linux-kernel - [tip: perf/urgent] perf/x86/intel: Fix ARCH_PERFMON_NUM_COUNTER

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Message-ID: <173928636641.10177.8036083101201125379.tip-bot2@tip-bot2>
Date: Tue, 11 Feb 2025 15:06:06 -0000
From: "tip-bot2 for Kan Liang" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Kan Liang <kan.liang@...ux.intel.com>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>, stable@...r.kernel.org,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: perf/urgent] perf/x86/intel: Fix ARCH_PERFMON_NUM_COUNTER_LEAF

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     47a973fd75639fe80d59f9e1860113bb2a0b112b
Gitweb:        https://git.kernel.org/tip/47a973fd75639fe80d59f9e1860113bb2a0b112b
Author:        Kan Liang <kan.liang@...ux.intel.com>
AuthorDate:    Wed, 29 Jan 2025 07:48:19 -08:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Sat, 08 Feb 2025 15:47:25 +01:00

perf/x86/intel: Fix ARCH_PERFMON_NUM_COUNTER_LEAF

The EAX of the CPUID Leaf 023H enumerates the mask of valid sub-leaves.
To tell the availability of the sub-leaf 1 (enumerate the counter mask),
perf should check the bit 1 (0x2) of EAS, rather than bit 0 (0x1).

The error is not user-visible on bare metal. Because the sub-leaf 0 and
the sub-leaf 1 are always available. However, it may bring issues in a
virtualization environment when a VMM only enumerates the sub-leaf 0.

Introduce the cpuid35_e?x to replace the macros, which makes the
implementation style consistent.

Fixes: eb467aaac21e ("perf/x86/intel: Support Architectural PerfMon Extension leaf")
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: stable@...r.kernel.org
Link: https://lkml.kernel.org/r/20250129154820.3755948-3-kan.liang@linux.intel.com
---
 arch/x86/events/intel/core.c      | 18 ++++++++++--------
 arch/x86/include/asm/perf_event.h | 28 +++++++++++++++++++++++++---
 2 files changed, 35 insertions(+), 11 deletions(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 966f783..f3d5b71 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4905,20 +4905,22 @@ static inline bool intel_pmu_broken_perf_cap(void)
 
 static void update_pmu_cap(struct x86_hybrid_pmu *pmu)
 {
-	unsigned int sub_bitmaps, eax, ebx, ecx, edx;
+	unsigned int cntr, fixed_cntr, ecx, edx;
+	union cpuid35_eax eax;
+	union cpuid35_ebx ebx;
 
-	cpuid(ARCH_PERFMON_EXT_LEAF, &sub_bitmaps, &ebx, &ecx, &edx);
+	cpuid(ARCH_PERFMON_EXT_LEAF, &eax.full, &ebx.full, &ecx, &edx);
 
-	if (ebx & ARCH_PERFMON_EXT_UMASK2)
+	if (ebx.split.umask2)
 		pmu->config_mask |= ARCH_PERFMON_EVENTSEL_UMASK2;
-	if (ebx & ARCH_PERFMON_EXT_EQ)
+	if (ebx.split.eq)
 		pmu->config_mask |= ARCH_PERFMON_EVENTSEL_EQ;
 
-	if (sub_bitmaps & ARCH_PERFMON_NUM_COUNTER_LEAF_BIT) {
+	if (eax.split.cntr_subleaf) {
 		cpuid_count(ARCH_PERFMON_EXT_LEAF, ARCH_PERFMON_NUM_COUNTER_LEAF,
-			    &eax, &ebx, &ecx, &edx);
-		pmu->cntr_mask64 = eax;
-		pmu->fixed_cntr_mask64 = ebx;
+			    &cntr, &fixed_cntr, &ecx, &edx);
+		pmu->cntr_mask64 = cntr;
+		pmu->fixed_cntr_mask64 = fixed_cntr;
 	}
 
 	if (!intel_pmu_broken_perf_cap()) {
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index 1ac79f3..0ba8d20 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -188,11 +188,33 @@ union cpuid10_edx {
  * detection/enumeration details:
  */
 #define ARCH_PERFMON_EXT_LEAF			0x00000023
-#define ARCH_PERFMON_EXT_UMASK2			0x1
-#define ARCH_PERFMON_EXT_EQ			0x2
-#define ARCH_PERFMON_NUM_COUNTER_LEAF_BIT	0x1
 #define ARCH_PERFMON_NUM_COUNTER_LEAF		0x1
 
+union cpuid35_eax {
+	struct {
+		unsigned int	leaf0:1;
+		/* Counters Sub-Leaf */
+		unsigned int    cntr_subleaf:1;
+		/* Auto Counter Reload Sub-Leaf */
+		unsigned int    acr_subleaf:1;
+		/* Events Sub-Leaf */
+		unsigned int    events_subleaf:1;
+		unsigned int	reserved:28;
+	} split;
+	unsigned int            full;
+};
+
+union cpuid35_ebx {
+	struct {
+		/* UnitMask2 Supported */
+		unsigned int    umask2:1;
+		/* EQ-bit Supported */
+		unsigned int    eq:1;
+		unsigned int	reserved:30;
+	} split;
+	unsigned int            full;
+};
+
 /*
  * Intel Architectural LBR CPUID detection/enumeration details:
  */