Received: by 2002:a05:6a10:17d3:0:0:0:0 with SMTP id hz19csp535043pxb; Thu, 15 Apr 2021 00:00:47 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzliVtmQ8rYJjSo8ngTyATgTi9S9xuqBU9jJkDXDz7aqC3+0EL00zi+xc2PMLSEqFNyyGLd X-Received: by 2002:a17:906:fb19:: with SMTP id lz25mr1844058ejb.544.1618470047758; Thu, 15 Apr 2021 00:00:47 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1618470047; cv=none; d=google.com; s=arc-20160816; b=SXBuEGcQZiovuKxGsaIYdjovzh4Gh0ESxEOFImwCRatWAXoCFFnV2VRpWpDPsZ288S iJOqd8jGUh/qrGv8mWMYARMWqqaigQ0CaGtZFX4edGaiOIIBIjr+QWb7vMRceW1Zzxg0 LGo+gBGL2lm/vCs36gCW9RldaoK/4tsrQOIkFJbuLt5k9WgXCK+0wiJhxfI77rulmKVN 1p5FCNJxBBmbW3V5ZPhY/w5JzUoYjOPDbvKPgp/TXkgaoLiL8sroytB7T8ZcmulK+8pD elJVASxGW2liszOY6pVTiTSFq3+/1Vm8SSDPylfcdQvx69VcfHD4l0SVSEnET6VqW/bU zkTA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:in-reply-to :mime-version:user-agent:date:message-id:from:cc:references:to :subject; bh=Sj5VgGYgm1P0vLrFhjnvNQfSuZVvLxom1Zt87S2OLRc=; b=LcJUkuRqZZFmBJJ/mzxyWfB3f8LhM88V5FhTHWCJSfMmqQer0ifLZRN2Zq0k14orPa TvNtI9bVfhBwphsen7l1Tik9NpN1HCfOxWifw1eIuu72JN00jDloUT7hSmhn5rpSZzv2 wTP37YhId4J5Mac7DLHtlp2A4WriqSPjEA10Urbaln8KRpqpLWWKkBZAL9KbKQW6M+ki gLK8P7blogXbp9SXHbkmZIEj59zp0sd2B+48xLsiCBCTW9uWp4JAvCM/QHBIp8BFf5fW 2TSWNU0/9tE/+r48TdjArXjg8wlz92oICa/oLzwORjHn139zSupPCJQe7Ne2y3Bjl5Ko EL4Q== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=huawei.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id q2si1390506ejj.541.2021.04.15.00.00.24; Thu, 15 Apr 2021 00:00:47 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=huawei.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231152AbhDOG7z (ORCPT + 99 others); Thu, 15 Apr 2021 02:59:55 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:16921 "EHLO szxga06-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229503AbhDOG7y (ORCPT ); Thu, 15 Apr 2021 02:59:54 -0400 Received: from DGGEMS405-HUB.china.huawei.com (unknown [172.30.72.60]) by szxga06-in.huawei.com (SkyGuard) with ESMTP id 4FLVXK11HGzjYhv; Thu, 15 Apr 2021 14:57:37 +0800 (CST) Received: from [10.174.187.224] (10.174.187.224) by DGGEMS405-HUB.china.huawei.com (10.3.19.205) with Microsoft SMTP Server id 14.3.498.0; Thu, 15 Apr 2021 14:59:26 +0800 Subject: Re: [PATCH 1/5] KVM: arm64: Divorce the perf code from oprofile helpers To: Marc Zyngier , , , , , , References: <20210414134409.1266357-1-maz@kernel.org> <20210414134409.1266357-2-maz@kernel.org> CC: Rich Felker , Yoshinori Sato , Peter Zijlstra , "Viresh Kumar" , Heiko Carstens , "Arnaldo Carvalho de Melo" , , "Christian Borntraeger" , , Will Deacon From: Keqian Zhu Message-ID: Date: Thu, 15 Apr 2021 14:59:26 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <20210414134409.1266357-2-maz@kernel.org> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.187.224] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Marc, On 2021/4/14 21:44, Marc Zyngier wrote: > KVM/arm64 is the sole user of perf_num_counters(), and really > could do without it. Stop using the obsolete API by relying on > the existing probing code. > > Signed-off-by: Marc Zyngier > --- > arch/arm64/kvm/perf.c | 7 +------ > arch/arm64/kvm/pmu-emul.c | 2 +- > include/kvm/arm_pmu.h | 4 ++++ > 3 files changed, 6 insertions(+), 7 deletions(-) > > diff --git a/arch/arm64/kvm/perf.c b/arch/arm64/kvm/perf.c > index 739164324afe..b8b398670ef2 100644 > --- a/arch/arm64/kvm/perf.c > +++ b/arch/arm64/kvm/perf.c > @@ -50,12 +50,7 @@ static struct perf_guest_info_callbacks kvm_guest_cbs = { > > int kvm_perf_init(void) > { > - /* > - * Check if HW_PERF_EVENTS are supported by checking the number of > - * hardware performance counters. This could ensure the presence of > - * a physical PMU and CONFIG_PERF_EVENT is selected. > - */ > - if (IS_ENABLED(CONFIG_ARM_PMU) && perf_num_counters() > 0) > + if (kvm_pmu_probe_pmuver() != 0xf) The probe() function may be called many times (kvm_arm_pmu_v3_set_attr also calls it). I don't know whether the first calling is enough. If so, can we use a static variable in it, so the following calling can return the result right away? Thanks, Keqian