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=-17.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 25BA9C433FE for ; Fri, 4 Dec 2020 17:06:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DCB4B22B43 for ; Fri, 4 Dec 2020 17:06:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388534AbgLDRGJ (ORCPT ); Fri, 4 Dec 2020 12:06:09 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:38146 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731079AbgLDRGI (ORCPT ); Fri, 4 Dec 2020 12:06:08 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607101482; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=HZCsLXtKca3nNAVY5L6E1QM442yGFMtulOgg+1asj1w=; b=WkNpJkR1h7Z66oawEbdWS2+ypIJyWyJW2zkJcgQ/PbqYplfee3VpGveH2OkX2RUR39rsQQ T9PCoRkB7B5yrbSx/pbWmdmrHrLlKjRGOSE+oNWRFdymOZb/o2OiDWPIGd3xptgx9vKsF+ DrayLFz0gNOpx2F/8GIh+yD1aJk5MtA= 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-143-JbAeTytJOpenl25RMLvAHw-1; Fri, 04 Dec 2020 12:04:40 -0500 X-MC-Unique: JbAeTytJOpenl25RMLvAHw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 60EB1800D55; Fri, 4 Dec 2020 17:04:38 +0000 (UTC) Received: from gondolin (ovpn-113-97.ams2.redhat.com [10.36.113.97]) by smtp.corp.redhat.com (Postfix) with ESMTP id ACD005C1C4; Fri, 4 Dec 2020 17:04:25 +0000 (UTC) Date: Fri, 4 Dec 2020 18:04:22 +0100 From: Cornelia Huck To: David Gibson Cc: pair@us.ibm.com, pbonzini@redhat.com, frankja@linux.ibm.com, brijesh.singh@amd.com, dgilbert@redhat.com, qemu-devel@nongnu.org, Eduardo Habkost , qemu-ppc@nongnu.org, rth@twiddle.net, thuth@redhat.com, berrange@redhat.com, mdroth@linux.vnet.ibm.com, Marcelo Tosatti , "Michael S. Tsirkin" , Marcel Apfelbaum , david@redhat.com, Richard Henderson , borntraeger@de.ibm.com, kvm@vger.kernel.org, qemu-s390x@nongnu.org, pasic@linux.ibm.com Subject: Re: [for-6.0 v5 12/13] securable guest memory: Alter virtio default properties for protected guests Message-ID: <20201204180422.4a7e8cfb.cohuck@redhat.com> In-Reply-To: <20201204054415.579042-13-david@gibson.dropbear.id.au> References: <20201204054415.579042-1-david@gibson.dropbear.id.au> <20201204054415.579042-13-david@gibson.dropbear.id.au> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, 4 Dec 2020 16:44:14 +1100 David Gibson 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 securable guest memory 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 > Reviewed-by: Dr. David Alan Gilbert > --- > hw/core/machine.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) Reviewed-by: Cornelia Huck