[Qemu-devel] Re: [PATCH RFC] net: add a flag to disable mac/vlan filtering

[Michael S. Tsirkin]

On Tue, Mar 09, 2010 at 08:19:12AM -0700, Alex Williamson wrote:
> On Tue, 2010-03-09 at 15:15 +0200, Michael S. Tsirkin wrote:
> > diff --git a/hw/virtio-net.c b/hw/virtio-net.c
> > index 5c0093e..01b45ed 100644
> > --- a/hw/virtio-net.c
> > +++ b/hw/virtio-net.c
> > @@ -47,6 +47,7 @@ typedef struct VirtIONet
> >      uint8_t nomulti;
> >      uint8_t nouni;
> >      uint8_t nobcast;
> > +    uint32_t filtering;
> >      struct {
> >          int in_use;
> >          int first_multi;
> > @@ -475,12 +476,17 @@ static int receive_filter(VirtIONet *n, const uint8_t 
> > *buf, int size)
> >          ptr += sizeof(struct virtio_net_hdr);
> >      }
> >  
> > -    if (!memcmp(&ptr[12], vlan, sizeof(vlan))) {
> > +    if ((n->filtering & (0x1 << NICCONF_F_VLAN_FILTERING)) &&
> > +        !memcmp(&ptr[12], vlan, sizeof(vlan))) {
> >          int vid = be16_to_cpup((uint16_t *)(ptr + 14)) & 0xfff;
> >          if (!(n->vlans[vid >> 5] & (1U << (vid & 0x1f))))
> >              return 0;
> >      }
> >  
> > +    if (!(n->filtering & (0x1 << NICCONF_F_MAC_FILTERING))) {
> > +            return 1;
> > +    }
> > +
> 
> A filtering flags bitmap is a logical choice here, but I found the
> overhead to be non-trivial, which is why we have separate variables for
> the other filtering options.

You suggest more flags for multicast etc?

> >      if (ptr[0] & 1) { // multicast
> >          if (!memcmp(ptr, bcast, sizeof(bcast))) {
> >              return !n->nobcast;
> > @@ -863,6 +869,8 @@ VirtIODevice *virtio_net_init(DeviceState *dev, NICConf 
> > *conf)
> >  
> >      n->mac_table.macs = qemu_mallocz(MAC_TABLE_ENTRIES * ETH_ALEN);
> >  
> > +    n->filtering = conf->filtering;
> > +
> 
> Since we're not touching this in the savevm code, I assume the intention
> is that we can transparently migrate between filtered bridges and
> non-filtered bridges, right?

Right.

>  Thanks,
> 
> Alex