Re: [RFC PATCH 04/32] KVM: PPC: Book3S HV: Extract PMU save/restore operations as C-callable functions

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On Fri, Sep 21, 2018 at 08:01:35PM +1000, Paul Mackerras wrote:
> This pulls out the assembler code that is responsible for saving and
> restoring the PMU state for the host and guest into separate functions
> so they can be used from an alternate entry path.  The calling
> convention is made compatible with C.
> 
> Signed-off-by: Paul Mackerras <paulus@xxxxxxxxxx>

Reviewed-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>

> ---
>  arch/powerpc/include/asm/asm-prototypes.h |   5 +
>  arch/powerpc/kvm/book3s_hv_interrupts.S   |  95 ++++----
>  arch/powerpc/kvm/book3s_hv_rmhandlers.S   | 363 ++++++++++++++++--------------
>  3 files changed, 253 insertions(+), 210 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/asm-prototypes.h b/arch/powerpc/include/asm/asm-prototypes.h
> index 1f4691c..024e8fc 100644
> --- a/arch/powerpc/include/asm/asm-prototypes.h
> +++ b/arch/powerpc/include/asm/asm-prototypes.h
> @@ -150,4 +150,9 @@ extern s32 patch__memset_nocache, patch__memcpy_nocache;
>  
>  extern long flush_count_cache;
>  
> +void kvmhv_save_host_pmu(void);
> +void kvmhv_load_host_pmu(void);
> +void kvmhv_save_guest_pmu(struct kvm_vcpu *vcpu, bool pmu_in_use);
> +void kvmhv_load_guest_pmu(struct kvm_vcpu *vcpu);
> +
>  #endif /* _ASM_POWERPC_ASM_PROTOTYPES_H */
> diff --git a/arch/powerpc/kvm/book3s_hv_interrupts.S b/arch/powerpc/kvm/book3s_hv_interrupts.S
> index 666b91c..a6d1001 100644
> --- a/arch/powerpc/kvm/book3s_hv_interrupts.S
> +++ b/arch/powerpc/kvm/book3s_hv_interrupts.S
> @@ -64,52 +64,7 @@ BEGIN_FTR_SECTION
>  END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S)
>  
>  	/* Save host PMU registers */
> -BEGIN_FTR_SECTION
> -	/* Work around P8 PMAE bug */
> -	li	r3, -1
> -	clrrdi	r3, r3, 10
> -	mfspr	r8, SPRN_MMCR2
> -	mtspr	SPRN_MMCR2, r3		/* freeze all counters using MMCR2 */
> -	isync
> -END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
> -	li	r3, 1
> -	sldi	r3, r3, 31		/* MMCR0_FC (freeze counters) bit */
> -	mfspr	r7, SPRN_MMCR0		/* save MMCR0 */
> -	mtspr	SPRN_MMCR0, r3		/* freeze all counters, disable interrupts */
> -	mfspr	r6, SPRN_MMCRA
> -	/* Clear MMCRA in order to disable SDAR updates */
> -	li	r5, 0
> -	mtspr	SPRN_MMCRA, r5
> -	isync
> -	lbz	r5, PACA_PMCINUSE(r13)	/* is the host using the PMU? */
> -	cmpwi	r5, 0
> -	beq	31f			/* skip if not */
> -	mfspr	r5, SPRN_MMCR1
> -	mfspr	r9, SPRN_SIAR
> -	mfspr	r10, SPRN_SDAR
> -	std	r7, HSTATE_MMCR0(r13)
> -	std	r5, HSTATE_MMCR1(r13)
> -	std	r6, HSTATE_MMCRA(r13)
