linux-kernel - [PATCH V2 1/3] perf/x86/intel: Fix ARCH_PERFMON_NUM_COUNTER

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Message-Id: <20241010192844.1006990-2-kan.liang@linux.intel.com>
Date: Thu, 10 Oct 2024 12:28:42 -0700
From: kan.liang@...ux.intel.com
To: peterz@...radead.org,
	mingo@...nel.org,
	acme@...nel.org,
	namhyung@...nel.org,
	irogers@...gle.com,
	adrian.hunter@...el.com,
	ak@...ux.intel.com,
	linux-kernel@...r.kernel.org
Cc: eranian@...gle.com,
	thomas.falcon@...el.com,
	Kan Liang <kan.liang@...ux.intel.com>,
	stable@...r.kernel.org
Subject: [PATCH V2 1/3] perf/x86/intel: Fix ARCH_PERFMON_NUM_COUNTER_LEAF

From: Kan Liang <kan.liang@...ux.intel.com>

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.

Fixes: eb467aaac21e ("perf/x86/intel: Support Architectural PerfMon Extension leaf")
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
Cc: stable@...r.kernel.org
---
 arch/x86/events/intel/core.c      | 4 ++--
 arch/x86/include/asm/perf_event.h | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 7ca40002a19b..2f3bf3bbbd77 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4886,8 +4886,8 @@ static void update_pmu_cap(struct x86_hybrid_pmu *pmu)
 	if (ebx & ARCH_PERFMON_EXT_EQ)
 		pmu->config_mask |= ARCH_PERFMON_EVENTSEL_EQ;
 
-	if (sub_bitmaps & ARCH_PERFMON_NUM_COUNTER_LEAF_BIT) {
-		cpuid_count(ARCH_PERFMON_EXT_LEAF, ARCH_PERFMON_NUM_COUNTER_LEAF,
+	if (sub_bitmaps & ARCH_PERFMON_NUM_COUNTER_LEAF) {
+		cpuid_count(ARCH_PERFMON_EXT_LEAF, ARCH_PERFMON_NUM_COUNTER_LEAF_BIT,
 			    &eax, &ebx, &ecx, &edx);
 		pmu->cntr_mask64 = eax;
 		pmu->fixed_cntr_mask64 = ebx;
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index 91b73571412f..41ace8431e01 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -190,7 +190,7 @@ union cpuid10_edx {
 #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
+#define ARCH_PERFMON_NUM_COUNTER_LEAF		BIT(ARCH_PERFMON_NUM_COUNTER_LEAF_BIT)
 
 /*
  * Intel Architectural LBR CPUID detection/enumeration details:
-- 
2.38.1