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From:   Wanpeng Li <kernellwp@gmail.com>
To:     linux-kernel@vger.kernel.org
Cc:     Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@redhat.com>, Like Xu <likexu@tencent.com>
Subject: [PATCH] perf/x86/lbr: Reset LBR_SELECT during vlbr reset
Date:   Fri,  5 Nov 2021 00:20:51 -0700
Message-Id: <1636096851-36623-1-git-send-email-wanpengli@tencent.com>
Precedence: bulk

From: Wanpeng Li <wanpengli@tencent.com>

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.

Cc: Like Xu <likexu@tencent.com>
Signed-off-by: Wanpeng Li <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 9e6d6eaeb4cb..1076de93a2f5 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -279,6 +279,8 @@ 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);
 }
 
 /*
-- 
2.25.1