The following commit has been merged into the perf/urgent branch of tip: Commit-ID: f3fd84a3b7754b60df67ebfe64e1d90623895111 Gitweb: https://git.kernel.org/tip/f3fd84a3b7754b60df67ebfe64e1d90623895111 Author: Song Liu <songliubraving@xxxxxx> AuthorDate: Thu, 11 Nov 2021 21:45:10 -08:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Wed, 17 Nov 2021 14:48:43 +01:00 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 <songliubraving@xxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Tested-by: Like Xu <likexu@xxxxxxxxxxx> Link: https://lore.kernel.org/r/20211112054510.2667030-1-songliubraving@xxxxxx --- 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 42cf01e..ec6444f 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);
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