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 Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1D1F7C433FE for ; Mon, 6 Dec 2021 16:33:23 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id BD8DC4036A; Mon, 6 Dec 2021 16:33:22 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id qaJ7p92Mz-ag; Mon, 6 Dec 2021 16:33:21 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp4.osuosl.org (Postfix) with ESMTPS id 8F70C4026B; Mon, 6 Dec 2021 16:33:21 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 796AFC001E; Mon, 6 Dec 2021 16:33:21 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 94712C0012 for ; Mon, 6 Dec 2021 16:33:20 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id 7531D607A6 for ; Mon, 6 Dec 2021 16:33:20 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id gdswVmPfT1tZ for ; Mon, 6 Dec 2021 16:33:19 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp3.osuosl.org (Postfix) with ESMTP id A8C4E607DD for ; Mon, 6 Dec 2021 16:33:19 +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 265E31042; Mon, 6 Dec 2021 08:33:19 -0800 (PST) Received: from [10.57.34.58] (unknown [10.57.34.58]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8128E3F73B; Mon, 6 Dec 2021 08:33:18 -0800 (PST) Message-ID: Date: Mon, 6 Dec 2021 16:33:17 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:91.0) Gecko/20100101 Thunderbird/91.3.2 Subject: Re: [PATCH 06/11] dma-direct: refactor the !coherent checks in dma_direct_alloc Content-Language: en-GB To: Christoph Hellwig , iommu@lists.linux-foundation.org References: <20211111065028.32761-1-hch@lst.de> <20211111065028.32761-7-hch@lst.de> From: Robin Murphy In-Reply-To: <20211111065028.32761-7-hch@lst.de> Cc: David Rientjes 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 2021-11-11 06:50, Christoph Hellwig wrote: > Add a big central !dev_is_dma_coherent(dev) block to deal with as much > as of the uncached allocation schemes and document the schemes a bit > better. With a clear mind and a side-by-side diff viewer, indeed the end result is much more readable than the patch itself :) Reviewed-by: Robin Murphy > Signed-off-by: Christoph Hellwig > --- > kernel/dma/direct.c | 66 ++++++++++++++++++++++++++++----------------- > 1 file changed, 41 insertions(+), 25 deletions(-) > > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > index 01104660ec439..f9658fe18498c 100644 > --- a/kernel/dma/direct.c > +++ b/kernel/dma/direct.c > @@ -201,29 +201,49 @@ void *dma_direct_alloc(struct device *dev, size_t size, > !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev)) > return dma_direct_alloc_no_mapping(dev, size, dma_handle, gfp); > > - if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) && > - !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) && > - !IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) && > - !dev_is_dma_coherent(dev) && > - !is_swiotlb_for_alloc(dev)) > - return arch_dma_alloc(dev, size, dma_handle, gfp, attrs); > + if (!dev_is_dma_coherent(dev)) { > + /* > + * Fallback to the arch handler if it exists. This should > + * eventually go away. > + */ > + if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) && > + !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) && > + !IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) && > + !is_swiotlb_for_alloc(dev)) > + return arch_dma_alloc(dev, size, dma_handle, gfp, > + attrs); > > - if (IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) && > - !dev_is_dma_coherent(dev)) > - return dma_alloc_from_global_coherent(dev, size, dma_handle); > + /* > + * If there is a global pool, always allocate from it for > + * non-coherent devices. > + */ > + if (IS_ENABLED(CONFIG_DMA_GLOBAL_POOL)) > + return dma_alloc_from_global_coherent(dev, size, > + dma_handle); > + > + /* > + * Otherwise remap if the architecture is asking for it. But > + * given that remapping memory is a blocking operation we'll > + * instead have to dip into the atomic pools. > + */ > + remap = IS_ENABLED(CONFIG_DMA_DIRECT_REMAP); > + if (remap) { > + if (!gfpflags_allow_blocking(gfp) && > + !is_swiotlb_for_alloc(dev)) > + return dma_direct_alloc_from_pool(dev, size, > + dma_handle, gfp); > + } else { > + if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED)) > + set_uncached = true; > + } > + } > > /* > - * Remapping or decrypting memory may block. If either is required and > - * we can't block, allocate the memory from the atomic pools. > - * If restricted DMA (i.e., is_swiotlb_for_alloc) is required, one must > - * set up another device coherent pool by shared-dma-pool and use > - * dma_alloc_from_dev_coherent instead. > + * Decrypting memory may block, so allocate the memory from the atomic > + * pools if we can't block. > */ > if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) && > - !gfpflags_allow_blocking(gfp) && > - (force_dma_unencrypted(dev) || > - (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) && > - !dev_is_dma_coherent(dev))) && > + force_dma_unencrypted(dev) && !gfpflags_allow_blocking(gfp) && > !is_swiotlb_for_alloc(dev)) > return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp); > > @@ -231,10 +251,7 @@ void *dma_direct_alloc(struct device *dev, size_t size, > page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO); > if (!page) > return NULL; > - > - if (!dev_is_dma_coherent(dev) && IS_ENABLED(CONFIG_DMA_DIRECT_REMAP)) { > - remap = true; > - } else if (PageHighMem(page)) { > + if (PageHighMem(page)) { > /* > * Depending on the cma= arguments and per-arch setup, > * dma_alloc_contiguous could return highmem pages. > @@ -246,9 +263,8 @@ void *dma_direct_alloc(struct device *dev, size_t size, > goto out_free_pages; > } > remap = true; > - } else if (!dev_is_dma_coherent(dev) && > - IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED)) > - set_uncached = true; > + set_uncached = false; > + } > > if (remap) { > /* remove any dirty cache lines on the kernel alias */ > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu