[Intel-wired-lan] [PATCH iwl-next v1 3/3] igc: allow configuring RSS key via ethtool set_rxfh

[Loktionov, Aleksandr]

> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces at osuosl.org> On Behalf
> Of Kohei Enju
> Sent: Saturday, October 25, 2025 5:02 PM
> To: intel-wired-lan at lists.osuosl.org; netdev at vger.kernel.org
> Cc: Nguyen, Anthony L <anthony.l.nguyen at intel.com>; Kitszel,
> Przemyslaw <przemyslaw.kitszel at intel.com>; Andrew Lunn
> <andrew+netdev at lunn.ch>; David S. Miller <davem at davemloft.net>; Eric
> Dumazet <edumazet at google.com>; Jakub Kicinski <kuba at kernel.org>; Paolo
> Abeni <pabeni at redhat.com>; kohei.enju at gmail.com; Kohei Enju
> <enjuk at amazon.com>
> Subject: [Intel-wired-lan] [PATCH iwl-next v1 3/3] igc: allow
> configuring RSS key via ethtool set_rxfh
> 
> Change igc_ethtool_set_rxfh() to accept and save a userspace-provided
> RSS key. When a key is provided, store it in the adapter and write the
> RSSRK registers accordingly.
> 
> This can be tested using `ethtool -X <dev> hkey <key>`.
> 
> Signed-off-by: Kohei Enju <enjuk at amazon.com>
> ---
>  drivers/net/ethernet/intel/igc/igc.h         |  1 +
>  drivers/net/ethernet/intel/igc/igc_ethtool.c | 31 ++++++++++++-------
> -
>  drivers/net/ethernet/intel/igc/igc_main.c    |  3 +-
>  3 files changed, 21 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/igc/igc.h
> b/drivers/net/ethernet/intel/igc/igc.h
> index dd159397d191..c894a5a99fc0 100644
> --- a/drivers/net/ethernet/intel/igc/igc.h
> +++ b/drivers/net/ethernet/intel/igc/igc.h
> @@ -304,6 +304,7 @@ struct igc_adapter {
> 
>  	u8 rss_indir_tbl[IGC_RETA_SIZE];
>  	u8 rss_key[IGC_RSS_KEY_SIZE];
> +	bool has_user_rss_key;
> 
>  	unsigned long link_check_timeout;
>  	struct igc_info ei;
> diff --git a/drivers/net/ethernet/intel/igc/igc_ethtool.c
> b/drivers/net/ethernet/intel/igc/igc_ethtool.c
> index 0482e590bc5a..64eac1ccb3ff 100644
> --- a/drivers/net/ethernet/intel/igc/igc_ethtool.c
> +++ b/drivers/net/ethernet/intel/igc/igc_ethtool.c
> @@ -1527,24 +1527,29 @@ static int igc_ethtool_set_rxfh(struct
> net_device *netdev,
>  	int i;
> 
>  	/* We do not allow change in unsupported parameters */
> -	if (rxfh->key ||
> -	    (rxfh->hfunc != ETH_RSS_HASH_NO_CHANGE &&
> -	     rxfh->hfunc != ETH_RSS_HASH_TOP))
> +	if (rxfh->hfunc != ETH_RSS_HASH_NO_CHANGE &&
> +	    rxfh->hfunc != ETH_RSS_HASH_TOP)
>  		return -EOPNOTSUPP;
> -	if (!rxfh->indir)
> -		return 0;
> 
> -	num_queues = adapter->rss_queues;
> +	if (rxfh->indir) {
> +		num_queues = adapter->rss_queues;
> 
> -	/* Verify user input. */
> -	for (i = 0; i < IGC_RETA_SIZE; i++)
> -		if (rxfh->indir[i] >= num_queues)
> -			return -EINVAL;
> +		/* Verify user input. */
> +		for (i = 0; i < IGC_RETA_SIZE; i++)
> +			if (rxfh->indir[i] >= num_queues)
> +				return -EINVAL;
> 
> -	for (i = 0; i < IGC_RETA_SIZE; i++)
> -		adapter->rss_indir_tbl[i] = rxfh->indir[i];
> +		for (i = 0; i < IGC_RETA_SIZE; i++)
> +			adapter->rss_indir_tbl[i] = rxfh->indir[i];
> 
> -	igc_write_rss_indir_tbl(adapter);
> +		igc_write_rss_indir_tbl(adapter);
> +	}
> +
> +	if (rxfh->key) {
> +		adapter->has_user_rss_key = true;
> +		memcpy(adapter->rss_key, rxfh->key, sizeof(adapter-
> >rss_key));
> +		igc_write_rss_key(adapter);
> +	}
> 
>  	return 0;
>  }
> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c
> b/drivers/net/ethernet/intel/igc/igc_main.c
> index 1f0a601cbcef..e977661bed2f 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -779,7 +779,8 @@ static void igc_setup_mrqc(struct igc_adapter
> *adapter)
>  	u32 j, num_rx_queues;
>  	u32 mrqc, rxcsum;
> 
> -	netdev_rss_key_fill(adapter->rss_key, sizeof(adapter-
> >rss_key));
> +	if (!adapter->has_user_rss_key)
> +		netdev_rss_key_fill(adapter->rss_key, sizeof(adapter-
> >rss_key));
>  	igc_write_rss_key(adapter);
> 
>  	num_rx_queues = adapter->rss_queues;
> --
> 2.51.0

Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov at intel.com>