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=-5.2 required=3.0 tests=BAYES_00, 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 2A781C433E0 for ; Thu, 4 Feb 2021 08:40:34 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (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 816D364F3F for ; Thu, 4 Feb 2021 08:40:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 816D364F3F 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 silver.osuosl.org (Postfix) with ESMTP id 4A2382044E; Thu, 4 Feb 2021 08:40:33 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 7yiSEUXwBazu; Thu, 4 Feb 2021 08:40:32 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by silver.osuosl.org (Postfix) with ESMTP id 715912010E; Thu, 4 Feb 2021 08:40:32 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 45CB2C0174; Thu, 4 Feb 2021 08:40:32 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id BEF35C013A for ; Thu, 4 Feb 2021 08:40:30 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id B1B5085FA2 for ; Thu, 4 Feb 2021 08:40:30 +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 87KnCJylP5hi for ; Thu, 4 Feb 2021 08:40:29 +0000 (UTC) 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 9776385F7D for ; Thu, 4 Feb 2021 08:40:29 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 77E4067373; Thu, 4 Feb 2021 09:40:23 +0100 (CET) Date: Thu, 4 Feb 2021 09:40:23 +0100 From: Christoph Hellwig To: Dongli Zhang Subject: Re: [PATCH RFC v1 5/6] xen-swiotlb: convert variables to arrays Message-ID: <20210204084023.GA32328@lst.de> References: <20210203233709.19819-1-dongli.zhang@oracle.com> <20210203233709.19819-6-dongli.zhang@oracle.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210203233709.19819-6-dongli.zhang@oracle.com> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: ulf.hansson@linaro.org, airlied@linux.ie, benh@kernel.crashing.org, joonas.lahtinen@linux.intel.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, bhelgaas@google.com, paulus@samba.org, hpa@zytor.com, hch@lst.de, sstabellini@kernel.org, adrian.hunter@intel.com, mpe@ellerman.id.au, x86@kernel.org, joe.jin@oracle.com, mingo@kernel.org, peterz@infradead.org, mingo@redhat.com, bskeggs@redhat.com, linux-pci@vger.kernel.org, xen-devel@lists.xenproject.org, matthew.auld@intel.com, thomas.lendacky@amd.com, konrad.wilk@oracle.com, intel-gfx@lists.freedesktop.org, jani.nikula@linux.intel.com, bp@alien8.de, rodrigo.vivi@intel.com, nouveau@lists.freedesktop.org, boris.ostrovsky@oracle.com, chris@chris-wilson.co.uk, jgross@suse.com, tsbogend@alpha.franken.de, robin.murphy@arm.com, linux-mmc@vger.kernel.org, linux-mips@vger.kernel.org, iommu@lists.linux-foundation.org, tglx@linutronix.de, daniel@ffwll.ch, akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org, rppt@kernel.org 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" So one thing that has been on my mind for a while: I'd really like to kill the separate dma ops in Xen swiotlb. If we compare xen-swiotlb to swiotlb the main difference seems to be: - additional reasons to bounce I/O vs the plain DMA capable - the possibility to do a hypercall on arm/arm64 - an extra translation layer before doing the phys_to_dma and vice versa - an special memory allocator I wonder if inbetween a few jump labels or other no overhead enablement options and possibly better use of the dma_range_map we could kill off most of swiotlb-xen instead of maintaining all this code duplication? _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu