Re: [dpdk-dev] [PATCH] net/mlx4: verify RSS supports num Rx Qs being used

[Matan Azrad <matan@mellanox.com>]

Hi Moti

Small comment below.

From: Mordechay Haimovsky
> This patch verifies that the number of Rx queues configured for RSS is
> supported by the device hardware.
> RSS support in mlx4 requires contiguous chunk of QPs to be reserved, there is a
> hardware limitation on the amount of contiguous QPs which is reported by the
> hardware. Ignoring this value will cause Rx queues creation to fail.
> 
> Signed-off-by: Moti Haimovsky <motih@mellanox.com>
> ---
>  drivers/net/mlx4/mlx4.c     | 3 +++
>  drivers/net/mlx4/mlx4.h     | 1 +
>  drivers/net/mlx4/mlx4_rxq.c | 6 ++++++
>  3 files changed, 10 insertions(+)
> 
> diff --git a/drivers/net/mlx4/mlx4.c b/drivers/net/mlx4/mlx4.c index
> c67d2c0..defc0d4 100644
> --- a/drivers/net/mlx4/mlx4.c
> +++ b/drivers/net/mlx4/mlx4.c
> @@ -673,6 +673,9 @@ struct mlx4_conf {
>  						   &device_attr_ex);
>  		DEBUG("supported RSS hash fields mask: %016" PRIx64,
>  		      priv->hw_rss_sup);
> +		priv->hw_rss_max_qps =
> +
> 	device_attr_ex.rss_caps.max_rwq_indirection_table_size;
> +		DEBUG("MAX RSS queues %d", priv->hw_rss_max_qps);
>  		priv->hw_fcs_strip = !!(device_attr_ex.raw_packet_caps &
> 
> 	IBV_RAW_PACKET_CAP_SCATTER_FCS);
>  		DEBUG("FCS stripping toggling is %ssupported", diff --git
> a/drivers/net/mlx4/mlx4.h b/drivers/net/mlx4/mlx4.h index 89d8c38..e6fb934
> 100644
> --- a/drivers/net/mlx4/mlx4.h
> +++ b/drivers/net/mlx4/mlx4.h
> @@ -95,6 +95,7 @@ struct priv {
>  	uint32_t hw_fcs_strip:1; /**< FCS stripping toggling is supported. */
>  	uint32_t tso:1; /**< Transmit segmentation offload is supported. */
>  	uint32_t tso_max_payload_sz; /**< Max supported TSO payload size.
> */
> +	uint32_t hw_rss_max_qps; /**< Max Rx Queues supported by RSS. */
>  	uint64_t hw_rss_sup; /**< Supported RSS hash fields (Verbs format). */
>  	struct rte_intr_handle intr_handle; /**< Port interrupt handle. */
>  	struct mlx4_drop *drop; /**< Shared resources for drop flow rules. */
> diff --git a/drivers/net/mlx4/mlx4_rxq.c b/drivers/net/mlx4/mlx4_rxq.c index
> 0cd9560..e8bef1d 100644
> --- a/drivers/net/mlx4/mlx4_rxq.c
> +++ b/drivers/net/mlx4/mlx4_rxq.c
> @@ -338,6 +338,12 @@ struct mlx4_rss *
> 
>  	if (priv->rss_init)
>  		return 0;
> +	if (priv->dev->data->nb_rx_queues > priv->hw_rss_max_qps) {
> +		ERROR("RSS does not support more than %d queues",
> +		      priv->hw_rss_max_qps);
> +		rte_errno = EINVAL;

What's about E2BIG ?

> +		return -rte_errno;
> +	}
>  	/* Prepare range for RSS contexts before creating the first WQ. */
>  	ret = mlx4_glue->dv_set_context_attr
>  		(priv->ctx,
> --
> 1.8.3.1

Besides that;
Acked-by: Matan Azrad <matan@mellanox.com>