[PATCH RFC 03/22] KVM: x86: hyper-v: Honor HV_MSR_VP_RUNTIME_AVAILABLE privilege bit

[Vitaly Kuznetsov]

HV_X64_MSR_VP_RUNTIME is only available to guest when
HV_MSR_VP_RUNTIME_AVAILABLE bit is exposed.

Note, writing to HV_X64_MSR_VP_RUNTIME is only available from the host so
kvm_hv_set_msr() doesn't need an additional check.

Signed-off-by: Vitaly Kuznetsov <vkuzn...@redhat.com>
---
 arch/x86/kvm/hyperv.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 781f9da9a418..b39445aabbc2 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1504,6 +1504,10 @@ static int kvm_hv_get_msr(struct kvm_vcpu *vcpu, u32 
msr, u64 *pdata,
                data = hv_vcpu->hv_vapic;
                break;
        case HV_X64_MSR_VP_RUNTIME:
+               if (unlikely(!host && !(hv_vcpu->cpuid_cache.features_eax &
+                                       HV_MSR_VP_RUNTIME_AVAILABLE)))
+                       return 1;
+
                data = current_task_runtime_100ns() + hv_vcpu->runtime_offset;
                break;
        case HV_X64_MSR_SCONTROL:
-- 
2.30.2