Re: [PATCH iwl-next v4 3/3] igb: allow configuring RSS key via ethtool set_rxfh

[Tony Nguyen <anthony.l.nguyen@intel.com>]

On 1/25/2026 5:12 AM, Kohei Enju wrote:
> On Tue, 20 Jan 2026 18:34:40 +0900, Takashi Kozu wrote:
> 
>> Change igc_set_rxfh() to accept and save a userspace-provided
>> RSS key. When a key is provided, store it in the adapter and write the
>> E1000 registers accordingly.
>>
>> This can be tested using `ethtool -X <dev> hkey <key>`.
>>
>> Signed-off-by: Takashi Kozu <takkozu@amazon.com>
>> ---
>>   drivers/net/ethernet/intel/igb/igb.h         |  1 +
>>   drivers/net/ethernet/intel/igb/igb_ethtool.c | 49 +++++++++++---------
>>   drivers/net/ethernet/intel/igb/igb_main.c    |  3 +-
>>   3 files changed, 30 insertions(+), 23 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/intel/igb/igb.h b/drivers/net/ethernet/intel/igb/igb.h
>> index 8c9b02058cec..2509ec30acf3 100644
>> --- a/drivers/net/ethernet/intel/igb/igb.h
>> +++ b/drivers/net/ethernet/intel/igb/igb.h
>> @@ -657,6 +657,7 @@ struct igb_adapter {
>>   	u32 rss_indir_tbl_init;
>>   	u8 rss_indir_tbl[IGB_RETA_SIZE];
>>   	u8 rss_key[IGB_RSS_KEY_SIZE];
>> +	bool has_user_rss_key;
> 
> Hi Kozu-san.
> 
> While preparing for testing, I noticed that now 'has_user_rss_key' is
> not necessary.
> 
> Since netdev_rss_key_fill() is called in igb_sw_init() and igb_sw_init()
> is called only once for the adapter's lifetime, adapter->rss_key
> wouldn't be changed except for user-intended change.
> 
> I'd drop that flag and related code (see below)

Hi Kohei,

I believe this igb implementation was based on your igc implementation 
which also has the same. Would it be possible for you to update the igc 
to do this as well?

Thanks,
Tony

>>   
>>   	unsigned long link_check_timeout;
>>   	int copper_tries;
>> diff --git a/drivers/net/ethernet/intel/igb/igb_ethtool.c b/drivers/net/ethernet/intel/igb/igb_ethtool.c
>> index b387121f0ea7..1db9c2447c91 100644
>> --- a/drivers/net/ethernet/intel/igb/igb_ethtool.c
>> +++ b/drivers/net/ethernet/intel/igb/igb_ethtool.c
>> @@ -3357,35 +3357,40 @@ static int igb_set_rxfh(struct net_device *netdev,
>>   	u32 num_queues;
>>   
>>   	/* 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;
>>   
>> -	switch (hw->mac.type) {
>> -	case e1000_82576:
>> -		/* 82576 supports 2 RSS queues for SR-IOV */
>> -		if (adapter->vfs_allocated_count)
>> -			num_queues = 2;
>> -		break;
>> -	default:
>> -		break;
>> -	}
>> +		switch (hw->mac.type) {
>> +		case e1000_82576:
>> +			/* 82576 supports 2 RSS queues for SR-IOV */
>> +			if (adapter->vfs_allocated_count)
>> +				num_queues = 2;
>> +			break;
>> +		default:
>> +			break;
>> +		}
>>   
>> -	/* Verify user input. */
>> -	for (i = 0; i < IGB_RETA_SIZE; i++)
>> -		if (rxfh->indir[i] >= num_queues)
>> -			return -EINVAL;
>> +		/* Verify user input. */
>> +		for (i = 0; i < IGB_RETA_SIZE; i++)
>> +			if (rxfh->indir[i] >= num_queues)
>> +				return -EINVAL;
>>   
>>   
>> -	for (i = 0; i < IGB_RETA_SIZE; i++)
>> -		adapter->rss_indir_tbl[i] = rxfh->indir[i];
>> +		for (i = 0; i < IGB_RETA_SIZE; i++)
>> +			adapter->rss_indir_tbl[i] = rxfh->indir[i];
>> +
>> +		igb_write_rss_indir_tbl(adapter);
>> +	}
>>   
>> -	igb_write_rss_indir_tbl(adapter);
>> +	if (rxfh->key) {
>> +		adapter->has_user_rss_key = true;
> 
> here
> 
>> +		memcpy(adapter->rss_key, rxfh->key, sizeof(adapter->rss_key));
>> +		igb_write_rss_key(adapter);
>> +	}
>>   
>>   	return 0;
>>   }
>> diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
>> index c703011b19ec..8dab133296ca 100644
>> --- a/drivers/net/ethernet/intel/igb/igb_main.c
>> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
>> @@ -4051,7 +4051,8 @@ static int igb_sw_init(struct igb_adapter *adapter)
>>   	pci_read_config_word(pdev, PCI_COMMAND, &hw->bus.pci_cmd_word);
>>   
>>   	/* init RSS key */
>> -	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));
> 
> and this diff.
> 
>>   
>>   	/* set default ring sizes */
>>   	adapter->tx_ring_count = IGB_DEFAULT_TXD;
>> -- 
>> 2.52.0
>