[PATCH v2 03/15] arm_mpam: propagate MSC read errors for hw_probe functions
Ben Horgan
ben.horgan at arm.com
Wed Jul 1 13:00:56 PDT 2026
Hi Andre,
On 7/2/26 17:22, Andre Przywara wrote:
> Allow the functions probing for MSC hardware and features to return an
> error, and propagate read errors from the lower level up.
>
> Signed-off-by: Andre Przywara <andre.przywara at arm.com>
> ---
> drivers/resctrl/mpam_devices.c | 62 ++++++++++++++++++++++++----------
> 1 file changed, 44 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
> index ce8738adb6ff..011d1e3544d7 100644
> --- a/drivers/resctrl/mpam_devices.c
> +++ b/drivers/resctrl/mpam_devices.c
> @@ -800,20 +800,22 @@ static bool mpam_ris_hw_probe_csu_nrdy(struct mpam_msc_ris *ris)
> mpam_write_monsel_reg(msc, CFG_CSU_CTL, ctl_val);
>
> _mpam_write_monsel_reg(msc, MSMON_CSU, MSMON___NRDY);
> - _mpam_read_monsel_reg(msc, MSMON_CSU, &now);
> + if (_mpam_read_monsel_reg(msc, MSMON_CSU, &now))
> + return false;
This early return leaves the mon_sel lock held.
> can_set = now & MSMON___NRDY;
As you're adding early returns to this function does it make sense to
return early if can_set is false?
Thanks,
Ben
>
> _mpam_write_monsel_reg(msc, MSMON_CSU, 0);
> /* Configuration change to try and coax hardware into setting nrdy */
> mpam_write_monsel_reg(msc, CFG_CSU_FLT, 0x1);
> - _mpam_read_monsel_reg(msc, MSMON_CSU, &now);
> + if (_mpam_read_monsel_reg(msc, MSMON_CSU, &now))
> + return false;
> can_clear = !(now & MSMON___NRDY);
> mpam_mon_sel_unlock(msc);
>
> return (!can_set || !can_clear);
> }
>
> -static void mpam_ris_hw_probe(struct mpam_msc_ris *ris)
> +static int mpam_ris_hw_probe(struct mpam_msc_ris *ris)
> {
> int err;
> struct mpam_msc *msc = ris->vmsc->msc;
> @@ -828,7 +830,9 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris)
> if (FIELD_GET(MPAMF_IDR_HAS_CCAP_PART, ris->idr)) {
> u32 ccap_features;
>
> - mpam_read_partsel_reg(msc, CCAP_IDR, &ccap_features);
> + err = mpam_read_partsel_reg(msc, CCAP_IDR, &ccap_features);
> + if (err)
> + return err;
>
> props->cmax_wd = FIELD_GET(MPAMF_CCAP_IDR_CMAX_WD, ccap_features);
> if (props->cmax_wd &&
> @@ -853,7 +857,9 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris)
> if (FIELD_GET(MPAMF_IDR_HAS_CPOR_PART, ris->idr)) {
> u32 cpor_features;
>
> - mpam_read_partsel_reg(msc, CPOR_IDR, &cpor_features);
> + err = mpam_read_partsel_reg(msc, CPOR_IDR, &cpor_features);
> + if (err)
> + return err;
>
> props->cpbm_wd = FIELD_GET(MPAMF_CPOR_IDR_CPBM_WD, cpor_features);
> if (props->cpbm_wd)
> @@ -863,8 +869,9 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris)
> /* Memory bandwidth partitioning */
> if (FIELD_GET(MPAMF_IDR_HAS_MBW_PART, ris->idr)) {
> u32 mbw_features;
> -
> - mpam_read_partsel_reg(msc, MBW_IDR, &mbw_features);
> + err = mpam_read_partsel_reg(msc, MBW_IDR, &mbw_features);
> + if (err)
> + return err;
>
> /* portion bitmap resolution */
> props->mbw_pbm_bits = FIELD_GET(MPAMF_MBW_IDR_BWPBM_WD, mbw_features);
> @@ -893,8 +900,9 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris)
> /* Priority partitioning */
> if (FIELD_GET(MPAMF_IDR_HAS_PRI_PART, ris->idr)) {
> u32 pri_features;
> -
> - mpam_read_partsel_reg(msc, PRI_IDR, &pri_features);
