[02/26] KVM: PPC: Book3S PR: add new parameter (guest MSR) for kvmppc_save_tm()/kvmppc_restore_tm()

Message ID 1515665499-31710-3-git-send-email-wei.guo.simon@gmail.com
State Changes Requested
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Series
  • [01/26] KVM: PPC: Book3S PR: Move kvmppc_save_tm/kvmppc_restore_tm to separate file
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Commit Message

Simon Guo Jan. 11, 2018, 10:11 a.m.
From: Simon Guo <wei.guo.simon@gmail.com>

HV KVM and PR KVM need different MSR source to indicate whether
treclaim. or trecheckpoint. is necessary.

This patch add new parameter (guest MSR) for these kvmppc_save_tm/
kvmppc_restore_tm() APIs:
- For HV KVM, it is VCPU_MSR
- For PR KVM, it is current host MSR or VCPU_SHADOW_SRR1

This enhancement enables these 2 APIs to be reused by PR KVM later.
And the patch keeps HV KVM logic unchanged.

This patch also reworks kvmppc_save_tm()/kvmppc_restore_tm() to
have a clean ABI: r3 for vcpu and r4 for guest_msr.

Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
---
 arch/powerpc/kvm/book3s_hv_rmhandlers.S | 12 ++++++-
 arch/powerpc/kvm/tm.S                   | 61 ++++++++++++++++++---------------
 2 files changed, 45 insertions(+), 28 deletions(-)

Comments

Paul Mackerras Jan. 23, 2018, 5:42 a.m. | #1
On Thu, Jan 11, 2018 at 06:11:15PM +0800, wei.guo.simon@gmail.com wrote:
> From: Simon Guo <wei.guo.simon@gmail.com>
> 
> HV KVM and PR KVM need different MSR source to indicate whether
> treclaim. or trecheckpoint. is necessary.
> 
> This patch add new parameter (guest MSR) for these kvmppc_save_tm/
> kvmppc_restore_tm() APIs:
> - For HV KVM, it is VCPU_MSR
> - For PR KVM, it is current host MSR or VCPU_SHADOW_SRR1
> 
> This enhancement enables these 2 APIs to be reused by PR KVM later.
> And the patch keeps HV KVM logic unchanged.
> 
> This patch also reworks kvmppc_save_tm()/kvmppc_restore_tm() to
> have a clean ABI: r3 for vcpu and r4 for guest_msr.
> 
> Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>

Question: why do you switch from using HSTATE_HOST_R1 to HSTATE_SCRATCH2

> @@ -42,11 +45,11 @@ _GLOBAL(kvmppc_save_tm)
>  	rldimi	r8, r0, MSR_TM_LG, 63-MSR_TM_LG
>  	mtmsrd	r8
>  
> -	ld	r5, VCPU_MSR(r9)
> -	rldicl. r5, r5, 64 - MSR_TS_S_LG, 62
> +	rldicl. r4, r4, 64 - MSR_TS_S_LG, 62
>  	beq	1f	/* TM not active in guest. */
>  
> -	std	r1, HSTATE_HOST_R1(r13)
> +	std	r1, HSTATE_SCRATCH2(r13)

... here?

> @@ -166,17 +173,17 @@ _GLOBAL(kvmppc_restore_tm)
>  	 * The user may change these outside of a transaction, so they must
>  	 * always be context switched.
>  	 */
> -	ld	r5, VCPU_TFHAR(r4)
> -	ld	r6, VCPU_TFIAR(r4)
> -	ld	r7, VCPU_TEXASR(r4)
> +	ld	r5, VCPU_TFHAR(r3)
> +	ld	r6, VCPU_TFIAR(r3)
> +	ld	r7, VCPU_TEXASR(r3)
>  	mtspr	SPRN_TFHAR, r5
>  	mtspr	SPRN_TFIAR, r6
>  	mtspr	SPRN_TEXASR, r7
>  
> -	ld	r5, VCPU_MSR(r4)
> +	mr	r5, r4
>  	rldicl. r5, r5, 64 - MSR_TS_S_LG, 62
>  	beqlr		/* TM not active in guest */
> -	std	r1, HSTATE_HOST_R1(r13)
> +	std	r1, HSTATE_SCRATCH2(r13)

and here?

Please add a paragraph to the patch description explaining why you are
making that change.

