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* [PATCH] KVM: PPC: Book3S HV: Save host FSCR in the P7/8 path
@ 2021-05-23 12:21 ` Nicholas Piggin
  0 siblings, 0 replies; 6+ messages in thread
From: Nicholas Piggin @ 2021-05-23 12:21 UTC (permalink / raw)
  Cc: Michael Neuling, linuxppc-dev, kvm-ppc, Nicholas Piggin, Fabiano Rosas

Similar to commit 25edcc50d76c ("KVM: PPC: Book3S HV: Save and restore
FSCR in the P9 path"), ensure the P7/8 path saves and restores the host
FSCR. The logic explained in that patch actually applies there to the
old path well: a context switch can be made before kvmppc_vcpu_run_hv
restores the host FSCR and returns.

Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/kvm/book3s_hv_rmhandlers.S | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 5e634db4809b..2b98e710c7a1 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -44,7 +44,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
 #define NAPPING_UNSPLIT	3
 
 /* Stack frame offsets for kvmppc_hv_entry */
-#define SFS			208
+#define SFS			216
 #define STACK_SLOT_TRAP		(SFS-4)
 #define STACK_SLOT_SHORT_PATH	(SFS-8)
 #define STACK_SLOT_TID		(SFS-16)
@@ -59,8 +59,9 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
 #define STACK_SLOT_UAMOR	(SFS-88)
 #define STACK_SLOT_DAWR1	(SFS-96)
 #define STACK_SLOT_DAWRX1	(SFS-104)
+#define STACK_SLOT_FSCR		(SFS-112)
 /* the following is used by the P9 short path */
-#define STACK_SLOT_NVGPRS	(SFS-152)	/* 18 gprs */
+#define STACK_SLOT_NVGPRS	(SFS-160)	/* 18 gprs */
 
 /*
  * Call kvmppc_hv_entry in real mode.
@@ -686,6 +687,8 @@ BEGIN_FTR_SECTION
 	std	r6, STACK_SLOT_DAWR0(r1)
 	std	r7, STACK_SLOT_DAWRX0(r1)
 	std	r8, STACK_SLOT_IAMR(r1)
+	mfspr	r5, SPRN_FSCR
+	std	r5, STACK_SLOT_FSCR(r1)
 END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
 BEGIN_FTR_SECTION
 	mfspr	r6, SPRN_DAWR1
@@ -1663,6 +1666,10 @@ FTR_SECTION_ELSE
 	ld	r7, STACK_SLOT_HFSCR(r1)
 	mtspr	SPRN_HFSCR, r7
 ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300)
+BEGIN_FTR_SECTION
+	ld	r5, STACK_SLOT_FSCR(r1)
+	mtspr	SPRN_FSCR, r5
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
 	/*
 	 * Restore various registers to 0, where non-zero values
 	 * set by the guest could disrupt the host.
-- 
2.23.0


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [PATCH] KVM: PPC: Book3S HV: Save host FSCR in the P7/8 path
@ 2021-05-23 12:21 ` Nicholas Piggin
  0 siblings, 0 replies; 6+ messages in thread
From: Nicholas Piggin @ 2021-05-23 12:21 UTC (permalink / raw)
  Cc: Michael Neuling, linuxppc-dev, kvm-ppc, Nicholas Piggin, Fabiano Rosas

Similar to commit 25edcc50d76c ("KVM: PPC: Book3S HV: Save and restore
FSCR in the P9 path"), ensure the P7/8 path saves and restores the host
FSCR. The logic explained in that patch actually applies there to the
old path well: a context switch can be made before kvmppc_vcpu_run_hv
restores the host FSCR and returns.

Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/kvm/book3s_hv_rmhandlers.S | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 5e634db4809b..2b98e710c7a1 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -44,7 +44,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
 #define NAPPING_UNSPLIT	3
 
 /* Stack frame offsets for kvmppc_hv_entry */
-#define SFS			208
+#define SFS			216
 #define STACK_SLOT_TRAP		(SFS-4)
 #define STACK_SLOT_SHORT_PATH	(SFS-8)
 #define STACK_SLOT_TID		(SFS-16)
@@ -59,8 +59,9 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
 #define STACK_SLOT_UAMOR	(SFS-88)
 #define STACK_SLOT_DAWR1	(SFS-96)
 #define STACK_SLOT_DAWRX1	(SFS-104)
+#define STACK_SLOT_FSCR		(SFS-112)
 /* the following is used by the P9 short path */
-#define STACK_SLOT_NVGPRS	(SFS-152)	/* 18 gprs */
+#define STACK_SLOT_NVGPRS	(SFS-160)	/* 18 gprs */
 
 /*
  * Call kvmppc_hv_entry in real mode.
@@ -686,6 +687,8 @@ BEGIN_FTR_SECTION
 	std	r6, STACK_SLOT_DAWR0(r1)
 	std	r7, STACK_SLOT_DAWRX0(r1)
 	std	r8, STACK_SLOT_IAMR(r1)
+	mfspr	r5, SPRN_FSCR
+	std	r5, STACK_SLOT_FSCR(r1)
 END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
 BEGIN_FTR_SECTION
 	mfspr	r6, SPRN_DAWR1
@@ -1663,6 +1666,10 @@ FTR_SECTION_ELSE
 	ld	r7, STACK_SLOT_HFSCR(r1)
 	mtspr	SPRN_HFSCR, r7
 ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300)
+BEGIN_FTR_SECTION
+	ld	r5, STACK_SLOT_FSCR(r1)
+	mtspr	SPRN_FSCR, r5
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
 	/*
 	 * Restore various registers to 0, where non-zero values
 	 * set by the guest could disrupt the host.
-- 
2.23.0

^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [PATCH] KVM: PPC: Book3S HV: Save host FSCR in the P7/8 path
  2021-05-23 12:21 ` Nicholas Piggin
@ 2021-05-23 14:02   ` Nicholas Piggin
  -1 siblings, 0 replies; 6+ messages in thread
From: Nicholas Piggin @ 2021-05-23 14:02 UTC (permalink / raw)
  Cc: Michael Neuling, linuxppc-dev, kvm-ppc, Fabiano Rosas

Excerpts from Nicholas Piggin's message of May 23, 2021 10:21 pm:
> Similar to commit 25edcc50d76c ("KVM: PPC: Book3S HV: Save and restore
> FSCR in the P9 path"), ensure the P7/8 path saves and restores the host
> FSCR. The logic explained in that patch actually applies there to the
> old path well: a context switch can be made before kvmppc_vcpu_run_hv
> restores the host FSCR and returns.
> 
> Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs")
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>  arch/powerpc/kvm/book3s_hv_rmhandlers.S | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> index 5e634db4809b..2b98e710c7a1 100644
> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> @@ -44,7 +44,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
>  #define NAPPING_UNSPLIT	3
>  
>  /* Stack frame offsets for kvmppc_hv_entry */
> -#define SFS			208
> +#define SFS			216
>  #define STACK_SLOT_TRAP		(SFS-4)
>  #define STACK_SLOT_SHORT_PATH	(SFS-8)
>  #define STACK_SLOT_TID		(SFS-16)
> @@ -59,8 +59,9 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
>  #define STACK_SLOT_UAMOR	(SFS-88)
>  #define STACK_SLOT_DAWR1	(SFS-96)
>  #define STACK_SLOT_DAWRX1	(SFS-104)
> +#define STACK_SLOT_FSCR		(SFS-112)
>  /* the following is used by the P9 short path */
> -#define STACK_SLOT_NVGPRS	(SFS-152)	/* 18 gprs */
> +#define STACK_SLOT_NVGPRS	(SFS-160)	/* 18 gprs */

Actually, hmm.. this is wrong because nvgprs are subtracted from
this offset. But then I can't work out why 95a6432ce9038 raised
SFS from 160 to 208.

Thanks,
Nick

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] KVM: PPC: Book3S HV: Save host FSCR in the P7/8 path
@ 2021-05-23 14:02   ` Nicholas Piggin
  0 siblings, 0 replies; 6+ messages in thread
From: Nicholas Piggin @ 2021-05-23 14:02 UTC (permalink / raw)
  Cc: Michael Neuling, linuxppc-dev, kvm-ppc, Fabiano Rosas

