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![Robin Murphy](/assets/img/avatar_default.png)
When mapping a non-page-aligned scatterlist entry, we copy the original offset to the output DMA address before aligning it to hand off to iommu_map_sg(), then later adding the IOVA page address portion to get the final mapped address. However, when the IOVA page size is smaller than the CPU page size, it is the offset within the IOVA page we want, not that within the CPU page, which can easily be larger than an IOVA page and thus result in an incorrect final address. Fix the bug by taking only the IOVA-aligned part of the offset as the basis of the DMA address, not the whole thing. Signed-off-by: Robin Murphy <robin.murphy@arm.com> Signed-off-by: Joerg Roedel <jroedel@suse.de>
529 lines
15 KiB
C
529 lines
15 KiB
C
/*
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* A fairly generic DMA-API to IOMMU-API glue layer.
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*
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* Copyright (C) 2014-2015 ARM Ltd.
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*
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* based in part on arch/arm/mm/dma-mapping.c:
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* Copyright (C) 2000-2004 Russell King
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/device.h>
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#include <linux/dma-iommu.h>
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#include <linux/gfp.h>
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#include <linux/huge_mm.h>
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#include <linux/iommu.h>
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#include <linux/iova.h>
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#include <linux/mm.h>
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#include <linux/scatterlist.h>
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#include <linux/vmalloc.h>
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int iommu_dma_init(void)
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{
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return iova_cache_get();
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}
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/**
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* iommu_get_dma_cookie - Acquire DMA-API resources for a domain
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* @domain: IOMMU domain to prepare for DMA-API usage
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*
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* IOMMU drivers should normally call this from their domain_alloc
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* callback when domain->type == IOMMU_DOMAIN_DMA.
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*/
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int iommu_get_dma_cookie(struct iommu_domain *domain)
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{
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struct iova_domain *iovad;
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if (domain->iova_cookie)
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return -EEXIST;
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iovad = kzalloc(sizeof(*iovad), GFP_KERNEL);
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domain->iova_cookie = iovad;
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return iovad ? 0 : -ENOMEM;
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}
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EXPORT_SYMBOL(iommu_get_dma_cookie);
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/**
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* iommu_put_dma_cookie - Release a domain's DMA mapping resources
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* @domain: IOMMU domain previously prepared by iommu_get_dma_cookie()
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*
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* IOMMU drivers should normally call this from their domain_free callback.
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*/
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void iommu_put_dma_cookie(struct iommu_domain *domain)
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{
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struct iova_domain *iovad = domain->iova_cookie;
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if (!iovad)
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return;
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put_iova_domain(iovad);
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kfree(iovad);
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domain->iova_cookie = NULL;
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}
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EXPORT_SYMBOL(iommu_put_dma_cookie);
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/**
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* iommu_dma_init_domain - Initialise a DMA mapping domain
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* @domain: IOMMU domain previously prepared by iommu_get_dma_cookie()
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* @base: IOVA at which the mappable address space starts
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* @size: Size of IOVA space
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*
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* @base and @size should be exact multiples of IOMMU page granularity to
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* avoid rounding surprises. If necessary, we reserve the page at address 0
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* to ensure it is an invalid IOVA. It is safe to reinitialise a domain, but
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* any change which could make prior IOVAs invalid will fail.
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*/
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int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base, u64 size)
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{
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struct iova_domain *iovad = domain->iova_cookie;
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unsigned long order, base_pfn, end_pfn;
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if (!iovad)
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return -ENODEV;
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/* Use the smallest supported page size for IOVA granularity */
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order = __ffs(domain->ops->pgsize_bitmap);
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base_pfn = max_t(unsigned long, 1, base >> order);
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end_pfn = (base + size - 1) >> order;
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/* Check the domain allows at least some access to the device... */
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if (domain->geometry.force_aperture) {
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if (base > domain->geometry.aperture_end ||
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base + size <= domain->geometry.aperture_start) {
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pr_warn("specified DMA range outside IOMMU capability\n");
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return -EFAULT;
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}
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/* ...then finally give it a kicking to make sure it fits */
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base_pfn = max_t(unsigned long, base_pfn,
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domain->geometry.aperture_start >> order);
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end_pfn = min_t(unsigned long, end_pfn,
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domain->geometry.aperture_end >> order);
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}
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/* All we can safely do with an existing domain is enlarge it */
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if (iovad->start_pfn) {
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if (1UL << order != iovad->granule ||
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base_pfn != iovad->start_pfn ||
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end_pfn < iovad->dma_32bit_pfn) {
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pr_warn("Incompatible range for DMA domain\n");
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return -EFAULT;
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}
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iovad->dma_32bit_pfn = end_pfn;
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} else {
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init_iova_domain(iovad, 1UL << order, base_pfn, end_pfn);
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}
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return 0;
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}
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EXPORT_SYMBOL(iommu_dma_init_domain);
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/**
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* dma_direction_to_prot - Translate DMA API directions to IOMMU API page flags
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* @dir: Direction of DMA transfer
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* @coherent: Is the DMA master cache-coherent?
