KVM: x86: hyper-v: Honor HV_MSR_HYPERCALL_AVAILABLE privilege bit

HV_X64_MSR_GUEST_OS_ID/HV_X64_MSR_HYPERCALL are only available to guest
when HV_MSR_HYPERCALL_AVAILABLE bit is exposed.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-6-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index ab8dc23..cb66842 100644 (file)
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1205,6 +1205,18 @@ out_unlock:
 
 static bool hv_check_msr_access(struct kvm_vcpu_hv *hv_vcpu, u32 msr)
 {
+       if (!hv_vcpu->enforce_cpuid)
+               return true;
+
+       switch (msr) {
+       case HV_X64_MSR_GUEST_OS_ID:
+       case HV_X64_MSR_HYPERCALL:
+               return hv_vcpu->cpuid_cache.features_eax &
+                       HV_MSR_HYPERCALL_AVAILABLE;
+       default:
+               break;
+       }
+
        return true;
 }