net/mlx5: E-Switch, Enable reg c1 loopback when possible

Enable reg c1 loopback if firmware reports it's supported,
as this is needed for restoring packet metadata (e.g chain).

Also define helper to query if it is enabled.
Signed-off-by: Paul Blakey <paulb@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -236,6 +236,7 @@ struct mlx5_esw_functions {
 
 enum {
 	MLX5_ESWITCH_VPORT_MATCH_METADATA = BIT(0),
+	MLX5_ESWITCH_REG_C1_LOOPBACK_ENABLED = BIT(1),
 };
 
 struct mlx5_eswitch {

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

@@ -763,14 +763,21 @@ void mlx5_eswitch_del_send_to_vport_rule(struct mlx5_flow_handle *rule)
 	mlx5_del_flow_rules(rule);
 }
 
+static bool mlx5_eswitch_reg_c1_loopback_supported(struct mlx5_eswitch *esw)
+{
+	return MLX5_CAP_ESW_FLOWTABLE(esw->dev, fdb_to_vport_reg_c_id) &
+	       MLX5_FDB_TO_VPORT_REG_C_1;
+}
+
 static int esw_set_passing_vport_metadata(struct mlx5_eswitch *esw, bool enable)
 {
 	u32 out[MLX5_ST_SZ_DW(query_esw_vport_context_out)] = {};
 	u32 in[MLX5_ST_SZ_DW(modify_esw_vport_context_in)] = {};
-	u8 fdb_to_vport_reg_c_id;
+	u8 curr, wanted;
 	int err;
 
-	if (!mlx5_eswitch_vport_match_metadata_enabled(esw))
+	if (!mlx5_eswitch_reg_c1_loopback_supported(esw) &&
+	    !mlx5_eswitch_vport_match_metadata_enabled(esw))
 		return 0;
 
 	err = mlx5_eswitch_query_esw_vport_context(esw->dev, 0, false,
@@ -778,24 +785,33 @@ static int esw_set_passing_vport_metadata(struct mlx5_eswitch *esw, bool enable)
 	if (err)
 		return err;
 
-	fdb_to_vport_reg_c_id = MLX5_GET(query_esw_vport_context_out, out,
-					 esw_vport_context.fdb_to_vport_reg_c_id);
+	curr = MLX5_GET(query_esw_vport_context_out, out,
+			esw_vport_context.fdb_to_vport_reg_c_id);
+	wanted = MLX5_FDB_TO_VPORT_REG_C_0;
+	if (mlx5_eswitch_reg_c1_loopback_supported(esw))
+		wanted |= MLX5_FDB_TO_VPORT_REG_C_1;
 
 	if (enable)
-		fdb_to_vport_reg_c_id |= MLX5_FDB_TO_VPORT_REG_C_0 |
-					 MLX5_FDB_TO_VPORT_REG_C_1;
+		curr |= wanted;
 	else
-		fdb_to_vport_reg_c_id &= ~(MLX5_FDB_TO_VPORT_REG_C_0 |
-					   MLX5_FDB_TO_VPORT_REG_C_1);
+		curr &= ~wanted;
 
 	MLX5_SET(modify_esw_vport_context_in, in,
-		 esw_vport_context.fdb_to_vport_reg_c_id, fdb_to_vport_reg_c_id);
+		 esw_vport_context.fdb_to_vport_reg_c_id, curr);
 
 	MLX5_SET(modify_esw_vport_context_in, in,
 		 field_select.fdb_to_vport_reg_c_id, 1);
 
-	return mlx5_eswitch_modify_esw_vport_context(esw->dev, 0, false,
-						     in, sizeof(in));
+	err = mlx5_eswitch_modify_esw_vport_context(esw->dev, 0, false, in,
+						    sizeof(in));
+	if (!err) {
+		if (enable && (curr & MLX5_FDB_TO_VPORT_REG_C_1))
+			esw->flags |= MLX5_ESWITCH_REG_C1_LOOPBACK_ENABLED;
+		else
+			esw->flags &= ~MLX5_ESWITCH_REG_C1_LOOPBACK_ENABLED;
+	}
+
+	return err;
 }
 
 static void peer_miss_rules_setup(struct mlx5_eswitch *esw,
@@ -2831,6 +2847,12 @@ bool mlx5_eswitch_is_vf_vport(const struct mlx5_eswitch *esw, u16 vport_num)
 	       vport_num <= esw->dev->priv.sriov.max_vfs;
 }
 
+bool mlx5_eswitch_reg_c1_loopback_enabled(const struct mlx5_eswitch *esw)
+{
+	return !!(esw->flags & MLX5_ESWITCH_REG_C1_LOOPBACK_ENABLED);
+}
+EXPORT_SYMBOL(mlx5_eswitch_reg_c1_loopback_enabled);
+
 bool mlx5_eswitch_vport_match_metadata_enabled(const struct mlx5_eswitch *esw)
 {
 	return !!(esw->flags & MLX5_ESWITCH_VPORT_MATCH_METADATA);

include/linux/mlx5/eswitch.h

@@ -70,6 +70,7 @@ u16 mlx5_eswitch_get_total_vports(const struct mlx5_core_dev *dev);
 enum devlink_eswitch_encap_mode
 mlx5_eswitch_get_encap_mode(const struct mlx5_core_dev *dev);
 
+bool mlx5_eswitch_reg_c1_loopback_enabled(const struct mlx5_eswitch *esw);
 bool mlx5_eswitch_vport_match_metadata_enabled(const struct mlx5_eswitch *esw);
 
 /* Reg C0 usage:
@@ -108,6 +109,12 @@ mlx5_eswitch_get_encap_mode(const struct mlx5_core_dev *dev)
 	return DEVLINK_ESWITCH_ENCAP_MODE_NONE;
 }
 
+static inline bool
+mlx5_eswitch_reg_c1_loopback_enabled(const struct mlx5_eswitch *esw)
+{
+	return false;
+};
+
 static inline bool
 mlx5_eswitch_vport_match_metadata_enabled(const struct mlx5_eswitch *esw)
 {