Process Element
+ *
+ * link_handle: the link handle associated with the process element
+ * pasid: the PASID for the AFU context
+ * tid: the new thread id for the process element
+ */
+extern int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid);
+
 /*
  * Remove a Process Element from the Shared Process Area for a link
  */
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 0af83d80fb3e..8d2748e69c84 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -48,6 +48,15 @@ struct ocxl_ioctl_metadata {
 	__u64 reserved[13]; // Total of 16*u64
 };
 
+struct ocxl_ioctl_p9_wait {
+	__u16 thread_id; // The thread ID required to wake this thread
+	__u16 reserved1;
+	__u32 reserved2;
+	__u64 reserved3[3];
+};
+
+};
+
 struct ocxl_ioctl_irq_fd {
 	__u64 irq_offset;
 	__s32 eventfd;
@@ -62,5 +71,6 @@ struct ocxl_ioctl_irq_fd {
 #define OCXL_IOCTL_IRQ_FREE	_IOW(OCXL_MAGIC, 0x12, __u64)
 #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
+#define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.3

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Re: [PATCH v3 5/7] ocxl: Expose the thread_id needed for wait on POWER9

[Michael Ellerman]

"Alastair D'Silva" <alastair@au1.ibm.com> writes:
> diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
> index 0af83d80fb3e..8d2748e69c84 100644
> --- a/include/uapi/misc/ocxl.h
> +++ b/include/uapi/misc/ocxl.h
> @@ -48,6 +48,15 @@ struct ocxl_ioctl_metadata {
>  	__u64 reserved[13]; // Total of 16*u64
>  };
>  
> +struct ocxl_ioctl_p9_wait {
> +	__u16 thread_id; // The thread ID required to wake this thread
> +	__u16 reserved1;
> +	__u32 reserved2;
> +	__u64 reserved3[3];
> +};
> +
> +};
> +

O_o

???

cheers

Re: [PATCH v3 5/7] ocxl: Expose the thread_id needed for wait on POWER9

[Michael Ellerman]

"Alastair D'Silva" <alastair@au1.ibm.com> writes:
> diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
> index 0af83d80fb3e..8d2748e69c84 100644
> --- a/include/uapi/misc/ocxl.h
> +++ b/include/uapi/misc/ocxl.h
> @@ -48,6 +48,15 @@ struct ocxl_ioctl_metadata {
>  	__u64 reserved[13]; // Total of 16*u64
>  };
>  
> +struct ocxl_ioctl_p9_wait {
> +	__u16 thread_id; // The thread ID required to wake this thread
> +	__u16 reserved1;
> +	__u32 reserved2;
> +	__u64 reserved3[3];
> +};
> +
> +};
> +

O_o

???

cheers
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[PATCH v3 6/7] ocxl: Add an IOCTL so userspace knows what OCXL features are available

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

In order for a userspace AFU driver to call the POWER9 specific
OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
make that call.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/misc/ocxl/file.c | 25 +++++++++++++++++++++++++
 include/uapi/misc/ocxl.h |  4 ++++
 2 files changed, 29 insertions(+)

diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index eb409a469f21..33ae46ce0a8a 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -168,12 +168,32 @@ static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
 }
 #endif
 
+
+static long afu_ioctl_get_features(struct ocxl_context *ctx,
+		struct ocxl_ioctl_features __user *uarg)
+{
+	struct ocxl_ioctl_features arg;
+
+	memset(&arg, 0, sizeof(arg));
+
+#ifdef CONFIG_PPC64
+	if (cpu_has_feature(CPU_FTR_P9_TIDR))
+		arg.flags[0] |= OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT;
+#endif
+
+	if (copy_to_user(uarg, &arg, sizeof(arg)))
+		return -EFAULT;
+
+	return 0;
+}
+
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
 			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
 			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
 			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
 			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
 			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
+			x == OCXL_IOCTL_GET_FEATURES ? "GET_FEATURES" :	\
 			"UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -239,6 +259,11 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 		break;
 #endif
 
+	case OCXL_IOCTL_GET_FEATURES:
+		rc = afu_ioctl_get_features(ctx,
+				(struct ocxl_ioctl_features __user *) args);
+		break;
+
 	default:
 		rc = -EINVAL;
 	}
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 8d2748e69c84..bb80f294b429 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -55,6 +55,9 @@ struct ocxl_ioctl_p9_wait {
 	__u64 reserved3[3];
 };
 
+#define OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT	0x01
+struct ocxl_ioctl_features {
+	__u64 flags[4];
 };
 
 struct ocxl_ioctl_irq_fd {
@@ -72,5 +75,6 @@ struct ocxl_ioctl_irq_fd {
 #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
 #define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
+#define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_platform)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.3

[PATCH v3 6/7] ocxl: Add an IOCTL so userspace knows what OCXL features are available

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

In order for a userspace AFU driver to call the POWER9 specific
OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
make that call.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/misc/ocxl/file.c | 25 +++++++++++++++++++++++++
 include/uapi/misc/ocxl.h |  4 ++++
 2 files changed, 29 insertions(+)

diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index eb409a469f21..33ae46ce0a8a 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -168,12 +168,32 @@ static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
 }
 #endif
 
+
+static long afu_ioctl_get_features(struct ocxl_context *ctx,
+		struct ocxl_ioctl_features __user *uarg)
+{
+	struct ocxl_ioctl_features arg;
+
+	memset(&arg, 0, sizeof(arg));
+
+#ifdef CONFIG_PPC64
+	if (cpu_has_feature(CPU_FTR_P9_TIDR))
+		arg.flags[0] |= OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT;
+#endif
+
+	if (copy_to_user(uarg, &arg, sizeof(arg)))
+		return -EFAULT;
+
+	return 0;
+}
+
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
 			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
 			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
 			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
 			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
 			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
+			x == OCXL_IOCTL_GET_FEATURES ? "GET_FEATURES" :	\
 			"UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -239,6 +259,11 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 		break;
 #endif
 
+	case OCXL_IOCTL_GET_FEATURES:
+		rc = afu_ioctl_get_features(ctx,
+				(struct ocxl_ioctl_features __user *) args);
+		break;
+
 	default:
 		rc = -EINVAL;
 	}
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 8d2748e69c84..bb80f294b429 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -55,6 +55,9 @@ struct ocxl_ioctl_p9_wait {
 	__u64 reserved3[3];
 };
 
+#define OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT	0x01
+struct ocxl_ioctl_features {
+	__u64 flags[4];
 };
 
 struct ocxl_ioctl_irq_fd {
@@ -72,5 +75,6 @@ struct ocxl_ioctl_irq_fd {
 #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
 #define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
+#define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_platform)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.3

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[PATCH v3 7/7] ocxl: Document new OCXL IOCTLs

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 Documentation/accelerators/ocxl.rst | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
index ddcc58d01cfb..14cefc020e2d 100644
--- a/Documentation/accelerators/ocxl.rst
+++ b/Documentation/accelerators/ocxl.rst
@@ -157,6 +157,17 @@ OCXL_IOCTL_GET_METADATA:
   Obtains configuration information from the card, such at the size of
   MMIO areas, the AFU version, and the PASID for the current context.
 
+OCXL_IOCTL_ENABLE_P9_WAIT:
+
+  Allows the AFU to wake a userspace thread executing 'wait'. Returns
+  information to userspace to allow it to configure the AFU. Note that
+  this is only available on POWER9.
+
+OCXL_IOCTL_GET_FEATURES:
+
+  Reports on which CPU features that affect OpenCAPI are usable from
+  userspace.
+
 
 mmap
 ----
-- 
2.14.3

[PATCH v3 7/7] ocxl: Document new OCXL IOCTLs

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 Documentation/accelerators/ocxl.rst | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
index ddcc58d01cfb..14cefc020e2d 100644
--- a/Documentation/accelerators/ocxl.rst
+++ b/Documentation/accelerators/ocxl.rst
@@ -157,6 +157,17 @@ OCXL_IOCTL_GET_METADATA:
   Obtains configuration information from the card, such at the size of
   MMIO areas, the AFU version, and the PASID for the current context.
 