Excerpts from Nicholas Piggin's message of May 23, 2021 10:21 pm:
> Similar to commit 25edcc50d76c ("KVM: PPC: Book3S HV: Save and restore
> FSCR in the P9 path"), ensure the P7/8 path saves and restores the host
> FSCR. The logic explained in that patch actually applies there to the
> old path well: a context switch can be made before kvmppc_vcpu_run_hv
> restores the host FSCR and returns.
> 
> Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs")
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>  arch/powerpc/kvm/book3s_hv_rmhandlers.S | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> index 5e634db4809b..2b98e710c7a1 100644
> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> @@ -44,7 +44,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
>  #define NAPPING_UNSPLIT	3
>  
>  /* Stack frame offsets for kvmppc_hv_entry */
> -#define SFS			208
> +#define SFS			216
>  #define STACK_SLOT_TRAP		(SFS-4)
>  #define STACK_SLOT_SHORT_PATH	(SFS-8)
>  #define STACK_SLOT_TID		(SFS-16)
> @@ -59,8 +59,9 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
>  #define STACK_SLOT_UAMOR	(SFS-88)
>  #define STACK_SLOT_DAWR1	(SFS-96)
>  #define STACK_SLOT_DAWRX1	(SFS-104)
> +#define STACK_SLOT_FSCR		(SFS-112)
>  /* the following is used by the P9 short path */
> -#define STACK_SLOT_NVGPRS	(SFS-152)	/* 18 gprs */
> +#define STACK_SLOT_NVGPRS	(SFS-160)	/* 18 gprs */

Actually, hmm.. this is wrong because nvgprs are subtracted from
this offset. But then I can't work out why 95a6432ce9038 raised
SFS from 160 to 208.

Thanks,
Nick

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] KVM: PPC: Book3S HV: Save host FSCR in the P7/8 path
  2021-05-23 12:21 ` Nicholas Piggin
@ 2021-05-24 12:49   ` Fabiano Rosas
  -1 siblings, 0 replies; 6+ messages in thread
From: Fabiano Rosas @ 2021-05-24 12:49 UTC (permalink / raw)
  To: Nicholas Piggin; +Cc: Michael Neuling, linuxppc-dev, kvm-ppc, Nicholas Piggin

Nicholas Piggin <npiggin@gmail.com> writes:

> Similar to commit 25edcc50d76c ("KVM: PPC: Book3S HV: Save and restore
> FSCR in the P9 path"), ensure the P7/8 path saves and restores the host
> FSCR. The logic explained in that patch actually applies there to the
> old path well: a context switch can be made before kvmppc_vcpu_run_hv
> restores the host FSCR and returns.
>
> Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs")
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>  arch/powerpc/kvm/book3s_hv_rmhandlers.S | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> index 5e634db4809b..2b98e710c7a1 100644
> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> @@ -44,7 +44,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
>  #define NAPPING_UNSPLIT	3
>  
>  /* Stack frame offsets for kvmppc_hv_entry */
> -#define SFS			208
> +#define SFS			216
>  #define STACK_SLOT_TRAP		(SFS-4)
>  #define STACK_SLOT_SHORT_PATH	(SFS-8)
>  #define STACK_SLOT_TID		(SFS-16)
> @@ -59,8 +59,9 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
>  #define STACK_SLOT_UAMOR	(SFS-88)
>  #define STACK_SLOT_DAWR1	(SFS-96)
>  #define STACK_SLOT_DAWRX1	(SFS-104)
> +#define STACK_SLOT_FSCR		(SFS-112)
>  /* the following is used by the P9 short path */
> -#define STACK_SLOT_NVGPRS	(SFS-152)	/* 18 gprs */
> +#define STACK_SLOT_NVGPRS	(SFS-160)	/* 18 gprs */
>  
>  /*
>   * Call kvmppc_hv_entry in real mode.
> @@ -686,6 +687,8 @@ BEGIN_FTR_SECTION
>  	std	r6, STACK_SLOT_DAWR0(r1)
>  	std	r7, STACK_SLOT_DAWRX0(r1)
>  	std	r8, STACK_SLOT_IAMR(r1)
> +	mfspr	r5, SPRN_FSCR
> +	std	r5, STACK_SLOT_FSCR(r1)
>  END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
>  BEGIN_FTR_SECTION
>  	mfspr	r6, SPRN_DAWR1
> @@ -1663,6 +1666,10 @@ FTR_SECTION_ELSE
>  	ld	r7, STACK_SLOT_HFSCR(r1)
>  	mtspr	SPRN_HFSCR, r7
>  ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300)
> +BEGIN_FTR_SECTION
> +	ld	r5, STACK_SLOT_FSCR(r1)
> +	mtspr	SPRN_FSCR, r5
> +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
>  	/*
>  	 * Restore various registers to 0, where non-zero values
>  	 * set by the guest could disrupt the host.