Paul.
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Simon Guo Jan. 30, 2018, 2:33 a.m. | #2
Hi Paul,
On Tue, Jan 23, 2018 at 04:42:09PM +1100, Paul Mackerras wrote:
> On Thu, Jan 11, 2018 at 06:11:15PM +0800, wei.guo.simon@gmail.com wrote:
> > From: Simon Guo <wei.guo.simon@gmail.com>
> > 
> > HV KVM and PR KVM need different MSR source to indicate whether
> > treclaim. or trecheckpoint. is necessary.
> > 
> > This patch add new parameter (guest MSR) for these kvmppc_save_tm/
> > kvmppc_restore_tm() APIs:
> > - For HV KVM, it is VCPU_MSR
> > - For PR KVM, it is current host MSR or VCPU_SHADOW_SRR1
> > 
> > This enhancement enables these 2 APIs to be reused by PR KVM later.
> > And the patch keeps HV KVM logic unchanged.
> > 
> > This patch also reworks kvmppc_save_tm()/kvmppc_restore_tm() to
> > have a clean ABI: r3 for vcpu and r4 for guest_msr.
> > 
> > Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
> 
> Question: why do you switch from using HSTATE_HOST_R1 to HSTATE_SCRATCH2
> 
> > @@ -42,11 +45,11 @@ _GLOBAL(kvmppc_save_tm)
> >  	rldimi	r8, r0, MSR_TM_LG, 63-MSR_TM_LG
> >  	mtmsrd	r8
> >  
> > -	ld	r5, VCPU_MSR(r9)
> > -	rldicl. r5, r5, 64 - MSR_TS_S_LG, 62
> > +	rldicl. r4, r4, 64 - MSR_TS_S_LG, 62
> >  	beq	1f	/* TM not active in guest. */
> >  
> > -	std	r1, HSTATE_HOST_R1(r13)
> > +	std	r1, HSTATE_SCRATCH2(r13)
> 
> ... here?
> 
> > @@ -166,17 +173,17 @@ _GLOBAL(kvmppc_restore_tm)
> >  	 * The user may change these outside of a transaction, so they must
> >  	 * always be context switched.
> >  	 */
> > -	ld	r5, VCPU_TFHAR(r4)
> > -	ld	r6, VCPU_TFIAR(r4)
> > -	ld	r7, VCPU_TEXASR(r4)
> > +	ld	r5, VCPU_TFHAR(r3)
> > +	ld	r6, VCPU_TFIAR(r3)
> > +	ld	r7, VCPU_TEXASR(r3)
> >  	mtspr	SPRN_TFHAR, r5
> >  	mtspr	SPRN_TFIAR, r6
> >  	mtspr	SPRN_TEXASR, r7
> >  
> > -	ld	r5, VCPU_MSR(r4)
> > +	mr	r5, r4
> >  	rldicl. r5, r5, 64 - MSR_TS_S_LG, 62
> >  	beqlr		/* TM not active in guest */
> > -	std	r1, HSTATE_HOST_R1(r13)
> > +	std	r1, HSTATE_SCRATCH2(r13)
> 
> and here?
> 
> Please add a paragraph to the patch description explaining why you are
> making that change.
In subsequent patches, kvmppc_save_tm/kvmppc_restore_tm() will be
invoked by wrapper function who setup addtional stack frame and 
update R1(then update HSTATE_HOST_R1 with addtional offset). Although 
HSTATE_HOST_R1 is now used safely(always PPC_STL before entering 
guest and PPC_LL in kvmppc_interrupt_pr()), I worried a future usage 
will take an assumption on HSTATE_HOST_R1 value and bring trouble.

As a result, in kvmppc_save_tm/kvmppc_restore_tm() case, I choose
HSTATE_SCRATCH2 to restore the r1. I will update the commit message. 


