net/mlx5: E-Switch, reserve and use same uplink metadata across ports

When in switchdev mode wire traffic will hit the FDB in one of two
scenarios.

- Shared FDB, in that case traffic from both physical ports should be
  tagged by the same metadata value so a single FDB rule could catch
  traffic from both ports.

- Two E-Switches, traffic from each physical port will hit the native
  E-Switch which means traffic from one physical port can't reach the
  E-Switch of the other one.

Looking at those two scenarios it means we can always use the same metadata
value to tag wire traffic regardless of the mode.

Reserve a single metadata value to be used to tag wire traffic.
Signed-off-by: Sunil Rani <sunrani@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

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

@@ -2845,6 +2845,19 @@ bool mlx5_esw_vport_match_metadata_supported(const struct mlx5_eswitch *esw)
 	return true;
 }
 
+#define MLX5_ESW_METADATA_RSVD_UPLINK 1
+
+/* Share the same metadata for uplink's. This is fine because:
+ * (a) In shared FDB mode (LAG) both uplink's are treated the
+ *     same and tagged with the same metadata.
+ * (b) In non shared FDB mode, packets from physical port0
+ *     cannot hit eswitch of PF1 and vice versa.
+ */
+static u32 mlx5_esw_match_metadata_reserved(struct mlx5_eswitch *esw)
+{
+	return MLX5_ESW_METADATA_RSVD_UPLINK;
+}
+
 u32 mlx5_esw_match_metadata_alloc(struct mlx5_eswitch *esw)
 {
 	u32 vport_end_ida = (1 << ESW_VPORT_BITS) - 1;
@@ -2859,8 +2872,10 @@ u32 mlx5_esw_match_metadata_alloc(struct mlx5_eswitch *esw)
 		return 0;
 
 	/* Metadata is 4 bits of PFNUM and 12 bits of unique id */
-	/* Use only non-zero vport_id (1-4095) for all PF's */
-	id = ida_alloc_range(&esw->offloads.vport_metadata_ida, 1, vport_end_ida, GFP_KERNEL);
+	/* Use only non-zero vport_id (2-4095) for all PF's */
+	id = ida_alloc_range(&esw->offloads.vport_metadata_ida,
+			     MLX5_ESW_METADATA_RSVD_UPLINK + 1,
+			     vport_end_ida, GFP_KERNEL);
 	if (id < 0)
 		return 0;
 	id = (pf_num << ESW_VPORT_BITS) | id;
@@ -2878,7 +2893,11 @@ void mlx5_esw_match_metadata_free(struct mlx5_eswitch *esw, u32 metadata)
 static int esw_offloads_vport_metadata_setup(struct mlx5_eswitch *esw,
 					     struct mlx5_vport *vport)
 {
-	vport->default_metadata = mlx5_esw_match_metadata_alloc(esw);
+	if (vport->vport == MLX5_VPORT_UPLINK)
+		vport->default_metadata = mlx5_esw_match_metadata_reserved(esw);
+	else
+		vport->default_metadata = mlx5_esw_match_metadata_alloc(esw);
+
 	vport->metadata = vport->default_metadata;
 	return vport->metadata ? 0 : -ENOSPC;
 }
@@ -2889,6 +2908,9 @@ static void esw_offloads_vport_metadata_cleanup(struct mlx5_eswitch *esw,
 	if (!vport->default_metadata)
 		return;
 
+	if (vport->vport == MLX5_VPORT_UPLINK)
+		return;
+
 	WARN_ON(vport->metadata != vport->default_metadata);
 	mlx5_esw_match_metadata_free(esw, vport->default_metadata);
 }