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=-2.3 required=3.0 tests=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 3A6BFC32750 for ; Tue, 13 Aug 2019 08:42:31 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0F68020679 for ; Tue, 13 Aug 2019 08:42:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0F68020679 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:50174 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hxSNy-0006cx-B3 for qemu-devel@archiver.kernel.org; Tue, 13 Aug 2019 04:42:30 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:45691) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hxSNb-0006D1-Fr for qemu-devel@nongnu.org; Tue, 13 Aug 2019 04:42:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hxSNa-0005rO-DG for qemu-devel@nongnu.org; Tue, 13 Aug 2019 04:42:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58818) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hxSNa-0005qy-5N for qemu-devel@nongnu.org; Tue, 13 Aug 2019 04:42:06 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C4662C053FDC; Tue, 13 Aug 2019 08:42:04 +0000 (UTC) Received: from [10.72.12.191] (ovpn-12-191.pek2.redhat.com [10.72.12.191]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0A9F382463; Tue, 13 Aug 2019 08:41:50 +0000 (UTC) To: Peter Xu , qemu-devel@nongnu.org References: <20190812074531.28970-1-peterx@redhat.com> From: Jason Wang Message-ID: <319f1d6a-ef55-cc1b-98d6-f99b365bd88a@redhat.com> Date: Tue, 13 Aug 2019 16:41:49 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190812074531.28970-1-peterx@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Tue, 13 Aug 2019 08:42:04 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH RFC 0/4] intel_iommu: Do sanity check of vfio-pci earlier X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= , Eduardo Habkost , "Michael S. Tsirkin" , Alex Williamson , Bandan Das , Igor Mammedov , Paolo Bonzini , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2019/8/12 =E4=B8=8B=E5=8D=883:45, Peter Xu wrote: > This is a RFC series. > > The VT-d code has some defects, one of them is that we cannot detect > the misuse of vIOMMU and vfio-pci early enough. > > For example, logically this is not allowed: > > -device intel-iommu,caching-mode=3Doff \ > -device vfio-pci,host=3D05:00.0 > > Because the caching mode is required to make vfio-pci devices > functional. > > Previously we did this sanity check in vtd_iommu_notify_flag_changed() > as when the memory regions change their attributes. However that's > too late in most cases! Because the memory region layouts will only > change after IOMMU is enabled, and that's in most cases during the > guest OS boots. So when the configuration is wrong, we will only bail > out during the guest boots rather than simply telling the user before > QEMU starts. > > The same problem happens on device hotplug, say, when we have this: > > -device intel-iommu,caching-mode=3Doff > > Then we do something like: > > (HMP) device_add vfio-pci,host=3D05:00.0,bus=3Dpcie.1 > > If at that time the vIOMMU is enabled in the guest then the QEMU > process will simply quit directly due to this hotplug event. This is > a bit insane... > > This series tries to solve above two problems by introducing two > sanity checks upon these places separately: > > - machine done > - hotplug device > > This is a bit awkward but I hope this could be better than before. > There is of course other solutions like hard-code the check into > vfio-pci but I feel it even more unpretty. I didn't think out any > better way to do this, if there is please kindly shout out. > > Please have a look to see whether this would be acceptable, thanks. > > Peter Xu (4): > intel_iommu: Sanity check vfio-pci config on machine init done > qdev/machine: Introduce hotplug_allowed hook > pc/q35: Disallow vfio-pci hotplug without VT-d caching mode > intel_iommu: Remove the caching-mode check during flag change > > hw/core/qdev.c | 17 +++++++++++++++++ > hw/i386/intel_iommu.c | 40 ++++++++++++++++++++++++++++++++++------ > hw/i386/pc.c | 21 +++++++++++++++++++++ > include/hw/boards.h | 9 +++++++++ > include/hw/qdev-core.h | 1 + > qdev-monitor.c | 7 +++++++ > 6 files changed, 89 insertions(+), 6 deletions(-) > Do we need a generic solution other than an Intel specific one? Thanks