Re: [PATCH v4 05/10] arm_mpam: propagate MSC access errors for __ris_msmon_read()

[Sudeep Holla]

On Thu, Jul 23, 2026 at 05:54:49PM +0200, Andre Przywara wrote:
> Allow the function for RIS accesses to return an error, and propagate
> read and write errors from the lower level up.
> This function is a bit special, since it can be called via an SMP
> helper, so the prototype must stay as void. So propagate any errors
> using the "err" field in the struct passed in as the sole argument to
> that function.
> 

Not sure if this was already discussed by build bisection regresses between
4/10 and 5/10 as you change function prototype there and caller here or
am I missing to read it correctly ?

> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> ---
>  drivers/resctrl/mpam_devices.c | 36 +++++++++++++++++++++++++---------
>  1 file changed, 27 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
> index 9ee4eb4db03f..bcff53477133 100644
> --- a/drivers/resctrl/mpam_devices.c
> +++ b/drivers/resctrl/mpam_devices.c
> @@ -1328,6 +1328,10 @@ static u64 mpam_msmon_overflow_val(enum mpam_device_features type,
>  	return overflow_val;
>  }
>  
> +/*
> + * This function might be called via smp_call_function_any(), so propagate
> + * errors inside the arg struct.
> + */
>  static void __ris_msmon_read(void *arg)
>  {
>  	u64 now;
> @@ -1351,7 +1355,9 @@ static void __ris_msmon_read(void *arg)
>  
>  	mon_sel = FIELD_PREP(MSMON_CFG_MON_SEL_MON_SEL, ctx->mon) |
>  		  FIELD_PREP(MSMON_CFG_MON_SEL_RIS, ris->ris_idx);
> -	mpam_write_monsel_reg(msc, CFG_MON_SEL, mon_sel);
> +	m->err = mpam_write_monsel_reg(msc, CFG_MON_SEL, mon_sel);
> +	if (m->err)
> +		return;
>  
>  	switch (m->type) {
>  	case mpam_feat_msmon_mbwu_31counter:
> @@ -1371,7 +1377,9 @@ static void __ris_msmon_read(void *arg)
>  	 * Read the existing configuration to avoid re-writing the same values.
>  	 * This saves waiting for 'nrdy' on subsequent reads.
>  	 */
> -	read_msmon_ctl_flt_vals(m, &cur_ctl, &cur_flt);
> +	m->err = read_msmon_ctl_flt_vals(m, &cur_ctl, &cur_flt);
> +	if (m->err)
> +		return;
> 

Atleast read_msmon_ctl_flt_vals() changed to return value in last patch.

-- 
Regards,
Sudeep