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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 50A58C31E45 for ; Thu, 13 Jun 2019 17:59:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 28FFE20645 for ; Thu, 13 Jun 2019 17:59:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727458AbfFMR7y (ORCPT ); Thu, 13 Jun 2019 13:59:54 -0400 Received: from mail-wm1-f65.google.com ([209.85.128.65]:52056 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726967AbfFMR7y (ORCPT ); Thu, 13 Jun 2019 13:59:54 -0400 Received: by mail-wm1-f65.google.com with SMTP id 207so3274741wma.1 for ; Thu, 13 Jun 2019 10:59:52 -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=X2ZdLgjxab9G9OdwLapH+oQwWyPX+4510e889t1xHvc=; b=jTeAO2B9rvIxYzEGTYrvFRWqPIarzQpnv7c4CuRv2grarK5aeQA5pz9qgsp0XJ8X0n u20DzaTQgTKrtpioQYREq0PWctF86NpHQAe8JDUfns2R+ywlzg3HQ/qAvoHzXQuMwcML oUACrvUcF/BzrpJ7xDA/AA7swdqfdy27OGuYoRrAQKmhbjL9Lwt7HSGA8ov4iI+UJ8Av WUDUf4Pi1GtTr1eF6k6WWE/pgRXw+ZZPlVplkxp4VOYf6CY0OG2GlcrZZ4Xr5F8Z+5ix AL2xjzpLlNuGZxKHckkaBzr8i39UMXYWLv/Co7W+l1FHQBLmwVQlGVchFy++ZXpMYy0w DiVA== X-Gm-Message-State: APjAAAWacTkSIvedSUi1+ml6shITxG0ZBdkOcDgpbT4oItOiPHimzBy6 W/Ho3Ukfof1qsDwPDHtRcJZpcA== X-Google-Smtp-Source: APXvYqyPjDOQTFPzIXYKvz5fSFrhNcefvCZw5GAeQuoOgkyppg9BIVx3c+GWFddFus6LA+KXbESm+g== X-Received: by 2002:a05:600c:1008:: with SMTP id c8mr4802303wmc.133.1560448792196; Thu, 13 Jun 2019 10:59:52 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:56e1:adff:fed9:caf0? ([2001:b07:6468:f312:56e1:adff:fed9:caf0]) by smtp.gmail.com with ESMTPSA id y17sm790742wrg.18.2019.06.13.10.59.51 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Thu, 13 Jun 2019 10:59:51 -0700 (PDT) Subject: Re: [PATCH 1/7] KVM: nVMX: Intercept VMWRITEs to read-only shadow VMCS fields To: Jim Mattson Cc: Sean Christopherson , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , kvm list , Liran Alon References: <20190507153629.3681-1-sean.j.christopherson@intel.com> <20190507153629.3681-2-sean.j.christopherson@intel.com> <9d82caf7-1735-a5e8-8206-bdec3ddf12d4@redhat.com> From: Paolo Bonzini Message-ID: <354f636b-c26d-e053-78a7-e7880e708d5d@redhat.com> Date: Thu, 13 Jun 2019 19:59:45 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 13/06/19 19:36, Jim Mattson wrote: >> Also, while this may vary dynamically based on the L2 guest that is >> running, this is much less true for unrestricted-guest processors. >> Without data on _which_ scenarios are bad for a static set of shadowed >> fields, I'm not really happy to add even more complexity. > > Data supporting which scenarios would lead you to entertain more > complexity? For example it would be interesting if some L1 hypervisor had 2x slower vmexits on some L2 guests, but otherwise fits the current set of shadowed fields. Paolo > Is it even worth collecting data on L3 performance, for > example? :-)