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Subject[tip: perf/urgent] perf/x86/lbr: Reset LBR_SELECT during vlbr reset
The following commit has been merged into the perf/urgent branch of tip:

Commit-ID: 0fe39a3929ac7af980347814d552a734b51adacf
Gitweb: https://git.kernel.org/tip/0fe39a3929ac7af980347814d552a734b51adacf
Author: Wanpeng Li <wanpengli@tencent.com>
AuthorDate: Fri, 05 Nov 2021 00:20:51 -07:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Thu, 11 Nov 2021 13:09:34 +01:00

perf/x86/lbr: Reset LBR_SELECT during vlbr reset

lbr_select in kvm guest has residual data even if kvm guest is poweroff.
We can get residual data in the next boot. Because lbr_select is not
reset during kvm vlbr release. Let's reset LBR_SELECT during vlbr reset.

Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/1636096851-36623-1-git-send-email-wanpengli@tencent.com
---
arch/x86/events/intel/lbr.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c
index 6b72e9b..8043213 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -265,6 +265,8 @@ void intel_pmu_lbr_reset(void)

cpuc->last_task_ctx = NULL;
cpuc->last_log_id = 0;
+ if (!static_cpu_has(X86_FEATURE_ARCH_LBR) && cpuc->lbr_select)
+ wrmsrl(MSR_LBR_SELECT, 0);
}

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