| Message ID | 20221209194957.2774423-2-aaronlewis@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Fix "Instructions Retired" from incorrectly counting | expand |
On Fri, Dec 09, 2022, Aaron Lewis wrote: > When counting "Instructions Retired" (0xc0) in a guest, KVM will > occasionally increment the PMU counter regardless of if that event is > being filtered. This is because some PMU events are incremented via > kvm_pmu_trigger_event(), which doesn't know about the event filter. Add > the event filter to kvm_pmu_trigger_event(), so events that are > disallowed do not increment their counters. > > Fixes: 9cd803d496e7 ("KVM: x86: Update vPMCs when retiring instructions") > Signed-off-by: Aaron Lewis <aaronlewis@google.com> > --- > arch/x86/kvm/pmu.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c > index 684393c22105..b87cf35a38b7 100644 > --- a/arch/x86/kvm/pmu.c > +++ b/arch/x86/kvm/pmu.c > @@ -581,7 +581,9 @@ void kvm_pmu_trigger_event(struct kvm_vcpu *vcpu, u64 perf_hw_id) > for_each_set_bit(i, pmu->all_valid_pmc_idx, X86_PMC_IDX_MAX) { > pmc = static_call(kvm_x86_pmu_pmc_idx_to_pmc)(pmu, i); > > - if (!pmc || !pmc_is_enabled(pmc) || !pmc_speculative_in_use(pmc)) > + if (!pmc || !pmc_is_enabled(pmc) || > + !pmc_speculative_in_use(pmc) || > + !check_pmu_event_filter(pmc)) reprogram_counter() has the same three checks, seems like we should combine them into a common helper. No idea what to call it though. Maybe? if (!pmc || !pmc_is_fully_enabled(pmc)) > continue; > > /* Ignore checks for edge detect, pin control, invert and CMASK bits */ > -- > 2.39.0.rc1.256.g54fd8350bd-goog >
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index 684393c22105..b87cf35a38b7 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -581,7 +581,9 @@ void kvm_pmu_trigger_event(struct kvm_vcpu *vcpu, u64 perf_hw_id) for_each_set_bit(i, pmu->all_valid_pmc_idx, X86_PMC_IDX_MAX) { pmc = static_call(kvm_x86_pmu_pmc_idx_to_pmc)(pmu, i); - if (!pmc || !pmc_is_enabled(pmc) || !pmc_speculative_in_use(pmc)) + if (!pmc || !pmc_is_enabled(pmc) || + !pmc_speculative_in_use(pmc) || + !check_pmu_event_filter(pmc)) continue; /* Ignore checks for edge detect, pin control, invert and CMASK bits */
When counting "Instructions Retired" (0xc0) in a guest, KVM will occasionally increment the PMU counter regardless of if that event is being filtered. This is because some PMU events are incremented via kvm_pmu_trigger_event(), which doesn't know about the event filter. Add the event filter to kvm_pmu_trigger_event(), so events that are disallowed do not increment their counters. Fixes: 9cd803d496e7 ("KVM: x86: Update vPMCs when retiring instructions") Signed-off-by: Aaron Lewis <aaronlewis@google.com> --- arch/x86/kvm/pmu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)