linux-kernel - [PATCH v4 22/31] x86/resctrl: Read core telemetry events

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Message-ID: <20250429003359.375508-23-tony.luck@intel.com>
Date: Mon, 28 Apr 2025 17:33:48 -0700
From: Tony Luck <tony.luck@...el.com>
To: Fenghua Yu <fenghuay@...dia.com>,
	Reinette Chatre <reinette.chatre@...el.com>,
	Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>,
	Peter Newman <peternewman@...gle.com>,
	James Morse <james.morse@....com>,
	Babu Moger <babu.moger@....com>,
	Drew Fustini <dfustini@...libre.com>,
	Dave Martin <Dave.Martin@....com>,
	Anil Keshavamurthy <anil.s.keshavamurthy@...el.com>,
	Chen Yu <yu.c.chen@...el.com>
Cc: x86@...nel.org,
	linux-kernel@...r.kernel.org,
	patches@...ts.linux.dev,
	Tony Luck <tony.luck@...el.com>
Subject: [PATCH v4 22/31] x86/resctrl: Read core telemetry events

The resctrl file system passes requests to read event monitor files to
the architecture resctrl_arch_rmid_read() function to collect values
from hardware counters.

Use the resctrl resource to differentiate between calls to read legacy
L3 events from the new telemetry events (which are attached to
RDT_RESOURCE_PERF_PKG).

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

Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 arch/x86/kernel/cpu/resctrl/internal.h  |  5 ++++
 arch/x86/kernel/cpu/resctrl/intel_aet.c | 34 +++++++++++++++++++++++++
 arch/x86/kernel/cpu/resctrl/monitor.c   |  3 +++
 3 files changed, 42 insertions(+)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 571db665eca6..dd5fe8a98304 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -170,9 +170,14 @@ 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, enum resctrl_event_id 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, enum resctrl_event_id 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 e1cb6bd4788d..0bbf991da981 100644
--- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
+++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
@@ -13,6 +13,7 @@
 
 #include <linux/cleanup.h>
 #include <linux/cpu.h>
+#include <linux/io.h>
 #include <linux/resctrl.h>
 
 /* Temporary - delete from final version */
@@ -246,3 +247,36 @@ void __exit intel_aet_exit(void)
 		free_mmio_info((*peg)->pkginfo);
 	}
 }
+
+#define VALID_BIT	BIT_ULL(63)
+#define DATA_BITS	GENMASK_ULL(62, 0)
+
+/*
+ * Read counter for an event on a domain (summing all aggregators
+ * on the domain).
+ */
+int intel_aet_read_event(int domid, int rmid, enum resctrl_event_id evtid, u64 *val)
+{
+	struct evtinfo *info = &evtinfo[evtid];
+	struct mmio_info *mmi;
+	u64 evtcount;
+	int idx;
+
+	idx = rmid * info->event_group->num_events;
+	idx += info->idx;
+	mmi = info->event_group->pkginfo[domid];
+
+	if (idx * sizeof(u64) > info->event_group->mmio_size) {
+		pr_warn_once("MMIO index %d out of range\n", idx);
+		return -EINVAL;
+	}
+
+	for (int i = 0; i < mmi->count; i++) {
+		evtcount = readq(mmi->addrs[i] + idx * sizeof(u64));
+		if (!(evtcount & VALID_BIT))
+			return -EINVAL;
+		*val += evtcount & DATA_BITS;
+	}
+
+	return 0;
+}
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 8d8ec86929fa..04214585824b 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -237,6 +237,9 @@ int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_l3_mon_domain *d,
 
 	resctrl_arch_rmid_read_context_check();
 
+	if (r->rid == RDT_RESOURCE_PERF_PKG)
+		return intel_aet_read_event(d->hdr.id, rmid, eventid, val);
+
 	prmid = logical_rmid_to_physical_rmid(cpu, rmid);
 	ret = __rmid_read_phys(prmid, eventid, &msr_val);
 	if (ret)
-- 
2.48.1