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*
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* Return: corresponding IOMMU API page protection flags
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*/
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int dma_direction_to_prot(enum dma_data_direction dir, bool coherent)
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{
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int prot = coherent ? IOMMU_CACHE : 0;
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switch (dir) {
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case DMA_BIDIRECTIONAL:
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return prot | IOMMU_READ | IOMMU_WRITE;
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case DMA_TO_DEVICE:
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return prot | IOMMU_READ;
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case DMA_FROM_DEVICE:
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return prot | IOMMU_WRITE;
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default:
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return 0;
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}
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}
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static struct iova *__alloc_iova(struct iova_domain *iovad, size_t size,
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dma_addr_t dma_limit)
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{
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unsigned long shift = iova_shift(iovad);
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unsigned long length = iova_align(iovad, size) >> shift;
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/*
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* Enforce size-alignment to be safe - there could perhaps be an
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* attribute to control this per-device, or at least per-domain...
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*/
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return alloc_iova(iovad, length, dma_limit >> shift, true);
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}
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/* The IOVA allocator knows what we mapped, so just unmap whatever that was */
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static void __iommu_dma_unmap(struct iommu_domain *domain, dma_addr_t dma_addr)
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{
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struct iova_domain *iovad = domain->iova_cookie;
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unsigned long shift = iova_shift(iovad);
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unsigned long pfn = dma_addr >> shift;
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struct iova *iova = find_iova(iovad, pfn);
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size_t size;
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if (WARN_ON(!iova))
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return;
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size = iova_size(iova) << shift;
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size -= iommu_unmap(domain, pfn << shift, size);
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/* ...and if we can't, then something is horribly, horribly wrong */
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WARN_ON(size > 0);
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__free_iova(iovad, iova);
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}
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static void __iommu_dma_free_pages(struct page **pages, int count)
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{
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while (count--)
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__free_page(pages[count]);
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kvfree(pages);
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}
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static struct page **__iommu_dma_alloc_pages(unsigned int count, gfp_t gfp)
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{
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struct page **pages;
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unsigned int i = 0, array_size = count * sizeof(*pages);
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unsigned int order = MAX_ORDER;
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if (array_size <= PAGE_SIZE)
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pages = kzalloc(array_size, GFP_KERNEL);
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else
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pages = vzalloc(array_size);
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if (!pages)
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return NULL;
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/* IOMMU can map any pages, so himem can also be used here */
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gfp |= __GFP_NOWARN | __GFP_HIGHMEM;
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while (count) {
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struct page *page = NULL;
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int j;
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/*
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* Higher-order allocations are a convenience rather
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* than a necessity, hence using __GFP_NORETRY until
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* falling back to single-page allocations.
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*/
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for (order = min_t(unsigned int, order, __fls(count));
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order > 0; order--) {
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page = alloc_pages(gfp | __GFP_NORETRY, order);
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if (!page)
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continue;
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if (PageCompound(page)) {
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if (!split_huge_page(page))
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break;
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__free_pages(page, order);
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} else {
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split_page(page, order);
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break;
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}
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}
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if (!page)
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page = alloc_page(gfp);
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if (!page) {
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__iommu_dma_free_pages(pages, i);
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return NULL;
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}
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j = 1 << order;
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count -= j;
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while (j--)
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pages[i++] = page++;
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}
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return pages;
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}
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/**
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* iommu_dma_free - Free a buffer allocated by iommu_dma_alloc()
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* @dev: Device which owns this buffer
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* @pages: Array of buffer pages as returned by iommu_dma_alloc()
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* @size: Size of buffer in bytes
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* @handle: DMA address of buffer
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*
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* Frees both the pages associated with the buffer, and the array
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* describing them
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*/
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void iommu_dma_free(struct device *dev, struct page **pages, size_t size,
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dma_addr_t *handle)
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{
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__iommu_dma_unmap(iommu_get_domain_for_dev(dev), *handle);
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__iommu_dma_free_pages(pages, PAGE_ALIGN(size) >> PAGE_SHIFT);
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*handle = DMA_ERROR_CODE;
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}
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/**
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* iommu_dma_alloc - Allocate and map a buffer contiguous in IOVA space
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* @dev: Device to allocate memory for. Must be a real device
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* attached to an iommu_dma_domain
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* @size: Size of buffer in bytes
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* @gfp: Allocation flags
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* @prot: IOMMU mapping flags
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* @handle: Out argument for allocated DMA handle
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* @flush_page: Arch callback which must ensure PAGE_SIZE bytes from the
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* given VA/PA are visible to the given non-coherent device.
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*
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* If @size is less than PAGE_SIZE, then a full CPU page will be allocated,
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* but an IOMMU which supports smaller pages might not map the whole thing.
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*
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* Return: Array of struct page pointers describing the buffer,
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* or NULL on failure.
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*/
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struct page **iommu_dma_alloc(struct device *dev, size_t size,
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gfp_t gfp, int prot, dma_addr_t *handle,
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void (*flush_page)(struct device *, const void *, phys_addr_t))
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{
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struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
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struct iova_domain *iovad = domain->iova_cookie;
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struct iova *iova;
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struct page **pages;
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struct sg_table sgt;
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dma_addr_t dma_addr;
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unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
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*handle = DMA_ERROR_CODE;
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pages = __iommu_dma_alloc_pages(count, gfp);
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if (!pages)
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return NULL;
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iova = __alloc_iova(iovad, size, dev->coherent_dma_mask);
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if (!iova)
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goto out_free_pages;
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size = iova_align(iovad, size);
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if (sg_alloc_table_from_pages(&sgt, pages, count, 0, size, GFP_KERNEL))
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goto out_free_iova;
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if (!(prot & IOMMU_CACHE)) {
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struct sg_mapping_iter miter;
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/*
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* The CPU-centric flushing implied by SG_MITER_TO_SG isn't
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* sufficient here, so skip it by using the "wrong" direction.
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*/
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sg_miter_start(&miter, sgt.sgl, sgt.orig_nents, SG_MITER_FROM_SG);
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while (sg_miter_next(&miter))
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flush_page(dev, miter.addr, page_to_phys(miter.page));
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sg_miter_stop(&miter);
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}
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dma_addr = iova_dma_addr(iovad, iova);
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if (iommu_map_sg(domain, dma_addr, sgt.sgl, sgt.orig_nents, prot)
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< size)
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goto out_free_sg;
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*handle = dma_addr;
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sg_free_table(&sgt);
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return pages;
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out_free_sg:
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sg_free_table(&sgt);
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out_free_iova:
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__free_iova(iovad, iova);
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out_free_pages:
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__iommu_dma_free_pages(pages, count);
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return NULL;
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}
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/**
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* iommu_dma_mmap - Map a buffer into provided user VMA
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* @pages: Array representing buffer from iommu_dma_alloc()
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* @size: Size of buffer in bytes
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* @vma: VMA describing requested userspace mapping
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*
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* Maps the pages of the buffer in @pages into @vma. The caller is responsible
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* for verifying the correct size and protection of @vma beforehand.
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*/
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int iommu_dma_mmap(struct page **pages, size_t size, struct vm_area_struct *vma)
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{
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unsigned long uaddr = vma->vm_start;
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unsigned int i, count = PAGE_ALIGN(size) >> PAGE_SHIFT;
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int ret = -ENXIO;
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for (i = vma->vm_pgoff; i < count && uaddr < vma->vm_end; i++) {
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ret = vm_insert_page(vma, uaddr, pages[i]);
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if (ret)
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break;
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uaddr += PAGE_SIZE;
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}
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return ret;
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}
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dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
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unsigned long offset, size_t size, int prot)
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{
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dma_addr_t dma_addr;
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struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
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struct iova_domain *iovad = domain->iova_cookie;
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phys_addr_t phys = page_to_phys(page) + offset;
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size_t iova_off = iova_offset(iovad, phys);
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size_t len = iova_align(iovad, size + iova_off);
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struct iova *iova = __alloc_iova(iovad, len, dma_get_mask(dev));
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if (!iova)
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return DMA_ERROR_CODE;
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dma_addr = iova_dma_addr(iovad, iova);
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if (iommu_map(domain, dma_addr, phys - iova_off, len, prot)) {
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__free_iova(iovad, iova);
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return DMA_ERROR_CODE;
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}
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return dma_addr + iova_off;
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}
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void iommu_dma_unmap_page(struct device *dev, dma_addr_t handle, size_t size,
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enum dma_data_direction dir, struct dma_attrs *attrs)
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{
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__iommu_dma_unmap(iommu_get_domain_for_dev(dev), handle);
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}
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/*
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* Prepare a successfully-mapped scatterlist to give back to the caller.
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* Handling IOVA concatenation can come later, if needed
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*/
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static int __finalise_sg(struct device *dev, struct scatterlist *sg, int nents,
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dma_addr_t dma_addr)
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{
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struct scatterlist *s;
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int i;
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for_each_sg(sg, s, nents, i) {
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/* Un-swizzling the fields here, hence the naming mismatch */
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unsigned int s_offset = sg_dma_address(s);
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unsigned int s_length = sg_dma_len(s);
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unsigned int s_dma_len = s->length;
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s->offset = s_offset;
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s->length = s_length;
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sg_dma_address(s) = dma_addr + s_offset;
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dma_addr += s_dma_len;
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}
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return i;
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}
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/*
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* If mapping failed, then just restore the original list,
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* but making sure the DMA fields are invalidated.
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*/
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static void __invalidate_sg(struct scatterlist *sg, int nents)
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{
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struct scatterlist *s;
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int i;
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for_each_sg(sg, s, nents, i) {
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if (sg_dma_address(s) != DMA_ERROR_CODE)
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s->offset = sg_dma_address(s);
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if (sg_dma_len(s))
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s->length = sg_dma_len(s);
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sg_dma_address(s) = DMA_ERROR_CODE;
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sg_dma_len(s) = 0;
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}
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}
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/*
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* The DMA API client is passing in a scatterlist which could describe
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* any old buffer layout, but the IOMMU API requires everything to be
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* aligned to IOMMU pages. Hence the need for this complicated bit of
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* impedance-matching, to be able to hand off a suitably-aligned list,
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* but still preserve the original offsets and sizes for the caller.
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*/
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int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
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int nents, int prot)
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{
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struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
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struct iova_domain *iovad = domain->iova_cookie;
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struct iova *iova;
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struct scatterlist *s, *prev = NULL;
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dma_addr_t dma_addr;
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size_t iova_len = 0;
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int i;
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/*
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* Work out how much IOVA space we need, and align the segments to
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* IOVA granules for the IOMMU driver to handle. With some clever
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* trickery we can modify the list in-place, but reversibly, by
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* hiding the original data in the as-yet-unused DMA fields.
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*/
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for_each_sg(sg, s, nents, i) {
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size_t s_offset = iova_offset(iovad, s->offset);
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size_t s_length = s->length;
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sg_dma_address(s) = s_offset;
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sg_dma_len(s) = s_length;
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s->offset -= s_offset;
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s_length = iova_align(iovad, s_length + s_offset);
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s->length = s_length;
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/*
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* The simple way to avoid the rare case of a segment
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* crossing the boundary mask is to pad the previous one
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* to end at a naturally-aligned IOVA for this one's size,
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* at the cost of potentially over-allocating a little.
|
|
*/
|
|
if (prev) {
|
|
size_t pad_len = roundup_pow_of_two(s_length);
|
|
|
|
pad_len = (pad_len - iova_len) & (pad_len - 1);
|
|
prev->length += pad_len;
|
|
iova_len += pad_len;
|
|
}
|
|
|
|
iova_len += s_length;
|
|
prev = s;
|
|
}
|
|
|
|
iova = __alloc_iova(iovad, iova_len, dma_get_mask(dev));
|
|
if (!iova)
|
|
goto out_restore_sg;
|
|
|
|
/*
|
|
* We'll leave any physical concatenation to the IOMMU driver's
|
|
* implementation - it knows better than we do.
|
|
*/
|
|
dma_addr = iova_dma_addr(iovad, iova);
|
|
if (iommu_map_sg(domain, dma_addr, sg, nents, prot) < iova_len)
|
|
goto out_free_iova;
|
|
|
|
return __finalise_sg(dev, sg, nents, dma_addr);
|
|
|
|
out_free_iova:
|
|
__free_iova(iovad, iova);
|
|
out_restore_sg:
|
|
__invalidate_sg(sg, nents);
|
|
return 0;
|
|
}
|
|
|
|
void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
|
|
enum dma_data_direction dir, struct dma_attrs *attrs)
|
|
{
|
|
/*
|
|
* The scatterlist segments are mapped into a single
|
|
* contiguous IOVA allocation, so this is incredibly easy.
|
|
*/
|
|
__iommu_dma_unmap(iommu_get_domain_for_dev(dev), sg_dma_address(sg));
|
|
}
|
|
|
|
int iommu_dma_supported(struct device *dev, u64 mask)
|
|
{
|
|
/*
|
|
* 'Special' IOMMUs which don't have the same addressing capability
|
|
* as the CPU will have to wait until we have some way to query that
|
|
* before they'll be able to use this framework.
|
|
*/
|
|
return 1;
|
|
}
|
|
|
|
int iommu_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
|
|
{
|
|
return dma_addr == DMA_ERROR_CODE;
|
|
}
|