Received: by 2002:a05:6358:11c7:b0:104:8066:f915 with SMTP id i7csp270074rwl; Thu, 6 Apr 2023 18:59:36 -0700 (PDT) X-Google-Smtp-Source: AKy350bR6x5XZ1mz5Tq4G5JtvWuF8Jgg3uE/usEdOZPOdkepK9UH9keO86UqXwAQhu3TaqQujvAs X-Received: by 2002:a17:906:3ec7:b0:895:58be:957 with SMTP id d7-20020a1709063ec700b0089558be0957mr759571ejj.2.1680832776564; Thu, 06 Apr 2023 18:59:36 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1680832776; cv=none; d=google.com; s=arc-20160816; b=yn0pn8foN4+rVXC7UwQuB90sl5K7deNaZbV7TQGAlUMxuzevjS8lD9s2y6PGhOgQEw R/U2GCNe4wNkcqA9OOvVU/5nSa+z9YB1xdnYARZ9ObRMX8A81sfzPGpthnNPoaQWdsgn 5Ke68POL+kgLvq4XdMEPc4s+xWyssk9Rv79NzGq1l4UQbUHHfIAf3xkLBnGAasU5FTUX Gy3SEf87sHrfjeg6WTi8wWLm4RGhjmMsENqBgXxt1tXSoy5Yo1atgb/v3iowgeoADe0b thQnhGfqKaQR2m+t9Jn24y4+roYo+7PJ6DuTDgDzOAaMTgWtPkF5O4qFS9LQEgynFT0P 3cPg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:dkim-signature; bh=JowVrky1sJdaqIz82N9TZtKH8APFD0brvsJqK7PiSgc=; b=glmMf2qYo4ZMfpcnBzG+6ZcX9i3aB97+DTs4hO4fB24X5m3qTuk+jPla6MqhtVwvkI 9Ng57zCV6f5I0dwnh0RWDxVsTSz3/kXivVOg6SHJSDEhRp7Nf5A2LMEmVkDqv+wIemu2 ysJColVXcE6Xa8y+1aqVesmTUSCqbmxZ66gRGzC3MpCPSU8ujZ4MRYrvm0yTSOhXQsI0 EGrUB0kndswM9xn41pSbZBMAtPf8NChkt7SVFCZZsSEP2Gubhwq6c8kPe8BfVw/3vbRZ XWU/nWFixpHYCcte001lo4/2V/Ny60VPnXzmir8adTnlXoWLeEKl/2AF/VZm+uOiSR7E Cjqw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20210112 header.b=VoAAmuxU; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Return-Path: Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id t17-20020a170906269100b0092bb8b36552si2321716ejc.615.2023.04.06.18.59.04; Thu, 06 Apr 2023 18:59:36 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20210112 header.b=VoAAmuxU; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239451AbjDGBu5 (ORCPT + 99 others); Thu, 6 Apr 2023 21:50:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44858 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231835AbjDGBu4 (ORCPT ); Thu, 6 Apr 2023 21:50:56 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3737B6581 for ; Thu, 6 Apr 2023 18:50:55 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id g187-20020a2520c4000000b00b74680a7904so40653058ybg.15 for ; Thu, 06 Apr 2023 18:50:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1680832254; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=JowVrky1sJdaqIz82N9TZtKH8APFD0brvsJqK7PiSgc=; b=VoAAmuxU0jHs+dSy5Fyk1n7oXhKdE/nFuTJCDoHeI+wV3/E+7tJ6st5i9QMFGkS+Xt KItff21bALWu17UcdoQsCk4XiahsCjGpIBYMvUNelibdo8r14VaYcNROVPG5YA8+XFrk 7LVfGY+8E0QxIiBdkgX1BnJ8nCh1Pvn1MGrn7iit+vG1px6v4FPYi1RRFeltwST6J1iX JML87NzWbjEqk6QEYRYGzu8zcnAgU1aJJLPkjjgl/TuV1/i6S+tNNBdFsrWYe5PURP7b oexE1r3Y739tjvJrNC6/ZPssrXyYjDzt2JPNDC7oVH/F/Llh9h5GgBLKkqA6LtUWtsaa tnyA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680832254; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=JowVrky1sJdaqIz82N9TZtKH8APFD0brvsJqK7PiSgc=; b=Ycjt9DDWMtvTJ6Oylf3+23CNQgi1kB+JLF3xfF2S+pQE/y8rw33+yqdrqXUHzw+6nA QIj+lv6GXGYAjGb4DCbeUU21lCxG5vm/JVM+Trkm+blLXDTQ7koIBxOUMFskkrl8eDEY 61U/FssvR3E0i1xPMn0aCxRUcrm/vSOBrqkXCMIuH7ILkBl1bZnhdcDcVQYVvk5TTqME IucGlCmrrLOjpk7UAvAAtvQuZMEEUAfrMNKFuT2k9aZBzfrkZux7qghEz9nRMxpxzzdu A67nAvs0f1iqTAi87kO63VptdetOmWadwsYqyS469UKMEPBoufqqZDtDwiJxxgZP3dX9 q2Zg== X-Gm-Message-State: AAQBX9eGxeHy0Pj1oxV1IjNkemB7YH83o660Mes849XZthSoM27NO2Sm UqDPNgmQU/zvDDyfZOH/UGRhBdFduIo= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:d4d1:0:b0:b68:d117:305b with SMTP id m200-20020a25d4d1000000b00b68d117305bmr767999ybf.10.1680832254517; Thu, 06 Apr 2023 18:50:54 -0700 (PDT) Date: Thu, 6 Apr 2023 18:50:53 -0700 In-Reply-To: <20230214050757.9623-13-likexu@tencent.com> Mime-Version: 1.0 References: <20230214050757.9623-1-likexu@tencent.com> <20230214050757.9623-13-likexu@tencent.com> Message-ID: Subject: Re: [PATCH v4 12/12] KVM: x86/cpuid: Add AMD CPUID ExtPerfMonAndDbg leaf 0x80000022 From: Sean Christopherson To: Like Xu Cc: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Sandipan Das Content-Type: text/plain; charset="us-ascii" X-Spam-Status: No, score=-7.7 required=5.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 14, 2023, Like Xu wrote: > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index f4a4691b4f4e..2472fa8746c2 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -4916,6 +4916,12 @@ static __init void svm_set_cpu_caps(void) > } else { > /* AMD PMU PERFCTR_CORE CPUID */ > kvm_cpu_cap_check_and_set(X86_FEATURE_PERFCTR_CORE); > + /* > + * KVM only supports AMD PerfMon V2, even if it supports V3+. Ha! A perfect example of why I strongly prefer that changelogs and comments avoid pronouns. The above "it" reads as: * KVM only supports AMD PerfMon V2, even if KVM supports V3+. which is clearly nonsensical. > + * For PerfMon V3+, it's unsafe to expect V2 bit is set or cleared. If it's unsafe to assume anything v3+ implying v2 support, then it's definitely not safe to assume that KVM can blindly set v2 without future changes. I don't see any reason not to do diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index bd324962bb7e..1192f605ad47 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -756,6 +756,10 @@ void kvm_set_cpu_caps(void) F(NULL_SEL_CLR_BASE) | F(AUTOIBRS) | 0 /* PrefetchCtlMsr */ ); + kvm_cpu_cap_mask(CPUID_8000_0022_EAX, + F(PERFMON_V2) + ); + /* * Synthesize "LFENCE is serializing" into the AMD-defined entry in * KVM's supported CPUID if the feature is reported as supported by the and then this code can be: if (kvm_pmu_cap.version != 2) kvm_cpu_cap_clear(X86_FEATURE_PERFMON_V2); Ah, but presumably the if (kvm_pmu_cap.num_counters_gp < AMD64_NUM_COUNTERS_CORE) path also needs to clear PERFMON_V2. I think I'd still vote to grab host CPUID and clear here (instead of setting). What is the relationship between PERFCTR_CORE and PERFMON_V2? E.g. if v2 depends on having PERFCTR_CORE, then we can do: if (enable_pmu) { if (kvm_pmu_cap.num_counters_gp < AMD64_NUM_COUNTERS_CORE) kvm_pmu_cap.num_counters_gp = AMD64_NUM_COUNTERS; else kvm_cpu_cap_check_and_set(X86_FEATURE_PERFCTR_CORE); if (kvm_pmu_cap.version != 2 || !kvm_cpu_cap_has(X86_FEATURE_PERFCTR_CORE)) kvm_cpu_cap_clear(X86_FEATURE_PERFMON_V2);