Thanks,
- Simon




> 
> Paul.
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Patch

diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index a5c8ecd..613fd27 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -808,7 +808,10 @@  BEGIN_FTR_SECTION
 	/*
 	 * NOTE THAT THIS TRASHES ALL NON-VOLATILE REGISTERS INCLUDING CR
 	 */
+	mr      r3, r4
+	ld      r4, VCPU_MSR(r3)
 	bl	kvmppc_restore_tm
+	ld	r4, HSTATE_KVM_VCPU(r13)
 END_FTR_SECTION_IFSET(CPU_FTR_TM)
 #endif
 
@@ -1680,7 +1683,10 @@  BEGIN_FTR_SECTION
 	/*
 	 * NOTE THAT THIS TRASHES ALL NON-VOLATILE REGISTERS INCLUDING CR
 	 */
+	mr      r3, r9
+	ld      r4, VCPU_MSR(r3)
 	bl	kvmppc_save_tm
+	ld	r9, HSTATE_KVM_VCPU(r13)
 END_FTR_SECTION_IFSET(CPU_FTR_TM)
 #endif
 
@@ -2543,7 +2549,8 @@  BEGIN_FTR_SECTION
 	/*
 	 * NOTE THAT THIS TRASHES ALL NON-VOLATILE REGISTERS INCLUDING CR
 	 */
-	ld	r9, HSTATE_KVM_VCPU(r13)
+	ld      r3, HSTATE_KVM_VCPU(r13)
+	ld      r4, VCPU_MSR(r3)
 	bl	kvmppc_save_tm
 END_FTR_SECTION_IFSET(CPU_FTR_TM)
 #endif
@@ -2656,7 +2663,10 @@  BEGIN_FTR_SECTION
 	/*
 	 * NOTE THAT THIS TRASHES ALL NON-VOLATILE REGISTERS INCLUDING CR
 	 */
+	mr      r3, r4
+	ld      r4, VCPU_MSR(r3)
 	bl	kvmppc_restore_tm
+	ld	r4, HSTATE_KVM_VCPU(r13)
 END_FTR_SECTION_IFSET(CPU_FTR_TM)
 #endif
 
diff --git a/arch/powerpc/kvm/tm.S b/arch/powerpc/kvm/tm.S
index 072d35e..e779b15 100644
--- a/arch/powerpc/kvm/tm.S
+++ b/arch/powerpc/kvm/tm.S
@@ -28,9 +28,12 @@ 
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
 /*
  * Save transactional state and TM-related registers.
- * Called with r9 pointing to the vcpu struct.
+ * Called with:
+ * - r3 pointing to the vcpu struct
+ * - r4 points to the MSR with current TS bits:
+ * 	(For HV KVM, it is VCPU_MSR ; For PR KVM, it is host MSR).
  * This can modify all checkpointed registers, but
- * restores r1, r2 and r9 (vcpu pointer) before exit.
+ * restores r1, r2 before exit.
  */
 _GLOBAL(kvmppc_save_tm)
 	mflr	r0
@@ -42,11 +45,11 @@  _GLOBAL(kvmppc_save_tm)
 	rldimi	r8, r0, MSR_TM_LG, 63-MSR_TM_LG
 	mtmsrd	r8
 
-	ld	r5, VCPU_MSR(r9)
-	rldicl. r5, r5, 64 - MSR_TS_S_LG, 62
+	rldicl. r4, r4, 64 - MSR_TS_S_LG, 62
 	beq	1f	/* TM not active in guest. */
 
-	std	r1, HSTATE_HOST_R1(r13)
+	std	r1, HSTATE_SCRATCH2(r13)
+	std	r3, HSTATE_SCRATCH1(r13)
 	li	r3, TM_CAUSE_KVM_RESCHED
 
 	/* Clear the MSR RI since r1, r13 are all going to be foobar. */
@@ -60,7 +63,7 @@  _GLOBAL(kvmppc_save_tm)
 	SET_SCRATCH0(r13)
 	GET_PACA(r13)
 	std	r9, PACATMSCRATCH(r13)
-	ld	r9, HSTATE_KVM_VCPU(r13)
+	ld	r9, HSTATE_SCRATCH1(r13)
 
 	/* Get a few more GPRs free. */
 	std	r29, VCPU_GPRS_TM(29)(r9)
@@ -92,7 +95,7 @@  _GLOBAL(kvmppc_save_tm)
 	std	r4, VCPU_GPRS_TM(9)(r9)
 
 	/* Reload stack pointer and TOC. */
-	ld	r1, HSTATE_HOST_R1(r13)
+	ld	r1, HSTATE_SCRATCH2(r13)
 	ld	r2, PACATOC(r13)
 
 	/* Set MSR RI now we have r1 and r13 back. */
@@ -145,9 +148,13 @@  _GLOBAL(kvmppc_save_tm)
 
