net/mlx5e: Don't allow forwarding between uplink

We can install forwarding packets rule between uplink
in switchdev mode, as show below. But the hardware does
not do that as expected (mlnx_perf -i $PF1, we can't get
the counter of the PF1). By the way, if we add the uplink
PF0, PF1 to Open vSwitch and enable hw-offload, the rules
can be offloaded but not work fine too. This patch add a
check and if so return -EOPNOTSUPP.

$ tc filter add dev $PF0 protocol all parent ffff: prio 1 handle 1 \
    flower skip_sw action mirred egress redirect dev $PF1

$ tc -d -s filter show dev $PF0 ingress
    skip_sw
    in_hw in_hw_count 1
    action order 1: mirred (Egress Redirect to device enp130s0f1) stolen
    ...
    Sent hardware 408954 bytes 4173 pkt
    ...

Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/en_rep.c

@@ -1464,6 +1464,11 @@ static const struct net_device_ops mlx5e_netdev_ops_uplink_rep = {
 	.ndo_set_features        = mlx5e_set_features,
 };
 
+bool mlx5e_eswitch_uplink_rep(struct net_device *netdev)
+{
+	return netdev->netdev_ops == &mlx5e_netdev_ops_uplink_rep;
+}
+
 bool mlx5e_eswitch_rep(struct net_device *netdev)
 {
 	if (netdev->netdev_ops == &mlx5e_netdev_ops_rep ||

drivers/net/ethernet/mellanox/mlx5/core/en_rep.h

@@ -200,6 +200,7 @@ void mlx5e_rep_encap_entry_detach(struct mlx5e_priv *priv,
 void mlx5e_rep_queue_neigh_stats_work(struct mlx5e_priv *priv);
 
 bool mlx5e_eswitch_rep(struct net_device *netdev);
+bool mlx5e_eswitch_uplink_rep(struct net_device *netdev);
 
 #else /* CONFIG_MLX5_ESWITCH */
 static inline bool mlx5e_is_uplink_rep(struct mlx5e_priv *priv) { return false; }

drivers/net/ethernet/mellanox/mlx5/core/en_tc.c

@@ -3405,6 +3405,7 @@ static int parse_tc_fdb_actions(struct mlx5e_priv *priv,
 				struct mlx5_eswitch *esw = priv->mdev->priv.eswitch;
 				struct net_device *uplink_dev = mlx5_eswitch_uplink_get_proto_dev(esw, REP_ETH);
 				struct net_device *uplink_upper;
+				struct mlx5e_rep_priv *rep_priv;
 
 				if (is_duplicated_output_device(priv->netdev,
 								out_dev,
@@ -3440,6 +3441,22 @@ static int parse_tc_fdb_actions(struct mlx5e_priv *priv,
 						return err;
 				}
 
+				/* Don't allow forwarding between uplink.
+				 *
+				 * Input vport was stored esw_attr->in_rep.
+				 * In LAG case, *priv* is the private data of
+				 * uplink which may be not the input vport.
+				 */
+				rep_priv = mlx5e_rep_to_rep_priv(attr->in_rep);
+				if (mlx5e_eswitch_uplink_rep(rep_priv->netdev) &&
+				    mlx5e_eswitch_uplink_rep(out_dev)) {
+					NL_SET_ERR_MSG_MOD(extack,
+							   "devices are both uplink, can't offload forwarding");
+					pr_err("devices %s %s are both uplink, can't offload forwarding\n",
+					       priv->netdev->name, out_dev->name);
+					return -EOPNOTSUPP;
+				}
+
 				if (!mlx5e_is_valid_eswitch_fwd_dev(priv, out_dev)) {
 					NL_SET_ERR_MSG_MOD(extack,
 							   "devices are not on same switch HW, can't offload forwarding");