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=-13.6 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 9EF70C433E6 for ; Tue, 1 Sep 2020 19:14:37 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (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 7ED9C20767 for ; Tue, 1 Sep 2020 19:14:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7ED9C20767 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 localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 4F68386C75; Tue, 1 Sep 2020 19:14:37 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id iE+-O7KZ5BCR; Tue, 1 Sep 2020 19:14:36 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by whitealder.osuosl.org (Postfix) with ESMTP id 3BE0C86C66; Tue, 1 Sep 2020 19:14:36 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 203F8C07FF; Tue, 1 Sep 2020 19:14:36 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 275C3C0051 for ; Tue, 1 Sep 2020 19:14:34 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 1991786C6F for ; Tue, 1 Sep 2020 19:14:34 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 7dOYBaL2Vth7 for ; Tue, 1 Sep 2020 19:14:32 +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 whitealder.osuosl.org (Postfix) with ESMTP id 8CB3386C66 for ; Tue, 1 Sep 2020 19:14:32 +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 F21C51FB; Tue, 1 Sep 2020 12:14:31 -0700 (PDT) Received: from [10.57.40.122] (unknown [10.57.40.122]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DC4A93F71F; Tue, 1 Sep 2020 12:14:29 -0700 (PDT) Subject: Re: [PATCH v9 12/32] drm: msm: fix common struct sg_table related issues To: Marek Szyprowski , dri-devel@lists.freedesktop.org, iommu@lists.linux-foundation.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org References: <20200826063316.23486-1-m.szyprowski@samsung.com> <20200826063316.23486-13-m.szyprowski@samsung.com> From: Robin Murphy Message-ID: Date: Tue, 1 Sep 2020 20:14:24 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20200826063316.23486-13-m.szyprowski@samsung.com> Content-Language: en-GB Cc: freedreno@lists.freedesktop.org, Bartlomiej Zolnierkiewicz , David Airlie , linux-arm-msm@vger.kernel.org, Daniel Vetter , Sean Paul , Christoph Hellwig , linux-arm-kernel@lists.infradead.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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 2020-08-26 07:32, Marek Szyprowski wrote: > The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function > returns the number of the created entries in the DMA address space. > However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and > dma_unmap_sg must be called with the original number of the entries > passed to the dma_map_sg(). > > struct sg_table is a common structure used for describing a non-contiguous > memory buffer, used commonly in the DRM and graphics subsystems. 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 DMA-mapping functions with a wrong number of entries or > ignoring the number of mapped entries returned by the dma_map_sg() > function. > > To avoid such issues, lets use a common dma-mapping wrappers operating > directly on the struct sg_table objects and use scatterlist page > iterators where possible. This, almost always, hides references to the > nents and orig_nents entries, making the code robust, easier to follow > and copy/paste safe. > > Signed-off-by: Marek Szyprowski > Acked-by: Rob Clark > --- > drivers/gpu/drm/msm/msm_gem.c | 13 +++++-------- > drivers/gpu/drm/msm/msm_gpummu.c | 14 ++++++-------- > drivers/gpu/drm/msm/msm_iommu.c | 2 +- > 3 files changed, 12 insertions(+), 17 deletions(-) > > diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c > index b2f49152b4d4..8c7ae812b813 100644 > --- a/drivers/gpu/drm/msm/msm_gem.c > +++ b/drivers/gpu/drm/msm/msm_gem.c > @@ -53,11 +53,10 @@ static void sync_for_device(struct msm_gem_object *msm_obj) > struct device *dev = msm_obj->base.dev->dev; > > if (get_dma_ops(dev) && IS_ENABLED(CONFIG_ARM64)) { > - dma_sync_sg_for_device(dev, msm_obj->sgt->sgl, > - msm_obj->sgt->nents, DMA_BIDIRECTIONAL); > + dma_sync_sgtable_for_device(dev, msm_obj->sgt, > + DMA_BIDIRECTIONAL); > } else { > - dma_map_sg(dev, msm_obj->sgt->sgl, > - msm_obj->sgt->nents, DMA_BIDIRECTIONAL); > + dma_map_sgtable(dev, msm_obj->sgt, DMA_BIDIRECTIONAL, 0); > } > } > > @@ -66,11 +65,9 @@ static void sync_for_cpu(struct msm_gem_object *msm_obj) > struct device *dev = msm_obj->base.dev->dev; > > if (get_dma_ops(dev) && IS_ENABLED(CONFIG_ARM64)) { > - dma_sync_sg_for_cpu(dev, msm_obj->sgt->sgl, > - msm_obj->sgt->nents, DMA_BIDIRECTIONAL); > + dma_sync_sgtable_for_cpu(dev, msm_obj->sgt, DMA_BIDIRECTIONAL); > } else { > - dma_unmap_sg(dev, msm_obj->sgt->sgl, > - msm_obj->sgt->nents, DMA_BIDIRECTIONAL); > + dma_unmap_sgtable(dev, msm_obj->sgt, DMA_BIDIRECTIONAL, 0); > } > } > > diff --git a/drivers/gpu/drm/msm/msm_gpummu.c b/drivers/gpu/drm/msm/msm_gpummu.c > index 310a31b05faa..319f06c28235 100644 > --- a/drivers/gpu/drm/msm/msm_gpummu.c > +++ b/drivers/gpu/drm/msm/msm_gpummu.c > @@ -30,21 +30,19 @@ static int msm_gpummu_map(struct msm_mmu *mmu, uint64_t iova, > { > struct msm_gpummu *gpummu = to_msm_gpummu(mmu); > unsigned idx = (iova - GPUMMU_VA_START) / GPUMMU_PAGE_SIZE; > - struct scatterlist *sg; > + struct sg_dma_page_iter dma_iter; > unsigned prot_bits = 0; > - unsigned i, j; > > if (prot & IOMMU_WRITE) > prot_bits |= 1; > if (prot & IOMMU_READ) > prot_bits |= 2; > > - for_each_sg(sgt->sgl, sg, sgt->nents, i) { > - dma_addr_t addr = sg->dma_address; > - for (j = 0; j < sg->length / GPUMMU_PAGE_SIZE; j++, idx++) { > - gpummu->table[idx] = addr | prot_bits; > - addr += GPUMMU_PAGE_SIZE; > - } > + for_each_sgtable_dma_page(sgt, &dma_iter, 0) { > + dma_addr_t addr = sg_page_iter_dma_address(&dma_iter); > + > + BUILD_BUG_ON(GPUMMU_PAGE_SIZE != PAGE_SIZE); > + gpummu->table[idx++] = addr | prot_bits; Given that the BUILD_BUG_ON might prevent valid arm64 configs from building, how about a simple tweak like: for (i = 0; i < PAGE_SIZE; i += GPUMMU_PAGE_SIZE) gpummu->table[idx++] = i + addr | prot_bits; ? Or alternatively perhaps some more aggressive #ifdefs or makefile tweaks to prevent the GPUMMU code building for arm64 at all if it's only relevant to 32-bit platforms (which I believe might be the case). Robin. > } > > /* we can improve by deferring flush for multiple map() */ > diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c > index 3a381a9674c9..6c31e65834c6 100644 > --- a/drivers/gpu/drm/msm/msm_iommu.c > +++ b/drivers/gpu/drm/msm/msm_iommu.c > @@ -36,7 +36,7 @@ static int msm_iommu_map(struct msm_mmu *mmu, uint64_t iova, > struct msm_iommu *iommu = to_msm_iommu(mmu); > size_t ret; > > - ret = iommu_map_sg(iommu->domain, iova, sgt->sgl, sgt->nents, prot); > + ret = iommu_map_sgtable(iommu->domain, iova, sgt, prot); > WARN_ON(!ret); > > return (ret == len) ? 0 : -EINVAL; > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu