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=-11.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 0A958C433E3 for ; Mon, 27 Jul 2020 15:05:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DA4EE2064B for ; Mon, 27 Jul 2020 15:05:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="TvKubWIa" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730044AbgG0PFf (ORCPT ); Mon, 27 Jul 2020 11:05:35 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:40858 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728933AbgG0PFf (ORCPT ); Mon, 27 Jul 2020 11:05:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1595862334; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=J7H68rHMGgj4y/RigpW4INmzQNkKVxj5I39s/CIOURI=; b=TvKubWIaqRUH8i7nQKBFyB9FUxrFrzligJZ+KS35KdAKqc25bxZfXE5GIhfp99tWksn7rF 79ddNXTY/djlmw6spoXWgGSzZH7OnREk0N1L5IuwRL7cUrPBpBAfdFoNYnAJh4SYiyOEyh /EUZ6V9UJF66Ox2uiiGiI3KazUYXBN0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-64-2cDVulTlP1Sb7Q_0ZVgRlQ-1; Mon, 27 Jul 2020 11:05:28 -0400 X-MC-Unique: 2cDVulTlP1Sb7Q_0ZVgRlQ-1 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id 13278800466; Mon, 27 Jul 2020 15:05:26 +0000 (UTC) Received: from work-vm (ovpn-114-135.ams2.redhat.com [10.36.114.135]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 138165F21D; Mon, 27 Jul 2020 15:05:16 +0000 (UTC) Date: Mon, 27 Jul 2020 16:05:14 +0100 From: "Dr. David Alan Gilbert" To: David Gibson Cc: frankja@linux.ibm.com, pair@us.ibm.com, qemu-devel@nongnu.org, pbonzini@redhat.com, brijesh.singh@amd.com, ehabkost@redhat.com, marcel.apfelbaum@gmail.com, "Michael S. Tsirkin" , qemu-ppc@nongnu.org, kvm@vger.kernel.org, pasic@linux.ibm.com, qemu-s390x@nongnu.org, David Hildenbrand , Christian Borntraeger , Richard Henderson , Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , mdroth@linux.vnet.ibm.com, Thomas Huth , Cornelia Huck Subject: Re: [for-5.2 v4 09/10] host trust limitation: Alter virtio default properties for protected guests Message-ID: <20200727150514.GQ3040@work-vm> References: <20200724025744.69644-1-david@gibson.dropbear.id.au> <20200724025744.69644-10-david@gibson.dropbear.id.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200724025744.69644-10-david@gibson.dropbear.id.au> User-Agent: Mutt/1.14.5 (2020-06-23) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org * 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"); > + 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