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 <vkuzn...@redhat.com>
---
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
