[PATCH] arm64/irq: report bug if NR_IPI greater than max SGI during compile time

[PATCH] arm64/irq: report bug if NR_IPI greater than max SGI during compile time

[Pingfan Liu]

Although there is a runtime WARN_ON() when NR_IPR > max SGI, it had better
do the check during built time, and associate these related code together.

Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 arch/arm64/kernel/smp.c                | 2 ++
 drivers/irqchip/irq-gic-v3.c           | 2 +-
 drivers/irqchip/irq-gic.c              | 2 +-
 include/linux/irqchip/arm-gic-common.h | 2 ++
 4 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 18e9727..9fc383c 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -33,6 +33,7 @@
 #include <linux/kernel_stat.h>
 #include <linux/kexec.h>
 #include <linux/kvm_host.h>
+#include <linux/irqchip/arm-gic-common.h>
 
 #include <asm/alternative.h>
 #include <asm/atomic.h>
@@ -76,6 +77,7 @@ enum ipi_msg_type {
 	IPI_WAKEUP,
 	NR_IPI
 };
+static_assert(NR_IPI <= MAX_SGI_NUM);
 
 static int ipi_irq_base __read_mostly;
 static int nr_ipi __read_mostly = NR_IPI;
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 16fecc0..ee13f85 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -1162,7 +1162,7 @@ static void __init gic_smp_init(void)
 				  gic_starting_cpu, NULL);
 
 	/* Register all 8 non-secure SGIs */
-	base_sgi = __irq_domain_alloc_irqs(gic_data.domain, -1, 8,
+	base_sgi = __irq_domain_alloc_irqs(gic_data.domain, -1, MAX_SGI_NUM,
 					   NUMA_NO_NODE, &sgi_fwspec,
 					   false, NULL);
 	if (WARN_ON(base_sgi <= 0))
diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
index 6053245..07d36de 100644
--- a/drivers/irqchip/irq-gic.c
+++ b/drivers/irqchip/irq-gic.c
@@ -845,7 +845,7 @@ static __init void gic_smp_init(void)
 				  "irqchip/arm/gic:starting",
 				  gic_starting_cpu, NULL);
 
-	base_sgi = __irq_domain_alloc_irqs(gic_data[0].domain, -1, 8,
+	base_sgi = __irq_domain_alloc_irqs(gic_data[0].domain, -1, MAX_SGI_NUM,
 					   NUMA_NO_NODE, &sgi_fwspec,
 					   false, NULL);
 	if (WARN_ON(base_sgi <= 0))
diff --git a/include/linux/irqchip/arm-gic-common.h b/include/linux/irqchip/arm-gic-common.h
index fa8c045..7e45a9f 100644
--- a/include/linux/irqchip/arm-gic-common.h
+++ b/include/linux/irqchip/arm-gic-common.h
@@ -16,6 +16,8 @@
 					(GICD_INT_DEF_PRI << 8) |\
 					GICD_INT_DEF_PRI)
 
+#define MAX_SGI_NUM			8
+
 enum gic_type {
 	GIC_V2,
 	GIC_V3,
-- 
2.7.5

[PATCH] arm64/irq: report bug if NR_IPI greater than max SGI during compile time

[Pingfan Liu]

Although there is a runtime WARN_ON() when NR_IPR > max SGI, it had better
do the check during built time, and associate these related code together.

Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 arch/arm64/kernel/smp.c                | 2 ++
 drivers/irqchip/irq-gic-v3.c           | 2 +-
 drivers/irqchip/irq-gic.c              | 2 +-
 include/linux/irqchip/arm-gic-common.h | 2 ++
 4 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 18e9727..9fc383c 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -33,6 +33,7 @@
 #include <linux/kernel_stat.h>
 #include <linux/kexec.h>
 #include <linux/kvm_host.h>
+#include <linux/irqchip/arm-gic-common.h>
 
 #include <asm/alternative.h>
 #include <asm/atomic.h>
@@ -76,6 +77,7 @@ enum ipi_msg_type {
 	IPI_WAKEUP,
 	NR_IPI
 };
+static_assert(NR_IPI <= MAX_SGI_NUM);
 
 static int ipi_irq_base __read_mostly;
 static int nr_ipi __read_mostly = NR_IPI;
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 16fecc0..ee13f85 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -1162,7 +1162,7 @@ static void __init gic_smp_init(void)
 				  gic_starting_cpu, NULL);
 
