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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 4FEC6C2D0EA for ; Wed, 8 Apr 2020 09:52:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 22C3E20787 for ; Wed, 8 Apr 2020 09:52:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=citrix.com header.i=@citrix.com header.b="KugTKP0Y" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727847AbgDHJwW (ORCPT ); Wed, 8 Apr 2020 05:52:22 -0400 Received: from esa3.hc3370-68.iphmx.com ([216.71.145.155]:43568 "EHLO esa3.hc3370-68.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725932AbgDHJwW (ORCPT ); Wed, 8 Apr 2020 05:52:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=citrix.com; s=securemail; t=1586339541; h=subject:to:cc:references:from:message-id:date: mime-version:in-reply-to:content-transfer-encoding; bh=s5R7D5BnyU070vlj0QlFtAb/87pkZkZ5QFo+14l3Few=; b=KugTKP0YQefozAGbeMkY8PsKugD/wr/BvVpAmyA4yBNRi7UTdadM0iPx Z/azB/tLNi9TO/XRilPOaMJMyO+S6H57gGUG3vKMULnk9hsKzHHo+mP6s VKIh2Bqx2BXHilV3dfkXUxSrcySOXUFcjomw2DS7D8SUZofxqtSLgZkEC Y=; Authentication-Results: esa3.hc3370-68.iphmx.com; dkim=none (message not signed) header.i=none; spf=None smtp.pra=andrew.cooper3@citrix.com; spf=Pass smtp.mailfrom=Andrew.Cooper3@citrix.com; spf=None smtp.helo=postmaster@mail.citrix.com Received-SPF: None (esa3.hc3370-68.iphmx.com: no sender authenticity information available from domain of andrew.cooper3@citrix.com) identity=pra; client-ip=162.221.158.21; receiver=esa3.hc3370-68.iphmx.com; envelope-from="Andrew.Cooper3@citrix.com"; x-sender="andrew.cooper3@citrix.com"; x-conformance=sidf_compatible Received-SPF: Pass (esa3.hc3370-68.iphmx.com: domain of Andrew.Cooper3@citrix.com designates 162.221.158.21 as permitted sender) identity=mailfrom; client-ip=162.221.158.21; receiver=esa3.hc3370-68.iphmx.com; envelope-from="Andrew.Cooper3@citrix.com"; x-sender="Andrew.Cooper3@citrix.com"; x-conformance=sidf_compatible; x-record-type="v=spf1"; x-record-text="v=spf1 ip4:209.167.231.154 ip4:178.63.86.133 ip4:195.66.111.40/30 ip4:85.115.9.32/28 ip4:199.102.83.4 ip4:192.28.146.160 ip4:192.28.146.107 ip4:216.52.6.88 ip4:216.52.6.188 ip4:162.221.158.21 ip4:162.221.156.83 ip4:168.245.78.127 ~all" Received-SPF: None (esa3.hc3370-68.iphmx.com: no sender authenticity information available from domain of postmaster@mail.citrix.com) identity=helo; client-ip=162.221.158.21; receiver=esa3.hc3370-68.iphmx.com; envelope-from="Andrew.Cooper3@citrix.com"; x-sender="postmaster@mail.citrix.com"; x-conformance=sidf_compatible IronPort-SDR: qQ748PLXSV8gr/0TeYSgN9/NIsPnRKOhEHsRpFu8s7tlrSOgUVIrMTbjV1xzZNhYhwGSDtx0ul GSciAXK4Th/GRUFWl/pXGNrZcdidd/u0i/UeRK75PdwUbIWQ2v9Fi37XL7vBfOoUxVxxvyESt4 hquQf+1G2nwwt/O1w5gPM4OVI7Rp1wiQQDQG2IR79lmltAAUyjtwckfT6kBHjd6v5aVmFbAkas hg1TQWbMfPhuHnYIWpn8bOcTVOFj2Xc3dxQ6jn/oh4KP/sSdF03Wp/k1orwt5zh1sFUSl1lppO Da8= X-SBRS: 2.7 X-MesageID: 15340486 X-Ironport-Server: esa3.hc3370-68.iphmx.com X-Remote-IP: 162.221.158.21 X-Policy: $RELAYED X-IronPort-AV: E=Sophos;i="5.72,357,1580792400"; d="scan'208";a="15340486" Subject: Re: [PATCH 4/4] x86,module: Detect CRn and DRn manipulation To: Paolo Bonzini , Nadav Amit , Peter Zijlstra CC: Thomas Gleixner , LKML , , Sean Christopherson , mingo , bp , , x86 , "Kenneth R. Crudup" , Jessica Yu , Rasmus Villemoes , Fenghua Yu , Xiaoyao Li , Thomas Hellstrom , Tony Luck , Steven Rostedt , Greg Kroah-Hartman , , , , "Doug Covelli" , References: <20200407110236.930134290@infradead.org> <20200407111007.429362016@infradead.org> <10ABBCEE-A74D-4100-99D9-05B4C1758FF6@gmail.com> <20200407193853.GP2452@worktop.programming.kicks-ass.net> <90B32DAE-0BB5-4455-8F73-C43037695E7C@gmail.com> <20200407205042.GT2452@worktop.programming.kicks-ass.net> <96C2F23A-D6F4-4A04-82B6-284788C5D2CC@gmail.com> <04f4fc03-95cd-df2e-e93d-e9c4fa221ae4@citrix.com> From: Andrew Cooper Message-ID: <1b90c04b-7c5a-80cb-0f28-5026cecf7f10@citrix.com> Date: Wed, 8 Apr 2020 10:52:12 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Language: en-GB X-ClientProxiedBy: AMSPEX02CAS01.citrite.net (10.69.22.112) To AMSPEX02CL02.citrite.net (10.69.22.126) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/04/2020 01:22, Paolo Bonzini wrote: > On 08/04/20 01:15, Andrew Cooper wrote: >>> Anyhow, I do not think it is the only use-case which is not covered by your >>> patches (even considering CRs/DRs alone). For example, there is no kernel >>> function to turn on CR4.VMXE, which is required to run hypervisors on x86. >> How about taking this opportunity to see if there is a way to improve on >> the status quo for co-existing hypervisor modules? > Almost serious question: why? I can understand VMware, but why can't at > least VirtualBox use KVM on Linux? I am not sure if they are still > running device emulation in ring zero, but if so do you really want to > do that these days? I see a lot of good reasons not to use the VirtualBox out-of-tree module specifically, but there are plenty of other out-of-tree hypervisors, including Jailhouse and Bareflank which come to mind. I'm not suggesting bending over backwards for them, but at the point you're already breaking all of them anyway, it seems silly not to try and address some of the other robustness issues. ~Andrew