Commit 8230ce9a authored by Christoph Hellwig's avatar Christoph Hellwig
Browse files

dma-iommu: refactor iommu_dma_alloc_remap 



Split out a new helper that only allocates a sg_table worth of
memory without mapping it into contiguous kernel address space.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarTomasz Figa <tfiga@chromium.org>
Tested-by: default avatarRicardo Ribalda <ribalda@chromium.org>
parent 7d5b5738

drivers/iommu/dma-iommu.c

+35 −32
Original line number Diff line number Diff line
@@ -650,23 +650,12 @@ static struct page **__iommu_dma_alloc_pages(struct device *dev, 
	return pages;

}



/**

 * iommu_dma_alloc_remap - Allocate and map a buffer contiguous in IOVA space

 * @dev: Device to allocate memory for. Must be a real device

 *	 attached to an iommu_dma_domain

 * @size: Size of buffer in bytes

 * @dma_handle: Out argument for allocated DMA handle

 * @gfp: Allocation flags

 * @prot: pgprot_t to use for the remapped mapping

 * @attrs: DMA attributes for this allocation

 *

 * If @size is less than PAGE_SIZE, then a full CPU page will be allocated,

/*

 * If size is less than PAGE_SIZE, then a full CPU page will be allocated,

 * but an IOMMU which supports smaller pages might not map the whole thing.

 *

 * Return: Mapped virtual address, or NULL on failure.

 */

static void *iommu_dma_alloc_remap(struct device *dev, size_t size,

		dma_addr_t *dma_handle, gfp_t gfp, pgprot_t prot,

static struct page **__iommu_dma_alloc_noncontiguous(struct device *dev,

		size_t size, struct sg_table *sgt, gfp_t gfp, pgprot_t prot,

		unsigned long attrs)

{

	struct iommu_domain *domain = iommu_get_dma_domain(dev);
@@ -676,11 +665,7 @@ static void *iommu_dma_alloc_remap(struct device *dev, size_t size, 
	int ioprot = dma_info_to_prot(DMA_BIDIRECTIONAL, coherent, attrs);

	unsigned int count, min_size, alloc_sizes = domain->pgsize_bitmap;

	struct page **pages;

	struct sg_table sgt;

	dma_addr_t iova;

	void *vaddr;



	*dma_handle = DMA_MAPPING_ERROR;



	if (static_branch_unlikely(&iommu_deferred_attach_enabled) &&

	    iommu_deferred_attach(dev, domain))
@@ -707,38 +692,56 @@ static void *iommu_dma_alloc_remap(struct device *dev, size_t size, 
	if (!iova)

		goto out_free_pages;



	if (sg_alloc_table_from_pages(&sgt, pages, count, 0, size, GFP_KERNEL))

	if (sg_alloc_table_from_pages(sgt, pages, count, 0, size, GFP_KERNEL))

		goto out_free_iova;



	if (!(ioprot & IOMMU_CACHE)) {

		struct scatterlist *sg;

		int i;



		for_each_sg(sgt.sgl, sg, sgt.orig_nents, i)

		for_each_sg(sgt->sgl, sg, sgt->orig_nents, i)

			arch_dma_prep_coherent(sg_page(sg), sg->length);

	}



	if (iommu_map_sg_atomic(domain, iova, sgt.sgl, sgt.orig_nents, ioprot)

	if (iommu_map_sg_atomic(domain, iova, sgt->sgl, sgt->orig_nents, ioprot)

			< size)

		goto out_free_sg;



	sgt->sgl->dma_address = iova;

	return pages;



out_free_sg:

	sg_free_table(sgt);

out_free_iova:

	iommu_dma_free_iova(cookie, iova, size, NULL);

out_free_pages:

	__iommu_dma_free_pages(pages, count);

	return NULL;

}



static void *iommu_dma_alloc_remap(struct device *dev, size_t size,

		dma_addr_t *dma_handle, gfp_t gfp, pgprot_t prot,

		unsigned long attrs)

{

	struct page **pages;

	struct sg_table sgt;

	void *vaddr;



	pages = __iommu_dma_alloc_noncontiguous(dev, size, &sgt, gfp, prot,

						attrs);

	if (!pages)

		return NULL;

	*dma_handle = sgt.sgl->dma_address;

	sg_free_table(&sgt);

	vaddr = dma_common_pages_remap(pages, size, prot,

			__builtin_return_address(0));

	if (!vaddr)

		goto out_unmap;



	*dma_handle = iova;

	sg_free_table(&sgt);

	return vaddr;



out_unmap:

	__iommu_dma_unmap(dev, iova, size);

out_free_sg:

	sg_free_table(&sgt);

out_free_iova:

	iommu_dma_free_iova(cookie, iova, size, NULL);

out_free_pages:

	__iommu_dma_free_pages(pages, count);

	__iommu_dma_unmap(dev, *dma_handle, size);

	__iommu_dma_free_pages(pages, PAGE_ALIGN(size) >> PAGE_SHIFT);

	return NULL;

}