[PATCH net-next v2 3/4] virtio_net: Map NAPIs to queues

[Joe Damato <jdamato@fastly.com>]

Use netif_queue_set_napi to map NAPIs to queue IDs so that the mapping
can be accessed by user apps.

$ ethtool -i ens4 | grep driver
driver: virtio_net

$ sudo ethtool -L ens4 combined 4

$ ./tools/net/ynl/pyynl/cli.py \
       --spec Documentation/netlink/specs/netdev.yaml \
       --dump queue-get --json='{"ifindex": 2}'
[{'id': 0, 'ifindex': 2, 'napi-id': 8289, 'type': 'rx'},
 {'id': 1, 'ifindex': 2, 'napi-id': 8290, 'type': 'rx'},
 {'id': 2, 'ifindex': 2, 'napi-id': 8291, 'type': 'rx'},
 {'id': 3, 'ifindex': 2, 'napi-id': 8292, 'type': 'rx'},
 {'id': 0, 'ifindex': 2, 'type': 'tx'},
 {'id': 1, 'ifindex': 2, 'type': 'tx'},
 {'id': 2, 'ifindex': 2, 'type': 'tx'},
 {'id': 3, 'ifindex': 2, 'type': 'tx'}]

Note that virtio_net has TX-only NAPIs which do not have NAPI IDs, so
the lack of 'napi-id' in the above output is expected.

Signed-off-by: Joe Damato <jdamato@fastly.com>
---
 v2:
   - Eliminate RTNL code paths using the API Jakub introduced in patch 1
     of this v2.
   - Added virtnet_napi_disable to reduce code duplication as
     suggested by Jason Wang.

 drivers/net/virtio_net.c | 34 +++++++++++++++++++++++++++++-----
 1 file changed, 29 insertions(+), 5 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index cff18c66b54a..c6fda756dd07 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2803,9 +2803,18 @@ static void virtnet_napi_do_enable(struct virtqueue *vq,
 	local_bh_enable();
 }
 
-static void virtnet_napi_enable(struct virtqueue *vq, struct napi_struct *napi)
+static void virtnet_napi_enable(struct virtqueue *vq,
+				struct napi_struct *napi)
 {
+	struct virtnet_info *vi = vq->vdev->priv;
+	int q = vq2rxq(vq);
+	u16 curr_qs;
+
 	virtnet_napi_do_enable(vq, napi);
+
+	curr_qs = vi->curr_queue_pairs - vi->xdp_queue_pairs;
+	if (!vi->xdp_enabled || q < curr_qs)
+		netif_queue_set_napi(vi->dev, q, NETDEV_QUEUE_TYPE_RX, napi);
 }
 
 static void virtnet_napi_tx_enable(struct virtnet_info *vi,
@@ -2826,6 +2835,20 @@ static void virtnet_napi_tx_enable(struct virtnet_info *vi,
 	virtnet_napi_do_enable(vq, napi);
 }
 
+static void virtnet_napi_disable(struct virtqueue *vq,
+				 struct napi_struct *napi)
+{
+	struct virtnet_info *vi = vq->vdev->priv;
+	int q = vq2rxq(vq);
+	u16 curr_qs;
+
+	curr_qs = vi->curr_queue_pairs - vi->xdp_queue_pairs;
+	if (!vi->xdp_enabled || q < curr_qs)
+		netif_queue_set_napi(vi->dev, q, NETDEV_QUEUE_TYPE_RX, NULL);
+
+	napi_disable(napi);
+}
+
 static void virtnet_napi_tx_disable(struct napi_struct *napi)
 {
 	if (napi->weight)
@@ -2842,7 +2865,8 @@ static void refill_work(struct work_struct *work)
 	for (i = 0; i < vi->curr_queue_pairs; i++) {
 		struct receive_queue *rq = &vi->rq[i];
 
-		napi_disable(&rq->napi);
+		virtnet_napi_disable(rq->vq, &rq->napi);
+
 		still_empty = !try_fill_recv(vi, rq, GFP_KERNEL);
 		virtnet_napi_enable(rq->vq, &rq->napi);
 
@@ -3042,7 +3066,7 @@ static int virtnet_poll(struct napi_struct *napi, int budget)
 static void virtnet_disable_queue_pair(struct virtnet_info *vi, int qp_index)
 {
 	virtnet_napi_tx_disable(&vi->sq[qp_index].napi);
-	napi_disable(&vi->rq[qp_index].napi);
+	virtnet_napi_disable(vi->rq[qp_index].vq, &vi->rq[qp_index].napi);
 	xdp_rxq_info_unreg(&vi->rq[qp_index].xdp_rxq);
 }
 
@@ -3313,7 +3337,7 @@ static void virtnet_rx_pause(struct virtnet_info *vi, struct receive_queue *rq)
 	bool running = netif_running(vi->dev);
 
 	if (running) {
-		napi_disable(&rq->napi);
+		virtnet_napi_disable(rq->vq, &rq->napi);
 		virtnet_cancel_dim(vi, &rq->dim);
 	}
 }
@@ -5932,7 +5956,7 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog,
 	/* Make sure NAPI is not using any XDP TX queues for RX. */
 	if (netif_running(dev)) {
 		for (i = 0; i < vi->max_queue_pairs; i++) {
-			napi_disable(&vi->rq[i].napi);
+			virtnet_napi_disable(vi->rq[i].vq, &vi->rq[i].napi);
 			virtnet_napi_tx_disable(&vi->sq[i].napi);
 		}
 	}
-- 
2.25.1