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perf/x86: disable PEBS on a guest entry.

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If PMU counter has PEBS enabled it is not enough to disable counter
on a guest entry since PEBS memory write can overshoot guest entry
and corrupt guest memory. Disabling PEBS during guest entry solves
the problem.

Tested-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120809085234.GI3341@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Gleb Natapov 2012-08-09 11:52:34 +03:00 committed by Thomas Gleixner
parent cb37af7712
commit 26a4f3c08d
1 changed files with 9 additions and 1 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

10
arch/x86/kernel/cpu/perf_event_intel.c
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@ -1522,8 +1522,16 @@ static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr)
arr[0].msr = MSR_CORE_PERF_GLOBAL_CTRL;
arr[0].host = x86_pmu.intel_ctrl & ~cpuc->intel_ctrl_guest_mask;
arr[0].guest = x86_pmu.intel_ctrl & ~cpuc->intel_ctrl_host_mask;
/*
* If PMU counter has PEBS enabled it is not enough to disable counter
* on a guest entry since PEBS memory write can overshoot guest entry
* and corrupt guest memory. Disabling PEBS solves the problem.
*/
arr[1].msr = MSR_IA32_PEBS_ENABLE;
arr[1].host = cpuc->pebs_enabled;
arr[1].guest = 0;
*nr = 1;
*nr = 2;
return arr;
}