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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 9FEDEC282CB for ; Mon, 4 Feb 2019 18:16:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7958D2082E for ; Mon, 4 Feb 2019 18:16:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729723AbfBDSQI (ORCPT ); Mon, 4 Feb 2019 13:16:08 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:37394 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729540AbfBDSP5 (ORCPT ); Mon, 4 Feb 2019 13:15:57 -0500 Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x14IAekI073387 for ; Mon, 4 Feb 2019 13:15:56 -0500 Received: from e16.ny.us.ibm.com (e16.ny.us.ibm.com [129.33.205.206]) by mx0a-001b2d01.pphosted.com with ESMTP id 2qercreeqq-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 04 Feb 2019 13:15:55 -0500 Received: from localhost by e16.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 4 Feb 2019 18:15:51 -0000 Received: from b01ledav006.gho.pok.ibm.com (b01ledav006.gho.pok.ibm.com [9.57.199.111]) by b01cxnp23034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x14IFoeH21299298 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 4 Feb 2019 18:15:50 GMT Received: from b01ledav006.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 49A35AC05F; Mon, 4 Feb 2019 18:15:50 +0000 (GMT) Received: from b01ledav006.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0B7F0AC060; Mon, 4 Feb 2019 18:15:47 +0000 (GMT) Received: from morokweng.localdomain (unknown [9.85.235.178]) by b01ledav006.gho.pok.ibm.com (Postfix) with ESMTPS; Mon, 4 Feb 2019 18:15:46 +0000 (GMT) References: <87zhrj8kcp.fsf@morokweng.localdomain> <87womn8inf.fsf@morokweng.localdomain> <20190129134750-mutt-send-email-mst@kernel.org> <6c68f7f7-1b28-6eba-9b8b-2c32efac9701@redhat.com> <20190129213137-mutt-send-email-mst@kernel.org> <20190130074427.GA29516@lst.de> User-agent: mu4e 1.0; emacs 26.1 From: Thiago Jung Bauermann To: Christoph Hellwig Cc: "Michael S. Tsirkin" , Jason Wang , virtualization@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, David Gibson , Alexey Kardashevskiy , Paul Mackerras , Benjamin Herrenschmidt , Ram Pai , Jean-Philippe Brucker Subject: Re: [RFC PATCH] virtio_ring: Use DMA API if guest memory is encrypted In-reply-to: <20190130074427.GA29516@lst.de> Date: Mon, 04 Feb 2019 16:15:41 -0200 MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 x-cbid: 19020418-0072-0000-0000-000003F491EC X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010536; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000279; SDB=6.01156339; UDB=6.00603145; IPR=6.00936798; MB=3.00025434; MTD=3.00000008; XFM=3.00000015; UTC=2019-02-04 18:15:54 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19020418-0073-0000-0000-00004B0F3C0F Message-Id: <875ztzxvw2.fsf@morokweng.localdomain> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-02-04_12:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=927 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1902040140 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Christoph Hellwig writes: > On Tue, Jan 29, 2019 at 09:36:08PM -0500, Michael S. Tsirkin wrote: >> This has been discussed ad nauseum. virtio is all about compatibility. >> Losing a couple of lines of code isn't worth breaking working setups. >> People that want "just use DMA API no tricks" now have the option. >> Setting a flag in a feature bit map is literally a single line >> of code in the hypervisor. So stop pushing for breaking working >> legacy setups and just fix it in the right place. > > I agree with the legacy aspect. What I am missing is an extremely > strong wording that says you SHOULD always set this flag for new > hosts, including an explanation why. My understanding of ACCESS_PLATFORM is that it means "this device will behave in all aspects like a regular device attached to this bus". Is that it? Therefore it should be set because it's the sane thing to do? -- Thiago Jung Bauermann IBM Linux Technology Center