+OCXL_IOCTL_ENABLE_P9_WAIT:
+
+  Allows the AFU to wake a userspace thread executing 'wait'. Returns
+  information to userspace to allow it to configure the AFU. Note that
+  this is only available on POWER9.
+
+OCXL_IOCTL_GET_FEATURES:
+
+  Reports on which CPU features that affect OpenCAPI are usable from
+  userspace.
+
 
 mmap
 ----
-- 
2.14.3

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[PATCH v4 0/7] ocxl: Implement Power9 as_notify/wait for OpenCAPI

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The Power 9 as_notify/wait feature provides a lower latency way to
signal a thread that work is complete. This series enables the use of
this feature from OpenCAPI adapters, as well as addressing a potential
starvation issue when allocating thread IDs.

Changelog:
v4:
  Remove the "unique" statement from the set_thread_tidr function and
    move the text explaining why it is safe from the commit message
    to the function description
v3:
  Fix references to POWER9
  Remove stray whitespace edit from docs
  Add more details to commit message for "use task_pid_nr()"
  Retitle patch 6 to indicate OCXL rather than CPU features
v2:
  Rename get_platform IOCTL to get_features
  Move stray edit from patch 1 to patch 3

Alastair D'Silva (7):
  powerpc: Add TIDR CPU feature for POWER9
  powerpc: Use TIDR CPU feature to control TIDR allocation
  powerpc: use task_pid_nr() for TID allocation
  ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action
  ocxl: Expose the thread_id needed for wait on POWER9
  ocxl: Add an IOCTL so userspace knows what OCXL features are available
  ocxl: Document new OCXL IOCTLs

 Documentation/accelerators/ocxl.rst   |  11 ++++
 arch/powerpc/include/asm/cputable.h   |   3 +-
 arch/powerpc/include/asm/pnv-ocxl.h   |   2 +-
 arch/powerpc/include/asm/switch_to.h  |   1 -
 arch/powerpc/kernel/dt_cpu_ftrs.c     |   1 +
 arch/powerpc/kernel/process.c         | 101 +---------------------------------
 arch/powerpc/platforms/powernv/ocxl.c |   4 +-
 drivers/misc/ocxl/context.c           |   5 +-
 drivers/misc/ocxl/file.c              |  78 ++++++++++++++++++++++++++
 drivers/misc/ocxl/link.c              |  38 ++++++++++++-
 drivers/misc/ocxl/ocxl_internal.h     |   1 +
 include/misc/ocxl.h                   |   9 +++
 include/uapi/misc/ocxl.h              |  14 +++++
 13 files changed, 163 insertions(+), 105 deletions(-)

-- 
2.14.3

[PATCH v4 0/7] ocxl: Implement Power9 as_notify/wait for OpenCAPI

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The Power 9 as_notify/wait feature provides a lower latency way to
signal a thread that work is complete. This series enables the use of
this feature from OpenCAPI adapters, as well as addressing a potential
starvation issue when allocating thread IDs.

Changelog:
v4:
  Remove the "unique" statement from the set_thread_tidr function and
    move the text explaining why it is safe from the commit message
    to the function description
v3:
  Fix references to POWER9
  Remove stray whitespace edit from docs
  Add more details to commit message for "use task_pid_nr()"
  Retitle patch 6 to indicate OCXL rather than CPU features
v2:
  Rename get_platform IOCTL to get_features
  Move stray edit from patch 1 to patch 3

Alastair D'Silva (7):
  powerpc: Add TIDR CPU feature for POWER9
  powerpc: Use TIDR CPU feature to control TIDR allocation
  powerpc: use task_pid_nr() for TID allocation
  ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action
  ocxl: Expose the thread_id needed for wait on POWER9
  ocxl: Add an IOCTL so userspace knows what OCXL features are available
  ocxl: Document new OCXL IOCTLs

 Documentation/accelerators/ocxl.rst   |  11 ++++
 arch/powerpc/include/asm/cputable.h   |   3 +-
 arch/powerpc/include/asm/pnv-ocxl.h   |   2 +-
 arch/powerpc/include/asm/switch_to.h  |   1 -
 arch/powerpc/kernel/dt_cpu_ftrs.c     |   1 +
 arch/powerpc/kernel/process.c         | 101 +---------------------------------
 arch/powerpc/platforms/powernv/ocxl.c |   4 +-
 drivers/misc/ocxl/context.c           |   5 +-
 drivers/misc/ocxl/file.c              |  78 ++++++++++++++++++++++++++
 drivers/misc/ocxl/link.c              |  38 ++++++++++++-
 drivers/misc/ocxl/ocxl_internal.h     |   1 +
 include/misc/ocxl.h                   |   9 +++
 include/uapi/misc/ocxl.h              |  14 +++++
 13 files changed, 163 insertions(+), 105 deletions(-)

-- 
2.14.3

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[PATCH v4 1/7] powerpc: Add TIDR CPU feature for POWER9

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

This patch adds a CPU feature bit to show whether the CPU has
the TIDR register available, enabling as_notify/wait in userspace.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/cputable.h | 3 ++-
 arch/powerpc/kernel/dt_cpu_ftrs.c   | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index 4e332f3531c5..54c4cbbe57b4 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -215,6 +215,7 @@ static inline void cpu_feature_keys_init(void) { }
 #define CPU_FTR_P9_TM_HV_ASSIST		LONG_ASM_CONST(0x0000100000000000)
 #define CPU_FTR_P9_TM_XER_SO_BUG	LONG_ASM_CONST(0x0000200000000000)
 #define CPU_FTR_P9_TLBIE_BUG		LONG_ASM_CONST(0x0000400000000000)
+#define CPU_FTR_P9_TIDR			LONG_ASM_CONST(0x0000800000000000)
 
 #ifndef __ASSEMBLY__
 
@@ -462,7 +463,7 @@ static inline void cpu_feature_keys_init(void) { }
 	    CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
 	    CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S | \
 	    CPU_FTR_TM_COMP | CPU_FTR_ARCH_300 | CPU_FTR_PKEY | \
-	    CPU_FTR_P9_TLBIE_BUG)
+	    CPU_FTR_P9_TLBIE_BUG | CPU_FTR_P9_TIDR)
 #define CPU_FTRS_POWER9_DD1 ((CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD1) & \
 			     (~CPU_FTR_SAO))
 #define CPU_FTRS_POWER9_DD2_0 CPU_FTRS_POWER9
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
index 11a3a4fed3fb..10f8b7f55637 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -722,6 +722,7 @@ static __init void cpufeatures_cpu_quirks(void)
 	if ((version & 0xffff0000) == 0x004e0000) {
 		cur_cpu_spec->cpu_features &= ~(CPU_FTR_DAWR);
 		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TLBIE_BUG;
+		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TIDR;
 	}
 }
 
-- 
2.14.3

[PATCH v4 1/7] powerpc: Add TIDR CPU feature for POWER9

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

This patch adds a CPU feature bit to show whether the CPU has
the TIDR register available, enabling as_notify/wait in userspace.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/cputable.h | 3 ++-
 arch/powerpc/kernel/dt_cpu_ftrs.c   | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index 4e332f3531c5..54c4cbbe57b4 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -215,6 +215,7 @@ static inline void cpu_feature_keys_init(void) { }
 #define CPU_FTR_P9_TM_HV_ASSIST		LONG_ASM_CONST(0x0000100000000000)
 #define CPU_FTR_P9_TM_XER_SO_BUG	LONG_ASM_CONST(0x0000200000000000)
 #define CPU_FTR_P9_TLBIE_BUG		LONG_ASM_CONST(0x0000400000000000)
+#define CPU_FTR_P9_TIDR			LONG_ASM_CONST(0x0000800000000000)
 
 #ifndef __ASSEMBLY__
 
@@ -462,7 +463,7 @@ static inline void cpu_feature_keys_init(void) { }
 	    CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
 	    CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S | \
 	    CPU_FTR_TM_COMP | CPU_FTR_ARCH_300 | CPU_FTR_PKEY | \
-	    CPU_FTR_P9_TLBIE_BUG)
+	    CPU_FTR_P9_TLBIE_BUG | CPU_FTR_P9_TIDR)
 #define CPU_FTRS_POWER9_DD1 ((CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD1) & \
 			     (~CPU_FTR_SAO))
 #define CPU_FTRS_POWER9_DD2_0 CPU_FTRS_POWER9
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
index 11a3a4fed3fb..10f8b7f55637 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -722,6 +722,7 @@ static __init void cpufeatures_cpu_quirks(void)
 	if ((version & 0xffff0000) == 0x004e0000) {
 		cur_cpu_spec->cpu_features &= ~(CPU_FTR_DAWR);
 		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TLBIE_BUG;
+		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TIDR;
 	}
 }
 
-- 
2.14.3

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[PATCH v4 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

Switch the use of TIDR on it's CPU feature, rather than assuming it
is available based on architecture.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/kernel/process.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 1237f13fed51..3b00da47699b 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1154,7 +1154,7 @@ static inline void restore_sprs(struct thread_struct *old_thread,
 			mtspr(SPRN_TAR, new_thread->tar);
 	}
 
-	if (cpu_has_feature(CPU_FTR_ARCH_300) &&
+	if (cpu_has_feature(CPU_FTR_P9_TIDR) &&
 	    old_thread->tidr != new_thread->tidr)
 		mtspr(SPRN_TIDR, new_thread->tidr);
 #endif
@@ -1570,7 +1570,7 @@ void clear_thread_tidr(struct task_struct *t)
 	if (!t->thread.tidr)
 		return;
 
-	if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
+	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
 		WARN_ON_ONCE(1);
 		return;
 	}
@@ -1593,7 +1593,7 @@ int set_thread_tidr(struct task_struct *t)
 {
 	int rc;
 
-	if (!cpu_has_feature(CPU_FTR_ARCH_300))
+	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
 		return -EINVAL;
 
 	if (t != current)
-- 
2.14.3

[PATCH v4 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

Switch the use of TIDR on it's CPU feature, rather than assuming it
is available based on architecture.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/kernel/process.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 1237f13fed51..3b00da47699b 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1154,7 +1154,7 @@ static inline void restore_sprs(struct thread_struct *old_thread,
 			mtspr(SPRN_TAR, new_thread->tar);
 	}
 
-	if (cpu_has_feature(CPU_FTR_ARCH_300) &&
+	if (cpu_has_feature(CPU_FTR_P9_TIDR) &&
 	    old_thread->tidr != new_thread->tidr)
 		mtspr(SPRN_TIDR, new_thread->tidr);
 #endif
@@ -1570,7 +1570,7 @@ void clear_thread_tidr(struct task_struct *t)
 	if (!t->thread.tidr)
 		return;
 
-	if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
+	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
 		WARN_ON_ONCE(1);
 		return;
 	}
@@ -1593,7 +1593,7 @@ int set_thread_tidr(struct task_struct *t)
 {
 	int rc;
 
-	if (!cpu_has_feature(CPU_FTR_ARCH_300))
+	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
 		return -EINVAL;
 
 	if (t != current)
-- 
2.14.3

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[PATCH v4 3/7] powerpc: use task_pid_nr() for TID allocation

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The current implementation of TID allocation, using a global IDR, may
result in an errant process starving the system of available TIDs.
Instead, use task_pid_nr(), as mentioned by the original author. The
scenario described which prevented it's use is not applicable, as
set_thread_tidr can only be called after the task struct has been
populated.

In the unlikely event that 2 threads share the TID and are waiting,
all potential outcomes have been determined safe.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/switch_to.h |   1 -
 arch/powerpc/kernel/process.c        | 122 ++++++++---------------------------
 2 files changed, 28 insertions(+), 95 deletions(-)

diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index be8c9fa23983..5b03d8a82409 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -94,6 +94,5 @@ static inline void clear_task_ebb(struct task_struct *t)
 extern int set_thread_uses_vas(void);
 
 extern int set_thread_tidr(struct task_struct *t);
-extern void clear_thread_tidr(struct task_struct *t);
 
 #endif /* _ASM_POWERPC_SWITCH_TO_H */
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 3b00da47699b..c5b8e53acbae 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1496,103 +1496,41 @@ int set_thread_uses_vas(void)
 }
 
 #ifdef CONFIG_PPC64
-static DEFINE_SPINLOCK(vas_thread_id_lock);
-static DEFINE_IDA(vas_thread_ida);
-
-/*
- * We need to assign a unique thread id to each thread in a process.
+/**
+ * Assign a TIDR (thread ID) for task @t and set it in the thread
+ * structure. For now, we only support setting TIDR for 'current' task.
  *
- * This thread id, referred to as TIDR, and separate from the Linux's tgid,
- * is intended to be used to direct an ASB_Notify from the hardware to the
- * thread, when a suitable event occurs in the system.
+ * Since the TID value is a truncated form of it PID, it is possible
+ * (but unlikely) for 2 threads to have the same TID. In the unlikely event
+ * that 2 threads share the same TID and are waiting, one of the following
+ * cases will happen:
  *
- * One such event is a "paste" instruction in the context of Fast Thread
- * Wakeup (aka Core-to-core wake up in the Virtual Accelerator Switchboard
- * (VAS) in POWER9.
+ * 1. The correct thread is running, the wrong thread is not
+ * In this situation, the correct thread is woken and proceeds to pass it's
+ * condition check.
  *
- * To get a unique TIDR per process we could simply reuse task_pid_nr() but
- * the problem is that task_pid_nr() is not yet available copy_thread() is
- * called. Fixing that would require changing more intrusive arch-neutral
- * code in code path in copy_process()?.
+ * 2. Neither threads are running
+ * In this situation, neither thread will be woken. When scheduled, the waiting
+ * threads will execute either a wait, which will return immediately, followed
+ * by a condition check, which will pass for the correct thread and fail
+ * for the wrong thread, or they will execute the condition check immediately.
  *
- * Further, to assign unique TIDRs within each process, we need an atomic
- * field (or an IDR) in task_struct, which again intrudes into the arch-
- * neutral code. So try to assign globally unique TIDRs for now.
+ * 3. The wrong thread is running, the correct thread is not
+ * The wrong thread will be woken, but will fail it's condition check and
+ * re-execute wait. The correct thread, when scheduled, will execute either
+ * it's condition check (which will pass), or wait, which returns immediately
+ * when called the first time after the thread is scheduled, followed by it's
+ * condition check (which will pass).
  *
- * NOTE: TIDR 0 indicates that the thread does not need a TIDR value.
- *	 For now, only threads that expect to be notified by the VAS
- *	 hardware need a TIDR value and we assign values > 0 for those.
- */
-#define MAX_THREAD_CONTEXT	((1 << 16) - 1)
-static int assign_thread_tidr(void)
-{
-	int index;
-	int err;
-	unsigned long flags;
-
-again:
-	if (!ida_pre_get(&vas_thread_ida, GFP_KERNEL))
-		return -ENOMEM;
-
-	spin_lock_irqsave(&vas_thread_id_lock, flags);
-	err = ida_get_new_above(&vas_thread_ida, 1, &index);
-	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-
-	if (err == -EAGAIN)
-		goto again;
-	else if (err)
-		return err;
-
-	if (index > MAX_THREAD_CONTEXT) {
-		spin_lock_irqsave(&vas_thread_id_lock, flags);
-		ida_remove(&vas_thread_ida, index);
-		spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-		return -ENOMEM;
-	}
-
-	return index;
-}
-
-static void free_thread_tidr(int id)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&vas_thread_id_lock, flags);
-	ida_remove(&vas_thread_ida, id);
-	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-}
-
-/*
- * Clear any TIDR value assigned to this thread.
- */
-void clear_thread_tidr(struct task_struct *t)
-{
-	if (!t->thread.tidr)
-		return;
-
-	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
-		WARN_ON_ONCE(1);
-		return;
-	}
-
-	mtspr(SPRN_TIDR, 0);
-	free_thread_tidr(t->thread.tidr);
-	t->thread.tidr = 0;
-}
-
-void arch_release_task_struct(struct task_struct *t)
-{
-	clear_thread_tidr(t);
-}
-
-/*
- * Assign a unique TIDR (thread id) for task @t and set it in the thread
- * structure. For now, we only support setting TIDR for 'current' task.
+ * 4. Both threads are running
+ * Both threads will be woken. The wrong thread will fail it's condition check
+ * and execute another wait, while the correct thread will pass it's condition
+ * check.
+ *
+ * @t: the task to set the thread ID for
  */
 int set_thread_tidr(struct task_struct *t)
 {
-	int rc;
-
 	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
 		return -EINVAL;
 
@@ -1602,11 +1540,7 @@ int set_thread_tidr(struct task_struct *t)
 	if (t->thread.tidr)
 		return 0;
 
-	rc = assign_thread_tidr();
-	if (rc < 0)
-		return rc;
-
-	t->thread.tidr = rc;
+	t->thread.tidr = (u16)task_pid_nr(t);
 	mtspr(SPRN_TIDR, t->thread.tidr);
 
 	return 0;
-- 
2.14.3

[PATCH v4 3/7] powerpc: use task_pid_nr() for TID allocation

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The current implementation of TID allocation, using a global IDR, may
result in an errant process starving the system of available TIDs.
Instead, use task_pid_nr(), as mentioned by the original author. The
scenario described which prevented it's use is not applicable, as
set_thread_tidr can only be called after the task struct has been
populated.

In the unlikely event that 2 threads share the TID and are waiting,
all potential outcomes have been determined safe.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/switch_to.h |   1 -
 arch/powerpc/kernel/process.c        | 122 ++++++++---------------------------
 2 files changed, 28 insertions(+), 95 deletions(-)

diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index be8c9fa23983..5b03d8a82409 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -94,6 +94,5 @@ static inline void clear_task_ebb(struct task_struct *t)
 extern int set_thread_uses_vas(void);
 
 extern int set_thread_tidr(struct task_struct *t);
-extern void clear_thread_tidr(struct task_struct *t);
 
 #endif /* _ASM_POWERPC_SWITCH_TO_H */
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 3b00da47699b..c5b8e53acbae 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1496,103 +1496,41 @@ int set_thread_uses_vas(void)
 }
 
 #ifdef CONFIG_PPC64
-static DEFINE_SPINLOCK(vas_thread_id_lock);
-static DEFINE_IDA(vas_thread_ida);
-
-/*
- * We need to assign a unique thread id to each thread in a process.
+/**
+ * Assign a TIDR (thread ID) for task @t and set it in the thread
+ * structure. For now, we only support setting TIDR for 'current' task.
  *
- * This thread id, referred to as TIDR, and separate from the Linux's tgid,
- * is intended to be used to direct an ASB_Notify from the hardware to the
- * thread, when a suitable event occurs in the system.
+ * Since the TID value is a truncated form of it PID, it is possible
+ * (but unlikely) for 2 threads to have the same TID. In the unlikely event
+ * that 2 threads share the same TID and are waiting, one of the following
+ * cases will happen:
  *
- * One such event is a "paste" instruction in the context of Fast Thread
- * Wakeup (aka Core-to-core wake up in the Virtual Accelerator Switchboard
- * (VAS) in POWER9.
+ * 1. The correct thread is running, the wrong thread is not
+ * In this situation, the correct thread is woken and proceeds to pass it's
+ * condition check.
  *
- * To get a unique TIDR per process we could simply reuse task_pid_nr() but
- * the problem is that task_pid_nr() is not yet available copy_thread() is
- * called. Fixing that would require changing more intrusive arch-neutral
- * code in code path in copy_process()?.
+ * 2. Neither threads are running
+ * In this situation, neither thread will be woken. When scheduled, the waiting
+ * threads will execute either a wait, which will return immediately, followed
+ * by a condition check, which will pass for the correct thread and fail
+ * for the wrong thread, or they will execute the condition check immediately.
  *
- * Further, to assign unique TIDRs within each process, we need an atomic
- * field (or an IDR) in task_struct, which again intrudes into the arch-
- * neutral code. So try to assign globally unique TIDRs for now.
+ * 3. The wrong thread is running, the correct thread is not
+ * The wrong thread will be woken, but will fail it's condition check and
+ * re-execute wait. The correct thread, when scheduled, will execute either
+ * it's condition check (which will pass), or wait, which returns immediately
+ * when called the first time after the thread is scheduled, followed by it's
+ * condition check (which will pass).
  *
- * NOTE: TIDR 0 indicates that the thread does not need a TIDR value.
- *	 For now, only threads that expect to be notified by the VAS
- *	 hardware need a TIDR value and we assign values > 0 for those.
- */
-#define MAX_THREAD_CONTEXT	((1 << 16) - 1)
-static int assign_thread_tidr(void)
-{
-	int index;
-	int err;
-	unsigned long flags;
-
-again:
-	if (!ida_pre_get(&vas_thread_ida, GFP_KERNEL))
-		return -ENOMEM;
-
-	spin_lock_irqsave(&vas_thread_id_lock, flags);
-	err = ida_get_new_above(&vas_thread_ida, 1, &index);
-	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-
-	if (err == -EAGAIN)
-		goto again;
-	else if (err)
-		return err;
-
-	if (index > MAX_THREAD_CONTEXT) {
-		spin_lock_irqsave(&vas_thread_id_lock, flags);
-		ida_remove(&vas_thread_ida, index);
-		spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-		return -ENOMEM;
-	}
-
-	return index;
-}
-
-static void free_thread_tidr(int id)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&vas_thread_id_lock, flags);
-	ida_remove(&vas_thread_ida, id);
-	spin_unlock_irqrestore(&vas_thread_id_lock, flags);
-}
-
-/*
- * Clear any TIDR value assigned to this thread.
- */
-void clear_thread_tidr(struct task_struct *t)
-{
-	if (!t->thread.tidr)
-		return;
-
-	if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
-		WARN_ON_ONCE(1);
-		return;
-	}
-
-	mtspr(SPRN_TIDR, 0);
-	free_thread_tidr(t->thread.tidr);
-	t->thread.tidr = 0;
-}
-
-void arch_release_task_struct(struct task_struct *t)
-{
-	clear_thread_tidr(t);
-}
-
-/*
- * Assign a unique TIDR (thread id) for task @t and set it in the thread
- * structure. For now, we only support setting TIDR for 'current' task.
+ * 4. Both threads are running
+ * Both threads will be woken. The wrong thread will fail it's condition check
+ * and execute another wait, while the correct thread will pass it's condition
+ * check.
+ *
+ * @t: the task to set the thread ID for
  */
 int set_thread_tidr(struct task_struct *t)
 {
-	int rc;
-
 	if (!cpu_has_feature(CPU_FTR_P9_TIDR))
 		return -EINVAL;
 
@@ -1602,11 +1540,7 @@ int set_thread_tidr(struct task_struct *t)
 	if (t->thread.tidr)
 		return 0;
 
-	rc = assign_thread_tidr();
-	if (rc < 0)
-		return rc;
-
-	t->thread.tidr = rc;
+	t->thread.tidr = (u16)task_pid_nr(t);
 	mtspr(SPRN_TIDR, t->thread.tidr);
 
 	return 0;
-- 
2.14.3

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[PATCH v4 4/7] ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The function removes the process element from NPU cache.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/pnv-ocxl.h   | 2 +-
 arch/powerpc/platforms/powernv/ocxl.c | 4 ++--
 drivers/misc/ocxl/link.c              | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/pnv-ocxl.h b/arch/powerpc/include/asm/pnv-ocxl.h
index f6945d3bc971..208b5503f4ed 100644
--- a/arch/powerpc/include/asm/pnv-ocxl.h
+++ b/arch/powerpc/include/asm/pnv-ocxl.h
@@ -28,7 +28,7 @@ extern int pnv_ocxl_map_xsl_regs(struct pci_dev *dev, void __iomem **dsisr,
 extern int pnv_ocxl_spa_setup(struct pci_dev *dev, void *spa_mem, int PE_mask,
 			void **platform_data);
 extern void pnv_ocxl_spa_release(void *platform_data);
-extern int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle);
+extern int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle);
 
 extern int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr);
 extern void pnv_ocxl_free_xive_irq(u32 irq);
diff --git a/arch/powerpc/platforms/powernv/ocxl.c b/arch/powerpc/platforms/powernv/ocxl.c
index fa9b53af3c7b..8c65aacda9c8 100644
--- a/arch/powerpc/platforms/powernv/ocxl.c
+++ b/arch/powerpc/platforms/powernv/ocxl.c
@@ -475,7 +475,7 @@ void pnv_ocxl_spa_release(void *platform_data)
 }
 EXPORT_SYMBOL_GPL(pnv_ocxl_spa_release);
 
-int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
+int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle)
 {
 	struct spa_data *data = (struct spa_data *) platform_data;
 	int rc;
@@ -483,7 +483,7 @@ int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
 	rc = opal_npu_spa_clear_cache(data->phb_opal_id, data->bdfn, pe_handle);
 	return rc;
 }
-EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe);
+EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe_from_cache);
 
 int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr)
 {
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index f30790582dc0..656e8610eec2 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -599,7 +599,7 @@ int ocxl_link_remove_pe(void *link_handle, int pasid)
 	 * On powerpc, the entry needs to be cleared from the context
 	 * cache of the NPU.
 	 */
-	rc = pnv_ocxl_spa_remove_pe(link->platform_data, pe_handle);
+	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
 	WARN_ON(rc);
 
 	pe_data = radix_tree_delete(&spa->pe_tree, pe_handle);
-- 
2.14.3

[PATCH v4 4/7] ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

The function removes the process element from NPU cache.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 arch/powerpc/include/asm/pnv-ocxl.h   | 2 +-
 arch/powerpc/platforms/powernv/ocxl.c | 4 ++--
 drivers/misc/ocxl/link.c              | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/pnv-ocxl.h b/arch/powerpc/include/asm/pnv-ocxl.h
index f6945d3bc971..208b5503f4ed 100644
--- a/arch/powerpc/include/asm/pnv-ocxl.h
+++ b/arch/powerpc/include/asm/pnv-ocxl.h
@@ -28,7 +28,7 @@ extern int pnv_ocxl_map_xsl_regs(struct pci_dev *dev, void __iomem **dsisr,
 extern int pnv_ocxl_spa_setup(struct pci_dev *dev, void *spa_mem, int PE_mask,
 			void **platform_data);
 extern void pnv_ocxl_spa_release(void *platform_data);
-extern int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle);
+extern int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle);
 
 extern int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr);
 extern void pnv_ocxl_free_xive_irq(u32 irq);
diff --git a/arch/powerpc/platforms/powernv/ocxl.c b/arch/powerpc/platforms/powernv/ocxl.c
index fa9b53af3c7b..8c65aacda9c8 100644
--- a/arch/powerpc/platforms/powernv/ocxl.c
+++ b/arch/powerpc/platforms/powernv/ocxl.c
@@ -475,7 +475,7 @@ void pnv_ocxl_spa_release(void *platform_data)
 }
 EXPORT_SYMBOL_GPL(pnv_ocxl_spa_release);
 
-int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
+int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle)
 {
 	struct spa_data *data = (struct spa_data *) platform_data;
 	int rc;
@@ -483,7 +483,7 @@ int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
 	rc = opal_npu_spa_clear_cache(data->phb_opal_id, data->bdfn, pe_handle);
 	return rc;
 }
-EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe);
+EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe_from_cache);
 
 int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr)
 {
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index f30790582dc0..656e8610eec2 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -599,7 +599,7 @@ int ocxl_link_remove_pe(void *link_handle, int pasid)
 	 * On powerpc, the entry needs to be cleared from the context
 	 * cache of the NPU.
 	 */
-	rc = pnv_ocxl_spa_remove_pe(link->platform_data, pe_handle);
+	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
 	WARN_ON(rc);
 
 	pe_data = radix_tree_delete(&spa->pe_tree, pe_handle);
-- 
2.14.3

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[PATCH v4 5/7] ocxl: Expose the thread_id needed for wait on POWER9

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

In order to successfully issue as_notify, an AFU needs to know the TID
to notify, which in turn means that this information should be
available in userspace so it can be communicated to the AFU.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/misc/ocxl/context.c       |  5 +++-
 drivers/misc/ocxl/file.c          | 53 +++++++++++++++++++++++++++++++++++++++
 drivers/misc/ocxl/link.c          | 36 ++++++++++++++++++++++++++
 drivers/misc/ocxl/ocxl_internal.h |  1 +
 include/misc/ocxl.h               |  9 +++++++
 include/uapi/misc/ocxl.h          | 10 ++++++++
 6 files changed, 113 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
index 909e8807824a..95f74623113e 100644
--- a/drivers/misc/ocxl/context.c
+++ b/drivers/misc/ocxl/context.c
@@ -34,6 +34,8 @@ int ocxl_context_init(struct ocxl_context *ctx, struct ocxl_afu *afu,
 	mutex_init(&ctx->xsl_error_lock);
 	mutex_init(&ctx->irq_lock);
 	idr_init(&ctx->irq_idr);
+	ctx->tidr = 0;
+
 	/*
 	 * Keep a reference on the AFU to make sure it's valid for the
 	 * duration of the life of the context
@@ -65,6 +67,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 {
 	int rc;
 
+	// Locks both status & tidr
 	mutex_lock(&ctx->status_mutex);
 	if (ctx->status != OPENED) {
 		rc = -EIO;
@@ -72,7 +75,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 	}
 
 	rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid,
-			current->mm->context.id, 0, amr, current->mm,
+			current->mm->context.id, ctx->tidr, amr, current->mm,
 			xsl_fault_error, ctx);
 	if (rc)
 		goto out;
diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index 038509e5d031..eb409a469f21 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -5,6 +5,8 @@
 #include <linux/sched/signal.h>
 #include <linux/uaccess.h>
 #include <uapi/misc/ocxl.h>
+#include <asm/reg.h>
+#include <asm/switch_to.h>
 #include "ocxl_internal.h"
 
 
@@ -123,11 +125,55 @@ static long afu_ioctl_get_metadata(struct ocxl_context *ctx,
 	return 0;
 }
 
+#ifdef CONFIG_PPC64
+static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
+		struct ocxl_ioctl_p9_wait __user *uarg)
+{
+	struct ocxl_ioctl_p9_wait arg;
+
+	memset(&arg, 0, sizeof(arg));
+
+	if (cpu_has_feature(CPU_FTR_P9_TIDR)) {
+		enum ocxl_context_status status;
+
+		// Locks both status & tidr
+		mutex_lock(&ctx->status_mutex);
+		if (!ctx->tidr) {
+			if (set_thread_tidr(current))
+				return -ENOENT;
+
+			ctx->tidr = current->thread.tidr;
+		}
+
+		status = ctx->status;
+		mutex_unlock(&ctx->status_mutex);
+
+		if (status == ATTACHED) {
+			int rc;
+			struct link *link = ctx->afu->fn->link;
+
+			rc = ocxl_link_update_pe(link, ctx->pasid, ctx->tidr);
+			if (rc)
+				return rc;
+		}
+
+		arg.thread_id = ctx->tidr;
+	} else
+		return -ENOENT;
+
+	if (copy_to_user(uarg, &arg, sizeof(arg)))
+		return -EFAULT;
+
+	return 0;
+}
+#endif
+
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
 			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
 			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
 			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
 			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
+			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
 			"UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -186,6 +232,13 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 				(struct ocxl_ioctl_metadata __user *) args);
 		break;
 
+#ifdef CONFIG_PPC64
+	case OCXL_IOCTL_ENABLE_P9_WAIT:
+		rc = afu_ioctl_enable_p9_wait(ctx,
+				(struct ocxl_ioctl_p9_wait __user *) args);
+		break;
+#endif
+
 	default:
 		rc = -EINVAL;
 	}
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index 656e8610eec2..88876ae8f330 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -544,6 +544,42 @@ int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
 }
 EXPORT_SYMBOL_GPL(ocxl_link_add_pe);
 
+int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid)
+{
+	struct link *link = (struct link *) link_handle;
+	struct spa *spa = link->spa;
+	struct ocxl_process_element *pe;
+	int pe_handle, rc;
+
+	if (pasid > SPA_PASID_MAX)
+		return -EINVAL;
+
+	pe_handle = pasid & SPA_PE_MASK;
+	pe = spa->spa_mem + pe_handle;
+
+	mutex_lock(&spa->spa_lock);
+
+	pe->tid = tid;
+
+	/*
+	 * The barrier makes sure the PE is updated
+	 * before we clear the NPU context cache below, so that the
+	 * old PE cannot be reloaded erroneously.
+	 */
+	mb();
+
+	/*
+	 * hook to platform code
+	 * On powerpc, the entry needs to be cleared from the context
+	 * cache of the NPU.
+	 */
+	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
+	WARN_ON(rc);
+
+	mutex_unlock(&spa->spa_lock);
+	return rc;
+}
+
 int ocxl_link_remove_pe(void *link_handle, int pasid)
 {
 	struct link *link = (struct link *) link_handle;
diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
index 5d421824afd9..a32f2151029f 100644
--- a/drivers/misc/ocxl/ocxl_internal.h
+++ b/drivers/misc/ocxl/ocxl_internal.h
@@ -77,6 +77,7 @@ struct ocxl_context {
 	struct ocxl_xsl_error xsl_error;
 	struct mutex irq_lock;
 	struct idr irq_idr;
+	u16 tidr; // Thread ID used for P9 wait implementation
 };
 
 struct ocxl_process_element {
diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
index 51ccf76db293..9ff6ddc28e22 100644
--- a/include/misc/ocxl.h
+++ b/include/misc/ocxl.h
@@ -188,6 +188,15 @@ extern int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
 		void (*xsl_err_cb)(void *data, u64 addr, u64 dsisr),
 		void *xsl_err_data);
 
+/**
+ * Update values within a Process Element
+ *
+ * link_handle: the link handle associated with the process element
+ * pasid: the PASID for the AFU context
+ * tid: the new thread id for the process element
+ */
+extern int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid);
+
 /*
  * Remove a Process Element from the Shared Process Area for a link
  */
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 0af83d80fb3e..8d2748e69c84 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -48,6 +48,15 @@ struct ocxl_ioctl_metadata {
 	__u64 reserved[13]; // Total of 16*u64
 };
 
+struct ocxl_ioctl_p9_wait {
+	__u16 thread_id; // The thread ID required to wake this thread
+	__u16 reserved1;
+	__u32 reserved2;
+	__u64 reserved3[3];
+};
+
+};
+
 struct ocxl_ioctl_irq_fd {
 	__u64 irq_offset;
 	__s32 eventfd;
@@ -62,5 +71,6 @@ struct ocxl_ioctl_irq_fd {
 #define OCXL_IOCTL_IRQ_FREE	_IOW(OCXL_MAGIC, 0x12, __u64)
 #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
+#define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.3

[PATCH v4 5/7] ocxl: Expose the thread_id needed for wait on POWER9

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

In order to successfully issue as_notify, an AFU needs to know the TID
to notify, which in turn means that this information should be
available in userspace so it can be communicated to the AFU.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/misc/ocxl/context.c       |  5 +++-
 drivers/misc/ocxl/file.c          | 53 +++++++++++++++++++++++++++++++++++++++
 drivers/misc/ocxl/link.c          | 36 ++++++++++++++++++++++++++
 drivers/misc/ocxl/ocxl_internal.h |  1 +
 include/misc/ocxl.h               |  9 +++++++
 include/uapi/misc/ocxl.h          | 10 ++++++++
 6 files changed, 113 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
index 909e8807824a..95f74623113e 100644
--- a/drivers/misc/ocxl/context.c
+++ b/drivers/misc/ocxl/context.c
@@ -34,6 +34,8 @@ int ocxl_context_init(struct ocxl_context *ctx, struct ocxl_afu *afu,
 	mutex_init(&ctx->xsl_error_lock);
 	mutex_init(&ctx->irq_lock);
 	idr_init(&ctx->irq_idr);
+	ctx->tidr = 0;
+
 	/*
 	 * Keep a reference on the AFU to make sure it's valid for the
 	 * duration of the life of the context
@@ -65,6 +67,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 {
 	int rc;
 
+	// Locks both status & tidr
 	mutex_lock(&ctx->status_mutex);
 	if (ctx->status != OPENED) {
 		rc = -EIO;
@@ -72,7 +75,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 	}
 
 	rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid,
-			current->mm->context.id, 0, amr, current->mm,
+			current->mm->context.id, ctx->tidr, amr, current->mm,
 			xsl_fault_error, ctx);
 	if (rc)
 		goto out;
diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index 038509e5d031..eb409a469f21 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -5,6 +5,8 @@
 #include <linux/sched/signal.h>
 #include <linux/uaccess.h>
 #include <uapi/misc/ocxl.h>
+#include <asm/reg.h>
+#include <asm/switch_to.h>
 #include "ocxl_internal.h"
 
 
@@ -123,11 +125,55 @@ static long afu_ioctl_get_metadata(struct ocxl_context *ctx,
 	return 0;
 }
 
+#ifdef CONFIG_PPC64
+static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
+		struct ocxl_ioctl_p9_wait __user *uarg)
+{
+	struct ocxl_ioctl_p9_wait arg;
+
+	memset(&arg, 0, sizeof(arg));
+
+	if (cpu_has_feature(CPU_FTR_P9_TIDR)) {
+		enum ocxl_context_status status;
+
+		// Locks both status & tidr
+		mutex_lock(&ctx->status_mutex);
+		if (!ctx->tidr) {
+			if (set_thread_tidr(current))
+				return -ENOENT;
+
+			ctx->tidr = current->thread.tidr;
+		}
+
+		status = ctx->status;
+		mutex_unlock(&ctx->status_mutex);
+
+		if (status == ATTACHED) {
+			int rc;
+			struct link *link = ctx->afu->fn->link;
+
+			rc = ocxl_link_update_pe(link, ctx->pasid, ctx->tidr);
+			if (rc)
+				return rc;
+		}
+
+		arg.thread_id = ctx->tidr;
+	} else
+		return -ENOENT;
+
+	if (copy_to_user(uarg, &arg, sizeof(arg)))
+		return -EFAULT;
+
+	return 0;
+}
+#endif
+
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
 			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
 			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
 			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
 			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
+			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
 			"UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -186,6 +232,13 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 				(struct ocxl_ioctl_metadata __user *) args);
 		break;
 
+#ifdef CONFIG_PPC64
+	case OCXL_IOCTL_ENABLE_P9_WAIT:
+		rc = afu_ioctl_enable_p9_wait(ctx,
+				(struct ocxl_ioctl_p9_wait __user *) args);
+		break;
+#endif
+
 	default:
 		rc = -EINVAL;
 	}
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index 656e8610eec2..88876ae8f330 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -544,6 +544,42 @@ int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
 }
 EXPORT_SYMBOL_GPL(ocxl_link_add_pe);
 
+int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid)
+{
+	struct link *link = (struct link *) link_handle;
+	struct spa *spa = link->spa;
+	struct ocxl_process_element *pe;
+	int pe_handle, rc;
+
+	if (pasid > SPA_PASID_MAX)
+		return -EINVAL;
+
+	pe_handle = pasid & SPA_PE_MASK;
+	pe = spa->spa_mem + pe_handle;
+
+	mutex_lock(&spa->spa_lock);
+
+	pe->tid = tid;
+
+	/*
+	 * The barrier makes sure the PE is updated
+	 * before we clear the NPU context cache below, so that the
+	 * old PE cannot be reloaded erroneously.
+	 */
+	mb();
+
+	/*
+	 * hook to platform code
+	 * On powerpc, the entry needs to be cleared from the context
+	 * cache of the NPU.
+	 */
+	rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
+	WARN_ON(rc);
+
+	mutex_unlock(&spa->spa_lock);
+	return rc;
+}
+
 int ocxl_link_remove_pe(void *link_handle, int pasid)
 {
 	struct link *link = (struct link *) link_handle;
diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
index 5d421824afd9..a32f2151029f 100644
--- a/drivers/misc/ocxl/ocxl_internal.h
+++ b/drivers/misc/ocxl/ocxl_internal.h
@@ -77,6 +77,7 @@ struct ocxl_context {
 	struct ocxl_xsl_error xsl_error;
 	struct mutex irq_lock;
 	struct idr irq_idr;
+	u16 tidr; // Thread ID used for P9 wait implementation
 };
 
 struct ocxl_process_element {
diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
index 51ccf76db293..9ff6ddc28e22 100644
--- a/include/misc/ocxl.h
+++ b/include/misc/ocxl.h
@@ -188,6 +188,15 @@ extern int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
 		void (*xsl_err_cb)(void *data, u64 addr, u64 dsisr),
 		void *xsl_err_data);
 
+/**
+ * Update values within a Process Element
+ *
+ * link_handle: the link handle associated with the process element
+ * pasid: the PASID for the AFU context
+ * tid: the new thread id for the process element
+ */
+extern int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid);
+
 /*
  * Remove a Process Element from the Shared Process Area for a link
  */
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 0af83d80fb3e..8d2748e69c84 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -48,6 +48,15 @@ struct ocxl_ioctl_metadata {
 	__u64 reserved[13]; // Total of 16*u64
 };
 
+struct ocxl_ioctl_p9_wait {
+	__u16 thread_id; // The thread ID required to wake this thread
+	__u16 reserved1;
+	__u32 reserved2;
+	__u64 reserved3[3];
+};
+
+};
+
 struct ocxl_ioctl_irq_fd {
 	__u64 irq_offset;
 	__s32 eventfd;
@@ -62,5 +71,6 @@ struct ocxl_ioctl_irq_fd {
 #define OCXL_IOCTL_IRQ_FREE	_IOW(OCXL_MAGIC, 0x12, __u64)
 #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
+#define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.3

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[PATCH v4 6/7] ocxl: Add an IOCTL so userspace knows what OCXL features are available

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

In order for a userspace AFU driver to call the POWER9 specific
OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
make that call.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/misc/ocxl/file.c | 25 +++++++++++++++++++++++++
 include/uapi/misc/ocxl.h |  4 ++++
 2 files changed, 29 insertions(+)

diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index eb409a469f21..33ae46ce0a8a 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -168,12 +168,32 @@ static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
 }
 #endif
 
+
+static long afu_ioctl_get_features(struct ocxl_context *ctx,
+		struct ocxl_ioctl_features __user *uarg)
+{
+	struct ocxl_ioctl_features arg;
+
+	memset(&arg, 0, sizeof(arg));
+
+#ifdef CONFIG_PPC64
+	if (cpu_has_feature(CPU_FTR_P9_TIDR))
+		arg.flags[0] |= OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT;
+#endif
+
+	if (copy_to_user(uarg, &arg, sizeof(arg)))
+		return -EFAULT;
+
+	return 0;
+}
+
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
 			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
 			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
 			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
 			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
 			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
+			x == OCXL_IOCTL_GET_FEATURES ? "GET_FEATURES" :	\
 			"UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -239,6 +259,11 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 		break;
 #endif
 
+	case OCXL_IOCTL_GET_FEATURES:
+		rc = afu_ioctl_get_features(ctx,
+				(struct ocxl_ioctl_features __user *) args);
+		break;
+
 	default:
 		rc = -EINVAL;
 	}
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 8d2748e69c84..bb80f294b429 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -55,6 +55,9 @@ struct ocxl_ioctl_p9_wait {
 	__u64 reserved3[3];
 };
 
+#define OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT	0x01
+struct ocxl_ioctl_features {
+	__u64 flags[4];
 };
 
 struct ocxl_ioctl_irq_fd {
@@ -72,5 +75,6 @@ struct ocxl_ioctl_irq_fd {
 #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
 #define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
+#define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_platform)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.3

[PATCH v4 6/7] ocxl: Add an IOCTL so userspace knows what OCXL features are available

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

In order for a userspace AFU driver to call the POWER9 specific
OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
make that call.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/misc/ocxl/file.c | 25 +++++++++++++++++++++++++
 include/uapi/misc/ocxl.h |  4 ++++
 2 files changed, 29 insertions(+)

diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index eb409a469f21..33ae46ce0a8a 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -168,12 +168,32 @@ static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
 }
 #endif
 
+
+static long afu_ioctl_get_features(struct ocxl_context *ctx,
+		struct ocxl_ioctl_features __user *uarg)
+{
+	struct ocxl_ioctl_features arg;
+
+	memset(&arg, 0, sizeof(arg));
+
+#ifdef CONFIG_PPC64
+	if (cpu_has_feature(CPU_FTR_P9_TIDR))
+		arg.flags[0] |= OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT;
+#endif
+
+	if (copy_to_user(uarg, &arg, sizeof(arg)))
+		return -EFAULT;
+
+	return 0;
+}
+
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
 			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
 			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
 			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
 			x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :	\
 			x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :	\
+			x == OCXL_IOCTL_GET_FEATURES ? "GET_FEATURES" :	\
 			"UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -239,6 +259,11 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 		break;
 #endif
 
+	case OCXL_IOCTL_GET_FEATURES:
+		rc = afu_ioctl_get_features(ctx,
+				(struct ocxl_ioctl_features __user *) args);
+		break;
+
 	default:
 		rc = -EINVAL;
 	}
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 8d2748e69c84..bb80f294b429 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -55,6 +55,9 @@ struct ocxl_ioctl_p9_wait {
 	__u64 reserved3[3];
 };
 
+#define OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT	0x01
+struct ocxl_ioctl_features {
+	__u64 flags[4];
 };
 
 struct ocxl_ioctl_irq_fd {
@@ -72,5 +75,6 @@ struct ocxl_ioctl_irq_fd {
 #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
 #define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
+#define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_platform)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.3

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Re: [PATCH v4 6/7] ocxl: Add an IOCTL so userspace knows what OCXL features are available

[Michael Ellerman]

"Alastair D'Silva" <alastair@au1.ibm.com> writes:

> diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
> index 8d2748e69c84..bb80f294b429 100644
> --- a/include/uapi/misc/ocxl.h
> +++ b/include/uapi/misc/ocxl.h
> @@ -72,5 +75,6 @@ struct ocxl_ioctl_irq_fd {
>  #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
>  #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
>  #define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
> +#define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_platform)

I don't have ocxl_ioctl_platform ?