> -	std	r9, HSTATE_SIAR(r13)
> -	std	r10, HSTATE_SDAR(r13)
> -BEGIN_FTR_SECTION
> -	mfspr	r9, SPRN_SIER
> -	std	r8, HSTATE_MMCR2(r13)
> -	std	r9, HSTATE_SIER(r13)
> -END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
> -	mfspr	r3, SPRN_PMC1
> -	mfspr	r5, SPRN_PMC2
> -	mfspr	r6, SPRN_PMC3
> -	mfspr	r7, SPRN_PMC4
> -	mfspr	r8, SPRN_PMC5
> -	mfspr	r9, SPRN_PMC6
> -	stw	r3, HSTATE_PMC1(r13)
> -	stw	r5, HSTATE_PMC2(r13)
> -	stw	r6, HSTATE_PMC3(r13)
> -	stw	r7, HSTATE_PMC4(r13)
> -	stw	r8, HSTATE_PMC5(r13)
> -	stw	r9, HSTATE_PMC6(r13)
> -31:
> +	bl	kvmhv_save_host_pmu
>  
>  	/*
>  	 * Put whatever is in the decrementer into the
> @@ -161,3 +116,51 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
>  	ld	r0, PPC_LR_STKOFF(r1)
>  	mtlr	r0
>  	blr
> +
> +_GLOBAL(kvmhv_save_host_pmu)
> +BEGIN_FTR_SECTION
> +	/* Work around P8 PMAE bug */
> +	li	r3, -1
> +	clrrdi	r3, r3, 10
> +	mfspr	r8, SPRN_MMCR2
> +	mtspr	SPRN_MMCR2, r3		/* freeze all counters using MMCR2 */
> +	isync
> +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
> +	li	r3, 1
> +	sldi	r3, r3, 31		/* MMCR0_FC (freeze counters) bit */
> +	mfspr	r7, SPRN_MMCR0		/* save MMCR0 */
> +	mtspr	SPRN_MMCR0, r3		/* freeze all counters, disable interrupts */
> +	mfspr	r6, SPRN_MMCRA
> +	/* Clear MMCRA in order to disable SDAR updates */
> +	li	r5, 0
> +	mtspr	SPRN_MMCRA, r5
> +	isync
> +	lbz	r5, PACA_PMCINUSE(r13)	/* is the host using the PMU? */
> +	cmpwi	r5, 0
> +	beq	31f			/* skip if not */
> +	mfspr	r5, SPRN_MMCR1
> +	mfspr	r9, SPRN_SIAR
> +	mfspr	r10, SPRN_SDAR
> +	std	r7, HSTATE_MMCR0(r13)
> +	std	r5, HSTATE_MMCR1(r13)
> +	std	r6, HSTATE_MMCRA(r13)
> +	std	r9, HSTATE_SIAR(r13)
> +	std	r10, HSTATE_SDAR(r13)
> +BEGIN_FTR_SECTION
> +	mfspr	r9, SPRN_SIER
> +	std	r8, HSTATE_MMCR2(r13)
> +	std	r9, HSTATE_SIER(r13)
> +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
> +	mfspr	r3, SPRN_PMC1
> +	mfspr	r5, SPRN_PMC2
> +	mfspr	r6, SPRN_PMC3
> +	mfspr	r7, SPRN_PMC4
> +	mfspr	r8, SPRN_PMC5
> +	mfspr	r9, SPRN_PMC6
> +	stw	r3, HSTATE_PMC1(r13)
> +	stw	r5, HSTATE_PMC2(r13)
> +	stw	r6, HSTATE_PMC3(r13)
> +	stw	r7, HSTATE_PMC4(r13)
> +	stw	r8, HSTATE_PMC5(r13)
> +	stw	r9, HSTATE_PMC6(r13)
> +31:	blr
> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> index 6752da1..5b2ae34 100644
> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> @@ -28,6 +28,7 @@
>  #include <asm/exception-64s.h>
>  #include <asm/kvm_book3s_asm.h>
>  #include <asm/book3s/64/mmu-hash.h>
> +#include <asm/export.h>
>  #include <asm/tm.h>
>  #include <asm/opal.h>
>  #include <asm/xive-regs.h>
> @@ -113,45 +114,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S)
