linux-kernel - [PATCH 2/2] perf/x86/intel: Fix wrong index calculation in intel_pmu_config

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Message-ID: <20250529080236.2552247-2-dapeng1.mi@linux.intel.com>
Date: Thu, 29 May 2025 08:02:36 +0000
From: Dapeng Mi <dapeng1.mi@...ux.intel.com>
To: Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Andi Kleen <ak@...ux.intel.com>,
	Eranian Stephane <eranian@...gle.com>
Cc: linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org,
	Dapeng Mi <dapeng1.mi@...el.com>,
	Dapeng Mi <dapeng1.mi@...ux.intel.com>
Subject: [PATCH 2/2] perf/x86/intel: Fix wrong index calculation in intel_pmu_config_acr()

To calculate fixed counter MSR address, the HW counter index "idx" is
subtracted by INTEL_PMC_IDX_FIXED. It leads to the ACR mask value of
fixed counters is incorrectly saved to the positions of GP counters
in acr_cfg_b[], e.g. For fixed counter 0, its ACR counter mask should be
saved to acr_cfg_b[32], but it's saved to acr_cfg_b[0] incorrectly.

Fix this issue.

Fixes: ec980e4facef ("perf/x86/intel: Support auto counter reload")
Signed-off-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
---
 arch/x86/events/intel/core.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 8d046b1a237e..b0fee684ec8c 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2899,6 +2899,7 @@ static void intel_pmu_config_acr(int idx, u64 mask, u32 reload)
 {
 	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
 	int msr_b, msr_c;
+	int msr_offset;
 
 	if (!mask && !cpuc->acr_cfg_b[idx])
 		return;
@@ -2906,19 +2907,20 @@ static void intel_pmu_config_acr(int idx, u64 mask, u32 reload)
 	if (idx < INTEL_PMC_IDX_FIXED) {
 		msr_b = MSR_IA32_PMC_V6_GP0_CFG_B;
 		msr_c = MSR_IA32_PMC_V6_GP0_CFG_C;
+		msr_offset = x86_pmu.addr_offset(idx, false);
 	} else {
 		msr_b = MSR_IA32_PMC_V6_FX0_CFG_B;
 		msr_c = MSR_IA32_PMC_V6_FX0_CFG_C;
-		idx -= INTEL_PMC_IDX_FIXED;
+		msr_offset = x86_pmu.addr_offset(idx - INTEL_PMC_IDX_FIXED, false);
 	}
 
 	if (cpuc->acr_cfg_b[idx] != mask) {
-		wrmsrl(msr_b + x86_pmu.addr_offset(idx, false), mask);
+		wrmsrl(msr_b + msr_offset, mask);
 		cpuc->acr_cfg_b[idx] = mask;
 	}
 	/* Only need to update the reload value when there is a valid config value. */
 	if (mask && cpuc->acr_cfg_c[idx] != reload) {
-		wrmsrl(msr_c + x86_pmu.addr_offset(idx, false), reload);
+		wrmsrl(msr_c + msr_offset, reload);
 		cpuc->acr_cfg_c[idx] = reload;
 	}
 }
-- 
2.43.0