> + err = mpam_read_partsel_reg(msc, PRI_IDR, &pri_features);
> + if (err)
> + return err;
>
> props->intpri_wd = FIELD_GET(MPAMF_PRI_IDR_INTPRI_WD, pri_features);
> if (props->intpri_wd && FIELD_GET(MPAMF_PRI_IDR_HAS_INTPRI, pri_features)) {
> @@ -915,7 +923,9 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris)
> if (FIELD_GET(MPAMF_IDR_HAS_MSMON, ris->idr)) {
> u32 msmon_features;
>
> - mpam_read_partsel_reg(msc, MSMON_IDR, &msmon_features);
> + err = mpam_read_partsel_reg(msc, MSMON_IDR, &msmon_features);
> + if (err)
> + return err;
>
> /*
> * If the firmware max-nrdy-us property is missing, the
> @@ -928,7 +938,9 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris)
> if (FIELD_GET(MPAMF_MSMON_IDR_MSMON_CSU, msmon_features)) {
> u32 csumonidr;
>
> - mpam_read_partsel_reg(msc, CSUMON_IDR, &csumonidr);
> + err = mpam_read_partsel_reg(msc, CSUMON_IDR, &csumonidr);
> + if (err)
> + return err;
>
> props->num_csu_mon = FIELD_GET(MPAMF_CSUMON_IDR_NUM_MON, csumonidr);
> if (props->num_csu_mon) {
> @@ -954,7 +966,9 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris)
> bool has_long;
> u32 mbwumon_idr;
>
> - mpam_read_partsel_reg(msc, MBWUMON_IDR, &mbwumon_idr);
> + err = mpam_read_partsel_reg(msc, MBWUMON_IDR, &mbwumon_idr);
> + if (err)
> + return err;
>
> props->num_mbwu_mon = FIELD_GET(MPAMF_MBWUMON_IDR_NUM_MON, mbwumon_idr);
> if (props->num_mbwu_mon) {
> @@ -987,16 +1001,22 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris)
> u16 partid_max;
> u32 nrwidr;
>
> - mpam_read_partsel_reg(msc, PARTID_NRW_IDR, &nrwidr);
> + err = mpam_read_partsel_reg(msc, PARTID_NRW_IDR, &nrwidr);
> + if (err)
> + return err;
> +
> partid_max = FIELD_GET(MPAMF_PARTID_NRW_IDR_INTPARTID_MAX, nrwidr);
>
> mpam_set_feature(mpam_feat_partid_nrw, props);
> msc->partid_max = min(msc->partid_max, partid_max);
> }
> +
> + return 0;
> }
>
> static int mpam_msc_hw_probe(struct mpam_msc *msc)
> {
> + int ret;
> u64 idr;
> u16 partid_max;
> u8 ris_idx, pmg_max;
> @@ -1012,10 +1032,12 @@ static int mpam_msc_hw_probe(struct mpam_msc *msc)
>
> /* Grab an IDR value to find out how many RIS there are */
> mutex_lock(&msc->part_sel_lock);
> - mpam_msc_read_idr(msc, &idr);
> - mpam_read_partsel_reg(msc, IIDR, &msc->iidr);
> -
> + ret = mpam_msc_read_idr(msc, &idr);
> + if (!ret)
> + ret = mpam_read_partsel_reg(msc, IIDR, &msc->iidr);
> mutex_unlock(&msc->part_sel_lock);
> + if (ret)
> + return ret;
>
> mpam_enable_quirks(msc);
>
> @@ -1028,8 +1050,10 @@ static int mpam_msc_hw_probe(struct mpam_msc *msc)
> for (ris_idx = 0; ris_idx <= msc->ris_max; ris_idx++) {
> mutex_lock(&msc->part_sel_lock);
> __mpam_part_sel(ris_idx, 0, msc);
> - mpam_msc_read_idr(msc, &idr);
> + ret = mpam_msc_read_idr(msc, &idr);
> mutex_unlock(&msc->part_sel_lock);
> + if (ret)
> + return ret;
>
> partid_max = FIELD_GET(MPAMF_IDR_PARTID_MAX, idr);
> pmg_max = FIELD_GET(MPAMF_IDR_PMG_MAX, idr);
> @@ -1046,8 +1070,10 @@ static int mpam_msc_hw_probe(struct mpam_msc *msc)
>
> mutex_lock(&msc->part_sel_lock);
> __mpam_part_sel(ris_idx, 0, msc);
> - mpam_ris_hw_probe(ris);
> + ret = mpam_ris_hw_probe(ris);
> mutex_unlock(&msc->part_sel_lock);
> + if (ret)
> + return ret;
> }
>
> /* Clear any stale errors */
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