>  	mtspr	SPRN_SPRG_VDSO_WRITE,r3
>  
>  	/* Reload the host's PMU registers */
> -	lbz	r4, PACA_PMCINUSE(r13) /* is the host using the PMU? */
> -	cmpwi	r4, 0
> -	beq	23f			/* skip if not */
> -BEGIN_FTR_SECTION
> -	ld	r3, HSTATE_MMCR0(r13)
> -	andi.	r4, r3, MMCR0_PMAO_SYNC | MMCR0_PMAO
> -	cmpwi	r4, MMCR0_PMAO
> -	beql	kvmppc_fix_pmao
> -END_FTR_SECTION_IFSET(CPU_FTR_PMAO_BUG)
> -	lwz	r3, HSTATE_PMC1(r13)
> -	lwz	r4, HSTATE_PMC2(r13)
> -	lwz	r5, HSTATE_PMC3(r13)
> -	lwz	r6, HSTATE_PMC4(r13)
> -	lwz	r8, HSTATE_PMC5(r13)
> -	lwz	r9, HSTATE_PMC6(r13)
> -	mtspr	SPRN_PMC1, r3
> -	mtspr	SPRN_PMC2, r4
> -	mtspr	SPRN_PMC3, r5
> -	mtspr	SPRN_PMC4, r6
> -	mtspr	SPRN_PMC5, r8
> -	mtspr	SPRN_PMC6, r9
> -	ld	r3, HSTATE_MMCR0(r13)
> -	ld	r4, HSTATE_MMCR1(r13)
> -	ld	r5, HSTATE_MMCRA(r13)
> -	ld	r6, HSTATE_SIAR(r13)
> -	ld	r7, HSTATE_SDAR(r13)
> -	mtspr	SPRN_MMCR1, r4
> -	mtspr	SPRN_MMCRA, r5
> -	mtspr	SPRN_SIAR, r6
> -	mtspr	SPRN_SDAR, r7
> -BEGIN_FTR_SECTION
> -	ld	r8, HSTATE_MMCR2(r13)
> -	ld	r9, HSTATE_SIER(r13)
> -	mtspr	SPRN_MMCR2, r8
> -	mtspr	SPRN_SIER, r9
> -END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
> -	mtspr	SPRN_MMCR0, r3
> -	isync
> -23:
> +	bl	kvmhv_load_host_pmu
>  
>  	/*
>  	 * Reload DEC.  HDEC interrupts were disabled when
> @@ -805,57 +768,12 @@ END_FTR_SECTION(CPU_FTR_TM | CPU_FTR_P9_TM_HV_ASSIST, 0)
>  91:
>  #endif
>  
> -	/* Load guest PMU registers */
> -	/* R4 is live here (vcpu pointer) */
> -	li	r3, 1
> -	sldi	r3, r3, 31		/* MMCR0_FC (freeze counters) bit */
> -	mtspr	SPRN_MMCR0, r3		/* freeze all counters, disable ints */
> -	isync
> -BEGIN_FTR_SECTION
> -	ld	r3, VCPU_MMCR(r4)
> -	andi.	r5, r3, MMCR0_PMAO_SYNC | MMCR0_PMAO
> -	cmpwi	r5, MMCR0_PMAO
> -	beql	kvmppc_fix_pmao
> -END_FTR_SECTION_IFSET(CPU_FTR_PMAO_BUG)
> -	lwz	r3, VCPU_PMC(r4)	/* always load up guest PMU registers */
> -	lwz	r5, VCPU_PMC + 4(r4)	/* to prevent information leak */
> -	lwz	r6, VCPU_PMC + 8(r4)
> -	lwz	r7, VCPU_PMC + 12(r4)
> -	lwz	r8, VCPU_PMC + 16(r4)
> -	lwz	r9, VCPU_PMC + 20(r4)
> -	mtspr	SPRN_PMC1, r3
> -	mtspr	SPRN_PMC2, r5
> -	mtspr	SPRN_PMC3, r6
> -	mtspr	SPRN_PMC4, r7
> -	mtspr	SPRN_PMC5, r8
> -	mtspr	SPRN_PMC6, r9
> -	ld	r3, VCPU_MMCR(r4)
> -	ld	r5, VCPU_MMCR + 8(r4)
> -	ld	r6, VCPU_MMCR + 16(r4)
> -	ld	r7, VCPU_SIAR(r4)
> -	ld	r8, VCPU_SDAR(r4)
> -	mtspr	SPRN_MMCR1, r5
> -	mtspr	SPRN_MMCRA, r6
> -	mtspr	SPRN_SIAR, r7
> -	mtspr	SPRN_SDAR, r8
> -BEGIN_FTR_SECTION
> -	ld	r5, VCPU_MMCR + 24(r4)
> -	ld	r6, VCPU_SIER(r4)
> -	mtspr	SPRN_MMCR2, r5
> -	mtspr	SPRN_SIER, r6
> -BEGIN_FTR_SECTION_NESTED(96)
> -	lwz	r7, VCPU_PMC + 24(r4)
> -	lwz	r8, VCPU_PMC + 28(r4)
> -	ld	r9, VCPU_MMCR + 32(r4)
> -	mtspr	SPRN_SPMC1, r7
> -	mtspr	SPRN_SPMC2, r8
> -	mtspr	SPRN_MMCRS, r9
> -END_FTR_SECTION_NESTED(CPU_FTR_ARCH_300, 0, 96)
> -END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
> -	mtspr	SPRN_MMCR0, r3
> -	isync
> +	/* Load guest PMU registers; r4 = vcpu pointer here */
> +	mr	r3, r4
> +	bl	kvmhv_load_guest_pmu
>  
>  	/* Load up FP, VMX and VSX registers */
> +	ld	r4, HSTATE_KVM_VCPU(r13)
>  	bl	kvmppc_load_fp
>  
>  	ld	r14, VCPU_GPR(R14)(r4)
> @@ -1766,83 +1684,12 @@ END_FTR_SECTION(CPU_FTR_TM | CPU_FTR_P9_TM_HV_ASSIST, 0)
>  25:
>  	/* Save PMU registers if requested */
>  	/* r8 and cr0.eq are live here */
> -BEGIN_FTR_SECTION
> -	/*
> -	 * POWER8 seems to have a hardware bug where setting
> -	 * MMCR0[PMAE] along with MMCR0[PMC1CE] and/or MMCR0[PMCjCE]
> -	 * when some counters are already negative doesn't seem
> -	 * to cause a performance monitor alert (and hence interrupt).
> -	 * The effect of this is that when saving the PMU state,
> -	 * if there is no PMU alert pending when we read MMCR0
> -	 * before freezing the counters, but one becomes pending
> -	 * before we read the counters, we lose it.
> -	 * To work around this, we need a way to freeze the counters
> -	 * before reading MMCR0.  Normally, freezing the counters
> -	 * is done by writing MMCR0 (to set MMCR0[FC]) which
> -	 * unavoidably writes MMCR0[PMA0] as well.  On POWER8,
> -	 * we can also freeze the counters using MMCR2, by writing
> -	 * 1s to all the counter freeze condition bits (there are
> -	 * 9 bits each for 6 counters).
> -	 */
> -	li	r3, -1			/* set all freeze bits */
> -	clrrdi	r3, r3, 10
> -	mfspr	r10, SPRN_MMCR2
> -	mtspr	SPRN_MMCR2, r3
> -	isync
> -END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
> -	li	r3, 1
> -	sldi	r3, r3, 31		/* MMCR0_FC (freeze counters) bit */
> -	mfspr	r4, SPRN_MMCR0		/* save MMCR0 */
> -	mtspr	SPRN_MMCR0, r3		/* freeze all counters, disable ints */
> -	mfspr	r6, SPRN_MMCRA
> -	/* Clear MMCRA in order to disable SDAR updates */
> -	li	r7, 0
> -	mtspr	SPRN_MMCRA, r7
> -	isync
> +	mr	r3, r9
> +	li	r4, 1
>  	beq	21f			/* if no VPA, save PMU stuff anyway */
> -	lbz	r7, LPPACA_PMCINUSE(r8)
> -	cmpwi	r7, 0			/* did they ask for PMU stuff to be saved? */
> -	bne	21f
> -	std	r3, VCPU_MMCR(r9)	/* if not, set saved MMCR0 to FC */
> -	b	22f
> -21:	mfspr	r5, SPRN_MMCR1
> -	mfspr	r7, SPRN_SIAR
> -	mfspr	r8, SPRN_SDAR
> -	std	r4, VCPU_MMCR(r9)
> -	std	r5, VCPU_MMCR + 8(r9)
> -	std	r6, VCPU_MMCR + 16(r9)
> -BEGIN_FTR_SECTION
> -	std	r10, VCPU_MMCR + 24(r9)
> -END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
> -	std	r7, VCPU_SIAR(r9)
> -	std	r8, VCPU_SDAR(r9)
> -	mfspr	r3, SPRN_PMC1
