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=-0.8 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 69E54C433EF for ; Sat, 16 Jun 2018 01:09:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 14426204EC for ; Sat, 16 Jun 2018 01:09:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 14426204EC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756198AbeFPBJU (ORCPT ); Fri, 15 Jun 2018 21:09:20 -0400 Received: from gate.crashing.org ([63.228.1.57]:36427 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753724AbeFPBJS (ORCPT ); Fri, 15 Jun 2018 21:09:18 -0400 Received: from localhost (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id w5G17OqR030994; Fri, 15 Jun 2018 20:07:25 -0500 Message-ID: <1b4732c5015ee4377fef1de0270065174cde397a.camel@kernel.crashing.org> Subject: Re: [RFC V2] virtio: Add platform specific DMA API translation for virito devices From: Benjamin Herrenschmidt To: Christoph Hellwig Cc: Ram Pai , "Michael S. Tsirkin" , robh@kernel.org, pawel.moll@arm.com, Tom Lendacky , aik@ozlabs.ru, jasowang@redhat.com, cohuck@redhat.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, joe@perches.com, "Rustad, Mark D" , david@gibson.dropbear.id.au, linuxppc-dev@lists.ozlabs.org, elfring@users.sourceforge.net, Anshuman Khandual Date: Sat, 16 Jun 2018 11:07:24 +1000 In-Reply-To: <20180615091624.GA1064@infradead.org> References: <20180524072104.GD6139@ram.oc3035372033.ibm.com> <0c508eb2-08df-3f76-c260-90cf7137af80@linux.vnet.ibm.com> <20180531204320-mutt-send-email-mst@kernel.org> <20180607052306.GA1532@infradead.org> <20180607185234-mutt-send-email-mst@kernel.org> <20180611023909.GA5726@ram.oc3035372033.ibm.com> <07b804fccd7373c650be79ac9fa77ae7f2375ced.camel@kernel.crashing.org> <20180613074141.GA12033@infradead.org> <5dbcafa73b065bc619fd6adc9ef47eb6367b8378.camel@kernel.crashing.org> <10bbd7122aaa67f51de7a8328df8154212a13f23.camel@kernel.crashing.org> <20180615091624.GA1064@infradead.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.1 (3.28.1-2.fc28) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2018-06-15 at 02:16 -0700, Christoph Hellwig wrote: > On Wed, Jun 13, 2018 at 11:11:01PM +1000, Benjamin Herrenschmidt wrote: > > Actually ... the stuff in lib/dma-direct.c seems to be just it, no ? > > > > There's no cache flushing and there's no architecture hooks that I can > > see other than the AMD security stuff which is probably fine. > > > > Or am I missing something ? > > You are missing the __phys_to_dma arch hook that allows architectures > to adjust the dma address. Various systems have offsets, or even > multiple banks with different offsets there. Most of them don't > use the dma-direct code yet (working on it), but there are a few > examples in the tree already. Ok and on those systems, qemu will bypass said offset ? Maybe we could just create a device DMA "flag" or (or use the attributes) to instruct dma-direct to not use that for legacy virtio ? Cheers, Ben. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Subject: Re: [RFC V2] virtio: Add platform specific DMA API translation for virito devices Date: Sat, 16 Jun 2018 11:07:24 +1000 Message-ID: <1b4732c5015ee4377fef1de0270065174cde397a.camel@kernel.crashing.org> References: <20180524072104.GD6139@ram.oc3035372033.ibm.com> <0c508eb2-08df-3f76-c260-90cf7137af80@linux.vnet.ibm.com> <20180531204320-mutt-send-email-mst@kernel.org> <20180607052306.GA1532@infradead.org> <20180607185234-mutt-send-email-mst@kernel.org> <20180611023909.GA5726@ram.oc3035372033.ibm.com> <07b804fccd7373c650be79ac9fa77ae7f2375ced.camel@kernel.crashing.org> <20180613074141.GA12033@infradead.org> <5dbcafa73b065bc619fd6adc9ef47eb6367b8378.camel@kernel.crashing.org> <10bbd7122aaa67f51de7a8328df8154212a13f23.camel@kernel.crashing.org> <20180615091624.GA1064@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180615091624.GA1064@infradead.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Christoph Hellwig Cc: robh@kernel.org, cohuck@redhat.com, pawel.moll@arm.com, Tom Lendacky , "Michael S. Tsirkin" , Ram Pai , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, joe@perches.com, "Rustad, Mark D" , Anshuman Khandual , linuxppc-dev@lists.ozlabs.org, elfring@users.sourceforge.net, david@gibson.dropbear.id.au List-Id: virtualization@lists.linuxfoundation.org On Fri, 2018-06-15 at 02:16 -0700, Christoph Hellwig wrote: > On Wed, Jun 13, 2018 at 11:11:01PM +1000, Benjamin Herrenschmidt wrote: > > Actually ... the stuff in lib/dma-direct.c seems to be just it, no ? > > > > There's no cache flushing and there's no architecture hooks that I can > > see other than the AMD security stuff which is probably fine. > > > > Or am I missing something ? > > You are missing the __phys_to_dma arch hook that allows architectures > to adjust the dma address. Various systems have offsets, or even > multiple banks with different offsets there. Most of them don't > use the dma-direct code yet (working on it), but there are a few > examples in the tree already. Ok and on those systems, qemu will bypass said offset ? Maybe we could just create a device DMA "flag" or (or use the attributes) to instruct dma-direct to not use that for legacy virtio ? Cheers, Ben.