Messages in this thread | | | Date | Sat, 13 Apr 2024 11:29:55 +0800 | Subject | Re: [RFC PATCH 27/41] KVM: x86/pmu: Clear PERF_METRICS MSR for guest | From | "Mi, Dapeng" <> |
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On 4/12/2024 5:50 AM, Sean Christopherson wrote: > On Fri, Jan 26, 2024, Xiong Zhang wrote: >> From: Dapeng Mi <dapeng1.mi@linux.intel.com> >> >> Since perf topdown metrics feature is not supported yet, clear >> PERF_METRICS MSR for guest. > Please rewrite with --verbose, I have no idea what MSR_PERF_METRICS, and thus no > clue why it needs to be zeroed when loading guest context, e.g. it's not passed > through, so why does it matter?
Sure. MSR_PERF_METRICS actually reports the perf topdown metrics portion. I would add more details.
> >> Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com> >> --- >> arch/x86/kvm/vmx/pmu_intel.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c >> index 4b4da7f17895..ad0434646a29 100644 >> --- a/arch/x86/kvm/vmx/pmu_intel.c >> +++ b/arch/x86/kvm/vmx/pmu_intel.c >> @@ -916,6 +916,10 @@ static void intel_restore_pmu_context(struct kvm_vcpu *vcpu) >> */ >> for (i = pmu->nr_arch_fixed_counters; i < kvm_pmu_cap.num_counters_fixed; i++) >> wrmsrl(MSR_CORE_PERF_FIXED_CTR0 + i, 0); >> + >> + /* Clear PERF_METRICS MSR since guest topdown metrics is not supported yet. */ >> + if (kvm_caps.host_perf_cap & PMU_CAP_PERF_METRICS) >> + wrmsrl(MSR_PERF_METRICS, 0); >> } >> >> struct kvm_pmu_ops intel_pmu_ops __initdata = { >> -- >> 2.34.1 >>
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