Commit dfdeda67 authored by Aaron Lewis's avatar Aaron Lewis Committed by Sean Christopherson
Browse files

KVM: x86/pmu: Prevent the PMU from counting disallowed events 



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: 9cd803d4 ("KVM: x86: Update vPMCs when retiring instructions")
Signed-off-by: default avatarAaron Lewis <aaronlewis@google.com>
Reviewed-by: default avatarLike Xu <likexu@tencent.com>
Link: https://lore.kernel.org/r/20230307141400.1486314-2-aaronlewis@google.com


[sean: prepend "pmc" to the new function]
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 4fa5843d

arch/x86/kvm/pmu.c

+8 −5
Original line number Diff line number Diff line
@@ -400,6 +400,12 @@ static bool check_pmu_event_filter(struct kvm_pmc *pmc) 
	return is_fixed_event_allowed(filter, pmc->idx);

}



static bool pmc_event_is_allowed(struct kvm_pmc *pmc)

{

	return pmc_is_globally_enabled(pmc) && pmc_speculative_in_use(pmc) &&

	       check_pmu_event_filter(pmc);

}



static void reprogram_counter(struct kvm_pmc *pmc)

{

	struct kvm_pmu *pmu = pmc_to_pmu(pmc);
@@ -409,10 +415,7 @@ static void reprogram_counter(struct kvm_pmc *pmc) 


	pmc_pause_counter(pmc);



	if (!pmc_speculative_in_use(pmc) || !pmc_is_globally_enabled(pmc))

		goto reprogram_complete;



	if (!check_pmu_event_filter(pmc))

	if (!pmc_event_is_allowed(pmc))

		goto reprogram_complete;



	if (pmc->counter < pmc->prev_counter)
@@ -688,7 +691,7 @@ 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_globally_enabled(pmc) || !pmc_speculative_in_use(pmc))

		if (!pmc || !pmc_event_is_allowed(pmc))

			continue;



		/* Ignore checks for edge detect, pin control, invert and CMASK bits */