[PATCH net-next 5/5] net/mlx5: Add balance ID support for LAG multiplane groups

Tariq Toukan
2025-10-23T09:18:16Z

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>
---
drivers/net/ethernet/mellanox/mlx5/core/main.c | 5 +++++
drivers/net/ethernet/mellanox/mlx5/core/vport.c | 4 ++++
include/linux/mlx5/driver.h | 2 +-
3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/main.c b/drivers/net/ethernet/mellanox/mlx5/core/main.c
index 1126e4db0318..cc6374b4e0b8 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/main.c
+++ b/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
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/vport.c b/drivers/net/ethernet/mellanox/mlx5/core/vport.c
index 4224e2750865..992873536c1b 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/vport.c
+++ b/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,
diff --git a/include/linux/mlx5/driver.h b/include/linux/mlx5/driver.h
index dcf262aa9ea6..046396269ccf 100644
--- a/include/linux/mlx5/driver.h
+++ b/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 */
--
2.31.1