 	/* Register all 8 non-secure SGIs */
-	base_sgi = __irq_domain_alloc_irqs(gic_data.domain, -1, 8,
+	base_sgi = __irq_domain_alloc_irqs(gic_data.domain, -1, MAX_SGI_NUM,
 					   NUMA_NO_NODE, &sgi_fwspec,
 					   false, NULL);
 	if (WARN_ON(base_sgi <= 0))
diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
index 6053245..07d36de 100644
--- a/drivers/irqchip/irq-gic.c
+++ b/drivers/irqchip/irq-gic.c
@@ -845,7 +845,7 @@ static __init void gic_smp_init(void)
 				  "irqchip/arm/gic:starting",
 				  gic_starting_cpu, NULL);
 
-	base_sgi = __irq_domain_alloc_irqs(gic_data[0].domain, -1, 8,
+	base_sgi = __irq_domain_alloc_irqs(gic_data[0].domain, -1, MAX_SGI_NUM,
 					   NUMA_NO_NODE, &sgi_fwspec,
 					   false, NULL);
 	if (WARN_ON(base_sgi <= 0))
diff --git a/include/linux/irqchip/arm-gic-common.h b/include/linux/irqchip/arm-gic-common.h
index fa8c045..7e45a9f 100644
--- a/include/linux/irqchip/arm-gic-common.h
+++ b/include/linux/irqchip/arm-gic-common.h
@@ -16,6 +16,8 @@
 					(GICD_INT_DEF_PRI << 8) |\
 					GICD_INT_DEF_PRI)
 
+#define MAX_SGI_NUM			8
+
 enum gic_type {
 	GIC_V2,
 	GIC_V3,
-- 
2.7.5


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Re: [PATCH] arm64/irq: report bug if NR_IPI greater than max SGI during compile time

[Marc Zyngier]

On 2020-12-08 09:21, Pingfan Liu wrote:
> Although there is a runtime WARN_ON() when NR_IPR > max SGI, it had 
> better
> do the check during built time, and associate these related code 
> together.
> 
> Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Jason Cooper <jason@lakedaemon.net>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> To: linux-arm-kernel@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  arch/arm64/kernel/smp.c                | 2 ++
>  drivers/irqchip/irq-gic-v3.c           | 2 +-
>  drivers/irqchip/irq-gic.c              | 2 +-
>  include/linux/irqchip/arm-gic-common.h | 2 ++
>  4 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 18e9727..9fc383c 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -33,6 +33,7 @@
>  #include <linux/kernel_stat.h>
>  #include <linux/kexec.h>
>  #include <linux/kvm_host.h>
> +#include <linux/irqchip/arm-gic-common.h>
> 
>  #include <asm/alternative.h>
>  #include <asm/atomic.h>
> @@ -76,6 +77,7 @@ enum ipi_msg_type {
>  	IPI_WAKEUP,
>  	NR_IPI
>  };
> +static_assert(NR_IPI <= MAX_SGI_NUM);

I am trying *very hard* to remove dependencies between the architecture
code and random drivers, so this kind of check really is 
counter-productive.

Driver code should not have to know the number of IPIs, because there is
no requirement that all IPIs should map 1:1 to SGIs. Conflating the two
is already wrong, and I really don't want to add more of that.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...

Re: [PATCH] arm64/irq: report bug if NR_IPI greater than max SGI during compile time

[Marc Zyngier]

On 2020-12-08 09:21, Pingfan Liu wrote:
> Although there is a runtime WARN_ON() when NR_IPR > max SGI, it had 
> better
> do the check during built time, and associate these related code 
> together.
> 
> Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Jason Cooper <jason@lakedaemon.net>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> To: linux-arm-kernel@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  arch/arm64/kernel/smp.c                | 2 ++
>  drivers/irqchip/irq-gic-v3.c           | 2 +-
>  drivers/irqchip/irq-gic.c              | 2 +-
>  include/linux/irqchip/arm-gic-common.h | 2 ++
>  4 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 18e9727..9fc383c 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -33,6 +33,7 @@
>  #include <linux/kernel_stat.h>
>  #include <linux/kexec.h>
>  #include <linux/kvm_host.h>
> +#include <linux/irqchip/arm-gic-common.h>
> 
>  #include <asm/alternative.h>
>  #include <asm/atomic.h>
> @@ -76,6 +77,7 @@ enum ipi_msg_type {
>  	IPI_WAKEUP,
>  	NR_IPI
>  };
> +static_assert(NR_IPI <= MAX_SGI_NUM);

I am trying *very hard* to remove dependencies between the architecture
code and random drivers, so this kind of check really is 
counter-productive.

Driver code should not have to know the number of IPIs, because there is
no requirement that all IPIs should map 1:1 to SGIs. Conflating the two
is already wrong, and I really don't want to add more of that.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH] arm64/irq: report bug if NR_IPI greater than max SGI during compile time

[Pingfan Liu]

On Tue, Dec 8, 2020 at 5:31 PM Marc Zyngier <maz@kernel.org> wrote:
>
> On 2020-12-08 09:21, Pingfan Liu wrote:
> > Although there is a runtime WARN_ON() when NR_IPR > max SGI, it had
> > better
> > do the check during built time, and associate these related code
> > together.
> >
> > Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > Cc: Will Deacon <will@kernel.org>
> > Cc: Thomas Gleixner <tglx@linutronix.de>
> > Cc: Jason Cooper <jason@lakedaemon.net>
> > Cc: Marc Zyngier <maz@kernel.org>
> > Cc: Mark Rutland <mark.rutland@arm.com>
> > To: linux-arm-kernel@lists.infradead.org
> > Cc: linux-kernel@vger.kernel.org
> > ---
> >  arch/arm64/kernel/smp.c                | 2 ++
> >  drivers/irqchip/irq-gic-v3.c           | 2 +-
> >  drivers/irqchip/irq-gic.c              | 2 +-
> >  include/linux/irqchip/arm-gic-common.h | 2 ++
> >  4 files changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> > index 18e9727..9fc383c 100644
> > --- a/arch/arm64/kernel/smp.c
> > +++ b/arch/arm64/kernel/smp.c
> > @@ -33,6 +33,7 @@
> >  #include <linux/kernel_stat.h>
> >  #include <linux/kexec.h>
> >  #include <linux/kvm_host.h>
> > +#include <linux/irqchip/arm-gic-common.h>
> >
> >  #include <asm/alternative.h>
> >  #include <asm/atomic.h>
> > @@ -76,6 +77,7 @@ enum ipi_msg_type {
> >       IPI_WAKEUP,
> >       NR_IPI
> >  };
> > +static_assert(NR_IPI <= MAX_SGI_NUM);
>
> I am trying *very hard* to remove dependencies between the architecture
> code and random drivers, so this kind of check really is
> counter-productive.
>
> Driver code should not have to know the number of IPIs, because there is
> no requirement that all IPIs should map 1:1 to SGIs. Conflating the two

Just curious about this. Is there an IPI which is not implemented by
SGI? Or mapping several IPIs to a single SGI, and scatter out due to a
global variable value?

Thanks,
Pingfan

> is already wrong, and I really don't want to add more of that.
>
> Thanks,
>
>          M.
> --
> Jazz is not dead. It just smells funny...

Re: [PATCH] arm64/irq: report bug if NR_IPI greater than max SGI during compile time

[Pingfan Liu]

On Tue, Dec 8, 2020 at 5:31 PM Marc Zyngier <maz@kernel.org> wrote:
>
> On 2020-12-08 09:21, Pingfan Liu wrote:
> > Although there is a runtime WARN_ON() when NR_IPR > max SGI, it had
> > better
> > do the check during built time, and associate these related code
> > together.
> >
> > Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > Cc: Will Deacon <will@kernel.org>
> > Cc: Thomas Gleixner <tglx@linutronix.de>
> > Cc: Jason Cooper <jason@lakedaemon.net>
> > Cc: Marc Zyngier <maz@kernel.org>
> > Cc: Mark Rutland <mark.rutland@arm.com>
> > To: linux-arm-kernel@lists.infradead.org
> > Cc: linux-kernel@vger.kernel.org
> > ---
> >  arch/arm64/kernel/smp.c                | 2 ++
> >  drivers/irqchip/irq-gic-v3.c           | 2 +-
> >  drivers/irqchip/irq-gic.c              | 2 +-
> >  include/linux/irqchip/arm-gic-common.h | 2 ++
> >  4 files changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> > index 18e9727..9fc383c 100644
> > --- a/arch/arm64/kernel/smp.c
> > +++ b/arch/arm64/kernel/smp.c
> > @@ -33,6 +33,7 @@
> >  #include <linux/kernel_stat.h>
> >  #include <linux/kexec.h>
> >  #include <linux/kvm_host.h>
> > +#include <linux/irqchip/arm-gic-common.h>
> >
> >  #include <asm/alternative.h>
> >  #include <asm/atomic.h>
> > @@ -76,6 +77,7 @@ enum ipi_msg_type {
> >       IPI_WAKEUP,
> >       NR_IPI
> >  };
> > +static_assert(NR_IPI <= MAX_SGI_NUM);
>
> I am trying *very hard* to remove dependencies between the architecture
> code and random drivers, so this kind of check really is
> counter-productive.
>
> Driver code should not have to know the number of IPIs, because there is
> no requirement that all IPIs should map 1:1 to SGIs. Conflating the two

Just curious about this. Is there an IPI which is not implemented by
SGI? Or mapping several IPIs to a single SGI, and scatter out due to a
global variable value?

