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=BAYES_00,DKIM_SIGNED, DKIM_VALID,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 D03D9C433DB for ; Fri, 15 Jan 2021 18:56:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 999EA23A59 for ; Fri, 15 Jan 2021 18:56:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730766AbhAOS4b (ORCPT ); Fri, 15 Jan 2021 13:56:31 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:50942 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727443AbhAOS4b (ORCPT ); Fri, 15 Jan 2021 13:56:31 -0500 Received: from pps.filterd (m0187473.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 10FIXKB1048120; Fri, 15 Jan 2021 13:55:29 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=date : from : to : cc : message-id : reply-to : references : mime-version : content-type : in-reply-to : subject; s=pp1; bh=gLkjcSk2zkN5prE8N5G7+0uj44eLd6dzpR8aLgmPUUo=; b=dQpL7/SfdCPmc8TXx/kv26twI1HMy9+tqiK9Y0FKz7NAhpaIqjZ1pd9gWc0wrov8f3XZ SwHGr9wIqRTH+neRZQMFcZZiWkyXq5oU6PX4aD1HP7WzDP4CAz2lVXCBYKBBrKaVvURK Myqu0Ff7nScRgNlI2GwNJw1NxzD5DhytJm2T3v1S86ixqc9cjofrmHVersrtp2UFVEK7 ZFIRhxyjp/zt88S9OTdjRbbWia0O84xEqZnHVrUfwjACiESRREhCVVT+rYPkBJXzFCGS jHjvtU7ur7ZMsfQimpB9hJmxV8QLwMhCNy4pNx+3D0c1pPbp4fjypr/2cLAsxFY8Amwm Pg== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 363gbmrkqg-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 15 Jan 2021 13:55:29 -0500 Received: from m0187473.ppops.net (m0187473.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 10FIXO34048323; Fri, 15 Jan 2021 13:55:28 -0500 Received: from ppma06ams.nl.ibm.com (66.31.33a9.ip4.static.sl-reverse.com [169.51.49.102]) by mx0a-001b2d01.pphosted.com with ESMTP id 363gbmrkpk-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 15 Jan 2021 13:55:28 -0500 Received: from pps.filterd (ppma06ams.nl.ibm.com [127.0.0.1]) by ppma06ams.nl.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 10FImINd030595; Fri, 15 Jan 2021 18:55:25 GMT Received: from b06avi18878370.portsmouth.uk.ibm.com (b06avi18878370.portsmouth.uk.ibm.com [9.149.26.194]) by ppma06ams.nl.ibm.com with ESMTP id 35ydrdfmk5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 15 Jan 2021 18:55:25 +0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06avi18878370.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 10FItHVo30146936 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 15 Jan 2021 18:55:17 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A3DCEA4053; Fri, 15 Jan 2021 18:55:22 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0A41FA4040; Fri, 15 Jan 2021 18:55:18 +0000 (GMT) Received: from ram-ibm-com.ibm.com (unknown [9.160.82.178]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Fri, 15 Jan 2021 18:55:17 +0000 (GMT) Date: Fri, 15 Jan 2021 10:55:14 -0800 From: Ram Pai To: Cornelia Huck Cc: Halil Pasic , Greg Kurz , pair@us.ibm.com, brijesh.singh@amd.com, kvm@vger.kernel.org, "Michael S. Tsirkin" , qemu-devel@nongnu.org, frankja@linux.ibm.com, david@redhat.com, mdroth@linux.vnet.ibm.com, borntraeger@de.ibm.com, David Gibson , thuth@redhat.com, Eduardo Habkost , Richard Henderson , dgilbert@redhat.com, qemu-s390x@nongnu.org, rth@twiddle.net, berrange@redhat.com, Marcelo Tosatti , qemu-ppc@nongnu.org, pbonzini@redhat.com Message-ID: <20210115185514.GB24076@ram-ibm-com.ibm.com> Reply-To: Ram Pai References: <20210104071550.GA22585@ram-ibm-com.ibm.com> <20210104134629.49997b53.pasic@linux.ibm.com> <20210104184026.GD4102@ram-ibm-com.ibm.com> <20210105115614.7daaadd6.pasic@linux.ibm.com> <20210105204125.GE4102@ram-ibm-com.ibm.com> <20210111175914.13adfa2e.cohuck@redhat.com> <20210111195830.GA23898@ram-ibm-com.ibm.com> <20210112091943.095c3b29.cohuck@redhat.com> <20210112185511.GB23898@ram-ibm-com.ibm.com> <20210113090629.2f41a9d3.cohuck@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210113090629.2f41a9d3.cohuck@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 Subject: Re: Re: [for-6.0 v5 11/13] spapr: PEF: prevent migration X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.343,18.0.737 definitions=2021-01-15_09:2021-01-15,2021-01-15 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 impostorscore=0 adultscore=0 spamscore=0 suspectscore=0 priorityscore=1501 malwarescore=0 bulkscore=0 phishscore=0 mlxlogscore=999 clxscore=1015 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2101150111 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Jan 13, 2021 at 09:06:29AM +0100, Cornelia Huck wrote: > On Tue, 12 Jan 2021 10:55:11 -0800 > Ram Pai wrote: > > > On Tue, Jan 12, 2021 at 09:19:43AM +0100, Cornelia Huck wrote: > > > On Mon, 11 Jan 2021 11:58:30 -0800 > > > Ram Pai wrote: > > > > > > > On Mon, Jan 11, 2021 at 05:59:14PM +0100, Cornelia Huck wrote: > > > > > On Tue, 5 Jan 2021 12:41:25 -0800 > > > > > Ram Pai wrote: > > > > > > > > > > > On Tue, Jan 05, 2021 at 11:56:14AM +0100, Halil Pasic wrote: > > > > > > > On Mon, 4 Jan 2021 10:40:26 -0800 > > > > > > > Ram Pai wrote: > > > > > > > > > > > > > The main difference between my proposal and the other proposal is... > > > > > > > > > > > > > > > > In my proposal the guest makes the compatibility decision and acts > > > > > > > > accordingly. In the other proposal QEMU makes the compatibility > > > > > > > > decision and acts accordingly. I argue that QEMU cannot make a good > > > > > > > > compatibility decision, because it wont know in advance, if the guest > > > > > > > > will or will-not switch-to-secure. > > > > > > > > > > > > > > > > > > > > > > You have a point there when you say that QEMU does not know in advance, > > > > > > > if the guest will or will-not switch-to-secure. I made that argument > > > > > > > regarding VIRTIO_F_ACCESS_PLATFORM (iommu_platform) myself. My idea > > > > > > > was to flip that property on demand when the conversion occurs. David > > > > > > > explained to me that this is not possible for ppc, and that having the > > > > > > > "securable-guest-memory" property (or whatever the name will be) > > > > > > > specified is a strong indication, that the VM is intended to be used as > > > > > > > a secure VM (thus it is OK to hurt the case where the guest does not > > > > > > > try to transition). That argument applies here as well. > > > > > > > > > > > > As suggested by Cornelia Huck, what if QEMU disabled the > > > > > > "securable-guest-memory" property if 'must-support-migrate' is enabled? > > > > > > Offcourse; this has to be done with a big fat warning stating > > > > > > "secure-guest-memory" feature is disabled on the machine. > > > > > > Doing so, will continue to support guest that do not try to transition. > > > > > > Guest that try to transition will fail and terminate themselves. > > > > > > > > > > Just to recap the s390x situation: > > > > > > > > > > - We currently offer a cpu feature that indicates secure execution to > > > > > be available to the guest if the host supports it. > > > > > - When we introduce the secure object, we still need to support > > > > > previous configurations and continue to offer the cpu feature, even > > > > > if the secure object is not specified. > > > > > - As migration is currently not supported for secured guests, we add a > > > > > blocker once the guest actually transitions. That means that > > > > > transition fails if --only-migratable was specified on the command > > > > > line. (Guests not transitioning will obviously not notice anything.) > > > > > - With the secure object, we will already fail starting QEMU if > > > > > --only-migratable was specified. > > > > > > > > > > My suggestion is now that we don't even offer the cpu feature if > > > > > --only-migratable has been specified. For a guest that does not want to > > > > > transition to secure mode, nothing changes; a guest that wants to > > > > > transition to secure mode will notice that the feature is not available > > > > > and fail appropriately (or ultimately, when the ultravisor call fails). > > > > > > > > > > > > On POWER, secure-execution is not **automatically** enabled even when > > > > the host supports it. The feature is enabled only if the secure-object > > > > is configured, and the host supports it. > > > > > > Yes, the cpu feature on s390x is simply pre-existing. > > > > > > > > > > > However the behavior proposed above will be consistent on POWER and > > > > on s390x, when '--only-migratable' is specified and 'secure-object' > > > > is NOT specified. > > > > > > > > So I am in agreement till now. > > > > > > > > > > > > > We'd still fail starting QEMU for the secure object + --only-migratable > > > > > combination. > > > > > > > > Why fail? > > > > > > > > Instead, print a warning and disable the secure-object; which will > > > > disable your cpu-feature. Guests that do not transition to secure, will > > > > continue to operate, and guests that transition to secure, will fail. > > > > > > But that would be consistent with how other non-migratable objects are > > > handled, no? It's simply a case of incompatible options on the command > > > line. > > > > Actually the two options are inherently NOT incompatible. Halil also > > mentioned this in one of his replies. > > > > Its just that the current implementation is lacking, which will be fixed > > in the near future. > > > > We can design it upfront, with the assumption that they both are compatible. > > In the short term disable one; preferrably the secure-object, if both > > options are specified. In the long term, remove the restriction, when > > the implemetation is complete. > > Can't we simply mark the object as non-migratable now, and then remove > that later? I don't see what is so special about it. This is fine too. However I am told that libvirt has some assumptions, where it assumes that the VM is guaranteed to be migratable if '--only-migratable' is specified. Silently turning off that option can be bad. -- Ram Pai