> -	mfspr	r4, SPRN_PMC2
> -	mfspr	r5, SPRN_PMC3
> -	mfspr	r6, SPRN_PMC4
> -	mfspr	r7, SPRN_PMC5
> -	mfspr	r8, SPRN_PMC6
> -	stw	r3, VCPU_PMC(r9)
> -	stw	r4, VCPU_PMC + 4(r9)
> -	stw	r5, VCPU_PMC + 8(r9)
> -	stw	r6, VCPU_PMC + 12(r9)
> -	stw	r7, VCPU_PMC + 16(r9)
> -	stw	r8, VCPU_PMC + 20(r9)
> -BEGIN_FTR_SECTION
> -	mfspr	r5, SPRN_SIER
> -	std	r5, VCPU_SIER(r9)
> -BEGIN_FTR_SECTION_NESTED(96)
> -	mfspr	r6, SPRN_SPMC1
> -	mfspr	r7, SPRN_SPMC2
> -	mfspr	r8, SPRN_MMCRS
> -	stw	r6, VCPU_PMC + 24(r9)
> -	stw	r7, VCPU_PMC + 28(r9)
> -	std	r8, VCPU_MMCR + 32(r9)
> -	lis	r4, 0x8000
> -	mtspr	SPRN_MMCRS, r4
> -END_FTR_SECTION_NESTED(CPU_FTR_ARCH_300, 0, 96)
> -END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
> -22:
> +	lbz	r4, LPPACA_PMCINUSE(r8)
> +21:	bl	kvmhv_save_guest_pmu
> +	ld	r9, HSTATE_KVM_VCPU(r13)
>  
>  	/* Restore host values of some registers */
>  BEGIN_FTR_SECTION
> @@ -3388,6 +3235,194 @@ kvmppc_msr_interrupt:
>  	blr
>  
>  /*
> + * Load up guest PMU state.  R3 points to the vcpu struct.
> + */
> +_GLOBAL(kvmhv_load_guest_pmu)
> +EXPORT_SYMBOL_GPL(kvmhv_load_guest_pmu)
> +	mr	r4, r3
> +	mflr	r0
> +	li	r3, 1
> +	sldi	r3, r3, 31		/* MMCR0_FC (freeze counters) bit */
> +	mtspr	SPRN_MMCR0, r3		/* freeze all counters, disable ints */
> +	isync
> +BEGIN_FTR_SECTION
> +	ld	r3, VCPU_MMCR(r4)
> +	andi.	r5, r3, MMCR0_PMAO_SYNC | MMCR0_PMAO
> +	cmpwi	r5, MMCR0_PMAO
> +	beql	kvmppc_fix_pmao
> +END_FTR_SECTION_IFSET(CPU_FTR_PMAO_BUG)
> +	lwz	r3, VCPU_PMC(r4)	/* always load up guest PMU registers */
> +	lwz	r5, VCPU_PMC + 4(r4)	/* to prevent information leak */
> +	lwz	r6, VCPU_PMC + 8(r4)
> +	lwz	r7, VCPU_PMC + 12(r4)
> +	lwz	r8, VCPU_PMC + 16(r4)
> +	lwz	r9, VCPU_PMC + 20(r4)
> +	mtspr	SPRN_PMC1, r3
> +	mtspr	SPRN_PMC2, r5
> +	mtspr	SPRN_PMC3, r6
> +	mtspr	SPRN_PMC4, r7
> +	mtspr	SPRN_PMC5, r8
> +	mtspr	SPRN_PMC6, r9
> +	ld	r3, VCPU_MMCR(r4)
> +	ld	r5, VCPU_MMCR + 8(r4)
> +	ld	r6, VCPU_MMCR + 16(r4)
> +	ld	r7, VCPU_SIAR(r4)
> +	ld	r8, VCPU_SDAR(r4)
> +	mtspr	SPRN_MMCR1, r5
> +	mtspr	SPRN_MMCRA, r6
> +	mtspr	SPRN_SIAR, r7
> +	mtspr	SPRN_SDAR, r8
> +BEGIN_FTR_SECTION
> +	ld	r5, VCPU_MMCR + 24(r4)
> +	ld	r6, VCPU_SIER(r4)
> +	mtspr	SPRN_MMCR2, r5
> +	mtspr	SPRN_SIER, r6
> +BEGIN_FTR_SECTION_NESTED(96)
> +	lwz	r7, VCPU_PMC + 24(r4)
> +	lwz	r8, VCPU_PMC + 28(r4)
> +	ld	r9, VCPU_MMCR + 32(r4)
> +	mtspr	SPRN_SPMC1, r7
> +	mtspr	SPRN_SPMC2, r8
> +	mtspr	SPRN_MMCRS, r9
> +END_FTR_SECTION_NESTED(CPU_FTR_ARCH_300, 0, 96)
> +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
> +	mtspr	SPRN_MMCR0, r3
> +	isync
> +	mtlr	r0
> +	blr
> +
> +/*
> + * Reload host PMU state saved in the PACA by kvmhv_save_host_pmu.
