From 86aa94cd50b138be0dd872b0779fa3036e641881 Mon Sep 17 00:00:00 2001 From: Dapeng Mi Date: Thu, 29 May 2025 08:02:36 +0000 Subject: [PATCH] perf/x86/intel: Fix incorrect MSR index calculations in intel_pmu_config_acr() The MSR offset calculations in intel_pmu_config_acr() are buggy. To calculate fixed counter MSR addresses in intel_pmu_config_acr(), the HW counter index "idx" is subtracted by INTEL_PMC_IDX_FIXED. This leads to the ACR mask value of fixed counters to be 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. [ mingo: Clarified & improved the changelog. ] Fixes: ec980e4facef ("perf/x86/intel: Support auto counter reload") Signed-off-by: Dapeng Mi Signed-off-by: Ingo Molnar Reviewed-by: Kan Liang Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20250529080236.2552247-2-dapeng1.mi@linux.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 466283326630..741b229f0718 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -2900,6 +2900,7 @@ 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; @@ -2907,19 +2908,20 @@ 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; } } -- 2.25.1