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 83DE4C433E0 for ; Wed, 13 Jan 2021 12:49:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 39D6F233CE for ; Wed, 13 Jan 2021 12:49:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726754AbhAMMte (ORCPT ); Wed, 13 Jan 2021 07:49:34 -0500 Received: from verein.lst.de ([213.95.11.211]:60093 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725857AbhAMMtd (ORCPT ); Wed, 13 Jan 2021 07:49:33 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id D787F68AFE; Wed, 13 Jan 2021 13:48:47 +0100 (CET) Date: Wed, 13 Jan 2021 13:48:47 +0100 From: Christoph Hellwig To: Claire Chang Cc: robh+dt@kernel.org, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, joro@8bytes.org, will@kernel.org, frowand.list@gmail.com, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, jgross@suse.com, sstabellini@kernel.org, hch@lst.de, m.szyprowski@samsung.com, robin.murphy@arm.com, grant.likely@arm.com, xypron.glpk@gmx.de, treding@nvidia.com, mingo@kernel.org, bauerman@linux.ibm.com, peterz@infradead.org, gregkh@linuxfoundation.org, saravanak@google.com, rafael.j.wysocki@intel.com, heikki.krogerus@linux.intel.com, andriy.shevchenko@linux.intel.com, rdunlap@infradead.org, dan.j.williams@intel.com, bgolaszewski@baylibre.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, iommu@lists.linux-foundation.org, xen-devel@lists.xenproject.org, tfiga@chromium.org, drinkcat@chromium.org Subject: Re: [RFC PATCH v3 4/6] swiotlb: Add restricted DMA alloc/free support. Message-ID: <20210113124847.GC1383@lst.de> References: <20210106034124.30560-1-tientzu@chromium.org> <20210106034124.30560-5-tientzu@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210106034124.30560-5-tientzu@chromium.org> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > +#ifdef CONFIG_SWIOTLB > + if (unlikely(dev->dma_io_tlb_mem)) > + return swiotlb_alloc(dev, size, dma_handle, attrs); > +#endif Another place where the dma_io_tlb_mem is useful to avoid the ifdef. > -phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr, > - size_t mapping_size, size_t alloc_size, > - enum dma_data_direction dir, unsigned long attrs) > +static int swiotlb_tbl_find_free_region(struct device *hwdev, > + dma_addr_t tbl_dma_addr, > + size_t alloc_size, > + unsigned long attrs) > +static void swiotlb_tbl_release_region(struct device *hwdev, int index, > + size_t size) This refactoring should be another prep patch. > +void *swiotlb_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle, > + unsigned long attrs) I'd rather have the names convey there are for the per-device bounce buffer in some form. > + struct io_tlb_mem *mem = dev->dma_io_tlb_mem; While we're at it I wonder if the io_tlb is something we could change while we're at it. Maybe replace io_tlb_mem with struct swiotlb and rename the field in struct device to dev_swiotlb? > + int index; > + void *vaddr; > + phys_addr_t tlb_addr; > + > + size = PAGE_ALIGN(size); > + index = swiotlb_tbl_find_free_region(dev, mem->start, size, attrs); > + if (index < 0) > + return NULL; > + > + tlb_addr = mem->start + (index << IO_TLB_SHIFT); > + *dma_handle = phys_to_dma_unencrypted(dev, tlb_addr); > + > + if (!dev_is_dma_coherent(dev)) { > + unsigned long pfn = PFN_DOWN(tlb_addr); > + > + /* remove any dirty cache lines on the kernel alias */ > + arch_dma_prep_coherent(pfn_to_page(pfn), size); Can we hook in somewhat lower level in the dma-direct code so that all the remapping in dma-direct can be reused instead of duplicated? That also becomes important if we want to use non-remapping uncached support, e.g. on mips or x86, or the direct changing of the attributes that Will planned to look into for arm64.