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x86/perf: Fix snapshot_branch_stack warning in VM

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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: c22ac2a3d4 ("perf: Enable branch record for software events")
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Like Xu <likexu@tencent.com>
Link: https://lore.kernel.org/r/20211112054510.2667030-1-songliubraving@fb.com
This commit is contained in:
Song Liu 2021-11-11 21:45:10 -08:00 committed by Peter Zijlstra
parent bdc0feee05
commit f3fd84a3b7
1 changed files with 0 additions and 2 deletions
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2
arch/x86/events/intel/core.c
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@ -2211,7 +2211,6 @@ intel_pmu_snapshot_branch_stack(struct perf_branch_entry *entries, unsigned int
/* must not have branches... */ /* must not have branches... */
local_irq_save(flags); local_irq_save(flags);
__intel_pmu_disable_all(false); /* we don't care about BTS */ __intel_pmu_disable_all(false); /* we don't care about BTS */
__intel_pmu_pebs_disable_all();
__intel_pmu_lbr_disable(); __intel_pmu_lbr_disable();
/* ... until here */ /* ... until here */
return __intel_pmu_snapshot_branch_stack(entries, cnt, flags); 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... */ /* must not have branches... */
local_irq_save(flags); local_irq_save(flags);
__intel_pmu_disable_all(false); /* we don't care about BTS */ __intel_pmu_disable_all(false); /* we don't care about BTS */
__intel_pmu_pebs_disable_all();
__intel_pmu_arch_lbr_disable(); __intel_pmu_arch_lbr_disable();
/* ... until here */ /* ... until here */
return __intel_pmu_snapshot_branch_stack(entries, cnt, flags); return __intel_pmu_snapshot_branch_stack(entries, cnt, flags);