Ian.

diff --git a/arch/ia64/include/asm/dma-mapping.h b/arch/ia64/include/ 

asm/dma-mapping.h
index 36c0009..026667f 100644

--- a/arch/ia64/include/asm/dma-mapping.h
+++ b/arch/ia64/include/asm/dma-mapping.h

@@ -174,4 +174,12 @@ dma_cache_sync (struct device *dev, void  

*vaddr, size_t size,

#define dma_is_consistent(d, h)	(1)	/* all we do is coherent  
memory... */

+static inline dma_addr_t dma_map_range(struct device *dev, u64 mask,
+				       phys_addr_t addr, size_t size)
+{
+	if (addr + size <= mask)
+		return addr;
+	return 0;
+}
+
#endif /* _ASM_IA64_DMA_MAPPING_H */

diff --git a/arch/x86/include/asm/dma-mapping.h b/arch/x86/include/ 

asm/dma-mapping.h
index 916cbb6..b2813ab 100644

--- a/arch/x86/include/asm/dma-mapping.h
+++ b/arch/x86/include/asm/dma-mapping.h

@@ -309,4 +309,20 @@ static inline void dma_free_coherent(struct  

device *dev, size_t size,
		ops->free_coherent(dev, size, vaddr, bus);
}

+static inline dma_addr_t dma_map_range(struct device *dev, u64 mask,
+				       phys_addr_t addr, size_t size)
+{
+	dma_addr_t dma_addr;
+#ifdef CONFIG_XEN
+	extern int xen_range_needs_mapping(phys_addr_t paddr, size_t size);
+	if (xen_pv_domain() && xen_range_needs_mapping(addr, size))
+		return 0;
+#endif
+
+	dma_addr = swiotlb_phys_to_bus(dev, addr);
+	if (dma_addr + size <= mask)
+		return 0;
+	return dma_addr;
+}
+
#endif

diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 2fffc22..c2b4196 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c

@@ -145,8 +145,8 @@ again:

	if (!page)
		return NULL;

-	addr = page_to_phys(page);
-	if (!is_buffer_dma_capable(dma_mask, addr, size)) {
+	addr = dma_map_range(dev, dma_mask, page_to_phys(page), size);
+	if (!(addr == 0)) {
		__free_pages(page, get_order(size));

		if (dma_mask < DMA_BIT_MASK(32) && !(flag & GFP_DMA)) {

diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci- 

gart_64.c
index 1e8920d..6a55770 100644

--- a/arch/x86/kernel/pci-gart_64.c
+++ b/arch/x86/kernel/pci-gart_64.c

@@ -191,13 +191,13 @@ static inline int

need_iommu(struct device *dev, unsigned long addr, size_t size)
{
	return force_iommu ||
-		!is_buffer_dma_capable(*dev->dma_mask, addr, size);
+		dma_map_range(dev, *dev->dma_mask, addr, size) == 0;
}

static inline int
nonforced_iommu(struct device *dev, unsigned long addr, size_t size)
{
-	return !is_buffer_dma_capable(*dev->dma_mask, addr, size);
+	return dma_map_range(dev, *dev->dma_mask, addr, size) == 0;
}

/* Map a single continuous physical area into the IOMMU.

diff --git a/arch/x86/kernel/pci-nommu.c b/arch/x86/kernel/pci-nommu.c
index 71d412a..712ce59 100644
--- a/arch/x86/kernel/pci-nommu.c
+++ b/arch/x86/kernel/pci-nommu.c

@@ -12,13 +12,13 @@

#include <asm/dma.h>

static int
-check_addr(char *name, struct device *hwdev, dma_addr_t bus, size_t  
size)
+check_addr(char *name, struct device *hwdev, phys_addr_t phys,  
size_t size)
{
-	if (hwdev && !is_buffer_dma_capable(*hwdev->dma_mask, bus, size)) {
+	if (hwdev && dma_map_range(hwdev, *hwdev->dma_mask, phys, size) ==  
0) {
		if (*hwdev->dma_mask >= DMA_BIT_MASK(32))
			printk(KERN_ERR
			    "nommu_%s: overflow %Lx+%zu of device mask %Lx\n",
-				name, (long long)bus, size,
+				name, (long long)phys, size,
				(long long)*hwdev->dma_mask);
		return 0;
	}

