Hi James,
On 8/22/25 16:29, James Morse wrote:
> Expand the probing support with the control and monitor types
> we can use with resctrl.
>
> CC: Dave Martin <Dave.Martin@arm.com>
> Signed-off-by: James Morse <james.morse@arm.com>
> ---
> Changes since RFC:
> * Made mpam_ris_hw_probe_hw_nrdy() more in C.
> * Added static assert on features bitmap size.
> ---
> drivers/resctrl/mpam_devices.c | 156 +++++++++++++++++++++++++++++++-
> drivers/resctrl/mpam_internal.h | 54 +++++++++++
> 2 files changed, 209 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
> index 012e09e80300..290a04f8654f 100644
> --- a/drivers/resctrl/mpam_devices.c
> +++ b/drivers/resctrl/mpam_devices.c
> @@ -102,7 +102,7 @@ static LLIST_HEAD(mpam_garbage);
>
> static u32 __mpam_read_reg(struct mpam_msc *msc, u16 reg)
> {
> - WARN_ON_ONCE(reg > msc->mapped_hwpage_sz);
> + WARN_ON_ONCE(reg + sizeof(u32) > msc->mapped_hwpage_sz);
Update in the patch that introduced this line.
> WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), &msc->accessibility));
>
> return readl_relaxed(msc->mapped_hwpage + reg);
> @@ -131,6 +131,20 @@ static inline void _mpam_write_partsel_reg(struct mpam_msc *msc, u16 reg, u32 va
> }
> #define mpam_write_partsel_reg(msc, reg, val) _mpam_write_partsel_reg(msc, MPAMCFG_##reg, val)
>
> +static inline u32 _mpam_read_monsel_reg(struct mpam_msc *msc, u16 reg)
> +{
> + mpam_mon_sel_lock_held(msc);
> + return __mpam_read_reg(msc, reg);
> +}
> +#define mpam_read_monsel_reg(msc, reg) _mpam_read_monsel_reg(msc, MSMON_##reg)
> +
> +static inline void _mpam_write_monsel_reg(struct mpam_msc *msc, u16 reg, u32 val)
> +{
> + mpam_mon_sel_lock_held(msc);
> + __mpam_write_reg(msc, reg, val);
> +}
> +#define mpam_write_monsel_reg(msc, reg, val) _mpam_write_monsel_reg(msc, MSMON_##reg, val)
> +
> static u64 mpam_msc_read_idr(struct mpam_msc *msc)
> {
> u64 idr_high = 0, idr_low;
> @@ -643,6 +657,139 @@ static struct mpam_msc_ris *mpam_get_or_create_ris(struct mpam_msc *msc,
> return found;
> }
>
> +/*
> + * IHI009A.a has this nugget: "If a monitor does not support automatic behaviour
> + * of NRDY, software can use this bit for any purpose" - so hardware might not
> + * implement this - but it isn't RES0.
> + *
> + * Try and see what values stick in this bit. If we can write either value,
> + * its probably not implemented by hardware.
> + */
> +static bool _mpam_ris_hw_probe_hw_nrdy(struct mpam_msc_ris * ris, u32 mon_reg)
> +{
> + u32 now;
> + u64 mon_sel;
> + bool can_set, can_clear;
> + struct mpam_msc *msc = ris->vmsc->msc;
> +
> + if (WARN_ON_ONCE(!mpam_mon_sel_inner_lock(msc)))
> + return false;
> +
> + mon_sel = FIELD_PREP(MSMON_CFG_MON_SEL_MON_SEL, 0) |
> + FIELD_PREP(MSMON_CFG_MON_SEL_RIS, ris->ris_idx);
> + _mpam_write_monsel_reg(msc, mon_reg, mon_sel);
> +
> + _mpam_write_monsel_reg(msc, mon_reg, MSMON___NRDY);
> + now = _mpam_read_monsel_reg(msc, mon_reg);
> + can_set = now & MSMON___NRDY;
> +
> + _mpam_write_monsel_reg(msc, mon_reg, 0);
> + now = _mpam_read_monsel_reg(msc, mon_reg);
> + can_clear = !(now & MSMON___NRDY);
> + mpam_mon_sel_inner_unlock(msc);
> +
> + return (!can_set || !can_clear);
> +}
> +
> +#define mpam_ris_hw_probe_hw_nrdy(_ris, _mon_reg) \
> + _mpam_ris_hw_probe_hw_nrdy(_ris, MSMON_##_mon_reg)
> +
> +static void mpam_ris_hw_probe(struct mpam_msc_ris *ris)
> +{
> + int err;
> + struct mpam_msc *msc = ris->vmsc->msc;
> + struct mpam_props *props = &ris->props;
> +
> + lockdep_assert_held(&msc->probe_lock);
> + lockdep_assert_held(&msc->part_sel_lock);
> +
> + /* Cache Portion partitioning */
> + if (FIELD_GET(MPAMF_IDR_HAS_CPOR_PART, ris->idr)) {
> + u32 cpor_features = mpam_read_partsel_reg(msc, CPOR_IDR);
> +
> + props->cpbm_wd = FIELD_GET(MPAMF_CPOR_IDR_CPBM_WD, cpor_features);
> + if (props->cpbm_wd)
> + mpam_set_feature(mpam_feat_cpor_part, props);
> + }
> +
> + /* Memory bandwidth partitioning */
> + if (FIELD_GET(MPAMF_IDR_HAS_MBW_PART, ris->idr)) {
> + u32 mbw_features = mpam_read_partsel_reg(msc, MBW_IDR);
> +
> + /* portion bitmap resolution */
> + props->mbw_pbm_bits = FIELD_GET(MPAMF_MBW_IDR_BWPBM_WD, mbw_features);
> + if (props->mbw_pbm_bits &&
> + FIELD_GET(MPAMF_MBW_IDR_HAS_PBM, mbw_features))
> + mpam_set_feature(mpam_feat_mbw_part, props);
> +
> + props->bwa_wd = FIELD_GET(MPAMF_MBW_IDR_BWA_WD, mbw_features);
> + if (props->bwa_wd && FIELD_GET(MPAMF_MBW_IDR_HAS_MAX, mbw_features))
> + mpam_set_feature(mpam_feat_mbw_max, props);
> + }
> +
> + /* Performance Monitoring */
> + if (FIELD_GET(MPAMF_IDR_HAS_MSMON, ris->idr)) {
> + u32 msmon_features = mpam_read_partsel_reg(msc, MSMON_IDR);
> +
> + /*
> + * If the firmware max-nrdy-us property is missing, the
> + * CSU counters can't be used. Should we wait forever?
> + */
> + err = device_property_read_u32(&msc->pdev->dev,
> + "arm,not-ready-us",
> + &msc->nrdy_usec);
> +
> + if (FIELD_GET(MPAMF_MSMON_IDR_MSMON_CSU, msmon_features)) {
> + u32 csumonidr;
> +
> + csumonidr = mpam_read_partsel_reg(msc, CSUMON_IDR);
> + props->num_csu_mon = FIELD_GET(MPAMF_CSUMON_IDR_NUM_MON, csumonidr);
> + if (props->num_csu_mon) {
> + bool hw_managed;
> +
> + mpam_set_feature(mpam_feat_msmon_csu, props);
> +
> + /* Is NRDY hardware managed? */
> + mpam_mon_sel_outer_lock(msc);
> + hw_managed = mpam_ris_hw_probe_hw_nrdy(ris, CSU);
> + mpam_mon_sel_outer_unlock(msc);
> + if (hw_managed)
> + mpam_set_feature(mpam_feat_msmon_csu_hw_nrdy, props);
> + }
> +
> + /*
> + * Accept the missing firmware property if NRDY appears
> + * un-implemented.
> + */
> + if (err && mpam_has_feature(mpam_feat_msmon_csu_hw_nrdy, props))
> + pr_err_once("Counters are not usable because not-ready timeout was not provided by firmware.");
> + }
> + if (FIELD_GET(MPAMF_MSMON_IDR_MSMON_MBWU, msmon_features)) {
> + bool hw_managed;
> + u32 mbwumonidr = mpam_read_partsel_reg(msc, MBWUMON_IDR);
> +
> + props->num_mbwu_mon = FIELD_GET(MPAMF_MBWUMON_IDR_NUM_MON, mbwumonidr);
> + if (props->num_mbwu_mon)
> + mpam_set_feature(mpam_feat_msmon_mbwu, props);
> +
> + if (FIELD_GET(MPAMF_MBWUMON_IDR_HAS_RWBW, mbwumonidr))
> + mpam_set_feature(mpam_feat_msmon_mbwu_rwbw, props);
> +
> + /* Is NRDY hardware managed? */
> + mpam_mon_sel_outer_lock(msc);
> + hw_managed = mpam_ris_hw_probe_hw_nrdy(ris, MBWU);
> + mpam_mon_sel_outer_unlock(msc);
> + if (hw_managed)
> + mpam_set_feature(mpam_feat_msmon_mbwu_hw_nrdy, props);
> +
> + /*
> + * Don't warn about any missing firmware property for
> + * MBWU NRDY - it doesn't make any sense!
