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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 CF1D2CA90AF for ; Wed, 13 May 2020 13:27:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7676220643 for ; Wed, 13 May 2020 13:27:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387603AbgEMN15 (ORCPT ); Wed, 13 May 2020 09:27:57 -0400 Received: from foss.arm.com ([217.140.110.172]:46022 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728341AbgEMN15 (ORCPT ); Wed, 13 May 2020 09:27:57 -0400 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 D01F230E; Wed, 13 May 2020 06:27:56 -0700 (PDT) Received: from [10.57.36.85] (unknown [10.57.36.85]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 101FC3F71E; Wed, 13 May 2020 06:27:54 -0700 (PDT) Subject: Re: [PATCH v4 03/38] iommu: add generic helper for mapping sgtable objects To: Marek Szyprowski , dri-devel@lists.freedesktop.org, iommu@lists.linux-foundation.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org Cc: Christoph Hellwig , Bartlomiej Zolnierkiewicz , linux-arm-kernel@lists.infradead.org, David Airlie , Daniel Vetter , Joerg Roedel References: <20200512085710.14688-1-m.szyprowski@samsung.com> <20200512090058.14910-1-m.szyprowski@samsung.com> <20200512090058.14910-3-m.szyprowski@samsung.com> From: Robin Murphy Message-ID: Date: Wed, 13 May 2020 14:27:52 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200512090058.14910-3-m.szyprowski@samsung.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-05-12 10:00 am, Marek Szyprowski wrote: > struct sg_table is a common structure used for describing a memory > buffer. It consists of a scatterlist with memory pages and DMA addresses > (sgl entry), as well as the number of scatterlist entries: CPU pages > (orig_nents entry) and DMA mapped pages (nents entry). > > It turned out that it was a common mistake to misuse nents and orig_nents > entries, calling mapping functions with a wrong number of entries. > > To avoid such issues, lets introduce a common wrapper operating directly > on the struct sg_table objects, which take care of the proper use of > the nents and orig_nents entries. Modulo Joerg's comments, Reviewed-by: Robin Murphy > Signed-off-by: Marek Szyprowski > --- > For more information, see '[PATCH v4 00/38] DRM: fix struct sg_table nents > vs. orig_nents misuse' thread: > https://lore.kernel.org/dri-devel/20200512085710.14688-1-m.szyprowski@samsung.com/T/ > --- > include/linux/iommu.h | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index 7cfd2dd..ba662ba 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -478,6 +478,22 @@ extern size_t iommu_map_sg_atomic(struct iommu_domain *domain, > extern void iommu_set_fault_handler(struct iommu_domain *domain, > iommu_fault_handler_t handler, void *token); > > +/** > + * iommu_map_sgtable - Map the given buffer to the IOMMU domain > + * @domain: The IOMMU domain to perfor > + * @iova: The start addrees to map the buffer > + * @sgt: The sg_table object describing the buffer > + * @prot: IOMMU protection bits > + * > + * Create a mapping at @iova for the buffer described by a scatterlist > + * stored in the given sg_table object in the provided IOMMU domain. > + */ > +static inline size_t iommu_map_sgtable(struct iommu_domain *domain, > + unsigned long iova, struct sg_table *sgt, int prot) > +{ > + return iommu_map_sg(domain, iova, sgt->sgl, sgt->orig_nents, prot); > +} > + > extern void iommu_get_resv_regions(struct device *dev, struct list_head *list); > extern void iommu_put_resv_regions(struct device *dev, struct list_head *list); > extern void generic_iommu_put_resv_regions(struct device *dev, >