[PATCH 27/33] arm_mpam: Add mpam_msmon_read() to read monitor value

[James Morse]

Hi Ben,

On 29/08/2025 16:55, Ben Horgan wrote:
> On 8/22/25 16:30, James Morse wrote:
>> Reading a monitor involves configuring what you want to monitor, and
>> reading the value. Components made up of multiple MSC may need values
>> from each MSC. MSCs may take time to configure, returning 'not ready'.
>> The maximum 'not ready' time should have been provided by firmware.
>>
>> Add mpam_msmon_read() to hide all this. If (one of) the MSC returns
>> not ready, then wait the full timeout value before trying again.

>> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
>> index e7e00c632512..9ce771aaf671 100644
>> --- a/drivers/resctrl/mpam_devices.c
>> +++ b/drivers/resctrl/mpam_devices.c
>> @@ -973,6 +973,228 @@ static int mpam_msc_hw_probe(struct mpam_msc *msc)

>> +static void gen_msmon_ctl_flt_vals(struct mon_read *m, u32 *ctl_val,
>> +				   u32 *flt_val)
>> +{
>> +	struct mon_cfg *ctx = m->ctx;
>> +
>> +	switch (m->type) {
>> +	case mpam_feat_msmon_csu:
>> +		*ctl_val = MSMON_CFG_CSU_CTL_TYPE_CSU;
>> +		break;
>> +	case mpam_feat_msmon_mbwu:
>> +		*ctl_val = MSMON_CFG_MBWU_CTL_TYPE_MBWU;
>> +		break;
>> +	default:
>> +		return;
>> +	}
>> +
>> +	/*
>> +	 * For CSU counters its implementation-defined what happens when not
>> +	 * filtering by partid.
>> +	 */
>> +	*ctl_val |= MSMON_CFG_x_CTL_MATCH_PARTID;
>> +
>> +	*flt_val = FIELD_PREP(MSMON_CFG_MBWU_FLT_PARTID, ctx->partid);
>> +	if (m->ctx->match_pmg) {
>> +		*ctl_val |= MSMON_CFG_x_CTL_MATCH_PMG;
>> +		*flt_val |= FIELD_PREP(MSMON_CFG_MBWU_FLT_PMG, ctx->pmg);
>> +	}

> As we are using MSMON_CFG_MBWU_FLT_{PMG,PARTID} for both CSU and MBWU
> how about changing to MSMON_CFG_x_FLT_{PMG,PARTID}?

Sure,


>> +
>> +	if (mpam_has_feature(mpam_feat_msmon_mbwu_rwbw, &m->ris->props))
>> +		*flt_val |= FIELD_PREP(MSMON_CFG_MBWU_FLT_RWBW, ctx->opts);

> This needs to be conditional on the type of the monitor being
> configured. There is an XCL bit here for CSU monitors.

Fixed ... that wasn't there last time I looked!
I may as well wire that up too...


Thanks,

James