Re: [PATCH v3 15/29] arm_mpam: Reset MSC controls from cpuhp callbacks

[Jonathan Cameron]

On Fri, 17 Oct 2025 18:56:31 +0000
James Morse <james.morse@xxxxxxx> wrote:

> 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>