Re: [PATCH v2 04/15] arm_mpam: propagate MSC read errors for mpam_msc_read_mbwu_l()

[Ben Horgan <ben.horgan@arm.com>]

Hi Andre,

On 7/2/26 17:22, Andre Przywara wrote:
> Allow the mpam_msc_read_mbwu_l() function to return an error, and
> propagate read errors from the lower level up.
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  drivers/resctrl/mpam_devices.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
> index 011d1e3544d7..1d06902fb970 100644
> --- a/drivers/resctrl/mpam_devices.c
> +++ b/drivers/resctrl/mpam_devices.c
> @@ -1106,6 +1106,7 @@ static bool mpam_ris_has_mbwu_long_counter(struct mpam_msc_ris *ris)
>  
>  static u64 mpam_msc_read_mbwu_l(struct mpam_msc *msc)

Now that your changing the other helpers to return an error and pass a
pointer to hold the register value it would seem more consistent for
this call to follow the same pattern.

Thanks,

Ben

>  {
> +	int ret;
>  	int retry = 3;
>  	u32 mbwu_l_low;
>  	u32 mbwu_l_high1, mbwu_l_high2;
> @@ -1115,11 +1116,17 @@ static u64 mpam_msc_read_mbwu_l(struct mpam_msc *msc)
>  	WARN_ON_ONCE((MSMON_MBWU_L + sizeof(u64)) > msc->mapped_hwpage_sz);
>  	WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), &msc->accessibility));
>  
> -	__mpam_read_reg(msc, MSMON_MBWU_L + 4, &mbwu_l_high2);
> +	ret = __mpam_read_reg(msc, MSMON_MBWU_L + 4, &mbwu_l_high2);
> +	if (ret)
> +		return MSMON___L_NRDY;
> +
>  	do {
>  		mbwu_l_high1 = mbwu_l_high2;
> -		__mpam_read_reg(msc, MSMON_MBWU_L, &mbwu_l_low);
> -		__mpam_read_reg(msc, MSMON_MBWU_L + 4, &mbwu_l_high2);
> +		ret = __mpam_read_reg(msc, MSMON_MBWU_L, &mbwu_l_low);
> +		if (!ret)
> +			ret = __mpam_read_reg(msc, MSMON_MBWU_L + 4, &mbwu_l_high2);
> +		if (ret)
> +			return MSMON___L_NRDY;
>  
>  		retry--;
>  	} while (mbwu_l_high1 != mbwu_l_high2 && retry > 0);