linux-kernel - Re: [PATCH v6 17/30] x86/resctrl: Discover hardware telemetry events

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Message-ID: <aGbyA-TVAdG5uUBk@agluck-desk3>
Date: Thu, 3 Jul 2025 14:11:31 -0700
From: "Luck, Tony" <tony.luck@...el.com>
To: Reinette Chatre <reinette.chatre@...el.com>
Cc: Fenghua Yu <fenghuay@...dia.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>, x86@...nel.org,
	linux-kernel@...r.kernel.org, patches@...ts.linux.dev
Subject: Re: [PATCH v6 17/30] x86/resctrl: Discover hardware telemetry events

On Thu, Jul 03, 2025 at 01:31:19PM -0700, Reinette Chatre wrote:
> I do not think resctrl should enforce dependency on a driver that is not
> valid for a platform.

Fewer stubs than I thought.  I can merge something along these
lines back into the series for the next version.

Suggestions welcome for the name of the config option. Do
I need a "_CPU" in CONFIG_X86_RESCTRL_INTEL_AET? It's already
very long.

"help" text is a placeholder. I can change that up to add more
details.

-Tony

---

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 11f25c225837..56615b1d3fc3 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -175,9 +175,19 @@ bool rdt_is_software_feature_enabled(char *option);
 
 bool rdt_is_software_feature_force_enabled(char *name);
 
+#ifdef CONFIG_X86_RESCTRL_INTEL_AET
 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,
 			 void *arch_priv, u64 *val);
+#else
+static inline bool intel_aet_get_events(void) { return false; }
+static inline void __exit intel_aet_exit(void) { }
+static inline int intel_aet_read_event(int domid, int rmid, enum resctrl_event_id evtid,
+				       void *arch_priv, u64 *val)
+{
+	return -EINVAL;
+}
+#endif
 
 #endif /* _ASM_X86_RESCTRL_INTERNAL_H */
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a6b6ecbd3877..ceb3eb371a3d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -512,9 +512,6 @@ config X86_CPU_RESCTRL
 	select ARCH_HAS_CPU_RESCTRL
 	select RESCTRL_FS
 	select RESCTRL_FS_PSEUDO_LOCK
-	select X86_PLATFORM_DEVICES
-	select INTEL_VSEC
-	select INTEL_PMT_TELEMETRY
 	help
 	  Enable x86 CPU resource control support.
 
@@ -531,6 +528,18 @@ config X86_CPU_RESCTRL
 
 	  Say N if unsure.
 
+config X86_RESCTRL_INTEL_AET
+	bool "Intel Application Energy Telemetry"
+	depends on X86_CPU_RESCTRL && CPU_SUP_INTEL && INTEL_PMT_DISCOVERY
+	help
+	  Enable per-RMID telemetry events in resctrl
+
+	  Intel feature that collects per-RMID execution data
+	  including core energy consumed by tasks. Data is aggregated
+	  per package.
+
+	  Say N if unsure.
+
 config X86_FRED
 	bool "Flexible Return and Event Delivery"
 	depends on X86_64
diff --git a/arch/x86/kernel/cpu/resctrl/Makefile b/arch/x86/kernel/cpu/resctrl/Makefile
index 97ceb4e44dfa..26fc957fb3dd 100644
--- a/arch/x86/kernel/cpu/resctrl/Makefile
+++ b/arch/x86/kernel/cpu/resctrl/Makefile
@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_X86_CPU_RESCTRL)		+= core.o rdtgroup.o monitor.o
 obj-$(CONFIG_X86_CPU_RESCTRL)		+= ctrlmondata.o
-obj-$(CONFIG_X86_CPU_RESCTRL)		+= intel_aet.o
+obj-$(CONFIG_X86_RESCTRL_INTEL_AET)	+= intel_aet.o
 obj-$(CONFIG_RESCTRL_FS_PSEUDO_LOCK)	+= pseudo_lock.o
 
 # To allow define_trace.h's recursive include:
-- 
2.50.0