net/mlx5: ft: Check prio and chain sanity for ft offload

Before changing the chain from original chain to ft offload chain,
make sure user doesn't actually use chains.

While here, normalize the prio range to that which we support.
Signed-off-by: Paul Blakey <paulb@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

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

@@ -1247,8 +1247,7 @@ static int mlx5e_rep_setup_tc_cb(enum tc_setup_type type, void *type_data,
 static int mlx5e_rep_setup_ft_cb(enum tc_setup_type type, void *type_data,
 				 void *cb_priv)
 {
-	struct flow_cls_offload *f = type_data;
-	struct flow_cls_offload cls_flower;
+	struct flow_cls_offload tmp, *f = type_data;
 	struct mlx5e_priv *priv = cb_priv;
 	struct mlx5_eswitch *esw;
 	unsigned long flags;
@@ -1261,16 +1260,30 @@ static int mlx5e_rep_setup_ft_cb(enum tc_setup_type type, void *type_data,
 
 	switch (type) {
 	case TC_SETUP_CLSFLOWER:
-		if (!mlx5_eswitch_prios_supported(esw) || f->common.chain_index)
+		memcpy(&tmp, f, sizeof(*f));
+
+		if (!mlx5_eswitch_prios_supported(esw) ||
+		    tmp.common.chain_index)
 			return -EOPNOTSUPP;
 
 		/* Re-use tc offload path by moving the ft flow to the
 		 * reserved ft chain.
+		 *
+		 * FT offload can use prio range [0, INT_MAX], so we
+		 * normalize it to range [1, mlx5_eswitch_get_prio_range(esw)]
+		 * as with tc, where prio 0 isn't supported.
+		 *
+		 * We only support chain 0 of FT offload.
 		 */
-		memcpy(&cls_flower, f, sizeof(*f));
-		cls_flower.common.chain_index = mlx5_eswitch_get_ft_chain(esw);
-		err = mlx5e_rep_setup_tc_cls_flower(priv, &cls_flower, flags);
-		memcpy(&f->stats, &cls_flower.stats, sizeof(f->stats));
+		if (tmp.common.prio >= mlx5_eswitch_get_prio_range(esw))
+			return -EOPNOTSUPP;
+		if (tmp.common.chain_index != 0)
+			return -EOPNOTSUPP;
+
+		tmp.common.chain_index = mlx5_eswitch_get_ft_chain(esw);
+		tmp.common.prio++;
+		err = mlx5e_rep_setup_tc_cls_flower(priv, &tmp, flags);
+		memcpy(&f->stats, &tmp.stats, sizeof(f->stats));
 		return err;
 	default:
 		return -EOPNOTSUPP;