diff options
| author | Vitaly Kuznetsov | 2021-03-16 15:37:33 +0100 |
|---|---|---|
| committer | Paolo Bonzini | 2021-03-17 04:02:49 -0400 |
| commit | d2547cf59793168b564372d75620897416cbaf87 (patch) | |
| tree | 1264c35869727553862346deffbefb48f3d35b8d | |
| parent | 08889894cc82bc3b213bdb192f274358e5a6b78d (diff) | |
KVM: x86: hyper-v: Limit guest to writing zero to HV_X64_MSR_TSC_EMULATION_STATUS
HV_X64_MSR_TSC_EMULATION_STATUS indicates whether TSC accesses are emulated
after migration (to accommodate for a different host TSC frequency when TSC
scaling is not supported; we don't implement this in KVM). Guest can use
the same MSR to stop TSC access emulation by writing zero. Writing anything
else is forbidden.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210316143736.964151-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/hyperv.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index 58fa8c029867..eefb85b86fe8 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -1229,6 +1229,9 @@ static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data, hv->hv_tsc_emulation_control = data; break; case HV_X64_MSR_TSC_EMULATION_STATUS: + if (data && !host) + return 1; + hv->hv_tsc_emulation_status = data; break; case HV_X64_MSR_TIME_REF_COUNT: |