[PATCH v3 18/26] x86/resctrl: Add code to read core telemetry events

Tony Luck
2025-04-07T23:40:59Z

The new telemetry events will be part of a new resctrl resource.
Add the RDT_RESOURCE_PERF_PKG to enum resctrl_res_level.

Add hook resctrl_arch_rmid_read() to pass reads on this
resource to the telemetry code.

There may be multiple devices tracking each package, so scan all of them
and add up counters.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
include/linux/resctrl_types.h | 1 +
arch/x86/kernel/cpu/resctrl/internal.h | 5 +++
arch/x86/kernel/cpu/resctrl/intel_aet.c | 58 +++++++++++++++++++++++++
arch/x86/kernel/cpu/resctrl/monitor.c | 6 +++
4 files changed, 70 insertions(+)

diff --git a/include/linux/resctrl_types.h b/include/linux/resctrl_types.h
index fbd4b55c41aa..3354f21e82ad 100644
--- a/include/linux/resctrl_types.h
+++ b/include/linux/resctrl_types.h
@@ -39,6 +39,7 @@ enum resctrl_res_level {
RDT_RESOURCE_L2,
RDT_RESOURCE_MBA,
RDT_RESOURCE_SMBA,
+ RDT_RESOURCE_PERF_PKG,

/* Must be the last */
RDT_NUM_RESOURCES,
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 70b63bbc429d..1b1cbb948a9a 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -175,9 +175,14 @@ void rdt_domain_reconfigure_cdp(struct rdt_resource *r);
#ifdef CONFIG_INTEL_AET_RESCTRL
bool intel_aet_get_events(void);
void __exit intel_aet_exit(void);
+int intel_aet_read_event(int domid, int rmid, int evtid, u64 *val);
#else
static inline bool intel_aet_get_events(void) { return false; }
static inline void intel_aet_exit(void) { };
+static inline int intel_aet_read_event(int domid, int rmid, int evtid, u64 *val)
+{
+ return -EINVAL;
+}
#endif

#endif /* _ASM_X86_RESCTRL_INTERNAL_H */
diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
index 44d2fe747ed8..67a1245858dc 100644
--- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
+++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
@@ -73,6 +73,12 @@ static struct evtinfo {
struct pmt_event *pmt_event;
} evtinfo[QOS_NUM_EVENTS];

+#define EVT_NUM_RMIDS(evtid) (evtinfo[evtid].telem_entry->num_rmids)
+#define EVT_NUM_EVENTS(evtid) (evtinfo[evtid].telem_entry->num_events)
+#define EVT_GUID(evtid) (evtinfo[evtid].telem_entry->guid)
+
+#define EVT_OFFSET(evtid) (evtinfo[evtid].pmt_event->evt_offset)
+
/* All known telemetry event groups */
static struct telem_entry *telem_entry[] = {
NULL
@@ -224,3 +230,55 @@ void __exit intel_aet_exit(void)
}
kfree(pkg_info);
}
+
+#define VALID_BIT BIT_ULL(63)
+#define DATA_BITS GENMASK_ULL(62, 0)
+
+/*
+ * Walk the array of telemetry groups on a specific package.
+ * Read and sum values for a specific counter (described by
+ * guid and offset).
+ * Return failure (~0x0ull) if any counter isn't valid.
+ */
+static u64 scan_pmt_devs(int package, int guid, int offset)
+{
+ u64 rval, val;
+ int ndev = 0;
+
+ rval = 0;
+
+ for (int i = 0; i < pkg_info[package].count; i++) {
+ if (pkg_info[package].regions[i].guid != guid)
+ continue;
+ ndev++;
+ val = readq(pkg_info[package].regions[i].addr + offset);
+
+ if (!(val & VALID_BIT))
+ return ~0ull;
+ rval += val & DATA_BITS;
+ }
+
+ return ndev ? rval : ~0ull;
+}
+
+/*
+ * Read counter for an event on a domain (summing all aggregators
+ * on the domain).
+ */
+int intel_aet_read_event(int domid, int rmid, int evtid, u64 *val)
+{
+ u64 evtcount;
+ int offset;
+
+ if (rmid >= EVT_NUM_RMIDS(evtid))
+ return -ENOENT;
+
+ offset = rmid * EVT_NUM_EVENTS(evtid) * sizeof(u64);
+ offset += EVT_OFFSET(evtid);
+ evtcount = scan_pmt_devs(domid, EVT_GUID(evtid), offset);
+
+ if (evtcount != ~0ull || *val == 0)
+ *val += evtcount;
+
+ return evtcount != ~0ull ? 0 : -EINVAL;
+}
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 06623d51d006..4fa297d463ba 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -236,6 +236,12 @@ int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_mon_domain *d,
u32 prmid;
int ret;

+ if (r->rid == RDT_RESOURCE_PERF_PKG) {
+ ret = intel_aet_read_event(d->hdr.id, rmid, eventid, val);
+
+ return ret ? ret : 0;
+ }
+
resctrl_arch_rmid_read_context_check();

prmid = logical_rmid_to_physical_rmid(cpu, rmid);
--
2.48.1