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

Synthetic debugging MSRs (HV_X64_MSR_SYNDBG_CONTROL,
HV_X64_MSR_SYNDBG_STATUS, HV_X64_MSR_SYNDBG_SEND_BUFFER,
HV_X64_MSR_SYNDBG_RECV_BUFFER, HV_X64_MSR_SYNDBG_PENDING_BUFFER,
HV_X64_MSR_SYNDBG_OPTIONS) are only available to guest when
HV_FEATURE_DEBUG_MSRS_AVAILABLE bit is exposed.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-18-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 7b7da05..3bf00a9 100644 (file)
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1266,6 +1266,10 @@ static bool hv_check_msr_access(struct kvm_vcpu_hv *hv_vcpu, u32 msr)
        case HV_X64_MSR_CRASH_CTL:
                return hv_vcpu->cpuid_cache.features_edx &
                        HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE;
+       case HV_X64_MSR_SYNDBG_OPTIONS:
+       case HV_X64_MSR_SYNDBG_CONTROL ... HV_X64_MSR_SYNDBG_PENDING_BUFFER:
+               return hv_vcpu->cpuid_cache.features_edx &
+                       HV_FEATURE_DEBUG_MSRS_AVAILABLE;
        default:
                break;
        }