KVM: x86/pmu: Check mediated PMU counter enablement before event filters

If the guest disables the counter (by clearing
ARCH_PERFMON_EVENTSEL_ENABLE), KVM still performs the PMU filter lookup,
even though it doesn't end up changing eventsel_hw.  Check if the
counter is enabled by the guest before doing the potentially expensive
PMU filter lookup.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260527234711.4175166-9-yosry@kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index afbc731e72174712b855325c36f1f7dc5c275aca..67dbbd4c730367cac5c449a268d79724b9653404 100644 (file)
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -532,7 +532,7 @@ static bool pmc_is_event_allowed(struct kvm_pmc *pmc)
 
 static void kvm_mediated_pmu_refresh_event_filter(struct kvm_pmc *pmc)
 {
-       bool allowed = pmc_is_event_allowed(pmc);
+       bool allowed = pmc_is_locally_enabled(pmc) && pmc_is_event_allowed(pmc);
        struct kvm_pmu *pmu = pmc_to_pmu(pmc);
 
        if (pmc_is_gp(pmc)) {