So it seems this line in kvmppc_vcpu_run_hv loses its purpose now?

        do{
        (...)
	} while (is_kvmppc_resume_guest(r));

        /* Restore userspace EBB and other register values */
        if (cpu_has_feature(CPU_FTR_ARCH_207S)) {
                mtspr(SPRN_EBBHR, ebb_regs[0]);
                mtspr(SPRN_EBBRR, ebb_regs[1]);
                mtspr(SPRN_BESCR, ebb_regs[2]);
                mtspr(SPRN_TAR, user_tar);
--->            mtspr(SPRN_FSCR, current->thread.fscr);
        }

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] KVM: PPC: Book3S HV: Save host FSCR in the P7/8 path
@ 2021-05-24 12:49   ` Fabiano Rosas
  0 siblings, 0 replies; 6+ messages in thread
From: Fabiano Rosas @ 2021-05-24 12:49 UTC (permalink / raw)
  To: Nicholas Piggin; +Cc: Michael Neuling, linuxppc-dev, kvm-ppc, Nicholas Piggin

Nicholas Piggin <npiggin@gmail.com> writes:

> Similar to commit 25edcc50d76c ("KVM: PPC: Book3S HV: Save and restore
> FSCR in the P9 path"), ensure the P7/8 path saves and restores the host
> FSCR. The logic explained in that patch actually applies there to the
> old path well: a context switch can be made before kvmppc_vcpu_run_hv
> restores the host FSCR and returns.
>
> Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs")
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>  arch/powerpc/kvm/book3s_hv_rmhandlers.S | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> index 5e634db4809b..2b98e710c7a1 100644
> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> @@ -44,7 +44,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
>  #define NAPPING_UNSPLIT	3
>  
>  /* Stack frame offsets for kvmppc_hv_entry */
> -#define SFS			208
> +#define SFS			216
>  #define STACK_SLOT_TRAP		(SFS-4)
>  #define STACK_SLOT_SHORT_PATH	(SFS-8)
>  #define STACK_SLOT_TID		(SFS-16)
> @@ -59,8 +59,9 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
>  #define STACK_SLOT_UAMOR	(SFS-88)
>  #define STACK_SLOT_DAWR1	(SFS-96)
>  #define STACK_SLOT_DAWRX1	(SFS-104)
> +#define STACK_SLOT_FSCR		(SFS-112)
>  /* the following is used by the P9 short path */
> -#define STACK_SLOT_NVGPRS	(SFS-152)	/* 18 gprs */
> +#define STACK_SLOT_NVGPRS	(SFS-160)	/* 18 gprs */
>  
>  /*
>   * Call kvmppc_hv_entry in real mode.
> @@ -686,6 +687,8 @@ BEGIN_FTR_SECTION
>  	std	r6, STACK_SLOT_DAWR0(r1)
>  	std	r7, STACK_SLOT_DAWRX0(r1)
>  	std	r8, STACK_SLOT_IAMR(r1)
> +	mfspr	r5, SPRN_FSCR
> +	std	r5, STACK_SLOT_FSCR(r1)
>  END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
>  BEGIN_FTR_SECTION
>  	mfspr	r6, SPRN_DAWR1
> @@ -1663,6 +1666,10 @@ FTR_SECTION_ELSE
>  	ld	r7, STACK_SLOT_HFSCR(r1)
>  	mtspr	SPRN_HFSCR, r7
>  ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300)
> +BEGIN_FTR_SECTION
> +	ld	r5, STACK_SLOT_FSCR(r1)
> +	mtspr	SPRN_FSCR, r5
> +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
>  	/*
>  	 * Restore various registers to 0, where non-zero values
>  	 * set by the guest could disrupt the host.

So it seems this line in kvmppc_vcpu_run_hv loses its purpose now?

        do{
        (...)
	} while (is_kvmppc_resume_guest(r));

        /* Restore userspace EBB and other register values */
        if (cpu_has_feature(CPU_FTR_ARCH_207S)) {
                mtspr(SPRN_EBBHR, ebb_regs[0]);
                mtspr(SPRN_EBBRR, ebb_regs[1]);
                mtspr(SPRN_BESCR, ebb_regs[2]);
                mtspr(SPRN_TAR, user_tar);
--->            mtspr(SPRN_FSCR, current->thread.fscr);
        }

^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-05-24 12:50 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-05-23 12:21 [PATCH] KVM: PPC: Book3S HV: Save host FSCR in the P7/8 path Nicholas Piggin
2021-05-23 12:21 ` Nicholas Piggin
2021-05-23 14:02 ` Nicholas Piggin
2021-05-23 14:02   ` Nicholas Piggin
2021-05-24 12:49 ` Fabiano Rosas
2021-05-24 12:49   ` Fabiano Rosas

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