linux-kernel - [RESEND PATCH v4 02/10] perf/x86/lbr: Simplify the exposure check for the LBR

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Date:   Mon, 10 May 2021 16:15:26 +0800
From:   Like Xu <like.xu@...ux.intel.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, weijiang.yang@...el.com,
        wei.w.wang@...el.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [RESEND PATCH v4 02/10] perf/x86/lbr: Simplify the exposure check for the LBR_INFO registers

The x86_pmu.lbr_info is 0 unless explicitly initialized, so there's
no point checking x86_pmu.intel_cap.lbr_format.

Cc: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Like Xu <like.xu@...ux.intel.com>
Reviewed-by: Kan Liang <kan.liang@...ux.intel.com>
Reviewed-by: Andi Kleen <ak@...ux.intel.com>
---
I personally recommend this patch to hit the mainline through the KVM tree.

 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 76dbab6ac9fb..f72276f4a5ce 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -1833,12 +1833,10 @@ 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;
 }
-- 
2.31.1