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Commit 8b35d9fe authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Konrad Rzeszutek Wilk
Browse files

swiotlb-xen: use ->map_page to implement ->map_sg 



We can simply loop over the segments and map them, removing lots of
duplicate code.

Reviewed-by: default avatarStefano Stabellini <sstabellini@kernel.org>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent aca351cc

drivers/xen/swiotlb-xen.c

+10 −58
Original line number Diff line number Diff line
@@ -514,24 +514,8 @@ xen_swiotlb_unmap_sg(struct device *hwdev, struct scatterlist *sgl, int nelems, 


}



/*

 * Map a set of buffers described by scatterlist in streaming mode for DMA.

 * This is the scatter-gather version of the above xen_swiotlb_map_page

 * interface.  Here the scatter gather list elements are each tagged with the

 * appropriate dma address and length.  They are obtained via

 * sg_dma_{address,length}(SG).

 *

 * NOTE: An implementation may be able to use a smaller number of

 *       DMA address/length pairs than there are SG table elements.

 *       (for example via virtual mapping capabilities)

 *       The routine returns the number of addr/length pairs actually

 *       used, at most nents.

 *

 * Device ownership issues as mentioned above for xen_swiotlb_map_page are the

 * same here.

 */

static int

xen_swiotlb_map_sg(struct device *hwdev, struct scatterlist *sgl, int nelems,

xen_swiotlb_map_sg(struct device *dev, struct scatterlist *sgl, int nelems,

		enum dma_data_direction dir, unsigned long attrs)

{

	struct scatterlist *sg;
@@ -540,50 +524,18 @@ xen_swiotlb_map_sg(struct device *hwdev, struct scatterlist *sgl, int nelems, 
	BUG_ON(dir == DMA_NONE);



	for_each_sg(sgl, sg, nelems, i) {

		phys_addr_t paddr = sg_phys(sg);

		dma_addr_t dev_addr = xen_phys_to_bus(paddr);



		if (swiotlb_force == SWIOTLB_FORCE ||

		    xen_arch_need_swiotlb(hwdev, paddr, dev_addr) ||

		    !dma_capable(hwdev, dev_addr, sg->length) ||

		    range_straddles_page_boundary(paddr, sg->length)) {

			phys_addr_t map = swiotlb_tbl_map_single(hwdev,

								 start_dma_addr,

								 sg_phys(sg),

								 sg->length,

								 dir, attrs);

			if (map == DMA_MAPPING_ERROR) {

				dev_warn(hwdev, "swiotlb buffer is full\n");

				/* Don't panic here, we expect map_sg users

				   to do proper error handling. */

				attrs |= DMA_ATTR_SKIP_CPU_SYNC;

				xen_swiotlb_unmap_sg(hwdev, sgl, i, dir, attrs);

				sg_dma_len(sgl) = 0;

				return 0;

			}

			dev_addr = xen_phys_to_bus(map);

			xen_dma_map_page(hwdev, pfn_to_page(map >> PAGE_SHIFT),

						dev_addr,

						map & ~PAGE_MASK,

						sg->length,

						dir,

						attrs);

			sg->dma_address = dev_addr;

		} else {

			/* we are not interested in the dma_addr returned by

			 * xen_dma_map_page, only in the potential cache flushes executed

			 * by the function. */

			xen_dma_map_page(hwdev, pfn_to_page(paddr >> PAGE_SHIFT),

						dev_addr,

						paddr & ~PAGE_MASK,

						sg->length,

						dir,

						attrs);

			sg->dma_address = dev_addr;

		}

		sg->dma_address = xen_swiotlb_map_page(dev, sg_page(sg),

				sg->offset, sg->length, dir, attrs);

		if (sg->dma_address == DMA_MAPPING_ERROR)

			goto out_unmap;

		sg_dma_len(sg) = sg->length;

	}



	return nelems;

out_unmap:

	xen_swiotlb_unmap_sg(dev, sgl, i, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC);

	sg_dma_len(sgl) = 0;

	return 0;

}



/*