Thanks,
Pingfan

> is already wrong, and I really don't want to add more of that.
>
> Thanks,
>
>          M.
> --
> Jazz is not dead. It just smells funny...

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH] arm64/irq: report bug if NR_IPI greater than max SGI during compile time

[Marc Zyngier]

On 2020-12-08 09:43, Pingfan Liu wrote:
> On Tue, Dec 8, 2020 at 5:31 PM Marc Zyngier <maz@kernel.org> wrote:
>> 
>> On 2020-12-08 09:21, Pingfan Liu wrote:
>> > Although there is a runtime WARN_ON() when NR_IPR > max SGI, it had
>> > better
>> > do the check during built time, and associate these related code
>> > together.
>> >
>> > Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
>> > Cc: Catalin Marinas <catalin.marinas@arm.com>
>> > Cc: Will Deacon <will@kernel.org>
>> > Cc: Thomas Gleixner <tglx@linutronix.de>
>> > Cc: Jason Cooper <jason@lakedaemon.net>
>> > Cc: Marc Zyngier <maz@kernel.org>
>> > Cc: Mark Rutland <mark.rutland@arm.com>
>> > To: linux-arm-kernel@lists.infradead.org
>> > Cc: linux-kernel@vger.kernel.org
>> > ---
>> >  arch/arm64/kernel/smp.c                | 2 ++
>> >  drivers/irqchip/irq-gic-v3.c           | 2 +-
>> >  drivers/irqchip/irq-gic.c              | 2 +-
>> >  include/linux/irqchip/arm-gic-common.h | 2 ++
>> >  4 files changed, 6 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
>> > index 18e9727..9fc383c 100644
>> > --- a/arch/arm64/kernel/smp.c
>> > +++ b/arch/arm64/kernel/smp.c
>> > @@ -33,6 +33,7 @@
>> >  #include <linux/kernel_stat.h>
>> >  #include <linux/kexec.h>
>> >  #include <linux/kvm_host.h>
>> > +#include <linux/irqchip/arm-gic-common.h>
>> >
>> >  #include <asm/alternative.h>
>> >  #include <asm/atomic.h>
>> > @@ -76,6 +77,7 @@ enum ipi_msg_type {
>> >       IPI_WAKEUP,
>> >       NR_IPI
>> >  };
>> > +static_assert(NR_IPI <= MAX_SGI_NUM);
>> 
>> I am trying *very hard* to remove dependencies between the 
>> architecture
>> code and random drivers, so this kind of check really is
>> counter-productive.
>> 
>> Driver code should not have to know the number of IPIs, because there 
>> is
>> no requirement that all IPIs should map 1:1 to SGIs. Conflating the 
>> two
> 
> Just curious about this. Is there an IPI which is not implemented by
> SGI? Or mapping several IPIs to a single SGI, and scatter out due to a
> global variable value?

We currently have a single NS SGI left, and I'd like to move some of the
non-critical IPIs over to dispatching mechanism (the two "CPU stop" IPIs
definitely are candidate for merging). That's not implemented yet, but
I don't see a need to add checks that would otherwise violate this
IPI/SGI distinction.

Thanks,

          M.
-- 
Jazz is not dead. It just smells funny...

Re: [PATCH] arm64/irq: report bug if NR_IPI greater than max SGI during compile time

[Marc Zyngier]

