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

[Cindy Lu]

sure, Thanks michael, I will address, these comment and send a new version

On Wed, Feb 24, 2021 at 3:59 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> > [PATCH] virtio-net: Add check for mac address while peer is vdpa
> please do keep numbering patch versions.
>
>
> On Wed, Feb 24, 2021 at 03:33:33PM +0800, Cindy Lu wrote:
> > Sometime vdpa get an all zero mac address from the hardware, this will 
> > cause the
> > traffic down, So we add the check for in part.if we get an zero mac address 
> > we will
> > use the default/cmdline mac address instead
>
> How does this differ from v4 of same patch?
>
> Lots of typos above. I guess I can just rewrite the whole log ...
>
> >
> > Signed-off-by: Cindy Lu <lulu@redhat.com>
> > ---
> >  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..f1648fc47d 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);
>
> Below needs a huge code comment explaining what is going on.
>
> E.g.  if we get a valid mac from peer, use it.
>
> If we get 0 instead
> then we don't know the peer mac but since the
> mac is 0 and that is not a legal value,
> try to proceed assume something else (management, hardware) sets up the mac
> correctly and consistently with the qemu configuration.
>
>
> > +            if (memcmp(&netcfg.mac, &zero, sizeof(zero)) != 0) {
>
> != 0 is not necessary
>
> > +                memcpy(config, &netcfg, n->config_size);
>
> > +        } else {
> > +                error_report("Get an all zero mac address from hardware");
>
> So why are you skipping the copying of the whole config space? Why not
> just skip the mac? Seems quite risky e.g. looks like it will break
> things like reporting the link status, right?
>
> > +            }
> >          }
> >      }
> >  }
> > --
> > 2.21.3
>