@@ -30,12 +30,12 @@ static dma_addr_t nommu_map_page(struct device  

*dev, struct page *page,
				 enum dma_data_direction dir,
				 struct dma_attrs *attrs)
{
-	dma_addr_t bus = page_to_phys(page) + offset;
+	phys_addr_t phys = page_to_phys(page) + offset;
	WARN_ON(size == 0);
-	if (!check_addr("map_single", dev, bus, size))
+	if (!check_addr("map_single", dev, phys, size))
		return bad_dma_address;
	flush_write_buffers();
-	return bus;
+	return phys;
}

/* Map a set of buffers described by scatterlist in streaming

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 8083b6a..85dafa1 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h

@@ -96,11 +96,6 @@ static inline int is_device_dma_capable(struct  

device *dev)
	return dev->dma_mask != NULL && *dev->dma_mask != DMA_MASK_NONE;
}

-static inline int is_buffer_dma_capable(u64 mask, dma_addr_t addr,  
size_t size)
-{
-	return addr + size <= mask;
-}
-
#ifdef CONFIG_HAS_DMA
#include <asm/dma-mapping.h>
#else

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index cec5f62..4fd5185 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c

@@ -147,17 +147,6 @@ void * __weak swiotlb_bus_to_virt(struct device  

*hwdev, dma_addr_t address)
	return phys_to_virt(swiotlb_bus_to_phys(hwdev, address));
}

-int __weak swiotlb_arch_address_needs_mapping(struct device *hwdev,
-					       dma_addr_t addr, size_t size)
-{
-	return !is_buffer_dma_capable(dma_get_mask(hwdev), addr, size);
-}
-
-int __weak swiotlb_arch_range_needs_mapping(phys_addr_t paddr,  
size_t size)
-{
-	return 0;
-}
-
static void swiotlb_print_info(unsigned long bytes)
{
	phys_addr_t pstart, pend;

@@ -318,17 +307,6 @@ cleanup1:

	return -ENOMEM;
}

-static inline int
-address_needs_mapping(struct device *hwdev, dma_addr_t addr, size_t  
size)
-{
-	return swiotlb_arch_address_needs_mapping(hwdev, addr, size);
-}
-
-static inline int range_needs_mapping(phys_addr_t paddr, size_t size)
-{
-	return swiotlb_force || swiotlb_arch_range_needs_mapping(paddr,  
size);
-}
-
static int is_swiotlb_buffer(char *addr)
{
	return addr >= io_tlb_start && addr < io_tlb_end;

@@ -555,18 +533,17 @@ void *

swiotlb_alloc_coherent(struct device *hwdev, size_t size,
		       dma_addr_t *dma_handle, gfp_t flags)
{
-	dma_addr_t dev_addr;
+	phys_addr_t phys;
	void *ret;
	int order = get_order(size);
	u64 dma_mask = DMA_BIT_MASK(32);
+	dma_addr_t dma_addr;

	if (hwdev && hwdev->coherent_dma_mask)
		dma_mask = hwdev->coherent_dma_mask;

	ret = (void *)__get_free_pages(flags, order);
-	if (ret &&
-	    !is_buffer_dma_capable(dma_mask, swiotlb_virt_to_bus(hwdev,  
ret),
-				   size)) {
+	if (ret && dma_map_range(hwdev, dma_mask, virt_to_phys(ret), size)  
== 0) {
		/*
		 * The allocated memory isn't reachable by the device.
		 */

@@ -585,19 +562,20 @@ swiotlb_alloc_coherent(struct device *hwdev,  

size_t size,
	}

	memset(ret, 0, size);
-	dev_addr = swiotlb_virt_to_bus(hwdev, ret);
+	phys = virt_to_phys(ret);

