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

[Alex Williamson]

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.

>      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?  Thanks,

Alex