../include/uapi/misc/ocxl.h:78:56: error: invalid application of ‘sizeof’ to incomplete type ‘struct ocxl_ioctl_platform’
 #define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_platform)
                                                        ^
../include/uapi/asm-generic/ioctl.h:73:5: note: in definition of macro ‘_IOC’
   ((size) << _IOC_SIZESHIFT))
     ^~~~
../include/uapi/asm-generic/ioctl.h:86:56: note: in expansion of macro ‘_IOC_TYPECHECK’
 #define _IOR(type,nr,size) _IOC(_IOC_READ,(type),(nr),(_IOC_TYPECHECK(size)))
                                                        ^~~~~~~~~~~~~~
../include/uapi/misc/ocxl.h:78:33: note: in expansion of macro ‘_IOR’
 #define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_platform)
                                 ^~~~
../drivers/misc/ocxl/file.c:262:7: note: in expansion of macro ‘OCXL_IOCTL_GET_FEATURES’
  case OCXL_IOCTL_GET_FEATURES:
       ^~~~~~~~~~~~~~~~~~~~~~~

cheers

Re: [PATCH v4 6/7] ocxl: Add an IOCTL so userspace knows what OCXL features are available

[Michael Ellerman]

"Alastair D'Silva" <alastair@au1.ibm.com> writes:

> diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
> index 8d2748e69c84..bb80f294b429 100644
> --- a/include/uapi/misc/ocxl.h
> +++ b/include/uapi/misc/ocxl.h
> @@ -72,5 +75,6 @@ struct ocxl_ioctl_irq_fd {
>  #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_i=
rq_fd)
>  #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl=
_metadata)
>  #define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioc=
tl_p9_wait)
> +#define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl=
_platform)

I don't have ocxl_ioctl_platform ?

../include/uapi/misc/ocxl.h:78:56: error: invalid application of =E2=80=98s=
izeof=E2=80=99 to incomplete type =E2=80=98struct ocxl_ioctl_platform=E2=80=
=99
 #define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_p=
latform)
                                                        ^
../include/uapi/asm-generic/ioctl.h:73:5: note: in definition of macro =E2=
=80=98_IOC=E2=80=99
   ((size) << _IOC_SIZESHIFT))
     ^~~~
../include/uapi/asm-generic/ioctl.h:86:56: note: in expansion of macro =E2=
=80=98_IOC_TYPECHECK=E2=80=99
 #define _IOR(type,nr,size) _IOC(_IOC_READ,(type),(nr),(_IOC_TYPECHECK(size=
)))
                                                        ^~~~~~~~~~~~~~
../include/uapi/misc/ocxl.h:78:33: note: in expansion of macro =E2=80=98_IO=
R=E2=80=99
 #define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_p=
latform)
                                 ^~~~
../drivers/misc/ocxl/file.c:262:7: note: in expansion of macro =E2=80=98OCX=
L_IOCTL_GET_FEATURES=E2=80=99
  case OCXL_IOCTL_GET_FEATURES:
       ^~~~~~~~~~~~~~~~~~~~~~~

cheers

Re: [PATCH v4 6/7] ocxl: Add an IOCTL so userspace knows what OCXL features are available

[Michael Ellerman]

"Alastair D'Silva" <alastair@au1.ibm.com> writes:

> diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
> index 8d2748e69c84..bb80f294b429 100644
> --- a/include/uapi/misc/ocxl.h
> +++ b/include/uapi/misc/ocxl.h
> @@ -72,5 +75,6 @@ struct ocxl_ioctl_irq_fd {
>  #define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
>  #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct ocxl_ioctl_metadata)
>  #define OCXL_IOCTL_ENABLE_P9_WAIT	_IOR(OCXL_MAGIC, 0x15, struct ocxl_ioctl_p9_wait)
> +#define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_platform)

I don't have ocxl_ioctl_platform ?

../include/uapi/misc/ocxl.h:78:56: error: invalid application of ‘sizeof’ to incomplete type ‘struct ocxl_ioctl_platform’
 #define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_platform)
                                                        ^
../include/uapi/asm-generic/ioctl.h:73:5: note: in definition of macro ‘_IOC’
   ((size) << _IOC_SIZESHIFT))
     ^~~~
../include/uapi/asm-generic/ioctl.h:86:56: note: in expansion of macro ‘_IOC_TYPECHECK’
 #define _IOR(type,nr,size) _IOC(_IOC_READ,(type),(nr),(_IOC_TYPECHECK(size)))
                                                        ^~~~~~~~~~~~~~
../include/uapi/misc/ocxl.h:78:33: note: in expansion of macro ‘_IOR’
 #define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct ocxl_ioctl_platform)
                                 ^~~~
../drivers/misc/ocxl/file.c:262:7: note: in expansion of macro ‘OCXL_IOCTL_GET_FEATURES’
  case OCXL_IOCTL_GET_FEATURES:
       ^~~~~~~~~~~~~~~~~~~~~~~

cheers
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[PATCH v4 7/7] ocxl: Document new OCXL IOCTLs

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 Documentation/accelerators/ocxl.rst | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
index ddcc58d01cfb..14cefc020e2d 100644
--- a/Documentation/accelerators/ocxl.rst
+++ b/Documentation/accelerators/ocxl.rst
@@ -157,6 +157,17 @@ OCXL_IOCTL_GET_METADATA:
   Obtains configuration information from the card, such at the size of
   MMIO areas, the AFU version, and the PASID for the current context.
 
+OCXL_IOCTL_ENABLE_P9_WAIT:
+
+  Allows the AFU to wake a userspace thread executing 'wait'. Returns
+  information to userspace to allow it to configure the AFU. Note that
+  this is only available on POWER9.
+
+OCXL_IOCTL_GET_FEATURES:
+
+  Reports on which CPU features that affect OpenCAPI are usable from
+  userspace.
+
 
 mmap
 ----
-- 
2.14.3

[PATCH v4 7/7] ocxl: Document new OCXL IOCTLs

[Alastair D'Silva]

From: Alastair D'Silva <alastair@d-silva.org>

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 Documentation/accelerators/ocxl.rst | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Documentation/accelerators/ocxl.rst b/Documentation/accelerators/ocxl.rst
index ddcc58d01cfb..14cefc020e2d 100644
--- a/Documentation/accelerators/ocxl.rst
+++ b/Documentation/accelerators/ocxl.rst
@@ -157,6 +157,17 @@ OCXL_IOCTL_GET_METADATA:
   Obtains configuration information from the card, such at the size of
   MMIO areas, the AFU version, and the PASID for the current context.
 
+OCXL_IOCTL_ENABLE_P9_WAIT:
+
+  Allows the AFU to wake a userspace thread executing 'wait'. Returns
+  information to userspace to allow it to configure the AFU. Note that
+  this is only available on POWER9.
+
+OCXL_IOCTL_GET_FEATURES:
+
+  Reports on which CPU features that affect OpenCAPI are usable from
+  userspace.
+
 
 mmap
 ----
-- 
2.14.3

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