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=-5.3 required=3.0 tests=BAYES_00, 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 B9383C433E0 for ; Tue, 16 Mar 2021 08:12:05 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6297464FB3 for ; Tue, 16 Mar 2021 08:12:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6297464FB3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D5F556B006E; Tue, 16 Mar 2021 04:12:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CE4716B0071; Tue, 16 Mar 2021 04:12:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B86DC6B0072; Tue, 16 Mar 2021 04:12:04 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0093.hostedemail.com [216.40.44.93]) by kanga.kvack.org (Postfix) with ESMTP id 996926B006E for ; Tue, 16 Mar 2021 04:12:04 -0400 (EDT) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 5EB5E173084D for ; Tue, 16 Mar 2021 08:12:04 +0000 (UTC) X-FDA: 77925019368.20.ED2AE5A Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf28.hostedemail.com (Postfix) with ESMTP id B8A1120001EA for ; Tue, 16 Mar 2021 08:12:02 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 68EB168C4E; Tue, 16 Mar 2021 09:11:57 +0100 (CET) Date: Tue, 16 Mar 2021 09:11:56 +0100 From: Christoph Hellwig To: Logan Gunthorpe Cc: linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Stephen Bates , Christoph Hellwig , Dan Williams , Jason Gunthorpe , Christian =?iso-8859-1?Q?K=F6nig?= , Ira Weiny , John Hubbard , Don Dutile , Matthew Wilcox , Daniel Vetter , Jakowski Andrzej , Minturn Dave B , Jason Ekstrand , Dave Hansen , Xiong Jianxin Subject: Re: [RFC PATCH v2 06/11] dma-direct: Support PCI P2PDMA pages in dma-direct map_sg Message-ID: <20210316081156.GA16595@lst.de> References: <20210311233142.7900-1-logang@deltatee.com> <20210311233142.7900-7-logang@deltatee.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210311233142.7900-7-logang@deltatee.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-Stat-Signature: de1ahi3ak3er7mpnq6e6ztbebgtcbtqh X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: B8A1120001EA Received-SPF: none (lst.de>: No applicable sender policy available) receiver=imf28; identity=mailfrom; envelope-from=""; helo=verein.lst.de; client-ip=213.95.11.211 X-HE-DKIM-Result: none/none X-HE-Tag: 1615882322-650142 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Mar 11, 2021 at 04:31:36PM -0700, Logan Gunthorpe wrote: > for_each_sg(sgl, sg, nents, i) { > + if (is_pci_p2pdma_page(sg_page(sg))) { > + if (sg_page(sg)->pgmap != pgmap) { > + pgmap = sg_page(sg)->pgmap; > + map = pci_p2pdma_dma_map_type(dev, pgmap); > + bus_off = pci_p2pdma_bus_offset(sg_page(sg)); > + } > + > + if (map < 0) { > + sg->dma_address = DMA_MAPPING_ERROR; > + ret = -EREMOTEIO; > + goto out_unmap; > + } > + > + if (map) { > + sg->dma_address = sg_phys(sg) + sg->offset - > + bus_off; > + sg_dma_len(sg) = sg->length; > + sg_mark_pci_p2pdma(sg); > + continue; > + } > + } This code needs to go into a separate noinline helper to reduce the impact on the fast path. Also as Robin noted the offset is already accounted for in sg_phys. We also don't ever set the dma_address in the scatterlist to DMA_MAPPING_ERROR, that is just a return value for the single entry mapping routines.