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=-2.2 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 8C877C3A59B for ; Sat, 17 Aug 2019 18:20:36 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (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 47708206DF for ; Sat, 17 Aug 2019 18:20:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 47708206DF Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id E5814FFB; Sat, 17 Aug 2019 18:20:35 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 5E74AFFA for ; Sat, 17 Aug 2019 18:20:34 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id 4AFF976D for ; Sat, 17 Aug 2019 18:20:33 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 50DD5337; Sat, 17 Aug 2019 11:20:31 -0700 (PDT) Received: from [10.37.12.25] (unknown [10.37.12.25]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8A66F3F706; Sat, 17 Aug 2019 11:20:29 -0700 (PDT) Subject: Re: [Xen-devel] [PATCH 07/11] swiotlb-xen: provide a single page-coherent.h header To: Christoph Hellwig References: <20190816130013.31154-1-hch@lst.de> <20190816130013.31154-8-hch@lst.de> <9a3261c6-5d92-cf6b-1ae8-3a8e8b5ef0d4@arm.com> <20190817065011.GA18599@lst.de> From: Julien Grall Message-ID: <21746bbf-618a-d12b-c767-f9e865f4dd20@arm.com> Date: Sat, 17 Aug 2019 19:20:27 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190817065011.GA18599@lst.de> Content-Language: en-US Cc: Stefano Stabellini , Konrad Rzeszutek Wilk , x86@kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, xen-devel@lists.xenproject.org, linux-arm-kernel@lists.infradead.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org Hi Christoph, On 8/17/19 7:50 AM, Christoph Hellwig wrote: > On Fri, Aug 16, 2019 at 11:40:43PM +0100, Julien Grall wrote: >> I am not sure I agree with this rename. The implementation of the helpers >> are very Arm specific as this is assuming Dom0 is 1:1 mapped. >> >> This was necessary due to the lack of IOMMU on Arm platforms back then. >> But this is now a pain to get rid of it on newer platform... > > So if you look at the final version of the header after the whole > series, what assumes a 1:1 mapping? It all just is > > if (pfn_valid()) > local cache sync; > else > call into the arch code; In the context of Xen Arm, the dev_addr is a host physical address. From my understanding pfn_valid() is dealing with a guest physical frame. Therefore by passing PFN_DOWN(dev_addr) in argument you assume that the host and guest address spaces are the same. > > are you concerned that the local cache sync might have to be split > up more for a non-1:1 map in that case? We could just movea > the xen_dma_* routines into the arch instead of __xen_dma, but it > really helps to have a common interface header. Moving xen_dma_* routines into the arch would be a good option. Although, I would still consider a stub version for arch not requiring specific DMA. Cheers, -- Julien Grall _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu