[PATCH V2 1/3] perf/x86/intel: Fix ARCH_PERFMON_NUM_COUNTER_LEAF

From: kan . liang
Date: Thu Oct 10 2024 - 15:27:53 EST


From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
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