diff --git a/sys/x86/x86/identcpu.c b/sys/x86/x86/identcpu.c
--- a/sys/x86/x86/identcpu.c
+++ b/sys/x86/x86/identcpu.c
@@ -1409,7 +1409,18 @@
 				 * If we found a specific hypervisor, then
 				 * we are finished.
 				 */
-				if (vm_guest != VM_GUEST_VM)
+				if (vm_guest != VM_GUEST_VM &&
+				    /*
+				     * Xen and other hypervisors can expose the
+				     * HyperV signature in addition to the
+				     * native one in order to support Viridian
+				     * extensions for Windows guests.
+				     *
+				     * Do the full cpuid scan if HyperV is
+				     * detected, as the native hypervisor is
+				     * preferred.
+				     */
+				    vm_guest != VM_GUEST_HV)
 					return;
 			}
 		}