[PATCH v7 24/26] virtio_net: support rx/tx queue reset

@@ -251,6 +251,11 @@ struct padded_vnet_hdr {
 	char padding[4];
 };
 
+static void virtnet_sq_free_unused_bufs(struct virtnet_info *vi,
+					struct send_queue *sq);
+static void virtnet_rq_free_unused_bufs(struct virtnet_info *vi,
+					struct receive_queue *rq);
+
 static bool is_xdp_frame(void *ptr)
 {
 	return (unsigned long)ptr & VIRTIO_XDP_FLAG;

@@ -1369,6 +1374,9 @@ static void virtnet_napi_enable(struct virtqueue *vq, struct napi_struct *napi)
 {
 	napi_enable(napi);
 
+	if (vq->reset)
+		return;
+
 	/* If all buffers were filled by other side before we napi_enabled, we
 	 * won't get another interrupt, so process any outstanding packets now.
 	 * Call local_bh_enable after to trigger softIRQ processing.

@@ -1413,6 +1421,10 @@ static void refill_work(struct work_struct *work)
 		struct receive_queue *rq = &vi->rq[i];
 
 		napi_disable(&rq->napi);
+		if (rq->vq->reset) {
+			virtnet_napi_enable(rq->vq, &rq->napi);
+			continue;
+		}
 		still_empty = !try_fill_recv(vi, rq, GFP_KERNEL);
 		virtnet_napi_enable(rq->vq, &rq->napi);
 

@@ -1523,6 +1535,9 @@ static void virtnet_poll_cleantx(struct receive_queue *rq)
 	if (!sq->napi.weight || is_xdp_raw_buffer_queue(vi, index))
 		return;
 
+	if (sq->vq->reset)
+		return;
+
 	if (__netif_tx_trylock(txq)) {
 		do {
 			virtqueue_disable_cb(sq->vq);

@@ -1769,6 +1784,98 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
 	return NETDEV_TX_OK;
 }
 
+static int virtnet_rx_vq_reset(struct virtnet_info *vi,
+			       struct receive_queue *rq, u32 ring_num)
+{
+	int err;
+
+	/* stop napi */
+	napi_disable(&rq->napi);
+
+	/* reset the queue */
+	err = virtio_reset_vq(rq->vq);
+	if (err)
+		goto err;
+
+	/* free bufs */
+	virtnet_rq_free_unused_bufs(vi, rq);
+
+	/* reset vring. */
+	err = virtqueue_reset_vring(rq->vq, ring_num);
+	if (err)
+		goto err;
+
+	/* enable reset queue */
+	err = virtio_enable_resetq(rq->vq);
+	if (err)
+		goto err;
+
+	/* fill recv */
+	if (!try_fill_recv(vi, rq, GFP_KERNEL))
+		schedule_delayed_work(&vi->refill, 0);
+
+	/* enable napi */
+	virtnet_napi_enable(rq->vq, &rq->napi);
+	return 0;
+
+err:
+	netdev_err(vi->dev,
+		   "reset rx reset vq fail: rx queue index: %ld err: %d\n",
+		   rq - vi->rq, err);
+	virtnet_napi_enable(rq->vq, &rq->napi);
+	return err;
+}
+
+static int virtnet_tx_vq_reset(struct virtnet_info *vi,
+			       struct send_queue *sq, u32 ring_num)
+{
+	struct netdev_queue *txq;
+	int err, qindex;
+
+	qindex = sq - vi->sq;
+
+	txq = netdev_get_tx_queue(vi->dev, qindex);
+	__netif_tx_lock_bh(txq);
+
+	/* stop tx queue and napi */
+	netif_stop_subqueue(vi->dev, qindex);
+	virtnet_napi_tx_disable(&sq->napi);
+
+	__netif_tx_unlock_bh(txq);
+
+	/* reset the queue */
+	err = virtio_reset_vq(sq->vq);
+	if (err) {
+		netif_start_subqueue(vi->dev, qindex);
+		goto err;
+	}
+
+	/* free bufs */
+	virtnet_sq_free_unused_bufs(vi, sq);
+
+	/* reset vring. */
+	err = virtqueue_reset_vring(sq->vq, ring_num);
+	if (err)
+		goto err;
+
+	/* enable reset queue */
+	err = virtio_enable_resetq(sq->vq);
+	if (err)
+		goto err;
+
+	/* start tx queue and napi */
+	netif_start_subqueue(vi->dev, qindex);
+	virtnet_napi_tx_enable(vi, sq->vq, &sq->napi);
+	return 0;
+
+err:
+	netdev_err(vi->dev,
+		   "reset tx reset vq fail: tx queue index: %ld err: %d\n",
+		   sq - vi->sq, err);
+	virtnet_napi_tx_enable(vi, sq->vq, &sq->napi);
+	return err;
+}
+
 /*
  * Send command via the control virtqueue and check status.  Commands
  * supported by the hypervisor, as indicated by feature bits, should