Re: [dpdk-dev] [PATCH v2] net/mlx5: set RSS key to NULL to indicate default RSS

[Shahaf Shuler <shahafs@mellanox.com>]

Hi Ophir, 

Thursday, November 1, 2018 10:59 AM, Ophir Munk:
> Subject: [PATCH v2] net/mlx5: set RSS key to NULL to indicate default RSS
> 
> Applications which add RSS rules must supply an RSS key and length.
> If an application is only interested in default RSS operation it should not care
> about the exact RSS key.
> By setting the key to NULL - the PMD will use the default RSS key.
> In addition if the application does not care about the RSS type it can set it to 0
> and the PMD will use the default type (ETH_RSS_IP).
> 
> Signed-off-by: Ophir Munk <ophirmu@mellanox.com>
> ---
>  doc/guides/nics/mlx5.rst           |  1 +
>  drivers/net/mlx5/mlx5_flow.c       |  8 +++++++-
>  drivers/net/mlx5/mlx5_flow_dv.c    |  8 ++++++--
>  drivers/net/mlx5/mlx5_flow_verbs.c |  9 +++++++--
>  drivers/net/mlx5/mlx5_rxq.c        | 14 ++++++--------
>  lib/librte_ethdev/rte_flow.h       |  2 +-
>  6 files changed, 28 insertions(+), 14 deletions(-)
> 
> diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst index
> 6769628..de8f15b 100644
> --- a/doc/guides/nics/mlx5.rst
> +++ b/doc/guides/nics/mlx5.rst
> @@ -54,6 +54,7 @@ Features
>  - Support for scattered TX and RX frames.
>  - IPv4, IPv6, TCPv4, TCPv6, UDPv4 and UDPv6 RSS on any number of queues.
>  - Several RSS hash keys, one for each flow type.
> +- NULL RSS key indicates default RSS key

I don't think it is a feature, it should be an API implementation. 

>  - Configurable RETA table.
>  - Support for multiple MAC addresses.
>  - VLAN filtering.
> diff --git a/drivers/net/mlx5/mlx5_flow.c b/drivers/net/mlx5/mlx5_flow.c
> index 280af0a..5742989 100644
> --- a/drivers/net/mlx5/mlx5_flow.c
> +++ b/drivers/net/mlx5/mlx5_flow.c
> @@ -912,7 +912,13 @@ uint32_t mlx5_flow_adjust_priority(struct
> rte_eth_dev *dev, int32_t priority,
> 
> RTE_FLOW_ERROR_TYPE_ACTION_CONF,
>  					  &rss->level,
>  					  "tunnel RSS is not supported");
> -	if (rss->key_len < MLX5_RSS_HASH_KEY_LEN)
> +	/* allow RSS key_len 0 in case of NULL (default) RSS key */

Missing period. 

> +	if (rss->key_len == 0 && rss->key != NULL)
> +		return rte_flow_error_set(error, ENOTSUP,
> +
> RTE_FLOW_ERROR_TYPE_ACTION_CONF,
> +					  &rss->key_len,
> +					  "RSS hash key length 0");
> +	if (rss->key_len > 0 && rss->key_len < MLX5_RSS_HASH_KEY_LEN)

Can't you simplify using a single condition: 
If (rss->key && rss->key_len < MLX5_RSS_HASH_KEY_LEN)

Same rss->key addition should be for the case the key_len is too large. 

>  		return rte_flow_error_set(error, ENOTSUP,
> 
> RTE_FLOW_ERROR_TYPE_ACTION_CONF,
>  					  &rss->key_len,
> diff --git a/drivers/net/mlx5/mlx5_flow_dv.c
> b/drivers/net/mlx5/mlx5_flow_dv.c index 8f729f4..fd52bf4 100644
> --- a/drivers/net/mlx5/mlx5_flow_dv.c
> +++ b/drivers/net/mlx5/mlx5_flow_dv.c
> @@ -1056,6 +1056,7 @@
>  {
>  	const struct rte_flow_action_queue *queue;
>  	const struct rte_flow_action_rss *rss;
> +	uint8_t	*rss_key;

Why no declare it inside the RSS case? 

>  	int actions_n = dev_flow->dv.actions_n;
>  	struct rte_flow *flow = dev_flow->flow;
> 
> @@ -1094,8 +1095,11 @@
>  			memcpy((*flow->queue), rss->queue,
>  			       rss->queue_num * sizeof(uint16_t));
>  		flow->rss.queue_num = rss->queue_num;
> -		memcpy(flow->key, rss->key, MLX5_RSS_HASH_KEY_LEN);
> -		flow->rss.types = rss->types;
> +		/* NULL RSS key indicates default RSS key */

Missing period. 

> +		rss_key = (!rss->key) ? rss_hash_default_key : rss->key;
> +		memcpy(flow->key, rss_key, MLX5_RSS_HASH_KEY_LEN);

For consistency you should also set the key_len on the flow structure to MLX5_RSS_HASH_KEY_LEN.

> +		/* RSS type 0 indicates default RSS type ETH_RSS_IP */

Period. 

