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

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Message-ID: <20250219184133.816753-15-sohil.mehta@intel.com>
Date: Wed, 19 Feb 2025 18:41:32 +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 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, due to the unrestricted call to p6_pmu_init(),
it could get called for any Family 6 processor if the architectural
perfmon feature is disabled on that processor.

To simplify, restrict the call to p6_pmu_init() to early Family 6
processors that do not have architectural perfmon support. 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 that do not have architectural perfmon support.

Also, use this opportunity to get rid of the unnecessary switch cases in
p6_pmu_init().  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.

Converting to a VFM based check gets rid of one last few Intel x86_model
comparisons.

Signed-off-by: Sohil Mehta <sohil.mehta@...el.com>
---
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 | 16 +++++++++++-----
 arch/x86/events/intel/p6.c   | 26 +++-----------------------
 2 files changed, 14 insertions(+), 28 deletions(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 7601196d1d18..c645d8c8ab87 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -6466,16 +6466,22 @@ __init int intel_pmu_init(void)
 	char *name;
 	struct x86_hybrid_pmu *pmu;
 
+	/* Architectural Perfmon was introduced starting with INTEL_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();
+		default:
+			pr_cont("unsupported CPU family %d model %d ",
+				boot_cpu_data.x86, boot_cpu_data.x86_model);
+			return -ENODEV;
 		}
-		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