xen/arm: use hypercall to flush caches in map_page

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@arm.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm/include/asm/xen/page-coherent.h b/arch/arm/include/asm/xen/page-coherent.h
index a309f42b411c8de0048f6a571c5283823346f7ed..efd5624128507fa5afd7f6ec981dc07edd2b2160 100644 (file)
--- 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 +35,15 @@ 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);
+       bool local = PFN_DOWN(dev_addr) == page_to_pfn(page);
+       /* Dom0 is mapped 1:1, so if pfn == mfn the page is local otherwise
+        * is a foreign page grant-mapped in dom0. If the page is local we
+        * can safely call the native dma_ops function, otherwise we call
+        * the xen specific function. */
+       if (local)
+               __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);
 }
 
 static inline 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 3ce9dc1efb0c222586b56fd9a8a0fde78ad0e864..c86919bbea8347a502191ae4f9c1aed43f78642e 100644 (file)
--- a/arch/arm/xen/mm32.c
+++ b/arch/arm/xen/mm32.c
@@ -43,6 +43,18 @@ 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)