virtio-net: synchronize operstate with admin state on up/down

This patch synchronizes operstate with admin state per RFC2863.

This is done by trying to toggle the carrier upon open/close and
synchronize with the config change work. This allows to propagate
status correctly to stacked devices like:

ip link add link enp0s3 macvlan0 type macvlan
ip link set link enp0s3 down
ip link show

Before this patch:

3: enp0s3: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000
    link/ether 00:00:05:00:00:09 brd ff:ff:ff:ff:ff:ff
......
5: macvlan0@enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
    link/ether b2:a9:c5:04:da:53 brd ff:ff:ff:ff:ff:ff

After this patch:

3: enp0s3: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000
    link/ether 00:00:05:00:00:09 brd ff:ff:ff:ff:ff:ff
...
5: macvlan0@enp0s3: <NO-CARRIER,BROADCAST,MULTICAST,UP,M-DOWN> mtu 1500 qdisc noqueue state LOWERLAYERDOWN mode DEFAULT group default qlen 1000
    link/ether b2:a9:c5:04:da:53 brd ff:ff:ff:ff:ff:ff

Cc: Venkat Venkatsubra <venkat.x.venkatsubra@oracle.com>
Cc: Gia-Khanh Nguyen <gia-khanh.nguyen@oracle.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://patch.msgid.link/20240814052228.4654-4-jasowang@redhat.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/virtio_net.c

@@ -2885,6 +2885,25 @@ static void virtnet_cancel_dim(struct virtnet_info *vi, struct dim *dim)
 	net_dim_work_cancel(dim);
 }
 
+static void virtnet_update_settings(struct virtnet_info *vi)
+{
+	u32 speed;
+	u8 duplex;
+
+	if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_SPEED_DUPLEX))
+		return;
+
+	virtio_cread_le(vi->vdev, struct virtio_net_config, speed, &speed);
+
+	if (ethtool_validate_speed(speed))
+		vi->speed = speed;
+
+	virtio_cread_le(vi->vdev, struct virtio_net_config, duplex, &duplex);
+
+	if (ethtool_validate_duplex(duplex))
+		vi->duplex = duplex;
+}
+
 static int virtnet_open(struct net_device *dev)
 {
 	struct virtnet_info *vi = netdev_priv(dev);
@@ -2903,6 +2922,15 @@ static int virtnet_open(struct net_device *dev)
 			goto err_enable_qp;
 	}
 
+	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) {
+		if (vi->status & VIRTIO_NET_S_LINK_UP)
+			netif_carrier_on(vi->dev);
+		virtio_config_driver_enable(vi->vdev);
+	} else {
+		vi->status = VIRTIO_NET_S_LINK_UP;
+		netif_carrier_on(dev);
+	}
+
 	return 0;
 
 err_enable_qp:
@@ -3381,12 +3409,22 @@ static int virtnet_close(struct net_device *dev)
 	disable_delayed_refill(vi);
 	/* Make sure refill_work doesn't re-enable napi! */
 	cancel_delayed_work_sync(&vi->refill);
+	/* Prevent the config change callback from changing carrier
+	 * after close
+	 */
+	virtio_config_driver_disable(vi->vdev);
+	/* Stop getting status/speed updates: we don't care until next
+	 * open
+	 */
+	cancel_work_sync(&vi->config_work);
 
 	for (i = 0; i < vi->max_queue_pairs; i++) {
 		virtnet_disable_queue_pair(vi, i);
 		virtnet_cancel_dim(vi, &vi->rq[i].dim);
 	}
 
+	netif_carrier_off(dev);
+
 	return 0;
 }
 
@@ -5095,25 +5133,6 @@ static void virtnet_init_settings(struct net_device *dev)
 	vi->duplex = DUPLEX_UNKNOWN;
 }
 
-static void virtnet_update_settings(struct virtnet_info *vi)
-{
-	u32 speed;
-	u8 duplex;
-
-	if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_SPEED_DUPLEX))
-		return;
-
-	virtio_cread_le(vi->vdev, struct virtio_net_config, speed, &speed);
-
-	if (ethtool_validate_speed(speed))
-		vi->speed = speed;
-
-	virtio_cread_le(vi->vdev, struct virtio_net_config, duplex, &duplex);
-
-	if (ethtool_validate_duplex(duplex))
-		vi->duplex = duplex;
-}
-
 static u32 virtnet_get_rxfh_key_size(struct net_device *dev)
 {
 	return ((struct virtnet_info *)netdev_priv(dev))->rss_key_size;
@@ -6524,6 +6543,9 @@ static int virtnet_probe(struct virtio_device *vdev)
 		goto free_failover;
 	}
 
+	/* Disable config change notification until ndo_open. */
+	virtio_config_driver_disable(vi->vdev);
+
 	virtio_device_ready(vdev);
 
 	virtnet_set_queues(vi, vi->curr_queue_pairs);
@@ -6573,25 +6595,25 @@ static int virtnet_probe(struct virtio_device *vdev)
 		vi->device_stats_cap = le64_to_cpu(v);
 	}
 
-	rtnl_unlock();
-
-	err = virtnet_cpu_notif_add(vi);
-	if (err) {
-		pr_debug("virtio_net: registering cpu notifier failed\n");
-		goto free_unregister_netdev;
-	}
-
 	/* Assume link up if device can't report link status,
 	   otherwise get link status from config. */
 	netif_carrier_off(dev);
 	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) {
-		schedule_work(&vi->config_work);
+		virtnet_config_changed_work(&vi->config_work);
 	} else {
 		vi->status = VIRTIO_NET_S_LINK_UP;
 		virtnet_update_settings(vi);
 		netif_carrier_on(dev);
 	}
 
+	rtnl_unlock();
+
+	err = virtnet_cpu_notif_add(vi);
+	if (err) {
+		pr_debug("virtio_net: registering cpu notifier failed\n");
+		goto free_unregister_netdev;
+	}
+
 	for (i = 0; i < ARRAY_SIZE(guest_offloads); i++)
 		if (virtio_has_feature(vi->vdev, guest_offloads[i]))
 			set_bit(guest_offloads[i], &vi->guest_offloads);