Re: [net-next rfc v7 2/3] virtio_net: multiqueue support

+static const struct ethtool_ops virtnet_ethtool_ops;
+
+/*
+ * Converting between virtqueue no. and kernel tx/rx queue no.
+ * 0:rx0 1:tx0 2:cvq 3:rx1 4:tx1 ... 2N+1:rxN 2N+2:txN
+ */
+static int vq2txq(struct virtqueue *vq)
+{
+	int index = virtqueue_get_queue_index(vq);
+	return index == 1 ? 0 : (index - 2) / 2;
+}
+
+static int txq2vq(int txq)
+{
+	return txq ? 2 * txq + 2 : 1;
+}
+
+static int vq2rxq(struct virtqueue *vq)
+{
+	int index = virtqueue_get_queue_index(vq);
+	return index ? (index - 1) / 2 : 0;
+}
+
+static int rxq2vq(int rxq)
+{
+	return rxq ? 2 * rxq + 1 : 0;
+}
+

+static int virtnet_set_queues(struct virtnet_info *vi)
+{
+	struct scatterlist sg;
+	struct virtio_net_ctrl_rfs s;
+	struct net_device *dev = vi->dev;
+
+	s.virtqueue_pairs = vi->curr_queue_pairs;
+	sg_init_one(&sg, &s, sizeof(s));
+
+	if (!vi->has_cvq)
+		return -EINVAL;
+
+	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_RFS,
+				  VIRTIO_NET_CTRL_RFS_VQ_PAIRS_SET, &sg, 1, 0)){
+		dev_warn(&dev->dev, "Fail to set the number of queue pairs to"
+			 " %d\n", vi->curr_queue_pairs);
+		return -EINVAL;
+	}

 static int virtnet_probe(struct virtio_device *vdev)
 {
-	int err;
+	int i, err;
 	struct net_device *dev;
 	struct virtnet_info *vi;
+	u16 curr_queue_pairs;
+
+	/* Find if host supports multiqueue virtio_net device */
+	err = virtio_config_val(vdev, VIRTIO_NET_F_RFS,
+				offsetof(struct virtio_net_config,
+				max_virtqueue_pairs), &curr_queue_pairs);
+
+	/* We need at least 2 queue's */
+	if (err)
+		curr_queue_pairs = 1;

+	if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
+		vi->has_cvq = true;
+
+	/* Use single tx/rx queue pair as default */
+	vi->curr_queue_pairs = 1;
+	vi->max_queue_pairs = curr_queue_pairs;