[PATCH RFC 06/22] KVM: x86: hyper-v: Honor HV_MSR_VP_INDEX_AVAILABLE privilege bit

[Vitaly Kuznetsov]

HV_X64_MSR_VP_INDEX is only available to guest when
HV_MSR_VP_INDEX_AVAILABLE bit is exposed.

Note, writing to HV_X64_MSR_VP_INDEX is only available from the host so
kvm_hv_set_msr() doesn't need an additional check.

Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
 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 7fdd9b9c50d6..07f1fc8575e5 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1514,6 +1514,10 @@ static int kvm_hv_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata,
 
 	switch (msr) {
 	case HV_X64_MSR_VP_INDEX:
+		if (unlikely(!host && !(hv_vcpu->cpuid_cache.features_eax &
+					HV_MSR_VP_INDEX_AVAILABLE)))
+			return 1;
+
 		data = hv_vcpu->vp_index;
 		break;
 	case HV_X64_MSR_EOI:
-- 
2.30.2