mlxsw: Add QinQ configuration vetoes

After adding support for QinQ, a.k.a 802.1ad protocol, there are a few
scenarios that should be vetoed.

The vetoes are motivated by various ASIC limitations.
For example, a port that is member in a 802.1ad bridge cannot have 802.1q
uppers as the port needs to be configured to treat 802.1q packets as
untagged packets.

Veto all those unsupported scenarios and return suitable messages.

Signed-off-by: Danielle Ratson <danieller@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mellanox/mlxsw/spectrum.c

@@ -3893,6 +3893,7 @@ static int mlxsw_sp_netdevice_port_upper_event(struct net_device *lower_dev,
 	struct net_device *upper_dev;
 	struct mlxsw_sp *mlxsw_sp;
 	int err = 0;
+	u16 proto;
 
 	mlxsw_sp_port = netdev_priv(dev);
 	mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
@@ -3950,6 +3951,36 @@ static int mlxsw_sp_netdevice_port_upper_event(struct net_device *lower_dev,
 			NL_SET_ERR_MSG_MOD(extack, "Can not put a VLAN on an OVS port");
 			return -EINVAL;
 		}
+		if (netif_is_bridge_master(upper_dev)) {
+			br_vlan_get_proto(upper_dev, &proto);
+			if (br_vlan_enabled(upper_dev) &&
+			    proto != ETH_P_8021Q && proto != ETH_P_8021AD) {
+				NL_SET_ERR_MSG_MOD(extack, "Enslaving a port to a bridge with unknown VLAN protocol is not supported");
+				return -EOPNOTSUPP;
+			}
+			if (vlan_uses_dev(lower_dev) &&
+			    br_vlan_enabled(upper_dev) &&
+			    proto == ETH_P_8021AD) {
+				NL_SET_ERR_MSG_MOD(extack, "Enslaving a port that already has a VLAN upper to an 802.1ad bridge is not supported");
+				return -EOPNOTSUPP;
+			}
+		}
+		if (netif_is_bridge_port(lower_dev) && is_vlan_dev(upper_dev)) {
+			struct net_device *br_dev = netdev_master_upper_dev_get(lower_dev);
+
+			if (br_vlan_enabled(br_dev)) {
+				br_vlan_get_proto(br_dev, &proto);
+				if (proto == ETH_P_8021AD) {
+					NL_SET_ERR_MSG_MOD(extack, "VLAN uppers are not supported on a port enslaved to an 802.1ad bridge");
+					return -EOPNOTSUPP;
+				}
+			}
+		}
+		if (is_vlan_dev(upper_dev) &&
+		    ntohs(vlan_dev_vlan_proto(upper_dev)) != ETH_P_8021Q) {
+			NL_SET_ERR_MSG_MOD(extack, "VLAN uppers are only supported with 802.1q VLAN protocol");
+			return -EOPNOTSUPP;
+		}
 		break;
 	case NETDEV_CHANGEUPPER:
 		upper_dev = info->upper_dev;
@@ -4215,6 +4246,7 @@ static int mlxsw_sp_netdevice_bridge_event(struct net_device *br_dev,
 	struct netdev_notifier_changeupper_info *info = ptr;
 	struct netlink_ext_ack *extack;
 	struct net_device *upper_dev;
+	u16 proto;
 
 	if (!mlxsw_sp)
 		return 0;
@@ -4230,6 +4262,18 @@ static int mlxsw_sp_netdevice_bridge_event(struct net_device *br_dev,
 		}
 		if (!info->linking)
 			break;
+		if (br_vlan_enabled(br_dev)) {
+			br_vlan_get_proto(br_dev, &proto);
+			if (proto == ETH_P_8021AD) {
+				NL_SET_ERR_MSG_MOD(extack, "Uppers are not supported on top of an 802.1ad bridge");
+				return -EOPNOTSUPP;
+			}
+		}
+		if (is_vlan_dev(upper_dev) &&
+		    ntohs(vlan_dev_vlan_proto(upper_dev)) != ETH_P_8021Q) {
+			NL_SET_ERR_MSG_MOD(extack, "VLAN uppers are only supported with 802.1q VLAN protocol");
+			return -EOPNOTSUPP;
+		}
 		if (netif_is_macvlan(upper_dev) &&
 		    !mlxsw_sp_rif_exists(mlxsw_sp, br_dev)) {
 			NL_SET_ERR_MSG_MOD(extack, "macvlan is only supported on top of router interfaces");

drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c

@@ -7857,6 +7857,15 @@ static int mlxsw_sp_inetaddr_bridge_event(struct mlxsw_sp *mlxsw_sp,
 
 	switch (event) {
 	case NETDEV_UP:
+		if (netif_is_bridge_master(l3_dev) && br_vlan_enabled(l3_dev)) {
+			u16 proto;
+
+			br_vlan_get_proto(l3_dev, &proto);
+			if (proto == ETH_P_8021AD) {
+				NL_SET_ERR_MSG_MOD(extack, "Adding an IP address to 802.1ad bridge is not supported");
+				return -EOPNOTSUPP;
+			}
+		}
 		rif = mlxsw_sp_rif_create(mlxsw_sp, &params, extack);
 		if (IS_ERR(rif))
 			return PTR_ERR(rif);

drivers/net/ethernet/mellanox/mlxsw/spectrum_switchdev.c

@@ -764,6 +764,25 @@ static int mlxsw_sp_port_attr_br_vlan_set(struct mlxsw_sp_port *mlxsw_sp_port,
 	return -EINVAL;
 }
 
+static int mlxsw_sp_port_attr_br_vlan_proto_set(struct mlxsw_sp_port *mlxsw_sp_port,
+						struct switchdev_trans *trans,
+						struct net_device *orig_dev,
+						u16 vlan_proto)
+{
+	struct mlxsw_sp *mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
+	struct mlxsw_sp_bridge_device *bridge_device;
+
+	if (!switchdev_trans_ph_prepare(trans))
+		return 0;
+
+	bridge_device = mlxsw_sp_bridge_device_find(mlxsw_sp->bridge, orig_dev);
+	if (WARN_ON(!bridge_device))
+		return -EINVAL;
+
+	netdev_err(bridge_device->dev, "VLAN protocol can't be changed on existing bridge\n");
+	return -EINVAL;
+}
+
 static int mlxsw_sp_port_attr_mrouter_set(struct mlxsw_sp_port *mlxsw_sp_port,
 					  struct switchdev_trans *trans,
 					  struct net_device *orig_dev,
@@ -933,6 +952,11 @@ static int mlxsw_sp_port_attr_set(struct net_device *dev,
 						     attr->orig_dev,
 						     attr->u.vlan_filtering);
 		break;
+	case SWITCHDEV_ATTR_ID_BRIDGE_VLAN_PROTOCOL:
+		err = mlxsw_sp_port_attr_br_vlan_proto_set(mlxsw_sp_port, trans,
+							   attr->orig_dev,
+							   attr->u.vlan_protocol);
+		break;
 	case SWITCHDEV_ATTR_ID_PORT_MROUTER:
 		err = mlxsw_sp_port_attr_mrouter_set(mlxsw_sp_port, trans,
 						     attr->orig_dev,