Re: [PATCH v3 07/47] arm64: mpam: Re-initialise MPAM regs when CPU comes online

[Gavin Shan]

On 1/13/26 12:58 AM, Ben Horgan wrote:
> From: James Morse <james.morse@xxxxxxx>
>
> Now that the MPAM system registers are expected to have values that change,
> reprogram them based on the previous value when a CPU is brought online.
>
> Previously MPAM's 'default PARTID' of 0 was always used for MPAM in
> kernel-space as this is the PARTID that hardware guarantees to
> reset. Because there are a limited number of PARTID, this value is exposed
> to user-space, meaning resctrl changes to the resctrl default group would
> also affect kernel threads.  Instead, use the task's PARTID value for
> kernel work on behalf of user-space too. The default of 0 is kept for both
> user-space and kernel-space when MPAM is not enabled.
>
> Reviewed-by: Jonathan Cameron <jonathan.cameron@xxxxxxxxxx>
> Signed-off-by: James Morse <james.morse@xxxxxxx>
> Signed-off-by: Ben Horgan <ben.horgan@xxxxxxx>
> ---
> Changes since rfc:
> CONFIG_MPAM -> CONFIG_ARM64_MPAM
> Check mpam_enabled
> Comment about relying on ERET for synchronisation
> Update commit message
> ---
>   arch/arm64/kernel/cpufeature.c | 19 ++++++++++++-------
>   1 file changed, 12 insertions(+), 7 deletions(-)

Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>