Re: [PATCH 19.11] net/mlx5: fix NIC egress flow mismatch in switchdev mode

[Christian Ehrhardt <christian.ehrhardt@canonical.com>]

On Sun, Mar 13, 2022 at 9:39 AM Jiawei Wang <jiaweiw@nvidia.com> wrote:
>
> [ upstream commit 6d4f1066be6cd60a95f21ef07a16a3c3676c5cd9 ]

Thank you - applied to 19.11 stable

> 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")
>
> Signed-off-by: Jiawei Wang <jiaweiw@nvidia.com>
> Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
> Acked-by: Ori Kam <orika@nvidia.com>
> ---
>  doc/guides/nics/mlx5.rst        |  2 ++
>  drivers/net/mlx5/mlx5_flow_dv.c | 26 +++++++++++++++++++++-----
>  2 files changed, 23 insertions(+), 5 deletions(-)
>
> diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
> index 546f0dd4c2..8f7b285271 100644
> --- a/doc/guides/nics/mlx5.rst
> +++ b/doc/guides/nics/mlx5.rst
> @@ -241,6 +241,8 @@ Limitations
>      from the reference "Clock Queue" completions,
>      the scheduled send timestamps should not be specified with non-zero MSB.
>
> +- The NIC egress flow rules on representor port are not supported.
> +
>  Statistics
>  ----------
>
> diff --git a/drivers/net/mlx5/mlx5_flow_dv.c b/drivers/net/mlx5/mlx5_flow_dv.c
> index dd62bbbbfb..f7e3d92045 100644
> --- a/drivers/net/mlx5/mlx5_flow_dv.c
> +++ b/drivers/net/mlx5/mlx5_flow_dv.c
> @@ -4833,8 +4833,10 @@ 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;
>                 default:
>                         return rte_flow_error_set(error, ENOTSUP,
> @@ -5313,6 +5315,18 @@ flow_dv_validate(struct rte_eth_dev *dev, const struct rte_flow_attr *attr,
>                                           NULL, "too many header modify"
>                                           " actions to support");
>         }
> +       /*
> +        * 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;
>  }
>
> @@ -7891,12 +7905,14 @@ __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) &&
> -           (priv->representor || priv->master)) {
> +           (priv->representor || priv->master) &&
> +           !(attr->egress && !attr->transfer)) {
>                 if (flow_dv_translate_item_port_id(dev, match_mask,
>                                                    match_value, NULL))
>                         return -rte_errno;
> --
> 2.18.1
>


-- 
Christian Ehrhardt
Staff Engineer, Ubuntu Server
Canonical Ltd