Merge tag 'dma-mapping-5.4' of git://git.infradead.org/users/hch/dma-mapping

Pull dma-mapping updates from Christoph Hellwig:

 - add dma-mapping and block layer helpers to take care of IOMMU merging
   for mmc plus subsequent fixups (Yoshihiro Shimoda)

 - rework handling of the pgprot bits for remapping (me)

 - take care of the dma direct infrastructure for swiotlb-xen (me)

 - improve the dma noncoherent remapping infrastructure (me)

 - better defaults for ->mmap, ->get_sgtable and ->get_required_mask
   (me)

 - cleanup mmaping of coherent DMA allocations (me)

 - various misc cleanups (Andy Shevchenko, me)

* tag 'dma-mapping-5.4' of git://git.infradead.org/users/hch/dma-mapping: (41 commits)
  mmc: renesas_sdhi_internal_dmac: Add MMC_CAP2_MERGE_CAPABLE
  mmc: queue: Fix bigger segments usage
  arm64: use asm-generic/dma-mapping.h
  swiotlb-xen: merge xen_unmap_single into xen_swiotlb_unmap_page
  swiotlb-xen: simplify cache maintainance
  swiotlb-xen: use the same foreign page check everywhere
  swiotlb-xen: remove xen_swiotlb_dma_mmap and xen_swiotlb_dma_get_sgtable
  xen: remove the exports for xen_{create,destroy}_contiguous_region
  xen/arm: remove xen_dma_ops
  xen/arm: simplify dma_cache_maint
  xen/arm: use dev_is_dma_coherent
  xen/arm: consolidate page-coherent.h
  xen/arm: use dma-noncoherent.h calls for xen-swiotlb cache maintainance
  arm: remove wrappers for the generic dma remap helpers
  dma-mapping: introduce a dma_common_find_pages helper
  dma-mapping: always use VM_DMA_COHERENT for generic DMA remap
  vmalloc: lift the arm flag for coherent mappings to common code
  dma-mapping: provide a better default ->get_required_mask
  dma-mapping: remove the dma_declare_coherent_memory export
  remoteproc: don't allow modular build
  ...

Documentation/DMA-API.txt

@@ -204,6 +204,14 @@ Returns the maximum size of a mapping for the device. The size parameter
 of the mapping functions like dma_map_single(), dma_map_page() and
 others should not be larger than the returned value.
 
+::
+
+	unsigned long
+	dma_get_merge_boundary(struct device *dev);
+
+Returns the DMA merge boundary. If the device cannot merge any the DMA address
+segments, the function returns 0.
+
 Part Id - Streaming DMA mappings
 --------------------------------
 
@@ -595,17 +603,6 @@ For reasons of efficiency, most platforms choose to track the declared
 region only at the granularity of a page.  For smaller allocations,
 you should use the dma_pool() API.
 
-::
-
-	void
-	dma_release_declared_memory(struct device *dev)
-
-Remove the memory region previously declared from the system.  This
-API performs *no* in-use checking for this region and will return
-unconditionally having removed all the required structures.  It is the
-driver's job to ensure that no parts of this memory region are
-currently in use.
-
 Part III - Debug drivers use of the DMA-API
 -------------------------------------------
 

Documentation/x86/x86_64/boot-options.rst

@@ -230,7 +230,7 @@ IOMMU (input/output memory management unit)
 ===========================================
 Multiple x86-64 PCI-DMA mapping implementations exist, for example:
 
-   1. <lib/dma-direct.c>: use no hardware/software IOMMU at all
+   1. <kernel/dma/direct.c>: use no hardware/software IOMMU at all
       (e.g. because you have < 3 GB memory).
       Kernel boot message: "PCI-DMA: Disabling IOMMU"
 

arch/Kconfig

@@ -793,9 +793,6 @@ config COMPAT_32BIT_TIME
 	  This is relevant on all 32-bit architectures, and 64-bit architectures
 	  as part of compat syscall handling.
 
-config ARCH_NO_COHERENT_DMA_MMAP
-	bool
-
 config ARCH_NO_PREEMPT
 	bool
 

arch/alpha/kernel/pci_iommu.c

@@ -955,5 +955,7 @@ const struct dma_map_ops alpha_pci_ops = {
 	.map_sg			= alpha_pci_map_sg,
 	.unmap_sg		= alpha_pci_unmap_sg,
 	.dma_supported		= alpha_pci_supported,
+	.mmap			= dma_common_mmap,
+	.get_sgtable		= dma_common_get_sgtable,
 };
 EXPORT_SYMBOL(alpha_pci_ops);

arch/arc/mm/dma.c

@@ -104,9 +104,3 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 	dev_info(dev, "use %scoherent DMA ops\n",
 		 dev->dma_coherent ? "" : "non");
 }
-
-static int __init atomic_pool_init(void)
-{
-	return dma_atomic_pool_init(GFP_KERNEL, pgprot_noncached(PAGE_KERNEL));
-}
-postcore_initcall(atomic_pool_init);

arch/arm/Kconfig

@@ -8,7 +8,7 @@ config ARM
 	select ARCH_HAS_DEBUG_VIRTUAL if MMU
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select ARCH_HAS_DMA_COHERENT_TO_PFN if SWIOTLB
-	select ARCH_HAS_DMA_MMAP_PGPROT if SWIOTLB
+	select ARCH_HAS_DMA_WRITE_COMBINE if !ARM_DMA_MEM_BUFFERABLE
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_KEEPINITRD

arch/arm/include/asm/device.h

@@ -14,9 +14,6 @@ struct dev_archdata {
 #endif
 #ifdef CONFIG_ARM_DMA_USE_IOMMU
 	struct dma_iommu_mapping	*mapping;
-#endif
-#ifdef CONFIG_XEN
-	const struct dma_map_ops *dev_dma_ops;
 #endif
 	unsigned int dma_coherent:1;
 	unsigned int dma_ops_setup:1;

arch/arm/include/asm/dma-mapping.h

@@ -91,12 +91,6 @@ static inline dma_addr_t virt_to_dma(struct device *dev, void *addr)
 }
 #endif
 
-/* do not use this function in a driver */
-static inline bool is_device_dma_coherent(struct device *dev)
-{
-	return dev->archdata.dma_coherent;
-}
-
 /**
  * arm_dma_alloc - allocate consistent memory for DMA
  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices

arch/arm/include/asm/pgtable-nommu.h

@@ -62,7 +62,6 @@ typedef pte_t *pte_addr_t;
  */
 #define pgprot_noncached(prot)	(prot)
 #define pgprot_writecombine(prot) (prot)
-#define pgprot_dmacoherent(prot) (prot)
 #define pgprot_device(prot)	(prot)
 
 

arch/arm/include/asm/xen/page-coherent.h

 /* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _ASM_ARM_XEN_PAGE_COHERENT_H
-#define _ASM_ARM_XEN_PAGE_COHERENT_H
-
-#include <linux/dma-mapping.h>
-#include <asm/page.h>
 #include <xen/arm/page-coherent.h>
-
-static inline const struct dma_map_ops *xen_get_dma_ops(struct device *dev)
-{
-	if (dev && dev->archdata.dev_dma_ops)
-		return dev->archdata.dev_dma_ops;
-	return get_arch_dma_ops(NULL);
-}
-
-static inline void *xen_alloc_coherent_pages(struct device *hwdev, size_t size,
-		dma_addr_t *dma_handle, gfp_t flags, unsigned long attrs)
-{
-	return xen_get_dma_ops(hwdev)->alloc(hwdev, size, dma_handle, flags, attrs);
-}
-
-static inline void xen_free_coherent_pages(struct device *hwdev, size_t size,
-		void *cpu_addr, dma_addr_t dma_handle, unsigned long attrs)
-{
-	xen_get_dma_ops(hwdev)->free(hwdev, size, cpu_addr, dma_handle, attrs);
-}
-
-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, unsigned long attrs)
-{
-	unsigned long page_pfn = page_to_xen_pfn(page);
-	unsigned long dev_pfn = XEN_PFN_DOWN(dev_addr);
-	unsigned long compound_pages =
-		(1<<compound_order(page)) * XEN_PFN_PER_PAGE;
-	bool local = (page_pfn <= dev_pfn) &&
-		(dev_pfn - page_pfn < compound_pages);
-
-	/*
-	 * Dom0 is mapped 1:1, while the Linux page can span across
-	 * multiple Xen pages, it's not possible for it to contain a
-	 * mix of local and foreign Xen pages. So if the first xen_pfn
-	 * == mfn the page is local otherwise it's 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)
-		xen_get_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,
-		size_t size, enum dma_data_direction dir, unsigned long attrs)
-{
-	unsigned long pfn = PFN_DOWN(handle);
-	/*
-	 * Dom0 is mapped 1:1, while the Linux page can be spanned accross
-	 * multiple Xen page, it's not possible to have a mix of local and
-	 * foreign Xen page. Dom0 is mapped 1:1, so calling pfn_valid on a
-	 * foreign mfn will always return false. If the page is local we can
-	 * safely call the native dma_ops function, otherwise we call the xen
-	 * specific function.
-	 */
-	if (pfn_valid(pfn)) {
-		if (xen_get_dma_ops(hwdev)->unmap_page)
-			xen_get_dma_ops(hwdev)->unmap_page(hwdev, handle, size, dir, attrs);
-	} else
-		__xen_dma_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)
-{
-	unsigned long pfn = PFN_DOWN(handle);
-	if (pfn_valid(pfn)) {
-		if (xen_get_dma_ops(hwdev)->sync_single_for_cpu)
-			xen_get_dma_ops(hwdev)->sync_single_for_cpu(hwdev, handle, size, dir);
-	} else
-		__xen_dma_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)
-{
-	unsigned long pfn = PFN_DOWN(handle);
-	if (pfn_valid(pfn)) {
-		if (xen_get_dma_ops(hwdev)->sync_single_for_device)
-			xen_get_dma_ops(hwdev)->sync_single_for_device(hwdev, handle, size, dir);
-	} else
-		__xen_dma_sync_single_for_device(hwdev, handle, size, dir);
-}
-
-#endif /* _ASM_ARM_XEN_PAGE_COHERENT_H */

arch/arm/mm/dma-mapping-nommu.c

@@ -68,8 +68,9 @@ static int arm_nommu_dma_mmap(struct device *dev, struct vm_area_struct *vma,
 
 	if (dma_mmap_from_global_coherent(vma, cpu_addr, size, &ret))
 		return ret;
-
-	return dma_common_mmap(dev, vma, cpu_addr, dma_addr, size, attrs);
+	if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
+		return ret;
+	return -ENXIO;
 }
 
