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[34.168.104.7]) by smtp.gmail.com with ESMTPSA id mm2-20020a17090b358200b0021937b2118bsm3465146pjb.54.2022.12.22.09.41.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Dec 2022 09:41:28 -0800 (PST) Date: Thu, 22 Dec 2022 17:41:24 +0000 From: Sean Christopherson To: Like Xu Cc: Peter Zijlstra , kan.liang@linux.intel.com, wei.w.wang@intel.com, Like Xu , Andi Kleen , "Paolo Bonzini - Distinguished Engineer (kernel-recipes.org) (KVM HoF)" , Jim Mattson , kvm list , "linux-kernel@vger.kernel.org" , Yang Weijiang Subject: Re: [PATCH v2 01/15] perf/x86/lbr: Simplify the exposure check for the LBR_INFO registers Message-ID: References: <20221125040604.5051-1-weijiang.yang@intel.com> <20221125040604.5051-2-weijiang.yang@intel.com> <449b561a-7053-8994-bcfe-581c0abb8d85@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <449b561a-7053-8994-bcfe-581c0abb8d85@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 22, 2022, Like Xu wrote: > Hi Peter, would you help apply this one in your tip/perf tree, > as it doesn't seem to be closely tied to the KVM changes. Thanks. > > On 25/11/2022 12:05 pm, Yang Weijiang wrote: > > From: Like Xu > > > > 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 > > Reviewed-by: Kan Liang > > Reviewed-by: Andi Kleen > > Signed-off-by: Like Xu > > Signed-off-by: Yang Weijiang > > --- > > 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 4dbde69c423b..e7caabfa1377 100644 > > --- a/arch/x86/events/intel/lbr.c > > +++ b/arch/x86/events/intel/lbr.c > > @@ -1606,12 +1606,10 @@ void __init intel_pmu_arch_lbr_init(void) > > */ > > void 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; This stable-worthy a bug fix, no? E.g. won't the existing code misreport lbr->info if the format is LBR_FORMAT_INFO2? > > } > > EXPORT_SYMBOL_GPL(x86_perf_get_lbr);