From 210c34dcd8d912dcc740f1f17625a7293af5cb56 Mon Sep 17 00:00:00 2001 From: Paul Durrant Date: Wed, 2 Sep 2015 17:58:36 +0100 Subject: xen-netback: add support for multicast control 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 Cc: Ian Campbell Cc: Wei Liu Acked-by: Wei Liu Signed-off-by: David S. Miller --- drivers/net/xen-netback/xenbus.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'drivers/net/xen-netback/xenbus.c') diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c index ec383b0f5443..929a6e7e5ecf 100644 --- a/drivers/net/xen-netback/xenbus.c +++ b/drivers/net/xen-netback/xenbus.c @@ -327,6 +327,14 @@ static int netback_probe(struct xenbus_device *dev, goto abort_transaction; } + /* We support multicast-control. */ + err = xenbus_printf(xbt, dev->nodename, + "feature-multicast-control", "%d", 1); + if (err) { + message = "writing feature-multicast-control"; + goto abort_transaction; + } + err = xenbus_transaction_end(xbt, 0); } while (err == -EAGAIN); @@ -1016,6 +1024,11 @@ static int read_xenbus_vif_flags(struct backend_info *be) val = 0; vif->ipv6_csum = !!val; + if (xenbus_scanf(XBT_NIL, dev->otherend, "request-multicast-control", + "%d", &val) < 0) + val = 0; + vif->multicast_control = !!val; + return 0; } -- cgit v1.2.3