Re: [PATCH v5 1/1] virtio-net: Add check for mac address while peer is vdpa

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

On Fri, Feb 26, 2021 at 12:55:06AM +0800, Cindy Lu wrote:
> While peer is vdpa, sometime qemu get an all zero mac address from the hardware,
> This is not a legal value. Add the check for this.if we get an zero mac address.
> qemu will use the default mac address or the mac address from qemu cmdline
> 
> Signed-off-by: Cindy Lu <lulu@redhat.com>

I guess I will have to rewrite the comments and commit log :(

It is all saying what does the patch do. We want it to rather
give motivation.

Sean could you please comment on whether this patch fixes your
config?

> ---
>  hw/net/virtio-net.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 9179013ac4..8f36ca5066 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));
> @@ -151,6 +152,15 @@ 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) {
> +            /*
> +             * Here is a work around, the 0 mac address is not a legal value.
> +             * if we got this from hardware, qemu will use the mac address
> +             * saved in VirtIONet->mac.
> +             */
> +            if (memcmp(&netcfg.mac, &zero, sizeof(zero)) == 0) {
> +                info_report("Get an all zero mac address from hardware");
> +                memcpy(netcfg.mac, n->mac, ETH_ALEN);
> +            }
>              memcpy(config, &netcfg, n->config_size);
>          }
>      }
> -- 
> 2.21.3