linux-kernel - [PATCH v3.1 14/15] perf/x86: Simplify Intel PMU initialization

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Message-ID: <20250227001615.1231958-1-sohil.mehta@intel.com>
Date: Thu, 27 Feb 2025 00:16:15 +0000
From: Sohil Mehta <sohil.mehta@...el.com>
To: x86@...nel.org,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Tony Luck <tony.luck@...el.com>
Cc: Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...en8.de>,
	"H . Peter Anvin" <hpa@...or.com>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>,
	Andy Lutomirski <luto@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Jean Delvare <jdelvare@...e.com>,
	Guenter Roeck <linux@...ck-us.net>,
	Zhang Rui <rui.zhang@...el.com>,
	Andrew Cooper <andrew.cooper3@...rix.com>,
	David Laight <david.laight.linux@...il.com>,
	Dapeng Mi <dapeng1.mi@...ux.intel.com>,
	Sohil Mehta <sohil.mehta@...el.com>,
	linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org,
	linux-pm@...r.kernel.org
Subject: [PATCH v3.1 14/15] perf/x86: Simplify Intel PMU initialization

Architectural Perfmon was introduced on the Family 6 "Core" processors
starting with Yonah. Processors before Yonah need their own customized
PMU initialization.

p6_pmu_init() is expected to provide that initialization for early
Family 6 processors. But, currently, it could get called for any Family
6 processor if the architectural perfmon feature is disabled on that
processor. To simplify, restrict the P6 PMU initialization to early
Family 6 processors that do not have architectural perfmon support and
truly need the special handling.

As a result, the "unsupported" console print becomes practically
unreachable because all the released P6 processors are covered by the
switch cases. Move the console print to a common location where it can
cover all modern processors (including Family >15) that may not have
architectural perfmon support enumerated.

Also, use this opportunity to get rid of the unnecessary switch cases in
P6 initialization. Only the Pentium Pro processor needs a quirk, and the
rest of the processors do not need any special handling. The gaps in the
case numbers are only due to no processor with those model numbers being
released.

Use decimal numbers for Intel Family numbers. Also, convert one of the
last few Intel x86_model comparison to a VFM based one.

Signed-off-by: Sohil Mehta <sohil.mehta@...el.com>
Reviewed-by: Kan Liang <kan.liang@...ux.intel.com>
---
Sending an updated version for this one since it's the only one with a
change. This would make it feasible to pickup the entire patchset in
this cycle if desired.

v3.1: Move the default case outside of the switch.
      Pickup the Reviewed-by tag from Kan Liang.

v3: Restrict calling p6_pmu_init() to only when needed.
    Move the console print to a common location.

v2: No change.
---
 arch/x86/events/intel/core.c | 14 ++++++++++----
 arch/x86/events/intel/p6.c   | 26 +++-----------------------
 2 files changed, 13 insertions(+), 27 deletions(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 7601196d1d18..ef59643a9d23 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -6466,15 +6466,21 @@ __init int intel_pmu_init(void)
 	char *name;
 	struct x86_hybrid_pmu *pmu;
 
+	/* Architectural Perfmon was introduced starting with Core "Yonah" */
 	if (!cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON)) {
 		switch (boot_cpu_data.x86) {
-		case 0x6:
-			return p6_pmu_init();
-		case 0xb:
+		case 6:
+			if (boot_cpu_data.x86_vfm < INTEL_CORE_YONAH)
+				return p6_pmu_init();
+			break;
+		case 11:
 			return knc_pmu_init();
-		case 0xf:
+		case 15:
 			return p4_pmu_init();
 		}
+
+		pr_cont("unsupported CPU family %d model %d ",
+			boot_cpu_data.x86, boot_cpu_data.x86_model);
 		return -ENODEV;
 	}
 
diff --git a/arch/x86/events/intel/p6.c b/arch/x86/events/intel/p6.c
index a6cffb4f4ef5..65b45e9d7016 100644
--- a/arch/x86/events/intel/p6.c
+++ b/arch/x86/events/intel/p6.c
@@ -2,6 +2,8 @@
 #include <linux/perf_event.h>
 #include <linux/types.h>
 
+#include <asm/cpu_device_id.h>
+
 #include "../perf_event.h"
 
 /*
@@ -248,30 +250,8 @@ __init int p6_pmu_init(void)
 {
 	x86_pmu = p6_pmu;
 
-	switch (boot_cpu_data.x86_model) {
-	case  1: /* Pentium Pro */
+	if (boot_cpu_data.x86_vfm == INTEL_PENTIUM_PRO)
 		x86_add_quirk(p6_pmu_rdpmc_quirk);
-		break;
-
-	case  3: /* Pentium II - Klamath */
-	case  5: /* Pentium II - Deschutes */
-	case  6: /* Pentium II - Mendocino */
-		break;
-
-	case  7: /* Pentium III - Katmai */
-	case  8: /* Pentium III - Coppermine */
-	case 10: /* Pentium III Xeon */
-	case 11: /* Pentium III - Tualatin */
-		break;
-
-	case  9: /* Pentium M - Banias */
-	case 13: /* Pentium M - Dothan */
-		break;
-
-	default:
-		pr_cont("unsupported p6 CPU model %d ", boot_cpu_data.x86_model);
-		return -ENODEV;
-	}
 
 	memcpy(hw_cache_event_ids, p6_hw_cache_event_ids,
 		sizeof(hw_cache_event_ids));
-- 
2.43.0