Re: [PATCH] net/vmxnet3: added checks for TCP for RSS Configuration

[Ferruh Yigit <ferruh.yigit@amd.com>]

On 12/22/2022 8:24 AM, Raghav Roy wrote:
> Added checks for TCP in vmxnet3_rss_configure()
> This check ensures the hashType for RSS, when enabled
> just for UDP, is not NONE.
> 

Mandatory hash functions for v4 already added in the past:
Commit 52ec00fd1474 ("net/vmxnet3: fix RSS setting on v4")

Now this commit adds it for all versions, why it was fine in the past
but it is needed now?

@Jochen, can you please help reviewing this patch?


> Signed-off-by: Raghav Roy <royra@vmware.com>
> ---
>  drivers/net/vmxnet3/vmxnet3_rxtx.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/vmxnet3/vmxnet3_rxtx.c b/drivers/net/vmxnet3/vmxnet3_rxtx.c
> index a875ffec07..e8407c9b2e 100644
> --- a/drivers/net/vmxnet3/vmxnet3_rxtx.c
> +++ b/drivers/net/vmxnet3/vmxnet3_rxtx.c
> @@ -1412,6 +1412,13 @@ vmxnet3_rss_configure(struct rte_eth_dev *dev)
>  	dev_rss_conf = hw->rss_conf;
>  	port_rss_conf = &dev->data->dev_conf.rx_adv_conf.rss_conf;
>  
> +	if ((port_rss_conf->rss_hf & VMXNET3_MANDATORY_V4_RSS) !=
> +	   VMXNET3_MANDATORY_V4_RSS) {
> +		PMD_INIT_LOG(WARNING, "RSS: IPv4/6 TCP is required for vmxnet3 RSS, "
> +			     "automatically setting it");
> +		port_rss_conf->rss_hf |= VMXNET3_MANDATORY_V4_RSS;
> +	}
> +

`
#define VMXNET3_MANDATORY_V4_RSS ( \
	RTE_ETH_RSS_NONFRAG_IPV4_TCP | \
	RTE_ETH_RSS_NONFRAG_IPV6_TCP)
`

Can you please describe why IPv4/6 TCP hash function is required for driver?
And what is the impact, I mean what is the observed behavior without
this patch, if RSS is failing without this change patch needs to be fix
patch and please describe since when RSS is failing.

>  	/* loading hashFunc */
>  	dev_rss_conf->hashFunc = VMXNET3_RSS_HASH_FUNC_TOEPLITZ;
>  	/* loading hashKeySize */
> @@ -1419,6 +1426,7 @@ vmxnet3_rss_configure(struct rte_eth_dev *dev)
>  	/* loading indTableSize: Must not exceed VMXNET3_RSS_MAX_IND_TABLE_SIZE (128)*/
>  	dev_rss_conf->indTableSize = (uint16_t)((MAX_RX_QUEUES(hw)) * 4);
>  
> +
>  	if (port_rss_conf->rss_key == NULL) {
>  		/* Default hash key */
>  		port_rss_conf->rss_key = rss_intel_key;
> @@ -1446,6 +1454,5 @@ vmxnet3_rss_configure(struct rte_eth_dev *dev)
>  		dev_rss_conf->hashType |= VMXNET3_RSS_HASH_TYPE_IPV6;
>  	if (rss_hf & RTE_ETH_RSS_NONFRAG_IPV6_TCP)
>  		dev_rss_conf->hashType |= VMXNET3_RSS_HASH_TYPE_TCP_IPV6;
> -

Please drop unrelated/unimportant syntax changes.

>  	return VMXNET3_SUCCESS;
>  }