On 2020-12-08 09:43, Pingfan Liu wrote:
> On Tue, Dec 8, 2020 at 5:31 PM Marc Zyngier <maz@kernel.org> wrote:
>> 
>> On 2020-12-08 09:21, Pingfan Liu wrote:
>> > Although there is a runtime WARN_ON() when NR_IPR > max SGI, it had
>> > better
>> > do the check during built time, and associate these related code
>> > together.
>> >
>> > Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
>> > Cc: Catalin Marinas <catalin.marinas@arm.com>
>> > Cc: Will Deacon <will@kernel.org>
>> > Cc: Thomas Gleixner <tglx@linutronix.de>
>> > Cc: Jason Cooper <jason@lakedaemon.net>
>> > Cc: Marc Zyngier <maz@kernel.org>
>> > Cc: Mark Rutland <mark.rutland@arm.com>
>> > To: linux-arm-kernel@lists.infradead.org
>> > Cc: linux-kernel@vger.kernel.org
>> > ---
>> >  arch/arm64/kernel/smp.c                | 2 ++
>> >  drivers/irqchip/irq-gic-v3.c           | 2 +-
>> >  drivers/irqchip/irq-gic.c              | 2 +-
>> >  include/linux/irqchip/arm-gic-common.h | 2 ++
>> >  4 files changed, 6 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
>> > index 18e9727..9fc383c 100644
>> > --- a/arch/arm64/kernel/smp.c
>> > +++ b/arch/arm64/kernel/smp.c
>> > @@ -33,6 +33,7 @@
>> >  #include <linux/kernel_stat.h>
>> >  #include <linux/kexec.h>
>> >  #include <linux/kvm_host.h>
>> > +#include <linux/irqchip/arm-gic-common.h>
>> >
>> >  #include <asm/alternative.h>
>> >  #include <asm/atomic.h>
>> > @@ -76,6 +77,7 @@ enum ipi_msg_type {
>> >       IPI_WAKEUP,
>> >       NR_IPI
>> >  };
>> > +static_assert(NR_IPI <= MAX_SGI_NUM);
>> 
>> I am trying *very hard* to remove dependencies between the 
>> architecture
>> code and random drivers, so this kind of check really is
>> counter-productive.
>> 
>> Driver code should not have to know the number of IPIs, because there 
>> is
>> no requirement that all IPIs should map 1:1 to SGIs. Conflating the 
>> two
> 
> Just curious about this. Is there an IPI which is not implemented by
> SGI? Or mapping several IPIs to a single SGI, and scatter out due to a
> global variable value?

We currently have a single NS SGI left, and I'd like to move some of the
non-critical IPIs over to dispatching mechanism (the two "CPU stop" IPIs
definitely are candidate for merging). That's not implemented yet, but
I don't see a need to add checks that would otherwise violate this
IPI/SGI distinction.

Thanks,

          M.
-- 
Jazz is not dead. It just smells funny...

_______________________________________________
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Re: [PATCH] arm64/irq: report bug if NR_IPI greater than max SGI during compile time

[Pingfan Liu]

On Tue, Dec 8, 2020 at 5:51 PM Marc Zyngier <maz@kernel.org> wrote:
>
> On 2020-12-08 09:43, Pingfan Liu wrote:
> > On Tue, Dec 8, 2020 at 5:31 PM Marc Zyngier <maz@kernel.org> wrote:
> >>
> >> On 2020-12-08 09:21, Pingfan Liu wrote:
> >> > Although there is a runtime WARN_ON() when NR_IPR > max SGI, it had
> >> > better
> >> > do the check during built time, and associate these related code
> >> > together.
> >> >
> >> > Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> >> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> >> > Cc: Will Deacon <will@kernel.org>
> >> > Cc: Thomas Gleixner <tglx@linutronix.de>
> >> > Cc: Jason Cooper <jason@lakedaemon.net>
> >> > Cc: Marc Zyngier <maz@kernel.org>
> >> > Cc: Mark Rutland <mark.rutland@arm.com>
> >> > To: linux-arm-kernel@lists.infradead.org
> >> > Cc: linux-kernel@vger.kernel.org
> >> > ---
> >> >  arch/arm64/kernel/smp.c                | 2 ++
> >> >  drivers/irqchip/irq-gic-v3.c           | 2 +-
> >> >  drivers/irqchip/irq-gic.c              | 2 +-
> >> >  include/linux/irqchip/arm-gic-common.h | 2 ++
> >> >  4 files changed, 6 insertions(+), 2 deletions(-)
> >> >
> >> > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> >> > index 18e9727..9fc383c 100644
> >> > --- a/arch/arm64/kernel/smp.c
> >> > +++ b/arch/arm64/kernel/smp.c
> >> > @@ -33,6 +33,7 @@
> >> >  #include <linux/kernel_stat.h>
> >> >  #include <linux/kexec.h>
> >> >  #include <linux/kvm_host.h>
> >> > +#include <linux/irqchip/arm-gic-common.h>
> >> >
> >> >  #include <asm/alternative.h>
> >> >  #include <asm/atomic.h>
> >> > @@ -76,6 +77,7 @@ enum ipi_msg_type {
> >> >       IPI_WAKEUP,
> >> >       NR_IPI
> >> >  };
> >> > +static_assert(NR_IPI <= MAX_SGI_NUM);
> >>
> >> I am trying *very hard* to remove dependencies between the
> >> architecture
> >> code and random drivers, so this kind of check really is
> >> counter-productive.
> >>
> >> Driver code should not have to know the number of IPIs, because there
> >> is
> >> no requirement that all IPIs should map 1:1 to SGIs. Conflating the
> >> two
> >
> > Just curious about this. Is there an IPI which is not implemented by
> > SGI? Or mapping several IPIs to a single SGI, and scatter out due to a
> > global variable value?
>
> We currently have a single NS SGI left, and I'd like to move some of the
> non-critical IPIs over to dispatching mechanism (the two "CPU stop" IPIs
> definitely are candidate for merging). That's not implemented yet, but
> I don't see a need to add checks that would otherwise violate this
> IPI/SGI distinction.

