net/mlx5e: Check for needed capability for cvlan matching

If not supported show an error and return instead of trying to offload
to the hardware and fail.

Fixes: 699e96d ("net/mlx5e: Support offloading tc double vlan headers match")
Reported-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

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

@@ -2015,11 +2015,13 @@ static int __parse_cls_flower(struct mlx5e_priv *priv,
 				    misc_parameters_3);
 	struct flow_rule *rule = flow_cls_offload_flow_rule(f);
 	struct flow_dissector *dissector = rule->match.dissector;
+	enum fs_flow_table_type fs_type;
 	u16 addr_type = 0;
 	u8 ip_proto = 0;
 	u8 *match_level;
 	int err;
 
+	fs_type = mlx5e_is_eswitch_flow(flow) ? FS_FT_FDB : FS_FT_NIC_RX;
 	match_level = outer_match_level;
 
 	if (dissector->used_keys &
@@ -2145,6 +2147,13 @@ static int __parse_cls_flower(struct mlx5e_priv *priv,
 		if (match.mask->vlan_id ||
 		    match.mask->vlan_priority ||
 		    match.mask->vlan_tpid) {
+			if (!MLX5_CAP_FLOWTABLE_TYPE(priv->mdev, ft_field_support.outer_second_vid,
+						     fs_type)) {
+				NL_SET_ERR_MSG_MOD(extack,
+						   "Matching on CVLAN is not supported");
+				return -EOPNOTSUPP;
+			}
+
 			if (match.key->vlan_tpid == htons(ETH_P_8021AD)) {
 				MLX5_SET(fte_match_set_misc, misc_c,
 					 outer_second_svlan_tag, 1);