HV_X64_MSR_TIME_REF_COUNT is only available to guest when
HV_MSR_TIME_REF_COUNT_AVAILABLE bit is exposed.
Note, writing to HV_X64_MSR_TIME_REF_COUNT is unsupported so
kvm_hv_set_msr_pw() doesn't need an additional check.
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
arch/x86/kvm/hyperv.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index b39445aabbc2..efb3d69c98fd 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1440,6 +1440,7 @@ static int kvm_hv_get_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata,
u64 data = 0;
struct kvm *kvm = vcpu->kvm;
struct kvm_hv *hv = to_kvm_hv(kvm);
+ struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
switch (msr) {
case HV_X64_MSR_GUEST_OS_ID:
@@ -1449,6 +1450,10 @@ static int kvm_hv_get_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata,
data = hv->hv_hypercall;
break;
case HV_X64_MSR_TIME_REF_COUNT:
+ if (unlikely(!host && !(hv_vcpu->cpuid_cache.features_eax &
+ HV_MSR_TIME_REF_COUNT_AVAILABLE)))
+ return 1;
+
data = get_time_ref_counter(kvm);
break;
case HV_X64_MSR_REFERENCE_TSC:
--
2.30.2
