Re: [PATCH v3] virtio-net: Add check for mac address while peer is vdpa

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Oct 26, 2020 at 02:21:26PM +0800, Cindy Lu wrote:
> Sometime vdpa get an all 0 mac address from the hardware, this will cause the traffic down
> So we add the check for this part.
> if we get an 0 mac address we will use the default mac address instead
> 
> Signed-off-by: Cindy Lu <lulu@redhat.com>

I wonder whether we can retrieve the mac earlier and fail init.
That would be better than second-guessing bad configs ...

> ---
>  hw/net/virtio-net.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 9179013ac4..65a3a84573 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -126,6 +126,7 @@ static void virtio_net_get_config(VirtIODevice *vdev, uint8_t *config)
>      VirtIONet *n = VIRTIO_NET(vdev);
>      struct virtio_net_config netcfg;
>      NetClientState *nc = qemu_get_queue(n->nic);
> +    static const MACAddr zero = { .a = { 0, 0, 0, 0, 0, 0 } };
>  
>      int ret = 0;
>      memset(&netcfg, 0 , sizeof(struct virtio_net_config));
> @@ -151,7 +152,11 @@ static void virtio_net_get_config(VirtIODevice *vdev, uint8_t *config)
>          ret = vhost_net_get_config(get_vhost_net(nc->peer), (uint8_t *)&netcfg,
>                                     n->config_size);
>          if (ret != -1) {
> -            memcpy(config, &netcfg, n->config_size);
> +            if (memcmp(&netcfg.mac, &zero, sizeof(zero)) != 0) {
> +                memcpy(config, &netcfg, n->config_size);
> +            } else {
> +                info_report("Get an all zero mac address from hardware");
> +            }
>          }
>      }
>  }
> -- 
> 2.21.3