Merge: virtio_net: notify MAC address change on device initialization

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/2037

# Merge Request Required Information

Bugzilla: https://bugzilla.redhat.com/2153210
Tested: by QE
Brew: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=50667660
Upstream: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git
          In maintainer's branch, not yet merged in master

## Summary of Changes

Update virtio-net driver to forward MAC address change to the backend, in our case vdpa.
The bug has been found with mlx5_vdpa driver.
The first patch is needed to add the netlink lock around the virtnet_send_command() call.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>

Approved-by: Eugenio Pérez <eperezma@redhat.com>
Approved-by: Cindy Lu <lulu@redhat.com>

Signed-off-by: Herton R. Krzesinski <herton@redhat.com>

Author: Herton R. Krzesinski

drivers/net/virtio_net.c

@@ -3100,6 +3100,12 @@ static int virtnet_validate(struct virtio_device *vdev)
 			__virtio_clear_bit(vdev, VIRTIO_NET_F_MTU);
 	}
 
+	if (virtio_has_feature(vdev, VIRTIO_NET_F_STANDBY) &&
+	    !virtio_has_feature(vdev, VIRTIO_NET_F_MAC)) {
+		dev_warn(&vdev->dev, "device advertises feature VIRTIO_NET_F_STANDBY but not VIRTIO_NET_F_MAC, disabling standby");
+		__virtio_clear_bit(vdev, VIRTIO_NET_F_STANDBY);
+	}
+
 	return 0;
 }
 
@@ -3180,8 +3186,11 @@ static int virtnet_probe(struct virtio_device *vdev)
 		virtio_cread_bytes(vdev,
 				   offsetof(struct virtio_net_config, mac),
 				   dev->dev_addr, dev->addr_len);
-	else
+	else {
 		eth_hw_addr_random(dev);
+		dev_info(&vdev->dev, "Assigned random MAC address %pM\n",
+			 dev->dev_addr);
+	}
 
 	/* Set up our device-specific information */
 	vi = netdev_priv(dev);
@@ -3269,14 +3278,38 @@ static int virtnet_probe(struct virtio_device *vdev)
 		}
 	}
 
-	err = register_netdev(dev);
+	/* serialize netdev register + virtio_device_ready() with ndo_open() */
+	rtnl_lock();
+
+	err = register_netdevice(dev);
 	if (err) {
 		pr_debug("virtio_net: registering device failed\n");
+		rtnl_unlock();
 		goto free_failover;
 	}
 
 	virtio_device_ready(vdev);
 
+	/* a random MAC address has been assigned, notify the device.
+	 * We don't fail probe if VIRTIO_NET_F_CTRL_MAC_ADDR is not there
+	 * because many devices work fine without getting MAC explicitly
+	 */
+	if (!virtio_has_feature(vdev, VIRTIO_NET_F_MAC) &&
+	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_MAC_ADDR)) {
+		struct scatterlist sg;
+
+		sg_init_one(&sg, dev->dev_addr, dev->addr_len);
+		if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
+					  VIRTIO_NET_CTRL_MAC_ADDR_SET, &sg)) {
+			pr_debug("virtio_net: setting MAC address failed\n");
+			rtnl_unlock();
+			err = -EINVAL;
+			goto free_unregister_netdev;
+		}
+	}
+
+	rtnl_unlock();
+
 	err = virtnet_cpu_notif_add(vi);
 	if (err) {
 		pr_debug("virtio_net: registering cpu notifier failed\n");