When running KVM selftest in a Hyper-V VM they stumble upon Unexpected result from KVM_GET_MSRS, r: 14 (failed MSR was 0x309) MSR_ARCH_PERFMON_FIXED_CTR[0..3] along with MSR_CORE_PERF_FIXED_CTR_CTRL, MSR_CORE_PERF_GLOBAL_STATUS, MSR_CORE_PERF_GLOBAL_CTRL, MSR_CORE_PERF_GLOBAL_OVF_CTRL are only valid for Intel PMU ver > 1 but Hyper-V instances have CPUID.0AH.EAX == 0 (so perf code falls back to p6_pmu instead of intel_pmu). Surprisingly, unlike on AMD hardware for example, our rdmsr_safe() check passes and MSRs are not filtered out. MSR_ARCH_PERFMON_FIXED_CTR[0..3] can probably be checked against x86_pmu.num_counters_fixed and the rest is only present with x86_pmu.version > 1. Unfortunately, full elimination of the disconnection between system-wide KVM_GET_MSR_INDEX_LIST/KVM_GET_MSR_FEATURE_INDEX_LIST and per-VCPU KVM_GET_MSRS/KVM_SET_MSRS seem to be impossible as per-vCPU PMU setup depends on guest CPUIDs which can always be altered. Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> --- arch/x86/kvm/x86.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ce856e0ece84..85d72b125fba 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5436,6 +5436,15 @@ static void kvm_init_msr_list(void) min(INTEL_PMC_MAX_GENERIC, x86_pmu.num_counters_gp)) continue; break; + case MSR_ARCH_PERFMON_FIXED_CTR0 ... MSR_ARCH_PERFMON_FIXED_CTR0 + 3: + if (msrs_to_save_all[i] - MSR_ARCH_PERFMON_FIXED_CTR0 >= + min(INTEL_PMC_MAX_FIXED, x86_pmu.num_counters_fixed)) + continue; + break; + case MSR_CORE_PERF_FIXED_CTR_CTRL ... MSR_CORE_PERF_GLOBAL_OVF_CTRL: + if (x86_pmu.version <= 1) + continue; + break; default: break; } -- 2.25.4
