[dpdk-dev] [PATCH v6 2/3] ethdev: extend RSS offload types

[Andrew Rybchenko]

On 9/29/19 8:11 AM, Simei Su wrote:
> This patch reserves several bits as input set selection from the
> high end of the 64 bits. It is combined with exisiting ETH_RSS_*
> to represent rss types.

rss -> RSS

> for example:
>    ETH_RSS_IPV4 | ETH_RSS_L3_SRC_ONLY: hash on src ip address only
>    ETH_RSS_IPV4_UDP | ETH_RSS_L4_DST_ONLY: hash on src/dst IP and
>                                            dst UDP port
>
> Signed-off-by: Simei Su <simei.su at intel.com>
> ---
>   lib/librte_ethdev/rte_ethdev.h | 13 +++++++++++++
>   1 file changed, 13 insertions(+)
>
> diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h
> index 7722f70..e68bca8 100644
> --- a/lib/librte_ethdev/rte_ethdev.h
> +++ b/lib/librte_ethdev/rte_ethdev.h
> @@ -505,6 +505,19 @@ struct rte_eth_rss_conf {
>   #define ETH_RSS_GENEVE             (1ULL << 20)
>   #define ETH_RSS_NVGRE              (1ULL << 21)
>   
> +/*
> + * We use the following macros to combine with above ETH_RSS_* for
> + * more specific input set selection. These bits are defined starting
> + * from the high end of the 64 bits.
> + * Note: If we use above ETH_RSS_* without SRC/DST_ONLY, it represents
> + * both SRC and DST are taken into account. SRC_ONLY and DST_ONLY of
> + * the same level can't be used simultaneously.
> + */
> +#define ETH_RSS_L3_SRC_ONLY        (1ULL << 63)
> +#define ETH_RSS_L3_DST_ONLY        (1ULL << 62)
> +#define ETH_RSS_L4_SRC_ONLY        (1ULL << 61)
> +#define ETH_RSS_L4_DST_ONLY        (1ULL << 60)
> +
>   #define ETH_RSS_IP ( \
>   	ETH_RSS_IPV4 | \
>   	ETH_RSS_FRAG_IPV4 | \

It could be tricky and inconvenient for apps to avoid both ONLY
bits on the same level. E.g. if driver/HW supports both only flags,
it will be reported in caps and if app simply inherits it from caps,
both bits will be set.

Anyway it requires checks in rte_eth_dev_rss_hash_update() and
rte_eth_dev_configure(). If both only flags are not allows, it should
be checked and denied. If both only flags are allows and equal to
no flags at all, it should be simplified automatically to one variant
(I would say no flags at all).