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

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

Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Christoph Hellwig 2019-04-11 09:19:58 +02:00 committed by Konrad Rzeszutek Wilk
parent aca351cc4c
commit 8b35d9feed
1 changed files with 10 additions and 58 deletions
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68
drivers/xen/swiotlb-xen.c
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@ -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 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) enum dma_data_direction dir, unsigned long attrs)
{ {
struct scatterlist *sg; struct scatterlist *sg;
@ -540,50 +524,18 @@ xen_swiotlb_map_sg(struct device *hwdev, struct scatterlist *sgl, int nelems,
BUG_ON(dir == DMA_NONE); BUG_ON(dir == DMA_NONE);
for_each_sg(sgl, sg, nelems, i) { for_each_sg(sgl, sg, nelems, i) {
phys_addr_t paddr = sg_phys(sg); sg->dma_address = xen_swiotlb_map_page(dev, sg_page(sg),
dma_addr_t dev_addr = xen_phys_to_bus(paddr); sg->offset, sg->length, dir, attrs);
if (sg->dma_address == DMA_MAPPING_ERROR)
if (swiotlb_force == SWIOTLB_FORCE || goto out_unmap;
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_len(sg) = sg->length; sg_dma_len(sg) = sg->length;
} }
return nelems; 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;
} }
/* /*