 

arch/arm/mm/dma-mapping.c

@@ -14,6 +14,7 @@
 #include <linux/list.h>
 #include <linux/init.h>
 #include <linux/device.h>
+#include <linux/dma-direct.h>
 #include <linux/dma-mapping.h>
 #include <linux/dma-noncoherent.h>
 #include <linux/dma-contiguous.h>
@@ -35,6 +36,7 @@
 #include <asm/mach/map.h>
 #include <asm/system_info.h>
 #include <asm/dma-contiguous.h>
+#include <xen/swiotlb-xen.h>
 
 #include "dma.h"
 #include "mm.h"
@@ -192,6 +194,7 @@ const struct dma_map_ops arm_dma_ops = {
 	.sync_sg_for_cpu	= arm_dma_sync_sg_for_cpu,
 	.sync_sg_for_device	= arm_dma_sync_sg_for_device,
 	.dma_supported		= arm_dma_supported,
+	.get_required_mask	= dma_direct_get_required_mask,
 };
 EXPORT_SYMBOL(arm_dma_ops);
 
@@ -212,6 +215,7 @@ const struct dma_map_ops arm_coherent_dma_ops = {
 	.map_sg			= arm_dma_map_sg,
 	.map_resource		= dma_direct_map_resource,
 	.dma_supported		= arm_dma_supported,
+	.get_required_mask	= dma_direct_get_required_mask,
 };
 EXPORT_SYMBOL(arm_coherent_dma_ops);
 
@@ -336,25 +340,6 @@ static void *__alloc_remap_buffer(struct device *dev, size_t size, gfp_t gfp,
 				 pgprot_t prot, struct page **ret_page,
 				 const void *caller, bool want_vaddr);
 
-static void *
-__dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot,
-	const void *caller)
-{
-	/*
-	 * DMA allocation can be mapped to user space, so lets
-	 * set VM_USERMAP flags too.
-	 */
-	return dma_common_contiguous_remap(page, size,
-			VM_ARM_DMA_CONSISTENT | VM_USERMAP,
-			prot, caller);
-}
-
-static void __dma_free_remap(void *cpu_addr, size_t size)
-{
-	dma_common_free_remap(cpu_addr, size,
-			VM_ARM_DMA_CONSISTENT | VM_USERMAP);
-}
-
 #define DEFAULT_DMA_COHERENT_POOL_SIZE	SZ_256K
 static struct gen_pool *atomic_pool __ro_after_init;
 
@@ -510,7 +495,7 @@ static void *__alloc_remap_buffer(struct device *dev, size_t size, gfp_t gfp,
 	if (!want_vaddr)
 		goto out;
 
-	ptr = __dma_alloc_remap(page, size, gfp, prot, caller);
+	ptr = dma_common_contiguous_remap(page, size, prot, caller);
 	if (!ptr) {
 		__dma_free_buffer(page, size);
 		return NULL;
@@ -577,7 +562,7 @@ static void *__alloc_from_contiguous(struct device *dev, size_t size,
 		goto out;
 
 	if (PageHighMem(page)) {
-		ptr = __dma_alloc_remap(page, size, GFP_KERNEL, prot, caller);
+		ptr = dma_common_contiguous_remap(page, size, prot, caller);
 		if (!ptr) {
 			dma_release_from_contiguous(dev, page, count);
 			return NULL;
@@ -597,7 +582,7 @@ static void __free_from_contiguous(struct device *dev, struct page *page,
 {
 	if (want_vaddr) {
 		if (PageHighMem(page))
-			__dma_free_remap(cpu_addr, size);
+			dma_common_free_remap(cpu_addr, size);
 		else
 			__dma_remap(page, size, PAGE_KERNEL);
 	}
@@ -689,7 +674,7 @@ static void *remap_allocator_alloc(struct arm_dma_alloc_args *args,
 static void remap_allocator_free(struct arm_dma_free_args *args)
 {
 	if (args->want_vaddr)
-		__dma_free_remap(args->cpu_addr, args->size);
+		dma_common_free_remap(args->cpu_addr, args->size);
 
 	__dma_free_buffer(args->page, args->size);
 }
@@ -877,17 +862,6 @@ static void arm_coherent_dma_free(struct device *dev, size_t size, void *cpu_add
 	__arm_dma_free(dev, size, cpu_addr, handle, attrs, true);
 }
 
-/*
- * The whole dma_get_sgtable() idea is fundamentally unsafe - it seems
- * that the intention is to allow exporting memory allocated via the
- * coherent DMA APIs through the dma_buf API, which only accepts a
- * scattertable.  This presents a couple of problems:
- * 1. Not all memory allocated via the coherent DMA APIs is backed by
- *    a struct page
- * 2. Passing coherent DMA memory into the streaming APIs is not allowed
- *    as we will try to flush the memory through a different alias to that
- *    actually being used (and the flushes are redundant.)
- */
 int arm_dma_get_sgtable(struct device *dev, struct sg_table *sgt,
 		 void *cpu_addr, dma_addr_t handle, size_t size,
 		 unsigned long attrs)
@@ -1132,10 +1106,6 @@ static const struct dma_map_ops *arm_get_dma_map_ops(bool coherent)
 	 * 32-bit DMA.
 	 * Use the generic dma-direct / swiotlb ops code in that case, as that
 	 * handles bounce buffering for us.
-	 *
-	 * Note: this checks CONFIG_ARM_LPAE instead of CONFIG_SWIOTLB as the
-	 * latter is also selected by the Xen code, but that code for now relies
-	 * on non-NULL dev_dma_ops.  To be cleaned up later.
 	 */
 	if (IS_ENABLED(CONFIG_ARM_LPAE))
 		return NULL;
@@ -1372,17 +1342,6 @@ static int __iommu_free_buffer(struct device *dev, struct page **pages,
 	return 0;
 }
 
