[RFC PATCH 19/31] x86/resctrl: Enable the region based events by adding them into the event
From: Chen Yu
Date: Sun Aug 02 2026 - 12:18:04 EST
The following MBM events will be displayed under each domain:
[root@ mon_data]# tree
.
├── mon_L3_00
│ ├── llc_occupancy
│ ├── mbm_region0_bytes
│ └── mbm_region1_bytes
├── mon_L3_01
│ ├── llc_occupancy
│ ├── mbm_region0_bytes
│ └── mbm_region1_bytes
├── mon_L3_02
│ ├── llc_occupancy
│ ├── mbm_region0_bytes
│ └── mbm_region1_bytes
└── mon_L3_03
├── llc_occupancy
├── mbm_region0_bytes
└── mbm_region1_bytes
Note, the actual maximum number of available memory regions
is provided by the MRRM table. Suppose the maximum number of
available memory regions exposed by MRRM is 2; then each domain
can access at most 2 regions.
Region-aware MBM counters live in MMIO rather than in the QM_CTR MSR, so
resctrl_arch_reset_rmid() must read the initial counter value through
erdt_mon_read() instead of __rmid_read_phys(). Add a "first" parameter to
tell erdt_read_region_mbm() which kind of read this is: when set, only
record the raw counter value in am->prev_mon_val so that later reads can
compute a delta from it, without accumulating that absolute value into
am->chunks as if it had been consumed.
Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
---
arch/x86/kernel/cpu/resctrl/core.c | 8 +++++
arch/x86/kernel/cpu/resctrl/erdt.c | 48 +++++++++++++++++++++++---
arch/x86/kernel/cpu/resctrl/internal.h | 4 ++-
arch/x86/kernel/cpu/resctrl/monitor.c | 14 ++++++--
fs/resctrl/monitor.c | 4 +++
include/linux/resctrl_types.h | 2 ++
6 files changed, 71 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index a7322f0ebaea..1827e3ea5fee 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -1081,6 +1081,13 @@ static __init bool get_rdt_mon_resources(void)
resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID, false, 0, NULL);
ret = true;
}
+
+ if (erdt_enable_mon()) {
+ ret = true;
+
+ goto done;
+ }
+
if (rdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL)) {
resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID, false, 0, NULL);
ret = true;
@@ -1092,6 +1099,7 @@ static __init bool get_rdt_mon_resources(void)
if (rdt_cpu_has(X86_FEATURE_ABMC))
ret = true;
+done:
if (!ret)
return false;
diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
index 35217f48b3d9..d16cd6af6648 100644
--- a/arch/x86/kernel/cpu/resctrl/erdt.c
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -49,9 +49,30 @@ bool erdt_support(int flag)
if (flag == X86_FEATURE_CQM_OCCUP_LLC)
return valid_subtbl_mask & BIT(ACPI_ERDT_TYPE_CMRC);
+ if (flag == X86_FEATURE_CQM_MBM_TOTAL)
+ return valid_subtbl_mask & BIT(ACPI_ERDT_TYPE_MMRC);
+
return false;
}
+bool erdt_enable_mon(void)
+{
+ int i, max_regions;
+
+ if (!erdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL))
+ return false;
+
+ max_regions = acpi_mrrm_max_mem_region();
+ for_each_rmbm_event_id(i) {
+ if (!max_regions--)
+ break;
+
+ resctrl_enable_mon_event(i, true, 0, NULL);
+ }
+
+ return true;
+}
+
int erdt_get_max_rmid(void)
{
return erdt_max_rmid;
@@ -130,9 +151,9 @@ static u64 apply_correction_factor(u64 val, u32 factor)
static int erdt_read_region_mbm(struct rdt_domain_hdr *hdr,
const struct erdt_domain_info *d, int rmid,
- int eventid, u64 *val)
+ int eventid, u64 *val, bool first)
{
- int region_idx = eventid - QOS_L3_MBM_R0_EVENT_ID;
+ int region_idx = RMBM_STATE_IDX(eventid);
int corr_factor_len, corr_factor = 0;
struct rdt_hw_l3_mon_domain *hw_dom;
u64 mbm_rmid_count = 0, chunks = 0;
@@ -163,6 +184,23 @@ static int erdt_read_region_mbm(struct rdt_domain_hdr *hdr,
(mbm_rmid_count & UNAVAILABLE_COUNTER))
return -EINVAL;
+ am = get_arch_mbm_state(hw_dom, rmid, eventid);
+
+ /*
+ * The first read only records the initial, non-zero count value so
+ * that later reads can compute a delta from it. Nothing is reported
+ * to the caller, and the software state must not accumulate the
+ * absolute counter value as if it had been consumed.
