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=-8.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 080E7C47096 for ; Thu, 3 Jun 2021 17:33:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C5D1D613E7 for ; Thu, 3 Jun 2021 17:33:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230416AbhFCRf1 (ORCPT ); Thu, 3 Jun 2021 13:35:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:60062 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229947AbhFCRfZ (ORCPT ); Thu, 3 Jun 2021 13:35:25 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8D919600EF; Thu, 3 Jun 2021 17:33:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622741621; bh=/UCRcRzeBqTtEan+hKQQytxiVuqK6B0k/wsPUAzHz04=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=MFTkiPeD9pCOCOqPoN5+CzEhXI99TCb/39pyxVHmsIu2k1fk8H/SddDyBYcnAZjdS xdHSwL+7enafUpzCDPPWhuip9DqrJ3fgknH6swTLZGTiCVZtJ3H91+7Jf4luWtvAsM t4nClvFCW1FHgSSW6qB2ZrbsTKofuoGjV47JEPaSNXeuxOGPapBCUc9lFVQruBLTTW 2Ws3Gqt1g/sEt2+i9gvAEBowH0WoN7WHRtG++WdSXO3iwwOv55pJU+p4KiINspejbD vefQqFY64InbySwuXs6s50UHsk9hQWmicWTdvP4UZup7oMXGa2YBPm9L/nb8oaeS9g ITvifMb0XbFfw== Subject: Re: [PATCH v1 1/8] virtio: Force only split mode with protected guest To: Andi Kleen , mst@redhat.com Cc: jasowang@redhat.com, virtualization@lists.linux-foundation.org, hch@lst.de, m.szyprowski@samsung.com, robin.murphy@arm.com, iommu@lists.linux-foundation.org, x86@kernel.org, sathyanarayanan.kuppuswamy@linux.intel.com, jpoimboe@redhat.com, linux-kernel@vger.kernel.org References: <20210603004133.4079390-1-ak@linux.intel.com> <20210603004133.4079390-2-ak@linux.intel.com> From: Andy Lutomirski Message-ID: Date: Thu, 3 Jun 2021 10:33:39 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20210603004133.4079390-2-ak@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/2/21 5:41 PM, Andi Kleen wrote: > Only allow split mode when in a protected guest. Followon > patches harden the split mode code paths, and we don't want > an malicious host to force anything else. Also disallow > indirect mode for similar reasons. I read this as "the virtio driver is buggy. Let's disable most of the buggy code in one special case in which we need a driver without bugs. In all the other cases (e.g. hardware virtio device connected over USB-C), driver bugs are still allowed." Can we just fix the driver without special cases? --Andy