[PATCH 2/5] arm_mpam: Split the locking around the mon_sel registers

[Niyas Sait]

Hi Andre,

On Wed, Apr 29, 2026 at 04:13:36PM +0200, Andre Przywara wrote:

> @@ -1635,8 +1643,11 @@ static int mpam_restore_mbwu_state(void *_ris)
>  	u64 val;
>  	struct mon_read mwbu_arg;
>  	struct mpam_msc_ris *ris = _ris;
> +	struct mpam_msc *msc = ris->vmsc->msc;
>  	struct mpam_class *class = ris->vmsc->comp->class;
>  
> +	mpam_mon_sel_outer_lock(msc);
> +
>  	for (i = 0; i < ris->props.num_mbwu_mon; i++) {
>  		if (ris->mbwu_state[i].enabled) {
>  			mwbu_arg.ris = ris;
> @@ -1648,10 +1659,12 @@ static int mpam_restore_mbwu_state(void *_ris)
>  		}
>  	}
>  
> +	mpam_mon_sel_outer_unlock(msc);
> +
>  	return 0;
>  }

There looks to be a lock nesting issue here. mpam_reprogram_msc() already
holds outer_mon_sel_lock when it calls mpam_restore_mbwu_state(), and
mpam_restore_mbwu_state() then takes the same outer lock again.

Thanks,
Niyas