> +		flow->rss.types = !rss->types ? ETH_RSS_IP : rss->types;
>  		flow->rss.level = rss->level;
>  		/* Added to array only in apply since we need the QP */
>  		flow->actions |= MLX5_FLOW_ACTION_RSS; diff --git
> a/drivers/net/mlx5/mlx5_flow_verbs.c
> b/drivers/net/mlx5/mlx5_flow_verbs.c
> index 81bc39f..ae9042f 100644
> --- a/drivers/net/mlx5/mlx5_flow_verbs.c
> +++ b/drivers/net/mlx5/mlx5_flow_verbs.c
> @@ -925,14 +925,19 @@
>  				struct mlx5_flow *dev_flow)
>  {
>  	const struct rte_flow_action_rss *rss = action->conf;
> +	const uint8_t *rss_key;
>  	struct rte_flow *flow = dev_flow->flow;
> 
>  	if (flow->queue)
>  		memcpy((*flow->queue), rss->queue,
>  		       rss->queue_num * sizeof(uint16_t));
>  	flow->rss.queue_num = rss->queue_num;
> -	memcpy(flow->key, rss->key, MLX5_RSS_HASH_KEY_LEN);
> -	flow->rss.types = rss->types;
> +
> +	/* NULL RSS key indicates default RSS key */

period

> +	rss_key = !rss->key ? rss_hash_default_key : rss->key;

For consistency you should also set the key_len on the flow structure to MLX5_RSS_HASH_KEY_LEN. 

> +	memcpy(flow->key, rss_key, MLX5_RSS_HASH_KEY_LEN);
> +	/* RSS type 0 indicates default RSS type (ETH_RSS_IP) */

period

> +	flow->rss.types = !rss->types ? ETH_RSS_IP : rss->types;
>  	flow->rss.level = rss->level;
>  	*action_flags |= MLX5_FLOW_ACTION_RSS;  } diff --git
> a/drivers/net/mlx5/mlx5_rxq.c b/drivers/net/mlx5/mlx5_rxq.c index
> ed993ea..36fc202 100644
> --- a/drivers/net/mlx5/mlx5_rxq.c
> +++ b/drivers/net/mlx5/mlx5_rxq.c
> @@ -1783,10 +1783,6 @@ struct mlx5_hrxq *
>  		rte_errno = ENOMEM;
>  		return NULL;
>  	}
> -	if (!rss_key_len) {
> -		rss_key_len = MLX5_RSS_HASH_KEY_LEN;
> -		rss_key = rss_hash_default_key;
> -	}
>  #ifdef HAVE_IBV_DEVICE_TUNNEL_SUPPORT
>  	qp = mlx5_glue->dv_create_qp
>  		(priv->ctx,
> @@ -1798,8 +1794,7 @@ struct mlx5_hrxq *
>  				IBV_QP_INIT_ATTR_RX_HASH,
>  			.rx_hash_conf = (struct ibv_rx_hash_conf){
>  				.rx_hash_function =
> IBV_RX_HASH_FUNC_TOEPLITZ,
> -				.rx_hash_key_len = rss_key_len ?
> rss_key_len :
> -						   MLX5_RSS_HASH_KEY_LEN,
> +				.rx_hash_key_len = rss_key_len,
>  				.rx_hash_key = rss_key ?
>  					       (void *)(uintptr_t)rss_key :
>  					       rss_hash_default_key,
> @@ -1824,8 +1819,7 @@ struct mlx5_hrxq *
>  				IBV_QP_INIT_ATTR_RX_HASH,
>  			.rx_hash_conf = (struct ibv_rx_hash_conf){
>  				.rx_hash_function =
> IBV_RX_HASH_FUNC_TOEPLITZ,
> -				.rx_hash_key_len = rss_key_len ?
> rss_key_len :
> -						   MLX5_RSS_HASH_KEY_LEN,
> +				.rx_hash_key_len = rss_key_len,
>  				.rx_hash_key = rss_key ?
>  					       (void *)(uintptr_t)rss_key :
>  					       rss_hash_default_key,
> @@ -1888,8 +1882,12 @@ struct mlx5_hrxq *
>  	LIST_FOREACH(hrxq, &priv->hrxqs, next) {
>  		struct mlx5_ind_table_ibv *ind_tbl;
> 
> +		if (!rss_key_len)
> +			rss_key_len = MLX5_RSS_HASH_KEY_LEN;

In the mlx5_hrxq_new above you trust the rss_key_len to be the correct one, and it is ok since you validate it on the rss validate function.
Why it is not the case here as well? 

>  		if (hrxq->rss_key_len != rss_key_len)
>  			continue;
> +		if (!rss_key)
> +			rss_key = rss_hash_default_key;

Same question. You already copied to correct key in flow_verbs_translate_action_rss or on the flow_dv_create_action funciton. 

>  		if (memcmp(hrxq->rss_key, rss_key, rss_key_len))
>  			continue;
>  		if (hrxq->hash_fields != hash_fields) diff --git
> a/lib/librte_ethdev/rte_flow.h b/lib/librte_ethdev/rte_flow.h index
> c0fe879..6cc72ab 100644
> --- a/lib/librte_ethdev/rte_flow.h
> +++ b/lib/librte_ethdev/rte_flow.h
> @@ -1785,7 +1785,7 @@ struct rte_flow_action_rss {
>  	uint64_t types; /**< Specific RSS hash types (see ETH_RSS_*). */
>  	uint32_t key_len; /**< Hash key length in bytes. */
>  	uint32_t queue_num; /**< Number of entries in @p queue. */
> -	const uint8_t *key; /**< Hash key. */
> +	const uint8_t *key; /**< Hash key. NULL should indicate default key

This change should be on a separate commit in a separate series. 
It is better to put the doc update above the function and not inline on the field so that you can elaborate more. 
Also you are missing the same doc update for the types field. 

Note: your patch for mlx5 can be accepted also w/o it, but it is better to align all vendors and I think it is aligned w/ the spirit of the rte_flow maintainer. 

> */
>  	const uint16_t *queue; /**< Queue indices to use. */  };
> 
> --
> 1.8.3.1