From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AFD1EC4CECD for ; Mon, 27 Apr 2020 19:10:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 95A88214AF for ; Mon, 27 Apr 2020 19:10:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Hv5WI99E" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726739AbgD0TKd (ORCPT ); Mon, 27 Apr 2020 15:10:33 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:49653 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726371AbgD0TKc (ORCPT ); Mon, 27 Apr 2020 15:10:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588014630; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=I0hVk/6G0HDWyNl0uhimzd8WziWxl6KqqJxBVaLL5oQ=; b=Hv5WI99EVG9PbL1gSwidJYL6t6VS/Y1P1Skqq5aW8euIyC5x4rTLvCjxIpu9DLgXrs2kE3 CwTRIp7LXY/d8EgGm09711mgIGKKIm6pGS+Lb1U+HxUV9m3tjI5akgTzLSzNW8kzyY+JTA pYDuYA7G/7UlSxsuOANO86WvGJiN9hE= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-15-8NES2kblOu-E-gvS6EWDdQ-1; Mon, 27 Apr 2020 15:10:29 -0400 X-MC-Unique: 8NES2kblOu-E-gvS6EWDdQ-1 Received: by mail-wm1-f72.google.com with SMTP id j5so45656wmi.4 for ; Mon, 27 Apr 2020 12:10:29 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=I0hVk/6G0HDWyNl0uhimzd8WziWxl6KqqJxBVaLL5oQ=; b=CXq4s/wDu48peiZR1NZxRR9Lr3cVVv72TakV2GJ311TowECeGH43vCis4UGNjShjA9 lAvi9XsMVBxly8Ldc66Odaz9sDH+r1J1Ro0bhGwsFXghyXPPR0h8QPuE7u8n/gq+m1/b ldUZsbMPssfLb4zqvQuzvUtrlA/1OzuiKEVhpuuSmyBXMQx4op14D+WawsTNoQAXup5X 7P4Q2rpd3DA+EE0L5GdMNa5T3+39UXqOlrR/o3dw78ZRldtHw+5cgT7vACrRI4oIrUw1 Un08bQaxQwKv1qxIB+PPgZIxS9yx6xKZo0iSdzF4pwzuOwySnE51s19qyVxSO4C9YMqf Brgw== X-Gm-Message-State: AGi0PuapNi4pJwQC9HUW5ZG6veYJO9lMs6+2OsIe73nWHdAQeEEyA/4b 8IIQxHnqVtdga9pAuOmATXlZkVQOhcNsslkZyjNzpjhKJ3RJQzHG2OwHoh8CD4V+PV2oy027DoQ bFYRke3P8w+zDdh/O2vvDzhG0 X-Received: by 2002:adf:cd04:: with SMTP id w4mr30392815wrm.357.1588014628249; Mon, 27 Apr 2020 12:10:28 -0700 (PDT) X-Google-Smtp-Source: APiQypIILVoJz/qNWYWE3ErDemAwYqp/nA424nLm5ZyRRhg+ICEM+y/HKkvpU9uy47Xz8+V0QcM6PQ== X-Received: by 2002:adf:cd04:: with SMTP id w4mr30392803wrm.357.1588014628029; Mon, 27 Apr 2020 12:10:28 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:ac19:d1fb:3f5f:d54f? ([2001:b07:6468:f312:ac19:d1fb:3f5f:d54f]) by smtp.gmail.com with ESMTPSA id k9sm23532061wrd.17.2020.04.27.12.10.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 27 Apr 2020 12:10:27 -0700 (PDT) Subject: Re: [PATCH] [RFC] kvm: x86: emulate APERF/MPERF registers To: Jim Mattson , "Li,Rongqing" Cc: Sean Christopherson , Peter Zijlstra , LKML , kvm list , the arch/x86 maintainers , "H . Peter Anvin" , Borislav Petkov , Ingo Molnar , Thomas Gleixner , Joerg Roedel , Wanpeng Li , Vitaly Kuznetsov References: <1587704935-30960-1-git-send-email-lirongqing@baidu.com> <20200424100143.GZ20730@hirez.programming.kicks-ass.net> <20200424144625.GB30013@linux.intel.com> From: Paolo Bonzini Message-ID: Date: Mon, 27 Apr 2020 21:10:26 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27/04/20 19:30, Jim Mattson wrote: >>>> I would like to see performance data before enabling this >>>> unconditionally. >>> I wouldn't want this to be enabled unconditionally anyway, >>> because you need to take into account live migration to and from >>> processors that do not have APERF/MPERF support. >>> >>> Paolo >> I will add a kvm parameter to consider whether enable MPERF/APERF >> emulations, and make default value to false > > Wouldn't it be better to add a per-VM capability to enable this > feature? Yes, you it would be better to use KVM_ENABLE_CAP indeed. Paolo