net/mlx5e: Use the inner headers to determine tc/pedit offload limitation on decap flows

In packets that need to be decaped the internal headers
have to be checked, not the external ones.

Fixes: bdd66ac0 ("net/mlx5e: Disallow TC offloading of unsupported match/action combinations")
Signed-off-by: Guy Shattah <sguy@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

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

@@ -2181,6 +2181,7 @@ static bool csum_offload_supported(struct mlx5e_priv *priv,
 
 static bool modify_header_match_supported(struct mlx5_flow_spec *spec,
 					  struct tcf_exts *exts,
+					  u32 actions,
 					  struct netlink_ext_ack *extack)
 {
 	const struct tc_action *a;
@@ -2190,7 +2191,11 @@ static bool modify_header_match_supported(struct mlx5_flow_spec *spec,
 	u16 ethertype;
 	int nkeys, i;
 
-	headers_v = MLX5_ADDR_OF(fte_match_param, spec->match_value, outer_headers);
+	if (actions & MLX5_FLOW_CONTEXT_ACTION_DECAP)
+		headers_v = MLX5_ADDR_OF(fte_match_param, spec->match_value, inner_headers);
+	else
+		headers_v = MLX5_ADDR_OF(fte_match_param, spec->match_value, outer_headers);
+
 	ethertype = MLX5_GET(fte_match_set_lyr_2_4, headers_v, ethertype);
 
 	/* for non-IP we only re-write MACs, so we're okay */
@@ -2247,7 +2252,7 @@ static bool actions_match_supported(struct mlx5e_priv *priv,
 
 	if (actions & MLX5_FLOW_CONTEXT_ACTION_MOD_HDR)
 		return modify_header_match_supported(&parse_attr->spec, exts,
-						     extack);
+						     actions, extack);
 
 	return true;
 }