Re: [Qemu-devel] [PATCH] virtio-net: Do not filter VLANs without F_CTRL_VLAN

[Stefan Fritsch]

On Fri, 21 Feb 2014, Amos Kong wrote:

> On Wed, Feb 12, 2014 at 10:46:28PM +0100, Stefan Fritsch wrote:
> > If VIRTIO_NET_F_CTRL_VLAN is not negotiated, do not filter out all
> > VLAN-tagged packets but send them to the guest.
> 
> Can we just update receive_filter() to filter out VLAN-tagged packets
> only when VIRTIO_NET_F_CTRL_VLAN is negotiated?

We could. But this adds a (very small) per-packet overhead while my patch 
only adds overhead during reset. Therefore I didn't take that approach. 
But if changing receive_filter() makes management much easier, that could 
be acceptable.

> 
> @@ -913,7 +940,8 @@ static int receive_filter(VirtIONet
> *n, const uint8_t *buf, int size)
>  
>      if (!memcmp(&ptr[12], vlan, sizeof(vlan))) {
>          int vid = be16_to_cpup((uint16_t *)(ptr + 14)) & 0xfff;
> -        if (!(n->vlans[vid >> 5] & (1U << (vid & 0x1f))))
> +        if ((vdev->guest_features & (1 << VIRTIO_NET_F_CTRL_VLAN)) &&
> +            !(n->vlans[vid >> 5] & (1U << (vid & 0x1f))))
>              return 0;
>      }
>  
> > Signed-off-by: Stefan Fritsch <address@hidden>
> > ---
> > 
> > This time CCing the maintainers.
> > 
> > This fixes VLANs with OpenBSD guests (and probably NetBSD, too, because
> > the OpenBSD driver started as a port from NetBSD).
> > 
> > 
> >  hw/net/virtio-net.c |   12 +++++++++++-
> >  1 file changed, 11 insertions(+), 1 deletion(-)
> > 
> > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> > index 3626608..0ae9a91 100644
> > --- a/hw/net/virtio-net.c
> > +++ b/hw/net/virtio-net.c
> > @@ -315,7 +315,11 @@ static void virtio_net_reset(VirtIODevice *vdev)
> >      memset(n->mac_table.macs, 0, MAC_TABLE_ENTRIES * ETH_ALEN);
> >      memcpy(&n->mac[0], &n->nic->conf->macaddr, sizeof(n->mac));
> >      qemu_format_nic_info_str(qemu_get_queue(n->nic), n->mac);
> > -    memset(n->vlans, 0, MAX_VLAN >> 3);
> > +    if (vdev->guest_features & (1 << VIRTIO_NET_F_CTRL_VLAN)) {
> > +        memset(n->vlans, 0, MAX_VLAN >> 3);
> > +    } else {
> > +        memset(n->vlans, 0xff, MAX_VLAN >> 3);
> > +    }
> >  }
> >  
> >  static void peer_test_vnet_hdr(VirtIONet *n)
> > @@ -515,6 +519,12 @@ static void virtio_net_set_features(VirtIODevice 
> > *vdev, uint32_t features)
> >          }
> >          vhost_net_ack_features(tap_get_vhost_net(nc->peer), features);
> >      }
> > +
> > +    if (vdev->guest_features & (1 << VIRTIO_NET_F_CTRL_VLAN)) {
> > +        memset(n->vlans, 0, MAX_VLAN >> 3);
> > +    } else {
> > +        memset(n->vlans, 0xff, MAX_VLAN >> 3);
> > +    }
> >  }
> >  
> >  static int virtio_net_handle_rx_mode(VirtIONet *n, uint8_t cmd,
> > -- 
> > 1.7.10.4
> 
> -- 
>                       Amos.
>