From f3fd84a3b7754b60df67ebfe64e1d90623895111 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Thu, 11 Nov 2021 21:45:10 -0800 Subject: [PATCH] x86/perf: Fix snapshot_branch_stack warning in VM When running in VM intel_pmu_snapshot_branch_stack triggers WRMSR warning like: [ ] unchecked MSR access error: WRMSR to 0x3f1 (tried to write 0x0000000000000000) at rIP: 0xffffffff81011a5b (intel_pmu_snapshot_branch_stack+0x3b/0xd0) This can be triggered with BPF selftests: tools/testing/selftests/bpf/test_progs -t get_branch_snapshot This warning is caused by __intel_pmu_pebs_disable_all() in the VM. Since it is not necessary to disable PEBS for LBR, remove it from intel_pmu_snapshot_branch_stack and intel_pmu_snapshot_arch_branch_stack. Fixes: c22ac2a3d4bd ("perf: Enable branch record for software events") Signed-off-by: Song Liu Signed-off-by: Peter Zijlstra (Intel) Tested-by: Like Xu Link: https://lore.kernel.org/r/20211112054510.2667030-1-songliubraving@fb.com --- arch/x86/events/intel/core.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index 42cf01ecdd13..ec6444f2c9dc 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -2211,7 +2211,6 @@ intel_pmu_snapshot_branch_stack(struct perf_branch_entry *entries, unsigned int /* must not have branches... */ local_irq_save(flags); __intel_pmu_disable_all(false); /* we don't care about BTS */ - __intel_pmu_pebs_disable_all(); __intel_pmu_lbr_disable(); /* ... until here */ return __intel_pmu_snapshot_branch_stack(entries, cnt, flags); @@ -2225,7 +2224,6 @@ intel_pmu_snapshot_arch_branch_stack(struct perf_branch_entry *entries, unsigned /* must not have branches... */ local_irq_save(flags); __intel_pmu_disable_all(false); /* we don't care about BTS */ - __intel_pmu_pebs_disable_all(); __intel_pmu_arch_lbr_disable(); /* ... until here */ return __intel_pmu_snapshot_branch_stack(entries, cnt, flags); -- 2.25.1