Re: [PATCH 31/33] arm_mpam: Add helper to reset saved mbwu state

Gavin Shan
2025-11-09T23:18:32Z

On 11/7/25 10:34 PM, Ben Horgan wrote:
> From: James Morse <james.morse@arm.com>
>
> resctrl expects to reset the bandwidth counters when the filesystem
> is mounted.
>
> To allow this, add a helper that clears the saved mbwu state. Instead
> of cross calling to each CPU that can access the component MSC to
> write to the counter, set a flag that causes it to be zero'd on the
> the next read. This is easily done by forcing a configuration update.
>
> Signed-off-by: James Morse <james.morse@arm.com>
> Reviewed-by: Fenghua Yu <fenghuay@nvdia.com>
> Tested-by: Fenghua Yu <fenghuay@nvidia.com>
> Cc: Peter Newman <peternewman@google.com>
> Signed-off-by: Ben Horgan <ben.horgan@arm.com>
> ---
> Changes since v3:
> Correct type checking, use mpam_feat_msmon_mbwu_<n>counter
> ---
> drivers/resctrl/mpam_devices.c | 48 ++++++++++++++++++++++++++++++++-
> drivers/resctrl/mpam_internal.h | 2 ++
> 2 files changed, 49 insertions(+), 1 deletion(-)
>
Reviewed-by: Gavin Shan <gshan@redhat.com>