> + */
> +_GLOBAL(kvmhv_load_host_pmu)
> +EXPORT_SYMBOL_GPL(kvmhv_load_host_pmu)
> +	mflr	r0
> +	lbz	r4, PACA_PMCINUSE(r13) /* is the host using the PMU? */
> +	cmpwi	r4, 0
> +	beq	23f			/* skip if not */
> +BEGIN_FTR_SECTION
> +	ld	r3, HSTATE_MMCR0(r13)
> +	andi.	r4, r3, MMCR0_PMAO_SYNC | MMCR0_PMAO
> +	cmpwi	r4, MMCR0_PMAO
> +	beql	kvmppc_fix_pmao
> +END_FTR_SECTION_IFSET(CPU_FTR_PMAO_BUG)
> +	lwz	r3, HSTATE_PMC1(r13)
> +	lwz	r4, HSTATE_PMC2(r13)
> +	lwz	r5, HSTATE_PMC3(r13)
> +	lwz	r6, HSTATE_PMC4(r13)
> +	lwz	r8, HSTATE_PMC5(r13)
> +	lwz	r9, HSTATE_PMC6(r13)
> +	mtspr	SPRN_PMC1, r3
> +	mtspr	SPRN_PMC2, r4
> +	mtspr	SPRN_PMC3, r5
> +	mtspr	SPRN_PMC4, r6
> +	mtspr	SPRN_PMC5, r8
> +	mtspr	SPRN_PMC6, r9
> +	ld	r3, HSTATE_MMCR0(r13)
> +	ld	r4, HSTATE_MMCR1(r13)
> +	ld	r5, HSTATE_MMCRA(r13)
> +	ld	r6, HSTATE_SIAR(r13)
> +	ld	r7, HSTATE_SDAR(r13)
> +	mtspr	SPRN_MMCR1, r4
> +	mtspr	SPRN_MMCRA, r5
> +	mtspr	SPRN_SIAR, r6
> +	mtspr	SPRN_SDAR, r7
> +BEGIN_FTR_SECTION
> +	ld	r8, HSTATE_MMCR2(r13)
> +	ld	r9, HSTATE_SIER(r13)
> +	mtspr	SPRN_MMCR2, r8
> +	mtspr	SPRN_SIER, r9
> +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
> +	mtspr	SPRN_MMCR0, r3
> +	isync
> +	mtlr	r0
> +23:	blr
> +
> +/*
> + * Save guest PMU state into the vcpu struct.
> + * r3 = vcpu, r4 = full save flag (PMU in use flag set in VPA)
> + */
> +_GLOBAL(kvmhv_save_guest_pmu)
> +EXPORT_SYMBOL_GPL(kvmhv_save_guest_pmu)
> +	mr	r9, r3
> +	mr	r8, r4
> +BEGIN_FTR_SECTION
> +	/*
> +	 * POWER8 seems to have a hardware bug where setting
> +	 * MMCR0[PMAE] along with MMCR0[PMC1CE] and/or MMCR0[PMCjCE]
> +	 * when some counters are already negative doesn't seem
> +	 * to cause a performance monitor alert (and hence interrupt).