-/*
- * Create a CPU mapping for a specified pages
- */
-static void *
-__iommu_alloc_remap(struct page **pages, size_t size, gfp_t gfp, pgprot_t prot,
-		    const void *caller)
-{
-	return dma_common_pages_remap(pages, size,
-			VM_ARM_DMA_CONSISTENT | VM_USERMAP, prot, caller);
-}
-
 /*
  * Create a mapping in device IO address space for specified pages
  */
@@ -1455,18 +1414,13 @@ static struct page **__atomic_get_pages(void *addr)
 
 static struct page **__iommu_get_pages(void *cpu_addr, unsigned long attrs)
 {
-	struct vm_struct *area;
-
 	if (__in_atomic_pool(cpu_addr, PAGE_SIZE))
 		return __atomic_get_pages(cpu_addr);
 
 	if (attrs & DMA_ATTR_NO_KERNEL_MAPPING)
 		return cpu_addr;
 
-	area = find_vm_area(cpu_addr);
-	if (area && (area->flags & VM_ARM_DMA_CONSISTENT))
-		return area->pages;
-	return NULL;
+	return dma_common_find_pages(cpu_addr);
 }
 
 static void *__iommu_alloc_simple(struct device *dev, size_t size, gfp_t gfp,
@@ -1539,7 +1493,7 @@ static void *__arm_iommu_alloc_attrs(struct device *dev, size_t size,
 	if (attrs & DMA_ATTR_NO_KERNEL_MAPPING)
 		return pages;
 
-	addr = __iommu_alloc_remap(pages, size, gfp, prot,
+	addr = dma_common_pages_remap(pages, size, prot,
 				   __builtin_return_address(0));
 	if (!addr)
 		goto err_mapping;
@@ -1622,10 +1576,8 @@ void __arm_iommu_free_attrs(struct device *dev, size_t size, void *cpu_addr,
 		return;
 	}
 
-	if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) == 0) {
-		dma_common_free_remap(cpu_addr, size,
-			VM_ARM_DMA_CONSISTENT | VM_USERMAP);
-	}
+	if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) == 0)
+		dma_common_free_remap(cpu_addr, size);
 
 	__iommu_remove_mapping(dev, handle, size);
 	__iommu_free_buffer(dev, pages, size, attrs);
@@ -2363,10 +2315,8 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 	set_dma_ops(dev, dma_ops);
 
 #ifdef CONFIG_XEN
-	if (xen_initial_domain()) {
-		dev->archdata.dev_dma_ops = dev->dma_ops;
-		dev->dma_ops = xen_dma_ops;
-	}
+	if (xen_initial_domain())
+		dev->dma_ops = &xen_swiotlb_dma_ops;
 #endif
 	dev->archdata.dma_ops_setup = true;
 }
@@ -2402,12 +2352,6 @@ long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr,
 	return dma_to_pfn(dev, dma_addr);
 }
 
-pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
-		unsigned long attrs)
-{
-	return __get_dma_pgprot(attrs, prot);
-}
-
 void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
 		gfp_t gfp, unsigned long attrs)
 {

arch/arm/mm/mm.h

@@ -70,9 +70,6 @@ extern void __flush_dcache_page(struct address_space *mapping, struct page *page
 #define VM_ARM_MTYPE(mt)		((mt) << 20)
 #define VM_ARM_MTYPE_MASK	(0x1f << 20)
 
-/* consistent regions used by dma_alloc_attrs() */
-#define VM_ARM_DMA_CONSISTENT	0x20000000
-
 
 struct static_vm {
 	struct vm_struct vm;

arch/arm/xen/mm.c

 // SPDX-License-Identifier: GPL-2.0-only
 #include <linux/cpu.h>
-#include <linux/dma-mapping.h>
+#include <linux/dma-noncoherent.h>
 #include <linux/gfp.h>
 #include <linux/highmem.h>
 #include <linux/export.h>
@@ -35,105 +35,56 @@ unsigned long xen_get_swiotlb_free_pages(unsigned int order)
 	return __get_free_pages(flags, order);
 }
 
-enum dma_cache_op {
-       DMA_UNMAP,
-       DMA_MAP,
-};
 static bool hypercall_cflush = false;
 
-/* functions called by SWIOTLB */
-
-static void dma_cache_maint(dma_addr_t handle, unsigned long offset,
-	size_t size, enum dma_data_direction dir, enum dma_cache_op op)
+/* buffers in highmem or foreign pages cannot cross page boundaries */
+static void dma_cache_maint(dma_addr_t handle, size_t size, u32 op)
 {
 	struct gnttab_cache_flush cflush;
-	unsigned long xen_pfn;
-	size_t left = size;
 
-	xen_pfn = (handle >> XEN_PAGE_SHIFT) + offset / XEN_PAGE_SIZE;
-	offset %= XEN_PAGE_SIZE;
+	cflush.a.dev_bus_addr = handle & XEN_PAGE_MASK;
+	cflush.offset = xen_offset_in_page(handle);
+	cflush.op = op;
 
 	do {
-		size_t len = left;
-	
-		/* buffers in highmem or foreign pages cannot cross page
-		 * boundaries */
-		if (len + offset > XEN_PAGE_SIZE)
-			len = XEN_PAGE_SIZE - offset;
-
-		cflush.op = 0;
-		cflush.a.dev_bus_addr = xen_pfn << XEN_PAGE_SHIFT;
-		cflush.offset = offset;
-		cflush.length = len;
-
-		if (op == DMA_UNMAP && dir != DMA_TO_DEVICE)
-			cflush.op = GNTTAB_CACHE_INVAL;
-		if (op == DMA_MAP) {
-			if (dir == DMA_FROM_DEVICE)
-				cflush.op = GNTTAB_CACHE_INVAL;
-			else
-				cflush.op = GNTTAB_CACHE_CLEAN;
-		}
-		if (cflush.op)
-			HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1);
+		if (size + cflush.offset > XEN_PAGE_SIZE)
+			cflush.length = XEN_PAGE_SIZE - cflush.offset;
+		else
+			cflush.length = size;
 
-		offset = 0;
-		xen_pfn++;
-		left -= len;
-	} while (left);
-}
+		HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1);
 
-static void __xen_dma_page_dev_to_cpu(struct device *hwdev, dma_addr_t handle,
-		size_t size, enum dma_data_direction dir)
-{
-	dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_UNMAP);
+		cflush.offset = 0;
+		cflush.a.dev_bus_addr += cflush.length;
+		size -= cflush.length;
+	} while (size);
 }
 
-static void __xen_dma_page_cpu_to_dev(struct device *hwdev, dma_addr_t handle,
-		size_t size, enum dma_data_direction dir)
+/*
+ * Dom0 is mapped 1:1, and while the Linux page can span across multiple Xen
+ * pages, it is not possible for it to contain a mix of local and foreign Xen
+ * pages.  Calling pfn_valid on a foreign mfn will always return false, so if
+ * pfn_valid returns true the pages is local and we can use the native
+ * dma-direct functions, otherwise we call the Xen specific version.
+ */
+void xen_dma_sync_for_cpu(struct device *dev, dma_addr_t handle,
+		phys_addr_t paddr, size_t size, enum dma_data_direction dir)
 {
-	dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_MAP);
+	if (pfn_valid(PFN_DOWN(handle)))
+		arch_sync_dma_for_cpu(dev, paddr, size, dir);
+	else if (dir != DMA_TO_DEVICE)
+		dma_cache_maint(handle, size, GNTTAB_CACHE_INVAL);
 }
 
-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, unsigned long attrs)
+void xen_dma_sync_for_device(struct device *dev, dma_addr_t handle,
+		phys_addr_t paddr, size_t size, enum dma_data_direction dir)
 {
-	if (is_device_dma_coherent(hwdev))
-		return;
-	if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
-		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,
-		unsigned long attrs)
-
-{
-	if (is_device_dma_coherent(hwdev))
-		return;
-	if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
-		return;
-
-	__xen_dma_page_dev_to_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)
-{
-	if (is_device_dma_coherent(hwdev))
-		return;
-	__xen_dma_page_dev_to_cpu(hwdev, handle, size, dir);
-}
-
-void __xen_dma_sync_single_for_device(struct device *hwdev,
-		dma_addr_t handle, size_t size, enum dma_data_direction dir)
-{
-	if (is_device_dma_coherent(hwdev))
-		return;
-	__xen_dma_page_cpu_to_dev(hwdev, handle, size, dir);
+	if (pfn_valid(PFN_DOWN(handle)))
+		arch_sync_dma_for_device(dev, paddr, size, dir);
+	else if (dir == DMA_FROM_DEVICE)
+		dma_cache_maint(handle, size, GNTTAB_CACHE_INVAL);
+	else
+		dma_cache_maint(handle, size, GNTTAB_CACHE_CLEAN);
 }
 
 bool xen_arch_need_swiotlb(struct device *dev,
@@ -159,7 +110,7 @@ bool xen_arch_need_swiotlb(struct device *dev,
 	 * memory and we are not able to flush the cache.
 	 */
 	return (!hypercall_cflush && (xen_pfn != bfn) &&
-		!is_device_dma_coherent(dev));
+		!dev_is_dma_coherent(dev));
 }
 
 int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
@@ -173,16 +124,11 @@ int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
 	*dma_handle = pstart;
 	return 0;
 }
-EXPORT_SYMBOL_GPL(xen_create_contiguous_region);
 
 void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
 {
 	return;
 }
-EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region);
-
-const struct dma_map_ops *xen_dma_ops;
-EXPORT_SYMBOL(xen_dma_ops);
 
 int __init xen_mm_init(void)
 {
@@ -190,7 +136,6 @@ int __init xen_mm_init(void)
 	if (!xen_initial_domain())
 		return 0;
 	xen_swiotlb_init(1, false);
-	xen_dma_ops = &xen_swiotlb_dma_ops;
 
 	cflush.op = 0;
 	cflush.a.dev_bus_addr = 0;

arch/arm64/Kconfig

@@ -13,7 +13,6 @@ config ARM64
 	select ARCH_HAS_DEBUG_VIRTUAL
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select ARCH_HAS_DMA_COHERENT_TO_PFN
-	select ARCH_HAS_DMA_MMAP_PGPROT
 	select ARCH_HAS_DMA_PREP_COHERENT
 	select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
 	select ARCH_HAS_ELF_RANDOMIZE

arch/arm64/include/asm/Kbuild

@@ -4,6 +4,7 @@ generic-y += delay.h
 generic-y += div64.h
 generic-y += dma.h
 generic-y += dma-contiguous.h
+generic-y += dma-mapping.h
 generic-y += early_ioremap.h
 generic-y += emergency-restart.h
 generic-y += hw_irq.h

arch/arm64/include/asm/dma-mapping.h

-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Copyright (C) 2012 ARM Ltd.
- */
-#ifndef __ASM_DMA_MAPPING_H
-#define __ASM_DMA_MAPPING_H
-
-#include <linux/types.h>
-#include <linux/vmalloc.h>
-
-#include <xen/xen.h>
-#include <asm/xen/hypervisor.h>
-
-static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
-{
-	return NULL;
-}
-
-/*
- * Do not use this function in a driver, it is only provided for
- * arch/arm/mm/xen.c, which is used by arm64 as well.
- */
-static inline bool is_device_dma_coherent(struct device *dev)
-{
-	return dev->dma_coherent;
-}
-
-#endif	/* __ASM_DMA_MAPPING_H */

arch/arm64/include/asm/pgtable.h

@@ -437,6 +437,18 @@ static inline pmd_t pmd_mkdevmap(pmd_t pmd)
 	__pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_NORMAL_NC) | PTE_PXN | PTE_UXN)
 #define pgprot_device(prot) \
 	__pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_DEVICE_nGnRE) | PTE_PXN | PTE_UXN)
+/*
+ * DMA allocations for non-coherent devices use what the Arm architecture calls
+ * "Normal non-cacheable" memory, which permits speculation, unaligned accesses
+ * and merging of writes.  This is different from "Device-nGnR[nE]" memory which
+ * is intended for MMIO and thus forbids speculation, preserves access size,
+ * requires strict alignment and can also force write responses to come from the
+ * endpoint.
+ */
+#define pgprot_dmacoherent(prot) \
+	__pgprot_modify(prot, PTE_ATTRINDX_MASK, \
+			PTE_ATTRINDX(MT_NORMAL_NC) | PTE_PXN | PTE_UXN)
+
 #define __HAVE_PHYS_MEM_ACCESS_PROT
 struct file;
 extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,

arch/arm64/include/asm/xen/page-coherent.h

 /* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _ASM_ARM64_XEN_PAGE_COHERENT_H
-#define _ASM_ARM64_XEN_PAGE_COHERENT_H
-
-#include <linux/dma-mapping.h>
-#include <asm/page.h>
 #include <xen/arm/page-coherent.h>
-
-static inline void *xen_alloc_coherent_pages(struct device *hwdev, size_t size,
-		dma_addr_t *dma_handle, gfp_t flags, unsigned long attrs)
-{
-	return dma_direct_alloc(hwdev, size, dma_handle, flags, attrs);
-}
-
-static inline void xen_free_coherent_pages(struct device *hwdev, size_t size,
-		void *cpu_addr, dma_addr_t dma_handle, unsigned long attrs)
-{
-	dma_direct_free(hwdev, size, cpu_addr, dma_handle, 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)
-{
-	unsigned long pfn = PFN_DOWN(handle);
-
-	if (pfn_valid(pfn))
-		dma_direct_sync_single_for_cpu(hwdev, handle, size, dir);
-	else
-		__xen_dma_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)
-{
-	unsigned long pfn = PFN_DOWN(handle);
-	if (pfn_valid(pfn))
-		dma_direct_sync_single_for_device(hwdev, handle, size, dir);
-	else
-		__xen_dma_sync_single_for_device(hwdev, handle, size, dir);
-}
-
-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, unsigned long attrs)
-{
-	unsigned long page_pfn = page_to_xen_pfn(page);
-	unsigned long dev_pfn = XEN_PFN_DOWN(dev_addr);
-	unsigned long compound_pages =
-		(1<<compound_order(page)) * XEN_PFN_PER_PAGE;
-	bool local = (page_pfn <= dev_pfn) &&
-		(dev_pfn - page_pfn < compound_pages);
-
-	if (local)
-		dma_direct_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,
-		size_t size, enum dma_data_direction dir, unsigned long attrs)
-{
-	unsigned long pfn = PFN_DOWN(handle);
-	/*
-	 * Dom0 is mapped 1:1, while the Linux page can be spanned accross
-	 * multiple Xen page, it's not possible to have a mix of local and
-	 * foreign Xen page. Dom0 is mapped 1:1, so calling pfn_valid on a
-	 * foreign mfn will always return false. If the page is local we can
-	 * safely call the native dma_ops function, otherwise we call the xen
-	 * specific function.
-	 */
-	if (pfn_valid(pfn))
-		dma_direct_unmap_page(hwdev, handle, size, dir, attrs);
-	else
-		__xen_dma_unmap_page(hwdev, handle, size, dir, attrs);
-}
-
-#endif /* _ASM_ARM64_XEN_PAGE_COHERENT_H */

arch/arm64/mm/dma-mapping.c

@@ -8,15 +8,11 @@
 #include <linux/cache.h>
 #include <linux/dma-noncoherent.h>
 #include <linux/dma-iommu.h>
+#include <xen/xen.h>
+#include <xen/swiotlb-xen.h>
 
 #include <asm/cacheflush.h>
 
-pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
-		unsigned long attrs)
-{
-	return pgprot_writecombine(prot);
-}
-
 void arch_sync_dma_for_device(struct device *dev, phys_addr_t paddr,
 		size_t size, enum dma_data_direction dir)
 {
@@ -34,12 +30,6 @@ void arch_dma_prep_coherent(struct page *page, size_t size)
 	__dma_flush_area(page_address(page), size);
 }
 
