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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,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 7F793C433DF for ; Thu, 13 Aug 2020 08:19:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 62C2520771 for ; Thu, 13 Aug 2020 08:19:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726419AbgHMITL (ORCPT ); Thu, 13 Aug 2020 04:19:11 -0400 Received: from smtpout1.mo804.mail-out.ovh.net ([79.137.123.220]:34373 "EHLO smtpout1.mo804.mail-out.ovh.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726048AbgHMITL (ORCPT ); Thu, 13 Aug 2020 04:19:11 -0400 Received: from mxplan5.mail.ovh.net (unknown [10.108.16.141]) by mo804.mail-out.ovh.net (Postfix) with ESMTPS id 9B2EE56B7D75; Thu, 13 Aug 2020 10:19:08 +0200 (CEST) Received: from kaod.org (37.59.142.101) by DAG8EX1.mxp5.local (172.16.2.71) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Thu, 13 Aug 2020 10:19:07 +0200 Authentication-Results: garm.ovh; auth=pass (GARM-101G004206af493-e3f7-496e-8ef0-21b805489ea6, 56FC6CFA6F9FB878813463EC2CBCCD0911300B36) smtp.auth=groug@kaod.org Date: Thu, 13 Aug 2020 10:19:06 +0200 From: Greg Kurz To: "Dr. David Alan Gilbert" CC: , , , , "Michael S. Tsirkin" , Cornelia Huck , David Hildenbrand , , , , , Christian Borntraeger , , , , , Thomas Huth , Daniel =?UTF-8?B?UC5CZXJyYW5nw6k=?= , Richard Henderson , David Gibson Subject: Re: [for-5.2 v4 09/10] host trust limitation: Alter virtio default properties for protected guests Message-ID: <20200813101906.799efe55@bahia.lan> In-Reply-To: <20200813094356.651f323c@bahia.lan> References: <20200724025744.69644-1-david@gibson.dropbear.id.au> <20200724025744.69644-10-david@gibson.dropbear.id.au> <20200727150514.GQ3040@work-vm> <20200813094356.651f323c@bahia.lan> X-Mailer: Claws Mail 3.17.6 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [37.59.142.101] X-ClientProxiedBy: DAG4EX1.mxp5.local (172.16.2.31) To DAG8EX1.mxp5.local (172.16.2.71) X-Ovh-Tracer-GUID: 7c42f844-0aae-44c2-bb35-5ab0c4b8b78d X-Ovh-Tracer-Id: 17833128628167940563 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgeduiedrleeggddtgecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfqggfjpdevjffgvefmvefgnecuuegrihhlohhuthemucehtddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpeffhffvuffkjghfofggtgfgihesthejredtredtvdenucfhrhhomhepifhrvghgucfmuhhriicuoehgrhhouhhgsehkrghougdrohhrgheqnecuggftrfgrthhtvghrnhepfedutdeijeejveehkeeileetgfelteekteehtedtieefffevhffflefftdefleejnecukfhppedtrddtrddtrddtpdefjedrheelrddugedvrddutddunecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmohguvgepshhmthhpqdhouhhtpdhhvghlohepmhigphhlrghnhedrmhgrihhlrdhovhhhrdhnvghtpdhinhgvtheptddrtddrtddrtddpmhgrihhlfhhrohhmpehgrhhouhhgsehkrghougdrohhrghdprhgtphhtthhopegurghvihgusehgihgsshhonhdrughrohhpsggvrghrrdhiugdrrghu Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, 13 Aug 2020 09:43:56 +0200 Greg Kurz wrote: > On Mon, 27 Jul 2020 16:05:14 +0100 > "Dr. David Alan Gilbert" wrote: > > > * David Gibson (david@gibson.dropbear.id.au) wrote: > > > The default behaviour for virtio devices is not to use the platforms normal > > > DMA paths, but instead to use the fact that it's running in a hypervisor > > > to directly access guest memory. That doesn't work if the guest's memory > > > is protected from hypervisor access, such as with AMD's SEV or POWER's PEF. > > > > > > So, if a host trust limitation mechanism is enabled, then apply the > > > iommu_platform=on option so it will go through normal DMA mechanisms. > > > Those will presumably have some way of marking memory as shared with the > > > hypervisor or hardware so that DMA will work. > > > > > > Signed-off-by: David Gibson > > > > Good, it's just too easy to forget them at the moment and get hopelessly > > confused. > > > > > > Reviewed-by: Dr. David Alan Gilbert > > > > > --- > > > hw/core/machine.c | 11 +++++++++++ > > > 1 file changed, 11 insertions(+) > > > > > > diff --git a/hw/core/machine.c b/hw/core/machine.c > > > index b599b0ba65..2a723bf07b 100644 > > > --- a/hw/core/machine.c > > > +++ b/hw/core/machine.c > > > @@ -28,6 +28,8 @@ > > > #include "hw/mem/nvdimm.h" > > > #include "migration/vmstate.h" > > > #include "exec/host-trust-limitation.h" > > > +#include "hw/virtio/virtio.h" > > > +#include "hw/virtio/virtio-pci.h" > > > > > > GlobalProperty hw_compat_5_0[] = { > > > { "virtio-balloon-device", "page-poison", "false" }, > > > @@ -1161,6 +1163,15 @@ void machine_run_board_init(MachineState *machine) > > > * areas. > > > */ > > > machine_set_mem_merge(OBJECT(machine), false, &error_abort); > > > + > > > + /* > > > + * Virtio devices can't count on directly accessing guest > > > + * memory, so they need iommu_platform=on to use normal DMA > > > + * mechanisms. That requires disabling legacy virtio support > > > + * for virtio pci devices > > > + */ > > > + object_register_sugar_prop(TYPE_VIRTIO_PCI, "disable-legacy", "on"); > > What about non-transitional devices (eg. vhost-user-fs-pci) ? They don't know > about "disable-legacy" since they don't need it. > Ok, it looks like we should add a bool argument to object_register_sugar_prop() that sets the .optional field of GlobalProperty. > > > + object_register_sugar_prop(TYPE_VIRTIO_DEVICE, "iommu_platform", "on"); > > > } > > > > > > machine_class->init(machine); > > > -- > > > 2.26.2 > > > > > -- > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > > > > > >