net/mlx5: Add balance ID support for LAG multiplane groups

Implement balance ID support for multiplane LAG configurations. This
feature enables per-multiplane group load balancing by extending the
software system image GUID with a balance ID component.

Key implementations:
- Enable lag_per_mp_group capability when supported by hardware.
- Append load_balance_id to software system image GUID when conditions
  are met.
- Increase MLX5_SW_IMAGE_GUID_MAX_BYTES from 8 to 9 to accommodate the
  extra byte.

The balance ID is appended to the system image GUID only when both
load_balance_id and lag_per_mp_group capabilities are available, ensuring
backward compatibility while enabling enhanced LAG functionality.

This enhancement allows for more granular load balancing control in complex
multi-plane LAG deployments, improving network performance and flexibility.

Signed-off-by: Mark Bloch <mbloch@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Shay Drori <shayd@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/1761211020-925651-6-git-send-email-tariqt@nvidia.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

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

@@ -575,6 +575,11 @@ static int handle_hca_cap_2(struct mlx5_core_dev *dev, void *set_ctx)
 		do_set = true;
 	}
 
+	if (MLX5_CAP_GEN_2_MAX(dev, lag_per_mp_group)) {
+		MLX5_SET(cmd_hca_cap_2, set_hca_cap, lag_per_mp_group, 1);
+		do_set = true;
+	}
+
 	/* some FW versions that support querying MLX5_CAP_GENERAL_2
 	 * capabilities but don't support setting them.
 	 * Skip unnecessary update to hca_cap_2 when no changes were introduced

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

@@ -1203,6 +1203,10 @@ void mlx5_query_nic_sw_system_image_guid(struct mlx5_core_dev *mdev, u8 *buf,
 
 	memcpy(buf, &fw_system_image_guid, sizeof(fw_system_image_guid));
 	*len += sizeof(fw_system_image_guid);
+
+	if (MLX5_CAP_GEN_2(mdev, load_balance_id) &&
+	    MLX5_CAP_GEN_2(mdev, lag_per_mp_group))
+		buf[(*len)++] = MLX5_CAP_GEN_2(mdev, load_balance_id);
 }
 
 static bool mlx5_vport_use_vhca_id_as_func_id(struct mlx5_core_dev *dev,

include/linux/mlx5/driver.h

@@ -1380,6 +1380,6 @@ static inline struct net *mlx5_core_net(struct mlx5_core_dev *dev)
 	return devlink_net(priv_to_devlink(dev));
 }
 
-#define MLX5_SW_IMAGE_GUID_MAX_BYTES 8
+#define MLX5_SW_IMAGE_GUID_MAX_BYTES 9
 
 #endif /* MLX5_DRIVER_H */