diff options
| -rw-r--r-- | arch/x86/kvm/vmx/pmu_intel.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c index a6216c874729..8207f8c03585 100644 --- a/arch/x86/kvm/vmx/pmu_intel.c +++ b/arch/x86/kvm/vmx/pmu_intel.c @@ -108,11 +108,24 @@ static bool intel_hw_event_available(struct kvm_pmc *pmc) u8 unit_mask = (pmc->eventsel & ARCH_PERFMON_EVENTSEL_UMASK) >> 8; int i; + /* + * Fixed counters are always available if KVM reaches this point. If a + * fixed counter is unsupported in hardware or guest CPUID, KVM doesn't + * allow the counter's corresponding MSR to be written. KVM does use + * architectural events to program fixed counters, as the interface to + * perf doesn't allow requesting a specific fixed counter, e.g. perf + * may (sadly) back a guest fixed PMC with a general purposed counter. + * But if _hardware_ doesn't support the associated event, KVM simply + * doesn't enumerate support for the fixed counter. + */ + if (pmc_is_fixed(pmc)) + return true; + BUILD_BUG_ON(ARRAY_SIZE(intel_arch_events) != NR_INTEL_ARCH_EVENTS); /* * Disallow events reported as unavailable in guest CPUID. Note, this - * doesn't apply to pseudo-architectural events. + * doesn't apply to pseudo-architectural events (see above). */ for (i = 0; i < NR_REAL_INTEL_ARCH_EVENTS; i++) { if (intel_arch_events[i].eventsel != event_select || |