The resctrl selftest currently exhibits several failures on Hygon CPUs
due to missing vendor detection and edge-case handling specific to
Hygon's architecture.

This patch series addresses three distinct issues:
1. A division-by-zero crash in SNC detection on some platforms (e.g.,
   Hygon).
2. Missing CPU vendor detection, causing the test to fail with
   "# Can not get vendor info..." on Hygon CPUs.
3. Incorrect handling of non-contiguous CBM support on Hygon CPUs.

These changes enable resctrl selftest to run successfully on
Hygon CPUs that support Platform QoS features.

Maintainer notes:
-----------------
Patch 1: selftests/resctrl: Fix a division by zero error on Hygon
 - This is a candidate for backport with "Fixes:" tag.

Patch 2: selftests/resctrl: Define CPU vendor IDs as bits to match usage
 - This is *not* a candidate for backport since it is an enhancement and
   preparatory patch for patch 3.

Patch 3: selftests/resctrl: Add CPU vendor detection for Hygon
Patch 4: selftests/resctrl: Fix non-contiguous CBM check for Hygon
 - Even though they are fixes they are *not* candidates for backport
   since they are based on another patch series (x86/resctrl: Fix
   Platform QoS issues for Hygon) which is in process of being added to
   resctrl.
-----------------

Changelog:
v5:
- Patch 2:
  1. Fix a nit of "reverse fir ordering" of the variable declarations in
     detect_vendor() in v4 patch series (Reinette).
  2. Add Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>.

v4:
- Cover letter: add maintainer notes outlining how these patches to be
  handled (Reinette).
- Re-organize the patch series to move original patch 3 to the beginning
  of series. The patch order has changed between v3 and v4 (Reinette):
     v3    ->    v4
  patch #3 -> patch #1
  patch #1 -> patch #2
  patch #2 -> patch #3
  patch #4 -> patch #4
- Patch 2:
  1. Resolve a conflict against latest upstream kernel (Reinette).
  2. Fix a nit to maintain the reverse fir ordering of variables in
     detect_vendor() (Reinette).
- Patch 3: add Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
- Patch 4: move the maintainer note into the cover letter (Reinette).

v3:
- Patch 1:
  1. Update the return types of detect_vendor() and get_vendor() from
     'int' to 'unsigned int' to align with their usage as bitmask values
     and to prevent potentially risky type conversions (Fenghua).
  2. Split the code changes of "define CPU vendor IDs as bits to match
     usage" from original patch 1 into a separate patch (this patch,
     suggested by Fenghua and Reinette).
  3. Introduce the flag 'initialized' to simplify the get_vendor() ->
     detect_vendor() logic (Reinette).
- Patch 2 (original patch 1):
  1. Move the code changes of "define CPU vendor IDs as bits to match
     usage" into patch 1.
- Patch 3 (original patch 2): 
  1. Fix a nit of code comment for affected platforms (Fenghua).
  2. Add Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>.
- Patch 4 (original patch 3): 
  1. Fix a nit to avoid calling get_vendor() twice (Fenghua).
  2. Add Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>.

v2:
- Patch 1: switch all of the vendor id bitmasks to use BIT() (Reinette)
- Patch 2: add Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
- Patch 3: add Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
           add a maintainer note to highlight it is not a candidate for
	   backport (Reinette)

Xiaochen Shen (4):
  selftests/resctrl: Fix a division by zero error on Hygon
  selftests/resctrl: Define CPU vendor IDs as bits to match usage
  selftests/resctrl: Add CPU vendor detection for Hygon
  selftests/resctrl: Fix non-contiguous CBM check for Hygon

 tools/testing/selftests/resctrl/cat_test.c    |  6 ++--
 tools/testing/selftests/resctrl/resctrl.h     |  8 ++++--
 .../testing/selftests/resctrl/resctrl_tests.c | 28 +++++++++++++------
 tools/testing/selftests/resctrl/resctrlfs.c   | 10 +++++++
 4 files changed, 39 insertions(+), 13 deletions(-)

-- 
2.47.3

Dear Shuah,

Could you please consider this series for inclusion?

Thank you very much.

Reinette

On 12/16/25 7:04 PM, Xiaochen Shen wrote:
> The resctrl selftest currently exhibits several failures on Hygon CPUs
> due to missing vendor detection and edge-case handling specific to
> Hygon's architecture.
> 
> This patch series addresses three distinct issues:
> 1. A division-by-zero crash in SNC detection on some platforms (e.g.,
>    Hygon).
> 2. Missing CPU vendor detection, causing the test to fail with
>    "# Can not get vendor info..." on Hygon CPUs.
> 3. Incorrect handling of non-contiguous CBM support on Hygon CPUs.
> 
> These changes enable resctrl selftest to run successfully on
> Hygon CPUs that support Platform QoS features.
> 
> Maintainer notes:
> -----------------
> Patch 1: selftests/resctrl: Fix a division by zero error on Hygon
>  - This is a candidate for backport with "Fixes:" tag.
> 
> Patch 2: selftests/resctrl: Define CPU vendor IDs as bits to match usage
>  - This is *not* a candidate for backport since it is an enhancement and
>    preparatory patch for patch 3.
> 
> Patch 3: selftests/resctrl: Add CPU vendor detection for Hygon
> Patch 4: selftests/resctrl: Fix non-contiguous CBM check for Hygon
>  - Even though they are fixes they are *not* candidates for backport
>    since they are based on another patch series (x86/resctrl: Fix
>    Platform QoS issues for Hygon) which is in process of being added to
>    resctrl.
> -----------------
> 
> Changelog:
> v5:
> - Patch 2:
>   1. Fix a nit of "reverse fir ordering" of the variable declarations in
>      detect_vendor() in v4 patch series (Reinette).
>   2. Add Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>.
> 
> v4:
> - Cover letter: add maintainer notes outlining how these patches to be
>   handled (Reinette).
> - Re-organize the patch series to move original patch 3 to the beginning
>   of series. The patch order has changed between v3 and v4 (Reinette):
>      v3    ->    v4
>   patch #3 -> patch #1
>   patch #1 -> patch #2
>   patch #2 -> patch #3
>   patch #4 -> patch #4
> - Patch 2:
>   1. Resolve a conflict against latest upstream kernel (Reinette).
>   2. Fix a nit to maintain the reverse fir ordering of variables in
>      detect_vendor() (Reinette).
> - Patch 3: add Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
> - Patch 4: move the maintainer note into the cover letter (Reinette).
> 
> v3:
> - Patch 1:
>   1. Update the return types of detect_vendor() and get_vendor() from
>      'int' to 'unsigned int' to align with their usage as bitmask values
>      and to prevent potentially risky type conversions (Fenghua).
>   2. Split the code changes of "define CPU vendor IDs as bits to match
>      usage" from original patch 1 into a separate patch (this patch,
>      suggested by Fenghua and Reinette).
>   3. Introduce the flag 'initialized' to simplify the get_vendor() ->
>      detect_vendor() logic (Reinette).
> - Patch 2 (original patch 1):
>   1. Move the code changes of "define CPU vendor IDs as bits to match
>      usage" into patch 1.
> - Patch 3 (original patch 2): 
>   1. Fix a nit of code comment for affected platforms (Fenghua).
>   2. Add Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>.
> - Patch 4 (original patch 3): 
>   1. Fix a nit to avoid calling get_vendor() twice (Fenghua).
>   2. Add Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>.
> 
> v2:
> - Patch 1: switch all of the vendor id bitmasks to use BIT() (Reinette)
> - Patch 2: add Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
> - Patch 3: add Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
>            add a maintainer note to highlight it is not a candidate for
> 	   backport (Reinette)
> 
> Xiaochen Shen (4):
>   selftests/resctrl: Fix a division by zero error on Hygon
>   selftests/resctrl: Define CPU vendor IDs as bits to match usage
>   selftests/resctrl: Add CPU vendor detection for Hygon
>   selftests/resctrl: Fix non-contiguous CBM check for Hygon
> 
>  tools/testing/selftests/resctrl/cat_test.c    |  6 ++--
>  tools/testing/selftests/resctrl/resctrl.h     |  8 ++++--
>  .../testing/selftests/resctrl/resctrl_tests.c | 28 +++++++++++++------
>  tools/testing/selftests/resctrl/resctrlfs.c   | 10 +++++++
>  4 files changed, 39 insertions(+), 13 deletions(-)
>

Hi Reinette,

On 1/8/26 09:02, Reinette Chatre wrote:
> Dear Shuah,
> 
> Could you please consider this series for inclusion?
> 
> Thank you very much.
> 
> Reinette
> 
> On 12/16/25 7:04 PM, Xiaochen Shen wrote:
>> The resctrl selftest currently exhibits several failures on Hygon CPUs
>> due to missing vendor detection and edge-case handling specific to
>> Hygon's architecture.
>>
>> This patch series addresses three distinct issues:
>> 1. A division-by-zero crash in SNC detection on some platforms (e.g.,
>>     Hygon).
>> 2. Missing CPU vendor detection, causing the test to fail with
>>     "# Can not get vendor info..." on Hygon CPUs.
>> 3. Incorrect handling of non-contiguous CBM support on Hygon CPUs.
>>
>> These changes enable resctrl selftest to run successfully on
>> Hygon CPUs that support Platform QoS features.
>>
>> Maintainer notes:
>> -----------------
>> Patch 1: selftests/resctrl: Fix a division by zero error on Hygon
>>   - This is a candidate for backport with "Fixes:" tag.
>>
>> Patch 2: selftests/resctrl: Define CPU vendor IDs as bits to match usage
>>   - This is *not* a candidate for backport since it is an enhancement and
>>     preparatory patch for patch 3.
>>
>> Patch 3: selftests/resctrl: Add CPU vendor detection for Hygon
>> Patch 4: selftests/resctrl: Fix non-contiguous CBM check for Hygon
>>   - Even though they are fixes they are *not* candidates for backport
>>     since they are based on another patch series (x86/resctrl: Fix
>>     Platform QoS issues for Hygon) which is in process of being added to
>>     resctrl.
>> -----------------

Applied to linux-kselftest next branch for Linux 6.20-rc1

thanks,
-- Shuah

On 1/9/26 3:51 PM, Shuah wrote:
> 
> Applied to linux-kselftest next branch for Linux 6.20-rc1

Thank you very much Shuah.

Reinette

Hi Shuah, Reinette, Tony and Fenghua,

On 1/10/2026 8:02 AM, Reinette Chatre wrote:
> 
> 
> On 1/9/26 3:51 PM, Shuah wrote:
>>
>> Applied to linux-kselftest next branch for Linux 6.20-rc1
> 
> Thank you very much Shuah.
> 
> Reinette


I truly appreciate your great help with the code review and patch merge - thanks!

Best regards,
Xiaochen Shen