 /*
  * Restore transactional state and TM-related registers.
- * Called with r4 pointing to the vcpu struct.
+ * Called with:
+ *  - r3 pointing to the vcpu struct.
+ *  - r4 is the guest MSR with desired TS bits:
+ * 	For HV KVM, it is VCPU_MSR
+ * 	For PR KVM, it is provided by caller
  * This potentially modifies all checkpointed registers.
- * It restores r1, r2, r4 from the PACA.
+ * It restores r1, r2 from the PACA.
  */
 _GLOBAL(kvmppc_restore_tm)
 	mflr	r0
@@ -166,17 +173,17 @@  _GLOBAL(kvmppc_restore_tm)
 	 * The user may change these outside of a transaction, so they must
 	 * always be context switched.
 	 */
-	ld	r5, VCPU_TFHAR(r4)
-	ld	r6, VCPU_TFIAR(r4)
-	ld	r7, VCPU_TEXASR(r4)
+	ld	r5, VCPU_TFHAR(r3)
+	ld	r6, VCPU_TFIAR(r3)
+	ld	r7, VCPU_TEXASR(r3)
 	mtspr	SPRN_TFHAR, r5
 	mtspr	SPRN_TFIAR, r6
 	mtspr	SPRN_TEXASR, r7
 
-	ld	r5, VCPU_MSR(r4)
+	mr	r5, r4
 	rldicl. r5, r5, 64 - MSR_TS_S_LG, 62
 	beqlr		/* TM not active in guest */
-	std	r1, HSTATE_HOST_R1(r13)
+	std	r1, HSTATE_SCRATCH2(r13)
 
 	/* Make sure the failure summary is set, otherwise we'll program check
 	 * when we trechkpt.  It's possible that this might have been not set
@@ -192,21 +199,21 @@  _GLOBAL(kvmppc_restore_tm)
 	 * some SPRs.
 	 */
 
-	mr	r31, r4
+	mr	r31, r3
 	addi	r3, r31, VCPU_FPRS_TM
 	bl	load_fp_state
 	addi	r3, r31, VCPU_VRS_TM
 	bl	load_vr_state
-	mr	r4, r31
-	lwz	r7, VCPU_VRSAVE_TM(r4)
+	mr	r3, r31
+	lwz	r7, VCPU_VRSAVE_TM(r3)
 	mtspr	SPRN_VRSAVE, r7
 
-	ld	r5, VCPU_LR_TM(r4)
-	lwz	r6, VCPU_CR_TM(r4)
-	ld	r7, VCPU_CTR_TM(r4)
-	ld	r8, VCPU_AMR_TM(r4)
-	ld	r9, VCPU_TAR_TM(r4)
-	ld	r10, VCPU_XER_TM(r4)
+	ld	r5, VCPU_LR_TM(r3)
+	lwz	r6, VCPU_CR_TM(r3)
+	ld	r7, VCPU_CTR_TM(r3)
+	ld	r8, VCPU_AMR_TM(r3)
+	ld	r9, VCPU_TAR_TM(r3)
+	ld	r10, VCPU_XER_TM(r3)
 	mtlr	r5
 	mtcr	r6
 	mtctr	r7
@@ -219,8 +226,8 @@  _GLOBAL(kvmppc_restore_tm)
 	 * till the last moment to avoid running with userspace PPR and DSCR for
 	 * too long.
 	 */
-	ld	r29, VCPU_DSCR_TM(r4)
-	ld	r30, VCPU_PPR_TM(r4)
+	ld	r29, VCPU_DSCR_TM(r3)
+	ld	r30, VCPU_PPR_TM(r3)
 
 	std	r2, PACATMSCRATCH(r13) /* Save TOC */
 
@@ -253,8 +260,7 @@  _GLOBAL(kvmppc_restore_tm)
 	ld	r29, HSTATE_DSCR(r13)
 	mtspr	SPRN_DSCR, r29
 #endif
-	ld	r4, HSTATE_KVM_VCPU(r13)
-	ld	r1, HSTATE_HOST_R1(r13)
+	ld	r1, HSTATE_SCRATCH2(r13)
 	ld	r2, PACATMSCRATCH(r13)
 
 	/* Set the MSR RI since we have our registers back. */
@@ -264,4 +270,5 @@  _GLOBAL(kvmppc_restore_tm)
 	ld	r0, PPC_LR_STKOFF(r1)
 	mtlr	r0
 	blr
+
 #endif