[PATCH v8 08/13] xen/arm: use hypercall to flush caches in map_page

[Stefano Stabellini]

In xen_dma_map_page, if the page is a local page, call the native
map_page dma_ops. If the page is foreign, call __xen_dma_map_page that
issues any required cache maintenane operations via hypercall.

The reason for doing this is that the native dma_ops map_page could
allocate buffers than need to be freed. If the page is foreign we don't
call the native unmap_page dma_ops function, resulting in a memory leak.

Suggested-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
 arch/arm/include/asm/xen/page-coherent.h |    9 ++++++++-
 arch/arm/xen/mm32.c                      |   12 ++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/xen/page-coherent.h b/arch/arm/include/asm/xen/page-coherent.h
index 25d450c..36b79a8 100644
--- a/arch/arm/include/asm/xen/page-coherent.h
+++ b/arch/arm/include/asm/xen/page-coherent.h
@@ -5,6 +5,9 @@
 #include <linux/dma-attrs.h>
 #include <linux/dma-mapping.h>
 
+void __xen_dma_map_page(struct device *hwdev, struct page *page,
+	     dma_addr_t dev_addr, unsigned long offset, size_t size,
+	     enum dma_data_direction dir, struct dma_attrs *attrs);
 void __xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
 		size_t size, enum dma_data_direction dir,
 		struct dma_attrs *attrs);
@@ -32,7 +35,11 @@ static inline void xen_dma_map_page(struct device *hwdev, struct page *page,
 	     dma_addr_t dev_addr, 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);
+	if (PFN_DOWN(dev_addr) == page_to_pfn(page)) {
+		if (__generic_dma_ops(hwdev)->map_page)
+			__generic_dma_ops(hwdev)->map_page(hwdev, page, offset, size, dir, attrs);
+	} else
+		__xen_dma_map_page(hwdev, page, dev_addr, offset, size, dir, attrs);
 }
 
 void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
diff --git a/arch/arm/xen/mm32.c b/arch/arm/xen/mm32.c
index 7824498..d611c4b 100644
--- a/arch/arm/xen/mm32.c
+++ b/arch/arm/xen/mm32.c
@@ -45,6 +45,18 @@ static void __xen_dma_page_cpu_to_dev(struct device *hwdev, dma_addr_t handle,
 	dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_MAP);
 }
 
+void __xen_dma_map_page(struct device *hwdev, struct page *page,
+	     dma_addr_t dev_addr, unsigned long offset, size_t size,
+	     enum dma_data_direction dir, struct dma_attrs *attrs)
+{
+	if (is_device_dma_coherent(hwdev))
+		return;
+	if (dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
+		return;
+
+	__xen_dma_page_cpu_to_dev(hwdev, dev_addr, size, dir);
+}
+
 void __xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
 		size_t size, enum dma_data_direction dir,
 		struct dma_attrs *attrs)
-- 
1.7.10.4

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