Re: [PATCH v2 net-next] xen-netback: add support for multicast control

[David Miller <davem@davemloft.net>]

From: Paul Durrant <paul.durrant@citrix.com>
Date: Wed, 2 Sep 2015 17:58:36 +0100

> Xen's PV network protocol includes messages to add/remove ethernet
> multicast addresses to/from a filter list in the backend. This allows
> the frontend to request the backend only forward multicast packets
> which are of interest thus preventing unnecessary noise on the shared
> ring.
> 
> The canonical netif header in git://xenbits.xen.org/xen.git specifies
> the message format (two more XEN_NETIF_EXTRA_TYPEs) so the minimal
> necessary changes have been pulled into include/xen/interface/io/netif.h.
> 
> To prevent the frontend from extending the multicast filter list
> arbitrarily a limit (XEN_NETBK_MCAST_MAX) has been set to 64 entries.
> This limit is not specified by the protocol and so may change in future.
> If the limit is reached then the next XEN_NETIF_EXTRA_TYPE_MCAST_ADD
> sent by the frontend will be failed with NETIF_RSP_ERROR.
> 
> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>

Applied.