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Message-ID: <07a24753-767b-4e1e-2bcf-21ec04bc044a@nvidia.com>
Date: Sun, 22 Jan 2023 15:47:08 +0200
From: Eli Cohen <elic@...dia.com>
To: Laurent Vivier <lvivier@...hat.com>, linux-kernel@...r.kernel.org
Cc: "Michael S. Tsirkin" <mst@...hat.com>,
Parav Pandit <parav@...dia.com>,
virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
Jason Wang <jasowang@...hat.com>,
Gautam Dawar <gautam.dawar@...inx.com>,
Cindy Lu <lulu@...hat.com>,
"David S. Miller" <davem@...emloft.net>,
Eugenio PĂ©rez <eperezma@...hat.com>
Subject: Re: [PATCH 1/4] virtio_net: notify MAC address change on device
initialization
On 22/01/2023 12:05, 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.
>
> Signed-off-by: Laurent Vivier <lvivier@...hat.com>
> ---
> drivers/net/virtio_net.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 7723b2a49d8e..25511a86590e 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -3800,6 +3800,8 @@ 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 */
> @@ -3956,6 +3958,18 @@ static int virtnet_probe(struct virtio_device *vdev)
> pr_debug("virtnet: registered device %s with %d RX and TX vq's\n",
> dev->name, max_queue_pairs);
>
> + /* a random MAC address has been assigned, notify the device */
> + if (dev->addr_assign_type == NET_ADDR_RANDOM &&
Maybe it's better to not count on addr_assign_type and use a local
variable to indicate that virtnet_probe assigned random MAC. The reason
is that the hardware driver might have done that as well and does not
need notification.
> + 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)) {
> + dev_warn(&vdev->dev, "Failed to update MAC address.\n");
> + }
> + }
> +
> return 0;
>
> free_unregister_netdev:
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