linux-kernel - [PATCH 2/6] perf/x86/lbr: Unify LBR_INFO registers exposure check condition

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Date:   Fri, 31 Jul 2020 15:43:58 +0800
From:   Like Xu <like.xu@...ux.intel.com>
To:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Joerg Roedel <joro@...tes.org>, wei.w.wang@...el.com,
        linux-kernel@...r.kernel.org, Like Xu <like.xu@...ux.intel.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: [PATCH 2/6] perf/x86/lbr: Unify LBR_INFO registers exposure check condition

Architectural LBR has IA32_LBR_x_INFO instead of LBR_FORMAT_INFO_x
to hold metadata for the operation, including mispredict, TSX, and
elapsed cycle time information.

The x86_pmu.lbr_info will be assigned in intel_pmu_?_lbr_init_?(),
it's safe to expose LBR_INFO in the x86_perf_get_lbr(), instead of
relying solely on 'lbr_format == LBR_FORMAT_INFO' check.

Cc: Kan Liang <kan.liang@...ux.intel.com>
Cc: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Like Xu <like.xu@...ux.intel.com>
---
 arch/x86/events/intel/lbr.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c
index 63f58bdf556c..8d816f580342 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -1832,12 +1832,10 @@ void __init intel_pmu_arch_lbr_init(void)
  */
 int x86_perf_get_lbr(struct x86_pmu_lbr *lbr)
 {
-	int lbr_fmt = x86_pmu.intel_cap.lbr_format;
-
 	lbr->nr = x86_pmu.lbr_nr;
 	lbr->from = x86_pmu.lbr_from;
 	lbr->to = x86_pmu.lbr_to;
-	lbr->info = (lbr_fmt == LBR_FORMAT_INFO) ? x86_pmu.lbr_info : 0;
+	lbr->info = x86_pmu.lbr_info;
 
 	return 0;
 }
-- 
2.21.3