Re: [PATCH v6 01/40] arm_mpam: Ensure in_reset_state is false after applying configuration

[Jinjie Ruan]

在 2026/3/13 22:45, Ben Horgan 写道:
> From: Zeng Heng <zengheng4@xxxxxxxxxx>
> 
> The per-RIS flag, in_reset_state, indicates whether or not the MSC
> registers are in reset state, and allows avoiding resetting when they are
> already in reset state. However, when mpam_apply_config() updates the
> configuration it doesn't update the in_reset_state flag and so even after
> the configuration update in_reset_state can be true and mpam_reset_ris()
> will skip the actual register restoration on subsequent resets.
> 
> Once resctrl has a MPAM backend it will use resctrl_arch_reset_all_ctrls()
> to reset the MSC configuration on unmount and, if the in_reset_state flag
> is bogusly true, fail to reset the MSC configuration. The resulting
> non-reset MSC configuration can lead to persistent performance restrictions
> even after resctrl is unmounted.
> 
> Fix by clearing in_reset_state to false immediately after successful
> configuration application, ensuring that the next reset operation
> properly restores MSC register defaults.
> 
> Fixes: 09b89d2a72f3 ("arm_mpam: Allow configuration to be applied and restored during cpu online")
> Signed-off-by: Zeng Heng <zengheng4@xxxxxxxxxx>
> Acked-by: Ben Horgan <ben.horgan@xxxxxxx>
> [Horgan: rewrite commit message to not be specific to resctrl unmount]
> Signed-off-by: Ben Horgan <ben.horgan@xxxxxxx>
> ---
> Subject was originally:
> arm_mpam: Fix MPAM reset on resctrl unmount by clearing in_reset_state
> ---
>  drivers/resctrl/mpam_devices.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
> index 1eebc2602187..0fd6590a9b5c 100644
> --- a/drivers/resctrl/mpam_devices.c
> +++ b/drivers/resctrl/mpam_devices.c
> @@ -2692,6 +2692,7 @@ int mpam_apply_config(struct mpam_component *comp, u16 partid,
>  					 srcu_read_lock_held(&mpam_srcu)) {
>  			arg.ris = ris;
>  			mpam_touch_msc(msc, __write_config, &arg);
> +			ris->in_reset_state = false;

Reviewed-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>

>  		}
>  		mutex_unlock(&msc->cfg_lock);
>  	}