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

[Cindy Lu]

On Mon, Mar 1, 2021 at 4:40 AM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Thu, Feb 25, 2021 at 02:14:39PM -0500, Michael S. Tsirkin wrote:
> > 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?
>
> ping. if I'm to try and merge this work around it's critical
> that someone with access to hardware confirm it actually works.
>
Hi Michael, I have tested this patch in qemu+vdpa+mlx environment.
it's working fine.
>
> > > ---
> > >  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
>