Subject: [net-next V2 12/15] net/mlx5: Cap the maximum flow group size to 16M entries

From: Saeed Mahameed <[email-masked]>
Date: Thu, 27 May 2021 11:56:21 -0700

From: Paul Blakey <[email-masked]>

The maximum number of large flow groups applies to both small and large
tables. For very large tables (such as the 2G SW steering tables) this may
create a small number of flow groups each with an unrealistic entries
domain (> 16M).

Set the maximum number of large flow groups to at least what user
requested, but with a maximum per group size of 16M entries.
For software steering, if user requested less than 128 large flow
groups, it will gives us about 128 16M groups in a 2G
entries tables.

Signed-off-by: Paul Blakey <[email-masked]>
Signed-off-by: Saeed Mahameed <[email-masked]>
---
 drivers/net/ethernet/mellanox/mlx5/core/fs_core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
index 6e20cbb4656a..1b7a1cde097c 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
@@ -1173,6 +1173,7 @@ mlx5_create_lag_demux_flow_table(struct mlx5_flow_namespace *ns,
 }
 EXPORT_SYMBOL(mlx5_create_lag_demux_flow_table);
 
+#define MAX_FLOW_GROUP_SIZE BIT(24)
 struct mlx5_flow_table*
 mlx5_create_auto_grouped_flow_table(struct mlx5_flow_namespace *ns,
 				    struct mlx5_flow_table_attr *ft_attr)
@@ -1192,6 +1193,10 @@ mlx5_create_auto_grouped_flow_table(struct mlx5_flow_namespace *ns,
 	if (num_reserved_entries > ft->max_fte)
 		goto err_validate;
 
+	/* Align the number of groups according to the largest group size */
+	if (autogroups_max_fte / (max_num_groups + 1) > MAX_FLOW_GROUP_SIZE)
+		max_num_groups = (autogroups_max_fte / MAX_FLOW_GROUP_SIZE) - 1;
+
 	ft->autogroup.active = true;
 	ft->autogroup.required_groups = max_num_groups;
 	ft->autogroup.max_fte = autogroups_max_fte;
-- 
2.31.1