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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 56AF5C282D4 for ; Wed, 30 Jan 2019 07:44:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3117720869 for ; Wed, 30 Jan 2019 07:44:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730130AbfA3Ho3 (ORCPT ); Wed, 30 Jan 2019 02:44:29 -0500 Received: from verein.lst.de ([213.95.11.211]:50668 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725819AbfA3Ho3 (ORCPT ); Wed, 30 Jan 2019 02:44:29 -0500 Received: by newverein.lst.de (Postfix, from userid 2407) id 9623068CEC; Wed, 30 Jan 2019 08:44:27 +0100 (CET) Date: Wed, 30 Jan 2019 08:44:27 +0100 From: Christoph Hellwig To: "Michael S. Tsirkin" Cc: Jason Wang , Thiago Jung Bauermann , virtualization@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Christoph Hellwig , 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 Message-ID: <20190130074427.GA29516@lst.de> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190129213137-mutt-send-email-mst@kernel.org> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. 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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 68BCEC282D4 for ; Wed, 30 Jan 2019 07:46:12 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D173B20869 for ; Wed, 30 Jan 2019 07:46:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D173B20869 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 43qFmK4MJmzDqTj for ; Wed, 30 Jan 2019 18:46:09 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=lst.de (client-ip=213.95.11.211; helo=newverein.lst.de; envelope-from=hch@lst.de; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=lst.de Received: from newverein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 43qFkR4gMPzDqT8 for ; Wed, 30 Jan 2019 18:44:30 +1100 (AEDT) Received: by newverein.lst.de (Postfix, from userid 2407) id 9623068CEC; Wed, 30 Jan 2019 08:44:27 +0100 (CET) Date: Wed, 30 Jan 2019 08:44:27 +0100 From: Christoph Hellwig To: "Michael S. Tsirkin" Subject: Re: [RFC PATCH] virtio_ring: Use DMA API if guest memory is encrypted Message-ID: <20190130074427.GA29516@lst.de> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190129213137-mutt-send-email-mst@kernel.org> User-Agent: Mutt/1.5.17 (2007-11-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jean-Philippe Brucker , Jason Wang , Alexey Kardashevskiy , Ram Pai , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, iommu@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, Christoph Hellwig , Thiago Jung Bauermann , David Gibson Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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.