Commit 86aa94cd authored by Dapeng Mi's avatar Dapeng Mi Committed by Ingo Molnar
Browse files

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: ec980e4f ("perf/x86/intel: Support auto counter reload")
Signed-off-by: default avatarDapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Reviewed-by: default avatarKan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250529080236.2552247-2-dapeng1.mi@linux.intel.com
parent dd3922cf

arch/x86/events/intel/core.c

+5 −3
Original line number Diff line number Diff line
@@ -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;

	}

}