	/* Confirm address can be DMA'd by device */
-	if (!is_buffer_dma_capable(dma_mask, dev_addr, size)) {
-		printk("hwdev DMA mask = 0x%016Lx, dev_addr = 0x%016Lx\n",
+	dma_addr = dma_map_range(hwdev, dma_mask, phys, size);
+	if (dma_addr == 0) {
+		printk("hwdev DMA mask = 0x%016Lx, physical addr = 0x%016Lx\n",
		       (unsigned long long)dma_mask,
-		       (unsigned long long)dev_addr);
+		       (unsigned long long)phys);

		/* DMA_TO_DEVICE to avoid memcpy in unmap_single */
		do_unmap_single(hwdev, ret, size, DMA_TO_DEVICE);
		return NULL;
	}
-	*dma_handle = dev_addr;
+	*dma_handle = dma_addr;
	return ret;
}
EXPORT_SYMBOL(swiotlb_alloc_coherent);

@@ -649,7 +627,7 @@ dma_addr_t swiotlb_map_page(struct device *dev,  

struct page *page,
			    struct dma_attrs *attrs)
{
	phys_addr_t phys = page_to_phys(page) + offset;
-	dma_addr_t dev_addr = swiotlb_phys_to_bus(dev, phys);
+	dma_addr_t dma_addr;
	void *map;

	BUG_ON(dir == DMA_NONE);

@@ -658,9 +636,9 @@ dma_addr_t swiotlb_map_page(struct device *dev,  

struct page *page,
	 * we can safely return the device addr and not worry about bounce
	 * buffering it.
	 */
-	if (!address_needs_mapping(dev, dev_addr, size) &&
-	    !range_needs_mapping(phys, size))
-		return dev_addr;
+	dma_addr = dma_map_range(dev, dma_get_mask(dev), phys, size);
+	if (dma_addr && !swiotlb_force)
+		return dma_addr;

	/*
	 * Oh well, have to allocate and map a bounce buffer.

@@ -671,15 +649,14 @@ dma_addr_t swiotlb_map_page(struct device  

*dev, struct page *page,
		map = io_tlb_overflow_buffer;
	}

-	dev_addr = swiotlb_virt_to_bus(dev, map);
-
	/*
	 * Ensure that the address returned is DMA'ble
	 */
-	if (address_needs_mapping(dev, dev_addr, size))
+	dma_addr = dma_map_range(dev, dma_get_mask(dev),  
virt_to_phys(map), size);
+	if (dma_addr == 0)
		panic("map_single: bounce buffer is not DMA'ble");

-	return dev_addr;
+	return dma_addr;
}
EXPORT_SYMBOL_GPL(swiotlb_map_page);

@@ -820,10 +797,8 @@ swiotlb_map_sg_attrs(struct device *hwdev,  

struct scatterlist *sgl, int nelems,

	for_each_sg(sgl, sg, nelems, i) {
		phys_addr_t paddr = sg_phys(sg);
-		dma_addr_t dev_addr = swiotlb_phys_to_bus(hwdev, paddr);
-
-		if (range_needs_mapping(paddr, sg->length) ||
-		    address_needs_mapping(hwdev, dev_addr, sg->length)) {
+		dma_addr_t dma_addr = dma_map_range(hwdev, dma_get_mask(hwdev),  
paddr, sg->length);
+		if (dma_addr == 0 || swiotlb_force) {
			void *map = map_single(hwdev, sg_phys(sg),
					       sg->length, dir);
			if (!map) {

@@ -835,9 +810,9 @@ swiotlb_map_sg_attrs(struct device *hwdev,  

struct scatterlist *sgl, int nelems,
				sgl[0].dma_length = 0;
				return 0;
			}
-			sg->dma_address = swiotlb_virt_to_bus(hwdev, map);
-		} else
-			sg->dma_address = dev_addr;
+			dma_addr = dma_map_range(hwdev, dma_get_mask(hwdev),  
virt_to_phys(map), sg->length);
+		}
+		sg->dma_address = dma_addr;
		sg->dma_length = sg->length;
	}
	return nelems;