> +	 * The effect of this is that when saving the PMU state,
> +	 * if there is no PMU alert pending when we read MMCR0
> +	 * before freezing the counters, but one becomes pending
> +	 * before we read the counters, we lose it.
> +	 * To work around this, we need a way to freeze the counters
> +	 * before reading MMCR0.  Normally, freezing the counters
> +	 * is done by writing MMCR0 (to set MMCR0[FC]) which
> +	 * unavoidably writes MMCR0[PMA0] as well.  On POWER8,
> +	 * we can also freeze the counters using MMCR2, by writing
> +	 * 1s to all the counter freeze condition bits (there are
> +	 * 9 bits each for 6 counters).
> +	 */
> +	li	r3, -1			/* set all freeze bits */
> +	clrrdi	r3, r3, 10
> +	mfspr	r10, SPRN_MMCR2
> +	mtspr	SPRN_MMCR2, r3
> +	isync
> +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
> +	li	r3, 1
> +	sldi	r3, r3, 31		/* MMCR0_FC (freeze counters) bit */
> +	mfspr	r4, SPRN_MMCR0		/* save MMCR0 */
> +	mtspr	SPRN_MMCR0, r3		/* freeze all counters, disable ints */
> +	mfspr	r6, SPRN_MMCRA
> +	/* Clear MMCRA in order to disable SDAR updates */
> +	li	r7, 0
> +	mtspr	SPRN_MMCRA, r7
> +	isync
> +	cmpwi	r8, 0			/* did they ask for PMU stuff to be saved? */
> +	bne	21f
> +	std	r3, VCPU_MMCR(r9)	/* if not, set saved MMCR0 to FC */
> +	b	22f
> +21:	mfspr	r5, SPRN_MMCR1
> +	mfspr	r7, SPRN_SIAR
> +	mfspr	r8, SPRN_SDAR
> +	std	r4, VCPU_MMCR(r9)
> +	std	r5, VCPU_MMCR + 8(r9)
> +	std	r6, VCPU_MMCR + 16(r9)
> +BEGIN_FTR_SECTION
> +	std	r10, VCPU_MMCR + 24(r9)
> +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
> +	std	r7, VCPU_SIAR(r9)
> +	std	r8, VCPU_SDAR(r9)
> +	mfspr	r3, SPRN_PMC1
> +	mfspr	r4, SPRN_PMC2
> +	mfspr	r5, SPRN_PMC3
> +	mfspr	r6, SPRN_PMC4
> +	mfspr	r7, SPRN_PMC5
> +	mfspr	r8, SPRN_PMC6
> +	stw	r3, VCPU_PMC(r9)
> +	stw	r4, VCPU_PMC + 4(r9)
> +	stw	r5, VCPU_PMC + 8(r9)
> +	stw	r6, VCPU_PMC + 12(r9)
> +	stw	r7, VCPU_PMC + 16(r9)
> +	stw	r8, VCPU_PMC + 20(r9)
> +BEGIN_FTR_SECTION
> +	mfspr	r5, SPRN_SIER
> +	std	r5, VCPU_SIER(r9)
> +BEGIN_FTR_SECTION_NESTED(96)
> +	mfspr	r6, SPRN_SPMC1
> +	mfspr	r7, SPRN_SPMC2
> +	mfspr	r8, SPRN_MMCRS
> +	stw	r6, VCPU_PMC + 24(r9)
> +	stw	r7, VCPU_PMC + 28(r9)
> +	std	r8, VCPU_MMCR + 32(r9)
> +	lis	r4, 0x8000
> +	mtspr	SPRN_MMCRS, r4
> +END_FTR_SECTION_NESTED(CPU_FTR_ARCH_300, 0, 96)
> +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
> +22:	blr
> +
> +/*
>   * This works around a hardware bug on POWER8E processors, where
>   * writing a 1 to the MMCR0[PMAO] bit doesn't generate a
>   * performance monitor interrupt.  Instead, when we need to have

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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