> + */
> + }
> + }
> +}
> +
> static int mpam_msc_hw_probe(struct mpam_msc *msc)
> {
> u64 idr;
> @@ -663,6 +810,7 @@ static int mpam_msc_hw_probe(struct mpam_msc *msc)
>
> idr = mpam_msc_read_idr(msc);
> mutex_unlock(&msc->part_sel_lock);
> +
> msc->ris_max = FIELD_GET(MPAMF_IDR_RIS_MAX, idr);
>
> /* Use these values so partid/pmg always starts with a valid value */
> @@ -683,6 +831,12 @@ static int mpam_msc_hw_probe(struct mpam_msc *msc)
> ris = mpam_get_or_create_ris(msc, ris_idx);
> if (IS_ERR(ris))
> return PTR_ERR(ris);
> + ris->idr = idr;
> +
> + mutex_lock(&msc->part_sel_lock);
> + __mpam_part_sel(ris_idx, 0, msc);
> + mpam_ris_hw_probe(ris);
> + mutex_unlock(&msc->part_sel_lock);
> }
>
> spin_lock(&partid_max_lock);
> diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
> index c6f087f9fa7d..9f6cd4a68cce 100644
> --- a/drivers/resctrl/mpam_internal.h
> +++ b/drivers/resctrl/mpam_internal.h
> @@ -136,6 +136,56 @@ static inline void mpam_mon_sel_lock_held(struct mpam_msc *msc)
> lockdep_assert_preemption_enabled();
> }
>
> +/*
> + * When we compact the supported features, we don't care what they are.
> + * Storing them as a bitmap makes life easy.
> + */
> +typedef u16 mpam_features_t;
> +
> +/* Bits for mpam_features_t */
> +enum mpam_device_features {
> + mpam_feat_ccap_part = 0,
> + mpam_feat_cpor_part,
> + mpam_feat_mbw_part,
> + mpam_feat_mbw_min,
> + mpam_feat_mbw_max,
> + mpam_feat_mbw_prop,
> + mpam_feat_msmon,
> + mpam_feat_msmon_csu,
> + mpam_feat_msmon_csu_capture,
> + mpam_feat_msmon_csu_hw_nrdy,
> + mpam_feat_msmon_mbwu,
> + mpam_feat_msmon_mbwu_capture,
> + mpam_feat_msmon_mbwu_rwbw,
> + mpam_feat_msmon_mbwu_hw_nrdy,
> + mpam_feat_msmon_capt,
> + MPAM_FEATURE_LAST,
This isn't all the features or just the features supported by resctrl.
Just add them all in this patch?
> +};
> +static_assert(BITS_PER_TYPE(mpam_features_t) >= MPAM_FEATURE_LAST);
> +#define MPAM_ALL_FEATURES ((1 << MPAM_FEATURE_LAST) - 1)
Unused?
> +
> +struct mpam_props {
> + mpam_features_t features;
> +
> + u16 cpbm_wd;
> + u16 mbw_pbm_bits;
> + u16 bwa_wd;
> + u16 num_csu_mon;
> + u16 num_mbwu_mon;
> +};
> +
> +static inline bool mpam_has_feature(enum mpam_device_features feat,
> + struct mpam_props *props)
> +{
> + return (1 << feat) & props->features;
> +}
> +
> +static inline void mpam_set_feature(enum mpam_device_features feat,
> + struct mpam_props *props)
> +{
> + props->features |= (1 << feat);
> +}
> +
> struct mpam_class {
> /* mpam_components in this class */
> struct list_head components;
> @@ -175,6 +225,8 @@ struct mpam_vmsc {
> /* mpam_msc_ris in this vmsc */
> struct list_head ris;
>
> + struct mpam_props props;
> +
> /* All RIS in this vMSC are members of this MSC */
> struct mpam_msc *msc;
>
> @@ -186,6 +238,8 @@ struct mpam_vmsc {
>
> struct mpam_msc_ris {
> u8 ris_idx;
> + u64 idr;
> + struct mpam_props props;
>
> cpumask_t affinity;
>
Thanks,
Ben