Re: [PATCH net v2 2/2] net/mlx5: HWS, fix modify header pool match for copy actions

[Yevgeny Kliteynik <kliteyn@nvidia.com>]

On 12-Oct-26 13:19, Alexandre Cassen wrote:
> mlx5_fs_hws_mh_pool_match() compares a single dword of each action
> since rules pass their values as arguments. Copy and add_field actions
> keep their destination in the second dword and HWS reads them from the
> pattern alone. Two modify headers whose copies differ only in
> destination then share a pool and the second rule writes to the wrong
> field.
> 
> Use the HWS core comparison that checks these actions in full.
> 
> Found while checking a Sashiko AI review report and confirmed against
> the HWS pattern code. Not reproduced. No in-kernel user puts such
> actions on the FDB but RDMA flow actions can.
> 
> Fixes: b36315ca69cb ("net/mlx5: fs, add HWS modify header API function")
> Signed-off-by: Alexandre Cassen <acassen@corp.free.fr>
> ---
>   .../mlx5/core/steering/hws/fs_hws_pools.c         | 10 +++-------
>   .../mellanox/mlx5/core/steering/hws/mlx5hws.h     | 15 +++++++++++++++
>   .../mellanox/mlx5/core/steering/hws/pat_arg.c     |  8 ++++----
>   3 files changed, 22 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/fs_hws_pools.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/fs_hws_pools.c
> index 86828e329187..cd888756e942 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/fs_hws_pools.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/fs_hws_pools.c
> @@ -389,7 +389,7 @@ bool mlx5_fs_hws_mh_pool_match(struct mlx5_fs_pool *mh_pool,
>   			       struct mlx5hws_action_mh_pattern *pattern)
>   {
>   	struct mlx5hws_action_mh_pattern *pool_pattern;
> -	int num_actions, i;
> +	int num_actions;
>   
>   	pool_pattern = mh_pool->pool_ctx;
>   	if (WARN_ON_ONCE(!pool_pattern))
> @@ -398,12 +398,8 @@ bool mlx5_fs_hws_mh_pool_match(struct mlx5_fs_pool *mh_pool,
>   	if (pattern->sz != pool_pattern->sz)
>   		return false;
>   	num_actions = pattern->sz / MLX5_UN_SZ_BYTES(set_add_copy_action_in_auto);
> -	for (i = 0; i < num_actions; i++) {
> -		if ((__force __be32)pattern->data[i] !=
> -		    (__force __be32)pool_pattern->data[i])
> -			return false;
> -	}
> -	return true;
> +	return mlx5hws_pat_compare_pattern(num_actions, pool_pattern->data,
> +					   num_actions, pattern->data);
>   }
>   
>   struct mlx5hws_action *mlx5_fc_get_hws_action(struct mlx5hws_context *ctx,
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/mlx5hws.h b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/mlx5hws.h
> index 1ad7a50d938b..13e9cdbc5d47 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/mlx5hws.h
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/mlx5hws.h
> @@ -688,6 +688,21 @@ mlx5hws_action_create_modify_header(struct mlx5hws_context *ctx,
>   				    u32 log_bulk_size,
>   				    u32 flags);
>   
> +/**
> + * mlx5hws_pat_compare_pattern - Compare two modify header patterns.
> + *
> + * @cur_num_of_actions: Number of actions in "cur_actions" array.
> + * @cur_actions: First pattern actions.
> + * @num_of_actions: Number of actions in "actions" array.
> + * @actions: Second pattern actions.
> + *
> + * Return: true if the patterns differ only in values, false otherwise.
> + */
> +bool mlx5hws_pat_compare_pattern(int cur_num_of_actions,
> +				 __be64 cur_actions[],
> +				 int num_of_actions,
> +				 __be64 actions[]);
> +

Please move this to pat_arg.h instead - this is not really a part of HWS API,
but an internal helper function.

-- YK


>   /**
>    * mlx5hws_action_create_aso_meter - Create direct rule ASO flow meter action.
>    *
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/pat_arg.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/pat_arg.c
> index 512299b59fd0..a49115f04025 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/pat_arg.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/pat_arg.c
> @@ -96,10 +96,10 @@ void mlx5hws_pat_uninit_pattern_cache(struct mlx5hws_pattern_cache *cache)
>   	kfree(cache);
>   }
>   
> -static bool mlx5hws_pat_compare_pattern(int cur_num_of_actions,
> -					__be64 cur_actions[],
> -					int num_of_actions,
> -					__be64 actions[])
> +bool mlx5hws_pat_compare_pattern(int cur_num_of_actions,
> +				 __be64 cur_actions[],
> +				 int num_of_actions,
> +				 __be64 actions[])
>   {
>   	int i;
>