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

Hyper-V partition must possess 'HV_DEBUGGING' privilege to issue HVCALL_POST_DEBUG_DATA/HVCALL_RETRIEVE_DEBUG_DATA/ HVCALL_RESET_DEBUG_SESSION hypercalls. Note, when SynDBG is disabled hv_check_hypercall_access() returns 'true' (like for any other unknown hypercall) so the result will be HV_STATUS_INVALID_HYPERCALL_CODE and not HV_STATUS_ACCESS_DENIED. Signed-off-by: Vitaly Kuznetsov <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]> Message-Id: <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]>
thedracle · Jun 17, 2021 · a921cf8 · a921cf8
1 parent a60b3c5
commit a921cf8
Showing 1 changed file with 9 additions and 0 deletions.
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
@@ -2103,6 +2103,15 @@ static bool hv_check_hypercall_access(struct kvm_vcpu_hv *hv_vcpu, u16 code)
 		return hv_vcpu->cpuid_cache.features_ebx & HV_POST_MESSAGES;
 	case HVCALL_SIGNAL_EVENT:
 		return hv_vcpu->cpuid_cache.features_ebx & HV_SIGNAL_EVENTS;
+	case HVCALL_POST_DEBUG_DATA:
+	case HVCALL_RETRIEVE_DEBUG_DATA:
+	case HVCALL_RESET_DEBUG_SESSION:
+		/*
+		 * Return 'true' when SynDBG is disabled so the resulting code
+		 * will be HV_STATUS_INVALID_HYPERCALL_CODE.
+		 */
+		return !kvm_hv_is_syndbg_enabled(hv_vcpu->vcpu) ||
+			hv_vcpu->cpuid_cache.features_ebx & HV_DEBUGGING;
 	default:
 		break;
 	}