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i386/kvm: advertise Hyper-V frequency MSRs

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As of kernel commit eb82feea59d6 ("KVM: hyperv: support HV_X64_MSR_TSC_FREQUENCY
and HV_X64_MSR_APIC_FREQUENCY"), KVM supports two new MSRs which are required
for nested Hyper-V to read timestamps with RDTSC + TSC page.

This commit makes QEMU advertise the MSRs with CPUID.40000003H:EAX[11] and
CPUID.40000003H:EDX[8] as specified in the Hyper-V TLFS and experimentally
verified on a Hyper-V host. The feature is enabled with the existing hv-time CPU
flag, and only if the TSC frequency is stable across migrations and known.

Signed-off-by: Ladi Prosek <lprosek@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Message-Id: <20170807085703.32267-5-lprosek@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Ladi Prosek 2017-08-07 10:57:03 +02:00 committed by Paolo Bonzini
parent 4bb95b82df
commit d72bc7f6f8
1 changed files with 11 additions and 1 deletions
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12
target/i386/kvm.c
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@ -89,6 +89,7 @@ static bool has_msr_hv_vpindex;
static bool has_msr_hv_runtime;
static bool has_msr_hv_synic;
static bool has_msr_hv_stimer;
static bool has_msr_hv_frequencies;
static bool has_msr_xss;
static bool has_msr_architectural_pmu;
@ -640,7 +641,13 @@ static int hyperv_handle_properties(CPUState *cs)
if (cpu->hyperv_time) {
env->features[FEAT_HYPERV_EAX] |= HV_X64_MSR_HYPERCALL_AVAILABLE;
env->features[FEAT_HYPERV_EAX] |= HV_X64_MSR_TIME_REF_COUNT_AVAILABLE;
env->features[FEAT_HYPERV_EAX] |= 0x200;
env->features[FEAT_HYPERV_EAX] |= HV_X64_MSR_REFERENCE_TSC_AVAILABLE;
if (has_msr_hv_frequencies && tsc_is_stable_and_known(env)) {
env->features[FEAT_HYPERV_EAX] |= HV_X64_ACCESS_FREQUENCY_MSRS;
env->features[FEAT_HYPERV_EDX] |=
HV_FEATURE_FREQUENCY_MSRS_AVAILABLE;
}
}
if (cpu->hyperv_crash && has_msr_hv_crash) {
env->features[FEAT_HYPERV_EDX] |= HV_X64_GUEST_CRASH_MSR_AVAILABLE;
@ -1134,6 +1141,9 @@ static int kvm_get_supported_msrs(KVMState *s)
case HV_X64_MSR_STIMER0_CONFIG:
has_msr_hv_stimer = true;
break;
case HV_X64_MSR_TSC_FREQUENCY:
has_msr_hv_frequencies = true;
break;
}
}
}