[PATCH v2 23/29] arm_mpam: Add mpam_msmon_read() to read monitor value

[James Morse]

Hi Ben,

On 12/09/2025 16:08, Ben Horgan wrote:
> On 9/11/25 16:46, Ben Horgan wrote:
>> On 9/10/25 21:43, 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 cf190f896de1..1543c33c5d6a 100644
>>> --- a/drivers/resctrl/mpam_devices.c
>>> +++ b/drivers/resctrl/mpam_devices.c
>>> +
>>> +static void gen_msmon_ctl_flt_vals(struct mon_read *m, u32 *ctl_val,
>>> +				   u32 *flt_val)
>>> +{
>>> +	struct mon_cfg *ctx = m->ctx;
>>> +
>>> +	/*
>>> +	 * 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_x_FLT_PARTID, ctx->partid);
>>> +	if (m->ctx->match_pmg) {
>>> +		*ctl_val |= MSMON_CFG_x_CTL_MATCH_PMG;
>>> +		*flt_val |= FIELD_PREP(MSMON_CFG_x_FLT_PMG, ctx->pmg);
>>> +	}
>>> +
>>> +	switch (m->type) {
>>> +	case mpam_feat_msmon_csu:
>>> +		*ctl_val = MSMON_CFG_CSU_CTL_TYPE_CSU;
>>> +
>>> +		if (mpam_has_feature(mpam_feat_msmon_csu_xcl, &m->ris->props))
>>> +			*flt_val |= FIELD_PREP(MSMON_CFG_CSU_FLT_XCL,
>>> +					       ctx->csu_exclude_clean);
>>> +
>>> +		break;
>>> +	case mpam_feat_msmon_mbwu:
>>> +		*ctl_val = MSMON_CFG_MBWU_CTL_TYPE_MBWU;
> 
> As you mentioned offline, this zeroes the other bits in *ctl_val.

Yes - a bug introduced during a late night, I've fixed this up.


Thanks,

James