bpf: virtio_net: Report bpf_prog ID during XDP_QUERY_PROG

Add support to virtio_net to report bpf_prog ID during XDP_QUERY_PROG.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Jason Wang <jasowang@redhat.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/virtio_net.c

@@ -1955,16 +1955,18 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog,
 	return err;
 }
 
-static bool virtnet_xdp_query(struct net_device *dev)
+static u32 virtnet_xdp_query(struct net_device *dev)
 {
 	struct virtnet_info *vi = netdev_priv(dev);
+	const struct bpf_prog *xdp_prog;
 	int i;
 
 	for (i = 0; i < vi->max_queue_pairs; i++) {
-		if (vi->rq[i].xdp_prog)
-			return true;
+		xdp_prog = rtnl_dereference(vi->rq[i].xdp_prog);
+		if (xdp_prog)
+			return xdp_prog->aux->id;
 	}
-	return false;
+	return 0;
 }
 
 static int virtnet_xdp(struct net_device *dev, struct netdev_xdp *xdp)
@@ -1973,7 +1975,8 @@ static int virtnet_xdp(struct net_device *dev, struct netdev_xdp *xdp)
 	case XDP_SETUP_PROG:
 		return virtnet_xdp_set(dev, xdp->prog, xdp->extack);
 	case XDP_QUERY_PROG:
-		xdp->prog_attached = virtnet_xdp_query(dev);
+		xdp->prog_id = virtnet_xdp_query(dev);
+		xdp->prog_attached = !!xdp->prog_id;
 		return 0;
 	default:
 		return -EINVAL;