Re: [PATCH v3 09/47] arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs

[Catalin Marinas <catalin.marinas@arm.com>]

On Mon, Jan 12, 2026 at 04:58:36PM +0000, Ben Horgan wrote:
> +static int mpam_pm_notifier(struct notifier_block *self,
> +			    unsigned long cmd, void *v)
> +{
> +	u64 regval;
> +	int cpu = smp_processor_id();
> +
> +	switch (cmd) {
> +	case CPU_PM_EXIT:
> +		/*
> +		 * Don't use mpam_thread_switch() as the system register
> +		 * value has changed under our feet.
> +		 */
> +		regval = READ_ONCE(per_cpu(arm64_mpam_current, cpu));
> +		write_sysreg_s(regval, SYS_MPAM1_EL1);
> +		isb();
> +
> +		write_sysreg_s(regval, SYS_MPAM0_EL1);
> +
> +		return NOTIFY_OK;
> +	default:
> +		return NOTIFY_DONE;
> +	}
> +}

This looks fine unless we decide to save/restore them in the low-level
suspend/resume functions.

-- 
Catalin