vxlan: Add vxlan_fdb_find_uc() for FDB querying

A switchdev-capable driver that is aware of VXLAN may need to query
VXLAN FDB. In the particular case of mlxsw, this functionality is
limited to querying UC FDBs. Those being easier to deal with than the
general case of RDST chain traversal, introduce an interface to query
specifically UC FDBs: vxlan_fdb_find_uc().
Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vxlan.c

@@ -504,6 +504,46 @@ static struct vxlan_rdst *vxlan_fdb_find_rdst(struct vxlan_fdb *f,
 	return NULL;
 }
 
+int vxlan_fdb_find_uc(struct net_device *dev, const u8 *mac, __be32 vni,
+		      struct switchdev_notifier_vxlan_fdb_info *fdb_info)
+{
+	struct vxlan_dev *vxlan = netdev_priv(dev);
+	u8 eth_addr[ETH_ALEN + 2] = { 0 };
+	struct vxlan_rdst *rdst;
+	struct vxlan_fdb *f;
+	int rc = 0;
+
+	if (is_multicast_ether_addr(mac) ||
+	    is_zero_ether_addr(mac))
+		return -EINVAL;
+
+	ether_addr_copy(eth_addr, mac);
+
+	rcu_read_lock();
+
+	f = __vxlan_find_mac(vxlan, eth_addr, vni);
+	if (!f) {
+		rc = -ENOENT;
+		goto out;
+	}
+
+	rdst = first_remote_rcu(f);
+
+	memset(fdb_info, 0, sizeof(*fdb_info));
+	fdb_info->info.dev = dev;
+	fdb_info->remote_ip = rdst->remote_ip;
+	fdb_info->remote_port = rdst->remote_port;
+	fdb_info->remote_vni = rdst->remote_vni;
+	fdb_info->remote_ifindex = rdst->remote_ifindex;
+	fdb_info->vni = vni;
+	ether_addr_copy(fdb_info->eth_addr, mac);
+
+out:
+	rcu_read_unlock();
+	return rc;
+}
+EXPORT_SYMBOL_GPL(vxlan_fdb_find_uc);
+
 /* Replace destination of unicast mac */
 static int vxlan_fdb_replace(struct vxlan_fdb *f,
 			     union vxlan_addr *ip, __be16 port, __be32 vni,

include/net/vxlan.h

@@ -420,4 +420,16 @@ struct switchdev_notifier_vxlan_fdb_info {
 	__be32 vni;
 };
 
+#if IS_ENABLED(CONFIG_VXLAN)
+int vxlan_fdb_find_uc(struct net_device *dev, const u8 *mac, __be32 vni,
+		      struct switchdev_notifier_vxlan_fdb_info *fdb_info);
+#else
+static inline int
+vxlan_fdb_find_uc(struct net_device *dev, const u8 *mac, __be32 vni,
+		  struct switchdev_notifier_vxlan_fdb_info *fdb_info)
+{
+	return -ENOENT;
+}
+#endif
+
 #endif