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authorStefano Stabellini <stefano.stabellini@eu.citrix.com>2014-09-11 02:49:41 +0400
committerStefano Stabellini <stefano.stabellini@eu.citrix.com>2014-09-11 22:11:53 +0400
commit340720be32d458ee11d1117719a8e4b6b82981b2 (patch)
tree11489bb337f841f9bf3cce1a77771c2412c566c2 /arch/arm/include/asm/xen
parent5ebc77de83c7b74543de774afa7395b3b790e65e (diff)
downloadlinux-340720be32d458ee11d1117719a8e4b6b82981b2.tar.xz
xen/arm: reimplement xen_dma_unmap_page & friends
xen_dma_unmap_page, xen_dma_sync_single_for_cpu and xen_dma_sync_single_for_device are currently implemented by calling into the corresponding generic ARM implementation of these functions. In order to do this, firstly the dma_addr_t handle, that on Xen is a machine address, needs to be translated into a physical address. The operation is expensive and inaccurate, given that a single machine address can correspond to multiple physical addresses in one domain, because the same page can be granted multiple times by the frontend. To avoid this problem, we introduce a Xen specific implementation of xen_dma_unmap_page, xen_dma_sync_single_for_cpu and xen_dma_sync_single_for_device, that can operate on machine addresses directly. The new implementation relies on the fact that the hypervisor creates a second p2m mapping of any grant pages at physical address == machine address of the page for dom0. Therefore we can access memory at physical address == dma_addr_r handle and perform the cache flushing there. Some cache maintenance operations require a virtual address. Instead of using ioremap_cache, that is not safe in interrupt context, we allocate a per-cpu PAGE_KERNEL scratch page and we manually update the pte for it. arm64 doesn't need cache maintenance operations on unmap for now. Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Tested-by: Denis Schneider <v1ne2go@gmail.com>
Diffstat (limited to 'arch/arm/include/asm/xen')
-rw-r--r--arch/arm/include/asm/xen/page-coherent.h25
1 files changed, 7 insertions, 18 deletions
diff --git a/arch/arm/include/asm/xen/page-coherent.h b/arch/arm/include/asm/xen/page-coherent.h
index 1109017499e5..e8275ea88e88 100644
--- a/arch/arm/include/asm/xen/page-coherent.h
+++ b/arch/arm/include/asm/xen/page-coherent.h
@@ -26,25 +26,14 @@ static inline void xen_dma_map_page(struct device *hwdev, struct page *page,
__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,
+void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
size_t size, enum dma_data_direction dir,
- struct dma_attrs *attrs)
-{
- if (__generic_dma_ops(hwdev)->unmap_page)
- __generic_dma_ops(hwdev)->unmap_page(hwdev, handle, size, dir, attrs);
-}
+ struct dma_attrs *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)
-{
- if (__generic_dma_ops(hwdev)->sync_single_for_cpu)
- __generic_dma_ops(hwdev)->sync_single_for_cpu(hwdev, handle, size, dir);
-}
+void xen_dma_sync_single_for_cpu(struct device *hwdev,
+ dma_addr_t handle, size_t size, enum dma_data_direction dir);
+
+void xen_dma_sync_single_for_device(struct device *hwdev,
+ dma_addr_t handle, size_t size, enum dma_data_direction 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)
-{
- if (__generic_dma_ops(hwdev)->sync_single_for_device)
- __generic_dma_ops(hwdev)->sync_single_for_device(hwdev, handle, size, dir);
-}
#endif /* _ASM_ARM_XEN_PAGE_COHERENT_H */