diff --git a/usr.sbin/bhyve/virtio.c b/usr.sbin/bhyve/virtio.c
--- a/usr.sbin/bhyve/virtio.c
+++ b/usr.sbin/bhyve/virtio.c
@@ -603,7 +603,10 @@
 		max = vc->vc_cfgsize ? vc->vc_cfgsize : 0x100000000;
 		if (newoff + size > max)
 			goto bad;
-		error = (*vc->vc_cfgread)(DEV_SOFTC(vs), newoff, size, &value);
+		if (vc->vc_cfgread != NULL)
+			error = (*vc->vc_cfgread)(DEV_SOFTC(vs), newoff, size, &value);
+		else
+			error = 0;
 		if (!error)
 			goto done;
 	}
@@ -719,7 +722,10 @@
 		max = vc->vc_cfgsize ? vc->vc_cfgsize : 0x100000000;
 		if (newoff + size > max)
 			goto bad;
-		error = (*vc->vc_cfgwrite)(DEV_SOFTC(vs), newoff, size, value);
+		if (vc->vc_cfgwrite != NULL)
+			error = (*vc->vc_cfgwrite)(DEV_SOFTC(vs), newoff, size, value);
+		else
+			error = 0;
 		if (!error)
 			goto done;
 	}