Got it. Thanks for your detailed explanation.

Regards,
Pingfan

Re: [PATCH] arm64/irq: report bug if NR_IPI greater than max SGI during compile time

[Pingfan Liu]

On Tue, Dec 8, 2020 at 5:51 PM Marc Zyngier <maz@kernel.org> wrote:
>
> On 2020-12-08 09:43, Pingfan Liu wrote:
> > On Tue, Dec 8, 2020 at 5:31 PM Marc Zyngier <maz@kernel.org> wrote:
> >>
> >> On 2020-12-08 09:21, Pingfan Liu wrote:
> >> > Although there is a runtime WARN_ON() when NR_IPR > max SGI, it had
> >> > better
> >> > do the check during built time, and associate these related code
> >> > together.
> >> >
> >> > Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> >> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> >> > Cc: Will Deacon <will@kernel.org>
> >> > Cc: Thomas Gleixner <tglx@linutronix.de>
> >> > Cc: Jason Cooper <jason@lakedaemon.net>
> >> > Cc: Marc Zyngier <maz@kernel.org>
> >> > Cc: Mark Rutland <mark.rutland@arm.com>
> >> > To: linux-arm-kernel@lists.infradead.org
> >> > Cc: linux-kernel@vger.kernel.org
> >> > ---
> >> >  arch/arm64/kernel/smp.c                | 2 ++
> >> >  drivers/irqchip/irq-gic-v3.c           | 2 +-
> >> >  drivers/irqchip/irq-gic.c              | 2 +-
> >> >  include/linux/irqchip/arm-gic-common.h | 2 ++
> >> >  4 files changed, 6 insertions(+), 2 deletions(-)
> >> >
> >> > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> >> > index 18e9727..9fc383c 100644
> >> > --- a/arch/arm64/kernel/smp.c
> >> > +++ b/arch/arm64/kernel/smp.c
> >> > @@ -33,6 +33,7 @@
> >> >  #include <linux/kernel_stat.h>
> >> >  #include <linux/kexec.h>
> >> >  #include <linux/kvm_host.h>
> >> > +#include <linux/irqchip/arm-gic-common.h>
> >> >
> >> >  #include <asm/alternative.h>
> >> >  #include <asm/atomic.h>
> >> > @@ -76,6 +77,7 @@ enum ipi_msg_type {
> >> >       IPI_WAKEUP,
> >> >       NR_IPI
> >> >  };
> >> > +static_assert(NR_IPI <= MAX_SGI_NUM);
> >>
> >> I am trying *very hard* to remove dependencies between the
> >> architecture
> >> code and random drivers, so this kind of check really is
> >> counter-productive.
> >>
> >> Driver code should not have to know the number of IPIs, because there
> >> is
> >> no requirement that all IPIs should map 1:1 to SGIs. Conflating the
> >> two
> >
> > Just curious about this. Is there an IPI which is not implemented by
> > SGI? Or mapping several IPIs to a single SGI, and scatter out due to a
> > global variable value?
>
> We currently have a single NS SGI left, and I'd like to move some of the
> non-critical IPIs over to dispatching mechanism (the two "CPU stop" IPIs
> definitely are candidate for merging). That's not implemented yet, but
> I don't see a need to add checks that would otherwise violate this
> IPI/SGI distinction.

Got it. Thanks for your detailed explanation.

Regards,
Pingfan

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