Re: [PATCH 18/33] arm_mpam: Reset MSC controls from cpuhp callbacks

[Gavin Shan]

On 11/7/25 10:34 PM, Ben Horgan wrote:
> From: James Morse <james.morse@xxxxxxx>
>
> When a CPU comes online, it may bring a newly accessible MSC with
> it. Only the default partid has its value reset by hardware, and
> even then the MSC might not have been reset since its config was
> previously dirtied. e.g. Kexec.
>
> Any in-use partid must have its configuration restored, or reset.
> In-use partids may be held in caches and evicted later.
>
> MSC are also reset when CPUs are taken offline to cover cases where
> firmware doesn't reset the MSC over reboot using UEFI, or kexec
> where there is no firmware involvement.
>
> If the configuration for a RIS has not been touched since it was
> brought online, it does not need resetting again.
>
> To reset, write the maximum values for all discovered controls.
>
> CC: Rohit Mathew <Rohit.Mathew@xxxxxxx>
> Signed-off-by: James Morse <james.morse@xxxxxxx>
> Reviewed-by: Fenghua Yu <fenghuay@xxxxxxxxxx>
> Tested-by: Fenghua Yu <fenghuay@xxxxxxxxxx>
> Reviewed-by: Jonathan Cameron <jonathan.cameron@xxxxxxxxxx>
> Reviewed-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
> Tested-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
> Tested-by: Peter Newman <peternewman@xxxxxxxxxx>
> Signed-off-by: Ben Horgan <ben.horgan@xxxxxxx>
> ---
> Changes since v3:
> Add tags - thanks!
> ---
>   drivers/resctrl/mpam_devices.c  | 109 ++++++++++++++++++++++++++++++++
>   drivers/resctrl/mpam_internal.h |   3 +
>   2 files changed, 112 insertions(+)

Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>