From 8b35d9feed8e4e66dc4048f776c356e26e2a8216 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Thu, 11 Apr 2019 09:19:58 +0200
Subject: [PATCH] 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: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
drivers/xen/swiotlb-xen.c | 68 ++++++---------------------------------
1 file changed, 10 insertions(+), 58 deletions(-)
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 272e4aef2a86..e40bf1b707e3 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -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;
}
/*