On Tue, 2023-01-31 at 08:43 -0500, Michael S. Tsirkin wrote:
> On Tue, Jan 31, 2023 at 10:01:53AM +0100, Paolo Abeni wrote:
> > On Fri, 2023-01-27 at 21:45 +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 <lvivier@xxxxxxxxxx>
> > > ---
> > > 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;
> >
> > Since the above is still dealing with device initialization, would it
> > make sense moving such init step before registering the netdevice?
> >
> > Cheers,
> >
> > Paolo
>
> We can't really, device has to be ready otherwise
> we can't send commands to it.
Thanks, I see. Also, Laurent already clarified the above.
Should I read your comment as you are ok with the patches in the
current form?
Cheers,
Paolo
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