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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 4398FC433E0 for ; Wed, 20 May 2020 12:17:29 +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 06D7A2070A for ; Wed, 20 May 2020 12:17:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 06D7A2070A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:33344 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jbNf6-0003by-8C for qemu-devel@archiver.kernel.org; Wed, 20 May 2020 08:17:28 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38388) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jbNeO-00039t-Qx; Wed, 20 May 2020 08:16:44 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:31574 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jbNeN-0004PL-Nb; Wed, 20 May 2020 08:16:44 -0400 Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 04KC4x6V172589; Wed, 20 May 2020 08:16:40 -0400 Received: from pps.reinject (localhost [127.0.0.1]) by mx0b-001b2d01.pphosted.com with ESMTP id 312aasy7mr-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 20 May 2020 08:16:40 -0400 Received: from m0098413.ppops.net (m0098413.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 04KC5YAL179132; Wed, 20 May 2020 08:16:40 -0400 Received: from ppma03ams.nl.ibm.com (62.31.33a9.ip4.static.sl-reverse.com [169.51.49.98]) by mx0b-001b2d01.pphosted.com with ESMTP id 312aasy7m2-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 20 May 2020 08:16:39 -0400 Received: from pps.filterd (ppma03ams.nl.ibm.com [127.0.0.1]) by ppma03ams.nl.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 04KCGSkX026308; Wed, 20 May 2020 12:16:38 GMT Received: from b06cxnps4074.portsmouth.uk.ibm.com (d06relay11.portsmouth.uk.ibm.com [9.149.109.196]) by ppma03ams.nl.ibm.com with ESMTP id 313xas3kjf-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 20 May 2020 12:16:38 +0000 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 04KCGZCQ60227668 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 20 May 2020 12:16:35 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4BC6511C04A; Wed, 20 May 2020 12:16:35 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 9EB5111C04C; Wed, 20 May 2020 12:16:34 +0000 (GMT) Received: from oc2783563651 (unknown [9.145.44.243]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 20 May 2020 12:16:34 +0000 (GMT) Date: Wed, 20 May 2020 14:16:33 +0200 From: Halil Pasic To: Cornelia Huck , Christian Borntraeger , qemu-s390x@nongnu.org, qemu-devel@nongnu.org Subject: Re: [PATCH v2 1/1] virtio-ccw: auto-manage VIRTIO_F_IOMMU_PLATFORM if PV Message-ID: <20200520141633.49e91a43.pasic@linux.ibm.com> In-Reply-To: <20200514221155.32079-1-pasic@linux.ibm.com> References: <20200514221155.32079-1-pasic@linux.ibm.com> Organization: IBM X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.31; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216, 18.0.676 definitions=2020-05-20_07:2020-05-19, 2020-05-20 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 mlxscore=0 lowpriorityscore=0 mlxlogscore=999 spamscore=0 clxscore=1015 impostorscore=0 adultscore=0 malwarescore=0 priorityscore=1501 bulkscore=0 suspectscore=0 cotscore=-2147483648 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2005200101 Received-SPF: pass client-ip=148.163.158.5; envelope-from=pasic@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/20 08:16:40 X-ACL-Warn: Detected OS = Linux 3.x [generic] X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, KHOP_DYNAMIC=0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action 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: Thomas Huth , Boris Fiuczynski , Janosch Frank , Pierre Morel , David Hildenbrand , "Michael S. Tsirkin" , Viktor Mihajlovski , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, 15 May 2020 00:11:55 +0200 Halil Pasic wrote: > The virtio specification tells that the device is to present > VIRTIO_F_ACCESS_PLATFORM (a.k.a. VIRTIO_F_IOMMU_PLATFORM) when the > device "can only access certain memory addresses with said access > specified and/or granted by the platform". This is the case for a > protected VMs, as the device can access only memory addresses that are > in pages that are currently shared (only the guest can share/unsare its > pages). > > No VM, however, starts out as a protected VM, but some VMs may be > converted to protected VMs if the guest decides so. > > Making the end user explicitly manage the VIRTIO_F_ACCESS_PLATFORM via > the property iommu_on is a minor disaster. Since the correctness of the > paravirtualized virtio devices depends (and thus in a sense the > correctness of the hypervisor) it, then the hypervisor should have the > last word about whether VIRTIO_F_ACCESS_PLATFORM is to be presented or > not. > > Currently presenting a PV guest with a (paravirtualized) virtio-ccw > device has catastrophic consequences for the VM (after the hypervisors > access to protected memory). This is especially grave in case of device > hotplug (because in this case the guest is more likely to be in the > middle of something important). > > Let us manage the VIRTIO_F_ACCESS_PLATFORM virtio feature automatically > for virtio-ccw devices, i.e. force it before we start the protected VM. > If the VM should cease to be protected, the original value is restored. > > Signed-off-by: Halil Pasic > --- > > NOTES: > > * Doing more system_resets() is a big hack. We should look into this. > * The user interface implications of this patch are also an ugly can of > worms. We need to discuss them. > > > v1 --> v2: > * Use the default or user supplied iommu_on flag when when !PV > * Use virtio functions for feature manipulation > > Link to v1: > https://www.mail-archive.com/qemu-devel@nongnu.org/msg683775.html > > Unfortunately the v1 did not see much discussion because we had more > pressing issues. > > polite ping