virtio: RSS support capa

[Andrew Rybchenko]

On 9/7/24 23:55, Morten Brørup wrote:
>> From: Morten Brørup [mailto:mb at smartsharesystems.com]
>> Sent: Friday, 6 September 2024 21.38
>>
>> Maxime, Chenbo,
>>
>> If the virtio PMD supports RSS, it should be announced in its
>> capabilities.
>>
>> I think this should be added to virtio_dev_info_get():
>>
>> 	if (host_features & (1ULL << VIRTIO_NET_F_RSS))
>> 		dev_info->rx_offload_capa |= RTE_ETH_RX_OFFLOAD_RSS_HASH;
> 
> Or perhaps I'm misunderstanding this capability flag.
> 
> I thought it indicated RSS ability, i.e. multi-queue, effectively shadowing rte_eth_conf.rxmode.mq_mode RTE_ETH_MQ_RX_RSS_FLAG.
> But maybe it doesn't. Maybe it indicates the ability to store the RSS hash value in the mbuf.
> 
> The RTE_ETH_RX_OFFLOAD_RSS_HASH flag is completely undocumented.
> 
> Can someone please clarify?
>
RTE_ETH_RX_OFFLOAD_RSS_HASH means that the driver can provide RSS hash
value in mbuf (it makes sense if HW can provide it to the driver).