Re: [PATCH iwl-next v1 14/15] ice: represent RSS LUTs as devlink resources

[Przemek Kitszel <przemyslaw.kitszel@intel.com>]

On 5/8/26 19:03, Loktionov, Aleksandr wrote:
> 
> 
>> -----Original Message-----
>> From: Kitszel, Przemyslaw <przemyslaw.kitszel@intel.com>
>> Sent: Friday, May 8, 2026 2:42 PM
>> To: intel-wired-lan@lists.osuosl.org; Schmidt, Michal
>> <mschmidt@redhat.com>; Jakub Kicinski <kuba@kernel.org>; Jiri Pirko
>> <jiri@resnulli.us>
>> Cc: netdev@vger.kernel.org; Simon Horman <horms@kernel.org>; Nguyen,
>> Anthony L <anthony.l.nguyen@intel.com>; Michal Swiatkowski
>> <michal.swiatkowski@linux.intel.com>; Richardson, Bruce
>> <bruce.richardson@intel.com>; Medvedkin, Vladimir
>> <vladimir.medvedkin@intel.com>; Connolly, Padraig J
>> <padraig.j.connolly@intel.com>; S, Ananth <ananth.s@intel.com>;
>> Miskell, Timothy <timothy.miskell@intel.com>; Keller, Jacob E
>> <jacob.e.keller@intel.com>; Czapnik, Lukasz
>> <lukasz.czapnik@intel.com>; Loktionov, Aleksandr
>> <aleksandr.loktionov@intel.com>; Andrew Lunn <andrew+netdev@lunn.ch>;
>> David S. Miller <davem@davemloft.net>; Eric Dumazet
>> <edumazet@google.com>; Paolo Abeni <pabeni@redhat.com>; Saeed Mahameed
>> <saeedm@nvidia.com>; Leon Romanovsky <leon@kernel.org>; Tariq Toukan
>> <tariqt@nvidia.com>; Mark Bloch <mbloch@nvidia.com>; Kitszel,
>> Przemyslaw <przemyslaw.kitszel@intel.com>
>> Subject: [PATCH iwl-next v1 14/15] ice: represent RSS LUTs as devlink
>> resources
>>
>> E800 family offers three kinds of RSS LUTs: VSI LUT (sized 64), GLOBAL
>> LUT (sized 256), and PF LUT (sized 2048). Until now the GLOBAL kind
>> was not used at all. There are two possible usages for it, subsequent
>> commit will give VF option to acquire it, and this one enables PF to
>> switch between PF LUT and GLOBAL LUT - switching to smaller one is,
>> again, to make it possible for VF to then acquire the former one.
>>
>> Devlink resources are used to let user show current usage and change
>> the allocation, see examples below.
>>
>> Default state on 8-port card, asking for aggregate "whole device"
>> usage, note that there are as many PF LUTs as there is PFs, and, for
>> e810, there are 16 GLOBAL LUTs:
>> $ devlink resource show devlink_index/11
>> devlink_index/11:
>>    name rss size 8 unit entry size_min 0 size_max 24 size_gran 1
>> dpipe_tables none
>>      resources:
>>        name lut_512 size 0 unit entry size_min 0 size_max 16 size_gran
>> 1 dpipe_tables none
>>        name lut_2048 size 8 unit entry size_min 0 size_max 8 size_gran
>> 1 dpipe_tables none
>>
>> Now let's add GLOBAL LUT for a single PF (on one-port NIC):
>> $ sudo devlink resource set pci/0000:18:00.0 path rss/lut_512 size 1
>> And show it's resources after that:
>> $ devlink resource show pci/0000:18:00.0
>> pci/0000:18:00.0:
>>    name rss size 2 unit entry size_min 0 size_max 2 size_gran 1
>> dpipe_tables none
>>      resources:
>>        name lut_512 size 1 unit entry size_min 0 size_max 1 size_gran 1
>> dpipe_tables none
>>        name lut_2048 size 1 unit entry size_min 0 size_max 1 size_gran
>> 1 dpipe_tables none Let's take the PF LUT out of that PF afterwards:
>> $ sudo devlink resource set pci/0000:18:00.0 path rss/lut_2048 size 0
>> now `ethtool -x $ifacename` will report smaller RSS table.
>>
>> Signed-off-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
>> ---
>>   drivers/net/ethernet/intel/ice/Makefile       |   1 +
>>   .../net/ethernet/intel/ice/devlink/resource.h |  19 +
>> drivers/net/ethernet/intel/ice/ice_adapter.h  |  40 ++
>>   drivers/net/ethernet/intel/ice/ice_common.h   |   1 +
>>   .../net/ethernet/intel/ice/devlink/resource.c | 469
>> ++++++++++++++++++  drivers/net/ethernet/intel/ice/ice_adapter.c  |
>> 12 +-
>>   drivers/net/ethernet/intel/ice/ice_common.c   |   2 +-
>>   drivers/net/ethernet/intel/ice/ice_lib.c      |  23 +-
>>   drivers/net/ethernet/intel/ice/ice_main.c     |  14 +-
>>   9 files changed, 573 insertions(+), 8 deletions(-)  create mode
>> 100644 drivers/net/ethernet/intel/ice/devlink/resource.h
>>   create mode 100644 drivers/net/ethernet/intel/ice/devlink/resource.c
>>
>> diff --git a/drivers/net/ethernet/intel/ice/Makefile
>> b/drivers/net/ethernet/intel/ice/Makefile
>> index 7f06d9bafe4a..0217ab6403de 100644
>> --- a/drivers/net/ethernet/intel/ice/Makefile
>> +++ b/drivers/net/ethernet/intel/ice/Makefile
>> @@ -37,6 +37,7 @@ ice-y := ice_main.o	\
>>   	 devlink/devlink.o	\
>>   	 devlink/health.o \
>>   	 devlink/port.o \
> 
> ...
> 
>> +
>> +static int ice_devl_res_take(struct ice_pf *pf,
>> +			     enum ice_devl_resource_id res_id, int slot,
>> +			     void *owner)
>> +{
>> +	struct ice_devl_resource *res = &pf->adapter-
>>> resources[res_id];
>> +	int end = slot == ICE_ANY_SLOT ? res->max_size : slot + 1;
>> +	int beg = slot == ICE_ANY_SLOT ? 0 : slot;
>> +	int err, new_id = ICE_ANY_SLOT;
>> +
>> +	for (int id = beg; id < end; id++) {
>> +		if (!res->owner[id]) {
>> +			new_id = id;
>> +			break;
>> +		}
>> +	}
>> +	if (new_id == ICE_ANY_SLOT)
>> +		return -ENOSPC;
>> +
>> +	if (res_id == ICE_RSS_LUT_GLOBAL) {
>> +		struct ice_vsi *vsi;
>> +		u16 lut_id;
>> +
>> +		err = ice_alloc_rss_global_lut(&pf->hw, &lut_id);
>> +		if (err)
>> +			return err;
>> +		if (lut_id != new_id)
>> +			return -ENOANO;
>   -ENOANO; looks for me very unusual choice.
> BTW won't LUT leak without calling ice_free_rss_global_lut() ?

I will replace it by WARN_ONCE() and just let use the ID we were
assigned by FW

> 
>> +
>> +		if (pf == owner)
>> +			vsi = ice_get_main_vsi(pf);
>> +		else
>> +			vsi = ice_get_vf_vsi(owner);
>> +
>> +		vsi->global_lut_id = new_id;
>> +	}
>> +
>> +	res->owner[new_id] = owner;
>> +	res->pf_id[new_id] = pf->hw.pf_id;
>> +	return new_id;
>> +}
> 
> ...
> 
>>
>>   	return status;
>>   }
>> --
>> 2.39.3
>