On 6/22/21 4:27 PM, Nicholas Piggin wrote:
KVM PMU management code looks for particular frozen/disabled bits in the PMU registers so it knows whether it must clear them when coming out of a guest or not. Setting this up helps KVM make these optimisations without getting confused. Longer term the better approach might be to move guest/host PMU switching to the perf subsystem. Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx> --- arch/powerpc/kernel/cpu_setup_power.c | 4 ++-- arch/powerpc/kernel/dt_cpu_ftrs.c | 6 +++--- arch/powerpc/kvm/book3s_hv.c | 5 +++++ arch/powerpc/perf/core-book3s.c | 7 +++++++ 4 files changed, 17 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/kernel/cpu_setup_power.c b/arch/powerpc/kernel/cpu_setup_power.c index a29dc8326622..3dc61e203f37 100644 --- a/arch/powerpc/kernel/cpu_setup_power.c +++ b/arch/powerpc/kernel/cpu_setup_power.c @@ -109,7 +109,7 @@ static void init_PMU_HV_ISA207(void) static void init_PMU(void) { mtspr(SPRN_MMCRA, 0); - mtspr(SPRN_MMCR0, 0); + mtspr(SPRN_MMCR0, MMCR0_FC);
Sticky point here is, currently if not frozen, pmc5/6 will keep countering. And not freezing them at boot is quiet useful sometime, like say when running in a simulation where we could calculate approx CPIs for micro benchmarks without perf subsystem.
mtspr(SPRN_MMCR1, 0); mtspr(SPRN_MMCR2, 0); } @@ -123,7 +123,7 @@ static void init_PMU_ISA31(void) { mtspr(SPRN_MMCR3, 0); mtspr(SPRN_MMCRA, MMCRA_BHRB_DISABLE); - mtspr(SPRN_MMCR0, MMCR0_PMCCEXT); + mtspr(SPRN_MMCR0, MMCR0_FC | MMCR0_PMCCEXT); } /* diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c index 0a6b36b4bda8..06a089fbeaa7 100644 --- a/arch/powerpc/kernel/dt_cpu_ftrs.c +++ b/arch/powerpc/kernel/dt_cpu_ftrs.c @@ -353,7 +353,7 @@ static void init_pmu_power8(void) } mtspr(SPRN_MMCRA, 0); - mtspr(SPRN_MMCR0, 0); + mtspr(SPRN_MMCR0, MMCR0_FC); mtspr(SPRN_MMCR1, 0); mtspr(SPRN_MMCR2, 0); mtspr(SPRN_MMCRS, 0); @@ -392,7 +392,7 @@ static void init_pmu_power9(void) mtspr(SPRN_MMCRC, 0); mtspr(SPRN_MMCRA, 0); - mtspr(SPRN_MMCR0, 0); + mtspr(SPRN_MMCR0, MMCR0_FC); mtspr(SPRN_MMCR1, 0); mtspr(SPRN_MMCR2, 0); } @@ -428,7 +428,7 @@ static void init_pmu_power10(void) mtspr(SPRN_MMCR3, 0); mtspr(SPRN_MMCRA, MMCRA_BHRB_DISABLE); - mtspr(SPRN_MMCR0, MMCR0_PMCCEXT); + mtspr(SPRN_MMCR0, MMCR0_FC | MMCR0_PMCCEXT); } static int __init feat_enable_pmu_power10(struct dt_cpu_feature *f) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 1f30f98b09d1..f7349d150828 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -2593,6 +2593,11 @@ static int kvmppc_core_vcpu_create_hv(struct kvm_vcpu *vcpu) #endif #endif vcpu->arch.mmcr[0] = MMCR0_FC; + if (cpu_has_feature(CPU_FTR_ARCH_31)) { + vcpu->arch.mmcr[0] |= MMCR0_PMCCEXT; + vcpu->arch.mmcra = MMCRA_BHRB_DISABLE; + } + vcpu->arch.ctrl = CTRL_RUNLATCH; /* default to host PVR, since we can't spoof it */ kvmppc_set_pvr_hv(vcpu, mfspr(SPRN_PVR)); diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c index 51622411a7cc..e33b29ec1a65 100644 --- a/arch/powerpc/perf/core-book3s.c +++ b/arch/powerpc/perf/core-book3s.c @@ -1361,6 +1361,13 @@ static void power_pmu_enable(struct pmu *pmu) goto out; if (cpuhw->n_events == 0) { + if (cpu_has_feature(CPU_FTR_ARCH_31)) { + mtspr(SPRN_MMCRA, MMCRA_BHRB_DISABLE); + mtspr(SPRN_MMCR0, MMCR0_FC | MMCR0_PMCCEXT); + } else { + mtspr(SPRN_MMCRA, 0); + mtspr(SPRN_MMCR0, MMCR0_FC); + } ppc_set_pmu_inuse(0); goto out; }