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 <paul.durrant@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index c6cb85a..6dc76c1 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -210,12 +210,22 @@
VIF_STATUS_CONNECTED,
};
+struct xenvif_mcast_addr {
+ struct list_head entry;
+ struct rcu_head rcu;
+ u8 addr[6];
+};
+
+#define XEN_NETBK_MCAST_MAX 64
+
struct xenvif {
/* Unique identifier for this interface. */
domid_t domid;
unsigned int handle;
u8 fe_dev_addr[6];
+ struct list_head fe_mcast_addr;
+ unsigned int fe_mcast_count;
/* Frontend feature information. */
int gso_mask;
@@ -224,6 +234,7 @@
u8 can_sg:1;
u8 ip_csum:1;
u8 ipv6_csum:1;
+ u8 multicast_control:1;
/* Is this interface disabled? True when backend discovers
* frontend is rogue.
@@ -341,4 +352,8 @@
struct sk_buff *skb);
void xenvif_skb_zerocopy_complete(struct xenvif_queue *queue);
+/* Multicast control */
+bool xenvif_mcast_match(struct xenvif *vif, const u8 *addr);
+void xenvif_mcast_addr_list_free(struct xenvif *vif);
+
#endif /* __XEN_NETBACK__COMMON_H__ */
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 28577a3..e7bd63e 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -171,6 +171,13 @@
!xenvif_schedulable(vif))
goto drop;
+ if (vif->multicast_control && skb->pkt_type == PACKET_MULTICAST) {
+ struct ethhdr *eth = (struct ethhdr *)skb->data;
+
+ if (!xenvif_mcast_match(vif, eth->h_dest))
+ goto drop;
+ }
+
cb = XENVIF_RX_CB(skb);
cb->expires = jiffies + vif->drain_timeout;
@@ -427,6 +434,7 @@
vif->num_queues = 0;
spin_lock_init(&vif->lock);
+ INIT_LIST_HEAD(&vif->fe_mcast_addr);
dev->netdev_ops = &xenvif_netdev_ops;
dev->hw_features = NETIF_F_SG |
@@ -661,6 +669,8 @@
xenvif_unmap_frontend_rings(queue);
}
+
+ xenvif_mcast_addr_list_free(vif);
}
/* Reverse the relevant parts of xenvif_init_queue().
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 3f44b52..42569b9 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -1157,6 +1157,80 @@
return false;
}
+/* No locking is required in xenvif_mcast_add/del() as they are
+ * only ever invoked from NAPI poll. An RCU list is used because
+ * xenvif_mcast_match() is called asynchronously, during start_xmit.
+ */
+
+static int xenvif_mcast_add(struct xenvif *vif, const u8 *addr)
+{
+ struct xenvif_mcast_addr *mcast;
+
+ if (vif->fe_mcast_count == XEN_NETBK_MCAST_MAX) {
+ if (net_ratelimit())
+ netdev_err(vif->dev,
+ "Too many multicast addresses\n");
+ return -ENOSPC;
+ }
+
+ mcast = kzalloc(sizeof(*mcast), GFP_ATOMIC);
+ if (!mcast)
+ return -ENOMEM;
+
+ ether_addr_copy(mcast->addr, addr);
+ list_add_tail_rcu(&mcast->entry, &vif->fe_mcast_addr);
+ vif->fe_mcast_count++;
+
+ return 0;
+}
+
+static void xenvif_mcast_del(struct xenvif *vif, const u8 *addr)
+{
+ struct xenvif_mcast_addr *mcast;
+
+ list_for_each_entry_rcu(mcast, &vif->fe_mcast_addr, entry) {
+ if (ether_addr_equal(addr, mcast->addr)) {
+ --vif->fe_mcast_count;
+ list_del_rcu(&mcast->entry);
+ kfree_rcu(mcast, rcu);
+ break;
+ }
+ }
+}
+
+bool xenvif_mcast_match(struct xenvif *vif, const u8 *addr)
+{
+ struct xenvif_mcast_addr *mcast;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(mcast, &vif->fe_mcast_addr, entry) {
+ if (ether_addr_equal(addr, mcast->addr)) {
+ rcu_read_unlock();
+ return true;
+ }
+ }
+ rcu_read_unlock();
+
+ return false;
+}
+
+void xenvif_mcast_addr_list_free(struct xenvif *vif)
+{
+ /* No need for locking or RCU here. NAPI poll and TX queue
+ * are stopped.
+ */
+ while (!list_empty(&vif->fe_mcast_addr)) {
+ struct xenvif_mcast_addr *mcast;
+
+ mcast = list_first_entry(&vif->fe_mcast_addr,
+ struct xenvif_mcast_addr,
+ entry);
+ --vif->fe_mcast_count;
+ list_del(&mcast->entry);
+ kfree(mcast);
+ }
+}
+
static void xenvif_tx_build_gops(struct xenvif_queue *queue,
int budget,
unsigned *copy_ops,
@@ -1215,6 +1289,31 @@
break;
}
+ if (extras[XEN_NETIF_EXTRA_TYPE_MCAST_ADD - 1].type) {
+ struct xen_netif_extra_info *extra;
+
+ extra = &extras[XEN_NETIF_EXTRA_TYPE_MCAST_ADD - 1];
+ ret = xenvif_mcast_add(queue->vif, extra->u.mcast.addr);
+
+ make_tx_response(queue, &txreq,
+ (ret == 0) ?
+ XEN_NETIF_RSP_OKAY :
+ XEN_NETIF_RSP_ERROR);
+ push_tx_responses(queue);
+ continue;
+ }
+
+ if (extras[XEN_NETIF_EXTRA_TYPE_MCAST_DEL - 1].type) {
+ struct xen_netif_extra_info *extra;
+
+ extra = &extras[XEN_NETIF_EXTRA_TYPE_MCAST_DEL - 1];
+ xenvif_mcast_del(queue->vif, extra->u.mcast.addr);
+
+ make_tx_response(queue, &txreq, XEN_NETIF_RSP_OKAY);
+ push_tx_responses(queue);
+ continue;
+ }
+
ret = xenvif_count_requests(queue, &txreq, txfrags, work_to_do);
if (unlikely(ret < 0))
break;
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index ec383b0..929a6e7 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -327,6 +327,14 @@
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 @@
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;
}
diff --git a/include/xen/interface/io/netif.h b/include/xen/interface/io/netif.h
index 70054cc..252ffd4 100644
--- a/include/xen/interface/io/netif.h
+++ b/include/xen/interface/io/netif.h
@@ -156,7 +156,9 @@
/* Types of xen_netif_extra_info descriptors. */
#define XEN_NETIF_EXTRA_TYPE_NONE (0) /* Never used - invalid */
#define XEN_NETIF_EXTRA_TYPE_GSO (1) /* u.gso */
-#define XEN_NETIF_EXTRA_TYPE_MAX (2)
+#define XEN_NETIF_EXTRA_TYPE_MCAST_ADD (2) /* u.mcast */
+#define XEN_NETIF_EXTRA_TYPE_MCAST_DEL (3) /* u.mcast */
+#define XEN_NETIF_EXTRA_TYPE_MAX (4)
/* xen_netif_extra_info flags. */
#define _XEN_NETIF_EXTRA_FLAG_MORE (0)
@@ -201,6 +203,10 @@
uint16_t features; /* XEN_NETIF_GSO_FEAT_* */
} gso;
+ struct {
+ uint8_t addr[6]; /* Address to add/remove. */
+ } mcast;
+
uint16_t pad[3];
} u;
};