+ */
+ if (first) {
+ if (am)
+ am->prev_mon_val = mbm_rmid_count;
+
+ *val = 0;
+
+ return 0;
+ }
+
corr_factor_len = mmrc->corr_factor_list_len;
if (corr_factor_len) {
/*
@@ -181,7 +219,6 @@ static int erdt_read_region_mbm(struct rdt_domain_hdr *hdr,
return -EINVAL;
}
- am = get_arch_mbm_state(hw_dom, rmid, eventid);
if (am) {
am->chunks += mbm_overflow_count(am->prev_mon_val, mbm_rmid_count,
mmrc->counter_width);
@@ -195,7 +232,8 @@ static int erdt_read_region_mbm(struct rdt_domain_hdr *hdr,
return 0;
}
-int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 rmid, u64 *val)
+int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 rmid,
+ u64 *val, bool first)
{
struct rdt_hw_l3_mon_domain *hw_dom;
const struct erdt_domain_info *d;
@@ -209,7 +247,7 @@ int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 r
return erdt_read_l3_occupancy(d, rmid, val);
if (rmbm_event(evtid))
- return erdt_read_region_mbm(hdr, d, rmid, evtid, val);
+ return erdt_read_region_mbm(hdr, d, rmid, evtid, val, first);
return -EIO;
}
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index b665b19b6f8b..c48e8d4a62d5 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -315,8 +315,10 @@ static inline bool intel_handle_aet_option(bool force_off, char *tok) { return f
bool erdt_support(int flag);
bool erdt_cpu_has(int flag);
+bool erdt_enable_mon(void);
int erdt_get_max_rmid(void);
-int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 rmid, u64 *val);
+int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 rmid,
+ u64 *val, bool first);
int erdt_init(void);
void erdt_exit(void);
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index c60d3d55a96c..21dd33eaafe9 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -179,14 +179,19 @@ void resctrl_arch_reset_rmid(struct rdt_resource *r, struct rdt_l3_mon_domain *d
int cpu = cpumask_any(&d->hdr.cpu_mask);
struct arch_mbm_state *am;
u32 prmid;
+ u64 tmp;
am = get_arch_mbm_state(hw_dom, rmid, eventid);
if (am) {
memset(am, 0, sizeof(*am));
- prmid = logical_rmid_to_physical_rmid(cpu, rmid);
/* Record any initial, non-zero count value. */
- __rmid_read_phys(prmid, eventid, &am->prev_mon_val);
+ if (rmbm_event(eventid) && erdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL)) {
+ erdt_mon_read(&d->hdr, eventid, rmid, &tmp, true);
+ } else {
+ prmid = logical_rmid_to_physical_rmid(cpu, rmid);
+ __rmid_read_phys(prmid, eventid, &am->prev_mon_val);
+ }
}
}
@@ -280,7 +285,10 @@ int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain_hdr *hdr,
case RDT_RESOURCE_L3:
if (eventid == QOS_L3_OCCUP_EVENT_ID &&
erdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC))
- return erdt_mon_read(hdr, eventid, rmid, val);
+ return erdt_mon_read(hdr, eventid, rmid, val, false);
+
+ if (rmbm_event(eventid) && erdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL))
+ return erdt_mon_read(hdr, eventid, rmid, val, false);
return arch_l3_read_event(hdr, rmid, eventid, val, r);
case RDT_RESOURCE_PERF_PKG:
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index aadac544576b..0a5a38b8ffda 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -1031,6 +1031,10 @@ struct mon_evt mon_event_all[QOS_NUM_EVENTS] = {
MON_EVENT(PMT_EVENT_AUTO_C6_RES, "c6_res", RDT_RESOURCE_PERF_PKG, false),
MON_EVENT(PMT_EVENT_UNHALTED_REF_CYCLES, "unhalted_ref_cycles", RDT_RESOURCE_PERF_PKG, false),
MON_EVENT(PMT_EVENT_UOPS_RETIRED, "uops_retired", RDT_RESOURCE_PERF_PKG, false),
+ MON_EVENT(QOS_L3_MBM_R0_EVENT_ID, "mbm_region0_bytes", RDT_RESOURCE_L3, false),
+ MON_EVENT(QOS_L3_MBM_R1_EVENT_ID, "mbm_region1_bytes", RDT_RESOURCE_L3, false),
+ MON_EVENT(QOS_L3_MBM_R2_EVENT_ID, "mbm_region2_bytes", RDT_RESOURCE_L3, false),
+ MON_EVENT(QOS_L3_MBM_R3_EVENT_ID, "mbm_region3_bytes", RDT_RESOURCE_L3, false),
};
bool resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu,
diff --git a/include/linux/resctrl_types.h b/include/linux/resctrl_types.h
index ee8fc7df22f9..95945dd71472 100644
--- a/include/linux/resctrl_types.h
+++ b/include/linux/resctrl_types.h
@@ -82,6 +82,8 @@ static inline bool rmbm_event(unsigned int e)
return (e >= QOS_L3_MBM_R0_EVENT_ID) && (e <= QOS_L3_MBM_R3_EVENT_ID);
}
+#define RMBM_STATE_IDX(evt) ((evt) - QOS_L3_MBM_R0_EVENT_ID)
+
#define QOS_NUM_L3_MBM_EVENTS (QOS_L3_MBM_R3_EVENT_ID - QOS_L3_MBM_TOTAL_EVENT_ID + 1)
#define MBM_STATE_IDX(evt) ((evt) - QOS_L3_MBM_TOTAL_EVENT_ID)
--
2.43.0