[PATCH v5 0/3] x86,fs/resctrl,arm_mpam: Factor MBA parse-time conversion to be per-arch

[Gavin Shan]

On 7/9/26 7:31 PM, Ben Horgan wrote:
> This version fixes a couple of non-functional mistakes in v4 pointed out by Reinette.
> 
> The patches should stay together so please could this all go via tip.
> 
> Changelogs in patches.
> 
>  From cover letter of v3:
> 
> This is a new version of Dave Martin's patch [1] to delegate rounding of
> bandwidth control user values to the arch code. As there is now more than one
> architecture using resctrl, I split the original patch into two, a core resctrl
> patch and an x86 patch, and added an MPAM patch. Please let me know if the patch
> break down and ordering is sensible and whether the pattern should be followed
> for any future similar changes.
> 
> This does have a user visible effect on MB schema when using MPAM hardware
> with 'bandwidth_gran' greater than 1. I'm not sure if MPAM hardware with such
> coarse controls exists in the wild but it is spec compliant and I've tested it
> on a model.
> 
> [1] https://lore.kernel.org/lkml/20251031154225.14799-1-Dave.Martin@arm.com/
> 
> v3: https://lore.kernel.org/lkml/20260515140612.1205251-1-ben.horgan@arm.com/
> v4: https://lore.kernel.org/lkml/20260706160639.2136674-1-ben.horgan@arm.com/
> 
> Based on v7.2-rc2
> 
> Ben Horgan (1):
>    arm_mpam: resctrl: Add pass-through resctrl_arch_preconvert_bw()
> 
> Dave Martin (2):
>    x86,fs/resctrl: Add resctrl_arch_preconvert_bw()
>    fs/resctrl: Factor MBA parse-time conversion to be per-arch
> 
>   Documentation/filesystems/resctrl.rst     | 17 +++++++++--------
>   arch/x86/kernel/cpu/resctrl/ctrlmondata.c |  6 ++++++
>   drivers/resctrl/mpam_resctrl.c            |  5 +++++
>   fs/resctrl/ctrlmondata.c                  |  6 +++---
>   include/linux/resctrl.h                   | 19 +++++++++++++++++++
>   5 files changed, 42 insertions(+), 11 deletions(-)
> 

Looks good in my tests on NVidia's grace-hopper machine. No errors found
from the kunit-tests and the MBW limiting works with more precise granularity.
The code changes look good to me either.

Tested-by: Gavin Shan <gshan at redhat.com>
Reviewed-by: Gavin Shan <gshan at redhat.com>

Thanks,
Gavin