From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robin Murphy Subject: Re: [PATCH 06/21] dma-iommu: use for_each_sg in iommu_dma_alloc Date: Fri, 5 Apr 2019 19:08:34 +0100 Message-ID: References: <20190327080448.5500-1-hch@lst.de> <20190327080448.5500-7-hch@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190327080448.5500-7-hch@lst.de> Content-Language: en-GB Sender: linux-kernel-owner@vger.kernel.org To: Christoph Hellwig Cc: Joerg Roedel , Catalin Marinas , Will Deacon , Tom Lendacky , iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org List-Id: iommu@lists.linux-foundation.org On 27/03/2019 08:04, Christoph Hellwig wrote: > arch_dma_prep_coherent can handle physically contiguous ranges larger > than PAGE_SIZE just fine, which means we don't need a page-based > iterator. Heh, I got several minutes into writing a "but highmem..." reply before finding csky's arch_dma_prep_coherent() implementation. And of course that's why it specifically takes a page instead of any addresses. In hindsight I now have no idea why I didn't just write the flush_page() logic to work that way in the first place... Reviewed-by: Robin Murphy > Signed-off-by: Christoph Hellwig > --- > drivers/iommu/dma-iommu.c | 14 +++++--------- > 1 file changed, 5 insertions(+), 9 deletions(-) > > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c > index 77d704c8f565..f915cb7c46e6 100644 > --- a/drivers/iommu/dma-iommu.c > +++ b/drivers/iommu/dma-iommu.c > @@ -577,15 +577,11 @@ struct page **iommu_dma_alloc(struct device *dev, size_t size, gfp_t gfp, > goto out_free_iova; > > if (!(prot & IOMMU_CACHE)) { > - struct sg_mapping_iter miter; > - /* > - * The CPU-centric flushing implied by SG_MITER_TO_SG isn't > - * sufficient here, so skip it by using the "wrong" direction. > - */ > - sg_miter_start(&miter, sgt.sgl, sgt.orig_nents, SG_MITER_FROM_SG); > - while (sg_miter_next(&miter)) > - arch_dma_prep_coherent(miter.page, PAGE_SIZE); > - sg_miter_stop(&miter); > + struct scatterlist *sg; > + int i; > + > + for_each_sg(sgt.sgl, sg, sgt.orig_nents, i) > + arch_dma_prep_coherent(sg_page(sg), sg->length); > } > > if (iommu_map_sg(domain, iova, sgt.sgl, sgt.orig_nents, prot) > 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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 94121C282CE for ; Fri, 5 Apr 2019 18:09:17 +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 6F60F2146F for ; Fri, 5 Apr 2019 18:09:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6F60F2146F 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 A6D322636; Fri, 5 Apr 2019 18:09:13 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id A87A3261D for ; Fri, 5 Apr 2019 18:08:37 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from foss.arm.com (foss.arm.com [217.140.101.70]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id 4B84EFD for ; Fri, 5 Apr 2019 18:08:37 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1C688168F; Fri, 5 Apr 2019 11:08:37 -0700 (PDT) Received: from [10.1.196.75] (e110467-lin.cambridge.arm.com [10.1.196.75]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B863D3F557; Fri, 5 Apr 2019 11:08:35 -0700 (PDT) Subject: Re: [PATCH 06/21] dma-iommu: use for_each_sg in iommu_dma_alloc To: Christoph Hellwig References: <20190327080448.5500-1-hch@lst.de> <20190327080448.5500-7-hch@lst.de> From: Robin Murphy Message-ID: Date: Fri, 5 Apr 2019 19:08:34 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190327080448.5500-7-hch@lst.de> Content-Language: en-GB Cc: Tom Lendacky , Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.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="UTF-8"; format="flowed" Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org Message-ID: <20190405180834.ZDa5SVv8Mtu5pZ6tGBmTfIuCE15LBovG42bAAj_ZylM@z> On 27/03/2019 08:04, Christoph Hellwig wrote: > arch_dma_prep_coherent can handle physically contiguous ranges larger > than PAGE_SIZE just fine, which means we don't need a page-based > iterator. Heh, I got several minutes into writing a "but highmem..." reply before finding csky's arch_dma_prep_coherent() implementation. And of course that's why it specifically takes a page instead of any addresses. In hindsight I now have no idea why I didn't just write the flush_page() logic to work that way in the first place... Reviewed-by: Robin Murphy > Signed-off-by: Christoph Hellwig > --- > drivers/iommu/dma-iommu.c | 14 +++++--------- > 1 file changed, 5 insertions(+), 9 deletions(-) > > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c > index 77d704c8f565..f915cb7c46e6 100644 > --- a/drivers/iommu/dma-iommu.c > +++ b/drivers/iommu/dma-iommu.c > @@ -577,15 +577,11 @@ struct page **iommu_dma_alloc(struct device *dev, size_t size, gfp_t gfp, > goto out_free_iova; > > if (!(prot & IOMMU_CACHE)) { > - struct sg_mapping_iter miter; > - /* > - * The CPU-centric flushing implied by SG_MITER_TO_SG isn't > - * sufficient here, so skip it by using the "wrong" direction. > - */ > - sg_miter_start(&miter, sgt.sgl, sgt.orig_nents, SG_MITER_FROM_SG); > - while (sg_miter_next(&miter)) > - arch_dma_prep_coherent(miter.page, PAGE_SIZE); > - sg_miter_stop(&miter); > + struct scatterlist *sg; > + int i; > + > + for_each_sg(sgt.sgl, sg, sgt.orig_nents, i) > + arch_dma_prep_coherent(sg_page(sg), sg->length); > } > > if (iommu_map_sg(domain, iova, sgt.sgl, sgt.orig_nents, prot) > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu