[Xen-devel] [PATCH] xen/arm64: do not call the swiotlb functions twice

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On arm64 the dma_map_ops implementation is based on the swiotlb.
swiotlb-xen, used by default in dom0 on Xen, is also based on the
swiotlb.

Avoid calling into the default arm64 dma_map_ops functions from
xen_dma_map_page, xen_dma_unmap_page, xen_dma_sync_single_for_cpu, and
xen_dma_sync_single_for_device otherwise we end up calling into the
swiotlb twice.

When arm64 gets a non-swiotlb based implementation of dma_map_ops, we'll
probably have to reintroduce dma_map_ops calls in page-coherent.h.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
CC: catalin.marinas@xxxxxxx
CC: Will.Deacon@xxxxxxx
CC: Ian.Campbell@xxxxxxxxxx
---
 arch/arm64/include/asm/xen/page-coherent.h |    4 ----
 1 file changed, 4 deletions(-)

diff --git a/arch/arm64/include/asm/xen/page-coherent.h 
b/arch/arm64/include/asm/xen/page-coherent.h
index 2820f1a..dde3fc9 100644
--- a/arch/arm64/include/asm/xen/page-coherent.h
+++ b/arch/arm64/include/asm/xen/page-coherent.h
@@ -23,25 +23,21 @@ static inline void xen_dma_map_page(struct device *hwdev, 
struct page *page,
             unsigned long offset, size_t size, enum dma_data_direction dir,
             struct dma_attrs *attrs)
 {
-       __generic_dma_ops(hwdev)->map_page(hwdev, page, offset, size, dir, 
attrs);
 }
 
 static inline void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
                size_t size, enum dma_data_direction dir,
                struct dma_attrs *attrs)
 {
-       __generic_dma_ops(hwdev)->unmap_page(hwdev, handle, size, dir, attrs);
 }
 
 static inline void xen_dma_sync_single_for_cpu(struct device *hwdev,
                dma_addr_t handle, size_t size, enum dma_data_direction dir)
 {
-       __generic_dma_ops(hwdev)->sync_single_for_cpu(hwdev, handle, size, dir);
 }
 
 static inline void xen_dma_sync_single_for_device(struct device *hwdev,
                dma_addr_t handle, size_t size, enum dma_data_direction dir)
 {
-       __generic_dma_ops(hwdev)->sync_single_for_device(hwdev, handle, size, 
dir);
 }
 #endif /* _ASM_ARM64_XEN_PAGE_COHERENT_H */
-- 
1.7.10.4


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