RE: [PATCH v3] net/mlx5: fix the NIC egress flow mismatch in switchdev mode

[Ori Kam <orika@nvidia.com>]

Hi Jiawei,

> -----Original Message-----
> From: Jiawei(Jonny) Wang <jiaweiw@nvidia.com>
> Sent: Friday, November 12, 2021 2:43 PM
> Subject: [PATCH v3] net/mlx5: fix the NIC egress flow mismatch in switchdev mode
> 
> When E-Switch mode was enabled, the NIC egress flows was implicitly
> appended with source vport to match on. If the metadata register C0
> was used to maintain the source vport, it was initialized to zero
> on packet steering engine entry, the flow could be hit only
> if source vport was zero, the register C0 of the packet was not correct
> to match in the TX side, this caused egress flow misses.
> 
> This patch:
>  - removes the implicit source vport match for NIC egress flow.
>  - rejects the NIC egress flows on the representor ports at validation.
>  - allows the internal NIC egress flows containing the TX_QUEUE items in
>    order to not impact hairpins.
> 
> Fixes: ce777b147bf8 ("net/mlx5: fix E-Switch flow without port item")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Jiawei Wang <jiaweiw@nvidia.com>
> Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
> ---
> v3: update the tx_item checking
> v2: fix one typo
> ---
>  doc/guides/nics/mlx5.rst        |  2 ++
>  drivers/net/mlx5/mlx5_flow_dv.c | 24 ++++++++++++++++++++----
>  2 files changed, 22 insertions(+), 4 deletions(-)
> 
> diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
> index 043d006a2b..267d25ebb8 100644
> --- a/doc/guides/nics/mlx5.rst
> +++ b/doc/guides/nics/mlx5.rst
> @@ -493,6 +493,8 @@ Limitations
>      completions, the scheduled send timestamps should not be specified
>      with non-zero msb
> 
> +- The NIC Egress flow on representor port is not supported.
> +
>  Statistics
>  ----------
> 
> diff --git a/drivers/net/mlx5/mlx5_flow_dv.c b/drivers/net/mlx5/mlx5_flow_dv.c
> index 28911d6f0f..201f04ca84 100644
> --- a/drivers/net/mlx5/mlx5_flow_dv.c
> +++ b/drivers/net/mlx5/mlx5_flow_dv.c
> @@ -7164,8 +7164,10 @@ flow_dv_validate(struct rte_eth_dev *dev, const struct rte_flow_attr
> *attr,
>  				return ret;
>  			last_item = MLX5_FLOW_ITEM_TAG;
>  			break;
> -		case MLX5_RTE_FLOW_ITEM_TYPE_TAG:
>  		case MLX5_RTE_FLOW_ITEM_TYPE_TX_QUEUE:
> +			last_item = MLX5_FLOW_ITEM_TX_QUEUE;
> +			break;
> +		case MLX5_RTE_FLOW_ITEM_TYPE_TAG:
>  			break;
>  		case RTE_FLOW_ITEM_TYPE_GTP:
>  			ret = flow_dv_validate_item_gtp(dev, items, item_flags,
> @@ -7999,6 +8001,18 @@ flow_dv_validate(struct rte_eth_dev *dev, const struct rte_flow_attr
> *attr,
>  		return rte_flow_error_set(error, EINVAL,
>  				RTE_FLOW_ERROR_TYPE_ACTION, NULL,
>  				"sample before modify action is not supported");
> +	/*
> +	 * Validation the NIC Egress flow on representor, except implicit
> +	 * hairpin default egress flow with TX_QUEUE item, other flows not
> +	 * work due to metadata regC0 mismatch.
> +	 */
> +	if ((!attr->transfer && attr->egress) && priv->representor &&
> +	    !(item_flags & MLX5_FLOW_ITEM_TX_QUEUE))
> +		return rte_flow_error_set(error, EINVAL,
> +					  RTE_FLOW_ERROR_TYPE_ITEM,
> +					  NULL,
> +					  "NIC egress rules on representors"
> +					  " is not supported");
>  	return 0;
>  }
> 
> @@ -13563,11 +13577,13 @@ flow_dv_translate(struct rte_eth_dev *dev,
>  	/*
>  	 * When E-Switch mode is enabled, we have two cases where we need to
>  	 * set the source port manually.
> -	 * The first one, is in case of Nic steering rule, and the second is
> -	 * E-Switch rule where no port_id item was found. In both cases
> -	 * the source port is set according the current port in use.
> +	 * The first one, is in case of NIC ingress steering rule, and the
> +	 * second is E-Switch rule where no port_id item was found.
> +	 * In both cases the source port is set according the current port
> +	 * in use.
>  	 */
>  	if (!(item_flags & MLX5_FLOW_ITEM_PORT_ID) &&
> +	    !(attr->egress && !attr->transfer) &&
>  	    (priv->representor || priv->master)) {
>  		if (flow_dv_translate_item_port_id(dev, match_mask,
>  						   match_value, NULL, attr))
> --
> 2.18.1

Acked-by: Ori Kam <orika@nvidia.com>
Best,
Ori