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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 1774CC35656 for ; Fri, 21 Feb 2020 16:35:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EC28B208E4 for ; Fri, 21 Feb 2020 16:35:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726681AbgBUQf1 (ORCPT ); Fri, 21 Feb 2020 11:35:27 -0500 Received: from verein.lst.de ([213.95.11.211]:56364 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726150AbgBUQf1 (ORCPT ); Fri, 21 Feb 2020 11:35:27 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 1B84A68BFE; Fri, 21 Feb 2020 17:35:24 +0100 (CET) Date: Fri, 21 Feb 2020 17:35:23 +0100 From: Christoph Hellwig To: "Michael S. Tsirkin" Cc: Halil Pasic , Jason Wang , Marek Szyprowski , Robin Murphy , Christoph Hellwig , linux-s390@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Christian Borntraeger , Janosch Frank , Viktor Mihajlovski , Cornelia Huck , Ram Pai , Thiago Jung Bauermann , David Gibson , "Lendacky, Thomas" , Michael Mueller Subject: Re: [PATCH 2/2] virtio: let virtio use DMA API when guest RAM is protected Message-ID: <20200221163523.GA10054@lst.de> References: <20200220160606.53156-1-pasic@linux.ibm.com> <20200220160606.53156-3-pasic@linux.ibm.com> <20200220154904-mutt-send-email-mst@kernel.org> <20200221141230.13eebc35.pasic@linux.ibm.com> <20200221104901-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200221104901-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 Fri, Feb 21, 2020 at 10:56:45AM -0500, Michael S. Tsirkin wrote: > > > - DMA API is giving us addresses that are actually also physical > > > addresses > > > > In case of s390 this is given. > > I talked with the power people before > > posting this, and they ensured me they can are willing to deal with > > this. I was hoping to talk abut this with the AMD SEV people here (hence > > the cc). > > We'd need a part of DMA API that promises this though. Platform > maintainers aren't going to go out of their way to do the > right thing just for virtio, and I can't track all arches > to make sure they don't violate virtio requirements. There is no way the DMA API is going to promise that you. All kinds of platforms have offsets to DMA, and they are communicated through interfaces like the device tree or ACPI. But the good thing is that your hypervisors is in control of that, neither the DMA API nor virtio have any business to interfer with that. In fact for harware virtio device we might need such an offset for them to work on lots of SOCs. 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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 E7E26C35656 for ; Fri, 21 Feb 2020 16:35:35 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (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 BB23724650 for ; Fri, 21 Feb 2020 16:35:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BB23724650 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 292E287F71; Fri, 21 Feb 2020 16:35:35 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id mtxDZACRpT1j; Fri, 21 Feb 2020 16:35:33 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by hemlock.osuosl.org (Postfix) with ESMTP id 6801E87F8E; Fri, 21 Feb 2020 16:35:33 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 52045C1D8E; Fri, 21 Feb 2020 16:35:33 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id C91C0C013E; Fri, 21 Feb 2020 16:35:30 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id B4CDE860AE; Fri, 21 Feb 2020 16:35:30 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 1k73wjz8hL4S; Fri, 21 Feb 2020 16:35:29 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by fraxinus.osuosl.org (Postfix) with ESMTPS id 5CAA18609D; Fri, 21 Feb 2020 16:35:29 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 1B84A68BFE; Fri, 21 Feb 2020 17:35:24 +0100 (CET) Date: Fri, 21 Feb 2020 17:35:23 +0100 From: Christoph Hellwig To: "Michael S. Tsirkin" Subject: Re: [PATCH 2/2] virtio: let virtio use DMA API when guest RAM is protected Message-ID: <20200221163523.GA10054@lst.de> References: <20200220160606.53156-1-pasic@linux.ibm.com> <20200220160606.53156-3-pasic@linux.ibm.com> <20200220154904-mutt-send-email-mst@kernel.org> <20200221141230.13eebc35.pasic@linux.ibm.com> <20200221104901-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200221104901-mutt-send-email-mst@kernel.org> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: linux-s390@vger.kernel.org, Janosch Frank , "Lendacky, Thomas" , Jason Wang , Cornelia Huck , Ram Pai , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Halil Pasic , Christian Borntraeger , iommu@lists.linux-foundation.org, David Gibson , Michael Mueller , Viktor Mihajlovski , Robin Murphy , Christoph Hellwig X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Fri, Feb 21, 2020 at 10:56:45AM -0500, Michael S. Tsirkin wrote: > > > - DMA API is giving us addresses that are actually also physical > > > addresses > > > > In case of s390 this is given. > > I talked with the power people before > > posting this, and they ensured me they can are willing to deal with > > this. I was hoping to talk abut this with the AMD SEV people here (hence > > the cc). > > We'd need a part of DMA API that promises this though. Platform > maintainers aren't going to go out of their way to do the > right thing just for virtio, and I can't track all arches > to make sure they don't violate virtio requirements. There is no way the DMA API is going to promise that you. All kinds of platforms have offsets to DMA, and they are communicated through interfaces like the device tree or ACPI. But the good thing is that your hypervisors is in control of that, neither the DMA API nor virtio have any business to interfer with that. In fact for harware virtio device we might need such an offset for them to work on lots of SOCs. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu