On Fri, Jan 27, 2023 at 09:45:00PM +0100, Laurent Vivier wrote:
> In virtnet_probe(), if the device doesn't provide a MAC address the
> driver assigns a random one.
> As we modify the MAC address we need to notify the device to allow it
> to update all the related information.
>
> The problem can be seen with vDPA and mlx5_vdpa driver as it doesn't
> assign a MAC address by default. The virtio_net device uses a random
> MAC address (we can see it with "ip link"), but we can't ping a net
> namespace from another one using the virtio-vdpa device because the
> new MAC address has not been provided to the hardware:
> RX packets are dropped since they don't go through the receive filters,
> TX packets go through unaffected.
>
> Signed-off-by: Laurent Vivier <lviv...@redhat.com>
Acked-by: Michael S. Tsirkin <m...@redhat.com>
> ---
> drivers/net/virtio_net.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 7d700f8e545a..704a05f1c279 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -3806,6 +3806,8 @@ static int virtnet_probe(struct virtio_device *vdev)
> eth_hw_addr_set(dev, addr);
> } 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 */
> @@ -3933,6 +3935,24 @@ static int virtnet_probe(struct virtio_device *vdev)
>
> 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);
> --
> 2.39.1
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