[PATCH] arm_mpam: Only program MATCH_PMG when the monitor supports it

[Ping Li]

An MSC of ours implements the MBWU monitor without PMG support:
MPAMF_MBWUMON_IDR.NO_MATCH_PMG is 1, so MSMON_CFG_x_CTL.MATCH_PMG is
RES0. On this hardware resctrl monitor reads always returned 0.

Tracking this down: __read_mon() unconditionally sets match_pmg,
because the resctrl (closid, rmid) model maps rmid to PMG. The
expected configuration generated by gen_msmon_ctl_flt_vals() then
contains MATCH_PMG, but the hardware ignores the bit, so the
configuration read back never matches, config_mismatch is always
true and the monitor is reprogrammed on every read - the counter
never accumulates.

The architecture allows an MSMON implementation without PMG
support, so read the NO_MATCH_PMG bits during probe and only
program MATCH_PMG when the monitor supports PMG filtering,
falling back to filtering by PARTID only. The CSU monitor has
the same issue and is covered the same way.

Signed-off-by: Ping Li <leeonion.muyu at gmail.com>
---
 drivers/resctrl/mpam_devices.c  | 22 +++++++++++++++++++++-
 drivers/resctrl/mpam_internal.h |  4 ++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index c067b6d57d71..2086ff121b59 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -1089,6 +1089,9 @@ static int mpam_ris_hw_probe(struct mpam_msc_ris *ris)
 				if (FIELD_GET(MPAMF_CSUMON_IDR_HAS_XCL, csumonidr))
 					mpam_set_feature(mpam_feat_msmon_csu_xcl, props);
 
+				if (!FIELD_GET(MPAMF_CSUMON_IDR_NO_MATCH_PMG, csumonidr))
+					mpam_set_feature(mpam_feat_msmon_csu_match_pmg, props);
+
 				/* Is NRDY hardware managed? */
 				err = mpam_ris_hw_probe_csu_nrdy(ris);
 				if (err < 0)
@@ -1118,6 +1121,9 @@ static int mpam_ris_hw_probe(struct mpam_msc_ris *ris)
 				if (FIELD_GET(MPAMF_MBWUMON_IDR_HAS_RWBW, mbwumon_idr))
 					mpam_set_feature(mpam_feat_msmon_mbwu_rwbw, props);
 
+				if (!FIELD_GET(MPAMF_MBWUMON_IDR_NO_MATCH_PMG, mbwumon_idr))
+					mpam_set_feature(mpam_feat_msmon_mbwu_match_pmg, props);
+
 				has_long = FIELD_GET(MPAMF_MBWUMON_IDR_HAS_LONG, mbwumon_idr);
 				if (has_long) {
 					if (FIELD_GET(MPAMF_MBWUMON_IDR_LWD, mbwumon_idr))
@@ -1309,6 +1315,20 @@ static int mpam_msc_zero_mbwu_l(struct mpam_msc *msc)
 	return __mpam_write_reg(msc, MSMON_MBWU_L + 4, 0);
 }
 
+static bool msmon_supports_match_pmg(struct mon_read *m)
+{
+	switch (m->type) {
+	case mpam_feat_msmon_csu:
+		return mpam_has_feature(mpam_feat_msmon_csu_match_pmg, &m->ris->props);
+	case mpam_feat_msmon_mbwu_31counter:
+	case mpam_feat_msmon_mbwu_44counter:
+	case mpam_feat_msmon_mbwu_63counter:
+		return mpam_has_feature(mpam_feat_msmon_mbwu_match_pmg, &m->ris->props);
+	default:
+		return true;
+	}
+}
+
 static void gen_msmon_ctl_flt_vals(struct mon_read *m, u32 *ctl_val,
 				   u32 *flt_val)
 {
@@ -1322,7 +1342,7 @@ static void gen_msmon_ctl_flt_vals(struct mon_read *m, u32 *ctl_val,
 
 	*flt_val = FIELD_PREP(MSMON_CFG_x_FLT_PARTID, ctx->partid);
 
-	if (m->ctx->match_pmg) {
+	if (m->ctx->match_pmg && msmon_supports_match_pmg(m)) {
 		*ctl_val |= MSMON_CFG_x_CTL_MATCH_PMG;
 		*flt_val |= FIELD_PREP(MSMON_CFG_x_FLT_PMG, ctx->pmg);
 	}
diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
index 1f86cc158100..88cd5ac4cde3 100644
--- a/drivers/resctrl/mpam_internal.h
+++ b/drivers/resctrl/mpam_internal.h
@@ -227,12 +227,14 @@ enum mpam_device_features {
 	mpam_feat_msmon_csu,
 	mpam_feat_msmon_csu_capture,
 	mpam_feat_msmon_csu_xcl,
+	mpam_feat_msmon_csu_match_pmg,
 	mpam_feat_msmon_mbwu,
 	mpam_feat_msmon_mbwu_31counter,
 	mpam_feat_msmon_mbwu_44counter,
 	mpam_feat_msmon_mbwu_63counter,
 	mpam_feat_msmon_mbwu_capture,
 	mpam_feat_msmon_mbwu_rwbw,
+	mpam_feat_msmon_mbwu_match_pmg,
 	mpam_feat_partid_nrw,
 	MPAM_FEATURE_LAST
 };
@@ -645,6 +647,7 @@ int mpam_fb_check_shared_buffer_size(struct mpam_msc *msc);
 
 /* MPAMF_CSUMON_IDR - MPAM cache storage usage monitor ID register */
 #define MPAMF_CSUMON_IDR_NUM_MON	GENMASK(15, 0)
+#define MPAMF_CSUMON_IDR_NO_MATCH_PMG	BIT(22)
 #define MPAMF_CSUMON_IDR_HAS_OFLOW_CAPT	BIT(24)
 #define MPAMF_CSUMON_IDR_HAS_CEVNT_OFLW	BIT(25)
 #define MPAMF_CSUMON_IDR_HAS_OFSR	BIT(26)
@@ -655,6 +658,7 @@ int mpam_fb_check_shared_buffer_size(struct mpam_msc *msc);
 
 /* MPAMF_MBWUMON_IDR - MPAM memory bandwidth usage monitor ID register */
 #define MPAMF_MBWUMON_IDR_NUM_MON	GENMASK(15, 0)
+#define MPAMF_MBWUMON_IDR_NO_MATCH_PMG	BIT(22)
 #define MPAMF_MBWUMON_IDR_HAS_RWBW	BIT(28)
 #define MPAMF_MBWUMON_IDR_LWD		BIT(29)
 #define MPAMF_MBWUMON_IDR_HAS_LONG	BIT(30)
-- 
2.34.1