-static int __init arm64_dma_init(void)
-{
-	return dma_atomic_pool_init(GFP_DMA32, __pgprot(PROT_NORMAL_NC));
-}
-arch_initcall(arm64_dma_init);
-
 #ifdef CONFIG_IOMMU_DMA
 void arch_teardown_dma_ops(struct device *dev)
 {
@@ -64,6 +54,6 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 
 #ifdef CONFIG_XEN
 	if (xen_initial_domain())
-		dev->dma_ops = xen_dma_ops;
+		dev->dma_ops = &xen_swiotlb_dma_ops;
 #endif
 }

arch/c6x/Kconfig

@@ -20,7 +20,6 @@ config C6X
 	select OF_EARLY_FLATTREE
 	select GENERIC_CLOCKEVENTS
 	select MODULES_USE_ELF_RELA
-	select ARCH_NO_COHERENT_DMA_MMAP
 	select MMU_GATHER_NO_RANGE if MMU
 
 config MMU

arch/csky/mm/dma-mapping.c

@@ -14,12 +14,6 @@
 #include <linux/version.h>
 #include <asm/cache.h>
 
-static int __init atomic_pool_init(void)
-{
-	return dma_atomic_pool_init(GFP_KERNEL, pgprot_noncached(PAGE_KERNEL));
-}
-postcore_initcall(atomic_pool_init);
-
 void arch_dma_prep_coherent(struct page *page, size_t size)
 {
 	if (PageHighMem(page)) {

arch/ia64/hp/common/sba_iommu.c

@@ -2069,6 +2069,8 @@ static const struct dma_map_ops sba_dma_ops = {
 	.map_sg			= sba_map_sg_attrs,
 	.unmap_sg		= sba_unmap_sg_attrs,
 	.dma_supported		= sba_dma_supported,
+	.mmap			= dma_common_mmap,
+	.get_sgtable		= dma_common_get_sgtable,
 };
 
 static int __init

arch/ia64/kernel/setup.c

@@ -259,7 +259,7 @@ __initcall(register_memory);
  * This function checks if the reserved crashkernel is allowed on the specific
  * IA64 machine flavour. Machines without an IO TLB use swiotlb and require
  * some memory below 4 GB (i.e. in 32 bit area), see the implementation of
- * lib/swiotlb.c. The hpzx1 architecture has an IO TLB but cannot use that
+ * kernel/dma/swiotlb.c. The hpzx1 architecture has an IO TLB but cannot use that
  * in kdump case. See the comment in sba_init() in sba_iommu.c.
  *
  * So, the only machvec that really supports loading the kdump kernel

arch/m68k/Kconfig

@@ -4,11 +4,9 @@ config M68K
 	default y
 	select ARCH_32BIT_OFF_T
 	select ARCH_HAS_BINFMT_FLAT
-	select ARCH_HAS_DMA_MMAP_PGPROT if MMU && !COLDFIRE
 	select ARCH_HAS_DMA_PREP_COHERENT if HAS_DMA && MMU && !COLDFIRE
 	select ARCH_HAS_SYNC_DMA_FOR_DEVICE if HAS_DMA
 	select ARCH_MIGHT_HAVE_PC_PARPORT if ISA
-	select ARCH_NO_COHERENT_DMA_MMAP if !MMU
 	select ARCH_NO_PREEMPT if !COLDFIRE
 	select BINFMT_FLAT_ARGVP_ENVP_ON_STACK
 	select DMA_DIRECT_REMAP if HAS_DMA && MMU && !COLDFIRE

arch/m68k/include/asm/pgtable_mm.h

@@ -169,6 +169,9 @@ static inline void update_mmu_cache(struct vm_area_struct *vma,
 	    ? (__pgprot((pgprot_val(prot) & _CACHEMASK040) | _PAGE_NOCACHE_S))	\
 	    : (prot)))
 
+pgprot_t pgprot_dmacoherent(pgprot_t prot);
+#define pgprot_dmacoherent(prot)	pgprot_dmacoherent(prot)
+
 #endif /* CONFIG_COLDFIRE */
 #include <asm-generic/pgtable.h>
 #endif /* !__ASSEMBLY__ */

arch/m68k/kernel/dma.c

@@ -23,8 +23,7 @@ void arch_dma_prep_coherent(struct page *page, size_t size)
 	cache_push(page_to_phys(page), size);
 }
 
-pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
-		unsigned long attrs)
+pgprot_t pgprot_dmacoherent(pgprot_t prot)
 {
 	if (CPU_IS_040_OR_060) {
 		pgprot_val(prot) &= ~_PAGE_CACHE040;

arch/microblaze/Kconfig

@@ -9,7 +9,6 @@ config MICROBLAZE
 	select ARCH_HAS_SYNC_DMA_FOR_CPU
 	select ARCH_HAS_SYNC_DMA_FOR_DEVICE
 	select ARCH_MIGHT_HAVE_PC_PARPORT
-	select ARCH_NO_COHERENT_DMA_MMAP if !MMU
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select BUILDTIME_EXTABLE_SORT
 	select TIMER_OF

arch/mips/Kconfig

@@ -1119,7 +1119,14 @@ config DMA_PERDEV_COHERENT
 
 config DMA_NONCOHERENT
 	bool
-	select ARCH_HAS_DMA_MMAP_PGPROT
+	#
+	# MIPS allows mixing "slightly different" Cacheability and Coherency
+	# Attribute bits.  It is believed that the uncached access through
+	# KSEG1 and the implementation specific "uncached accelerated" used
+	# by pgprot_writcombine can be mixed, and the latter sometimes provides
+	# significant advantages.
+	#
+	select ARCH_HAS_DMA_WRITE_COMBINE
 	select ARCH_HAS_SYNC_DMA_FOR_DEVICE
 	select ARCH_HAS_UNCACHED_SEGMENT
 	select NEED_DMA_MAP_STATE

arch/mips/jazz/jazzdma.c

@@ -682,5 +682,7 @@ const struct dma_map_ops jazz_dma_ops = {
 	.sync_sg_for_device	= jazz_dma_sync_sg_for_device,
 	.dma_supported		= dma_direct_supported,
 	.cache_sync		= arch_dma_cache_sync,
+	.mmap			= dma_common_mmap,
+	.get_sgtable		= dma_common_get_sgtable,
 };
 EXPORT_SYMBOL(jazz_dma_ops);

arch/mips/mm/dma-noncoherent.c

@@ -65,14 +65,6 @@ long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr,
 	return page_to_pfn(virt_to_page(cached_kernel_address(cpu_addr)));
 }
 
-pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
-		unsigned long attrs)
-{
-	if (attrs & DMA_ATTR_WRITE_COMBINE)
-		return pgprot_writecombine(prot);
-	return pgprot_noncached(prot);
-}
-
 static inline void dma_sync_virt(void *addr, size_t size,
 		enum dma_data_direction dir)
 {

arch/nds32/kernel/dma.c

@@ -80,9 +80,3 @@ void arch_dma_prep_coherent(struct page *page, size_t size)
 {
 	cache_op(page_to_phys(page), size, cpu_dma_wbinval_range);
 }
-
-static int __init atomic_pool_init(void)
-{
-	return dma_atomic_pool_init(GFP_KERNEL, pgprot_noncached(PAGE_KERNEL));
-}
-postcore_initcall(atomic_pool_init);

arch/parisc/Kconfig

@@ -52,7 +52,6 @@ config PARISC
 	select GENERIC_SCHED_CLOCK
 	select HAVE_UNSTABLE_SCHED_CLOCK if SMP
 	select GENERIC_CLOCKEVENTS
-	select ARCH_NO_COHERENT_DMA_MMAP
 	select CPU_NO_EFFICIENT_FFS
 	select NEED_DMA_MAP_STATE
 	select NEED_SG_DMA_LENGTH

arch/powerpc/kernel/dma-iommu.c

@@ -208,4 +208,6 @@ const struct dma_map_ops dma_iommu_ops = {
 	.sync_single_for_device	= dma_iommu_sync_for_device,
 	.sync_sg_for_cpu	= dma_iommu_sync_sg_for_cpu,
 	.sync_sg_for_device	= dma_iommu_sync_sg_for_device,
+	.mmap			= dma_common_mmap,
+	.get_sgtable		= dma_common_get_sgtable,
 };

arch/powerpc/platforms/ps3/system-bus.c

@@ -686,20 +686,16 @@ static int ps3_dma_supported(struct device *_dev, u64 mask)
 	return mask >= DMA_BIT_MASK(32);
 }
 
-static u64 ps3_dma_get_required_mask(struct device *_dev)
-{
-	return DMA_BIT_MASK(32);
-}
-
 static const struct dma_map_ops ps3_sb_dma_ops = {
 	.alloc = ps3_alloc_coherent,
 	.free = ps3_free_coherent,
 	.map_sg = ps3_sb_map_sg,
 	.unmap_sg = ps3_sb_unmap_sg,
 	.dma_supported = ps3_dma_supported,
-	.get_required_mask = ps3_dma_get_required_mask,
 	.map_page = ps3_sb_map_page,
 	.unmap_page = ps3_unmap_page,
+	.mmap = dma_common_mmap,
+	.get_sgtable = dma_common_get_sgtable,
 };
 
 static const struct dma_map_ops ps3_ioc0_dma_ops = {
@@ -708,9 +704,10 @@ static const struct dma_map_ops ps3_ioc0_dma_ops = {
 	.map_sg = ps3_ioc0_map_sg,
 	.unmap_sg = ps3_ioc0_unmap_sg,
 	.dma_supported = ps3_dma_supported,
-	.get_required_mask = ps3_dma_get_required_mask,
 	.map_page = ps3_ioc0_map_page,
 	.unmap_page = ps3_unmap_page,
+	.mmap = dma_common_mmap,
+	.get_sgtable = dma_common_get_sgtable,
 };
 
 /**

arch/powerpc/platforms/pseries/vio.c

@@ -605,6 +605,8 @@ static const struct dma_map_ops vio_dma_mapping_ops = {
 	.unmap_page        = vio_dma_iommu_unmap_page,
 	.dma_supported     = dma_iommu_dma_supported,
 	.get_required_mask = dma_iommu_get_required_mask,
+	.mmap		   = dma_common_mmap,
+	.get_sgtable	   = dma_common_get_sgtable,
 };
 
 /**

arch/s390/pci/pci_dma.c

@@ -668,6 +668,8 @@ const struct dma_map_ops s390_pci_dma_ops = {
 	.unmap_sg	= s390_dma_unmap_sg,
 	.map_page	= s390_dma_map_pages,
 	.unmap_page	= s390_dma_unmap_pages,
+	.mmap		= dma_common_mmap,
+	.get_sgtable	= dma_common_get_sgtable,
 	/* dma_supported is unconditionally true without a callback */
 };
 EXPORT_SYMBOL_GPL(s390_pci_dma_ops);

arch/sh/Kconfig

@@ -5,7 +5,6 @@ config SUPERH
 	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_MIGHT_HAVE_PC_PARPORT
-	select ARCH_NO_COHERENT_DMA_MMAP if !MMU
 	select HAVE_PATA_PLATFORM
 	select CLKDEV_LOOKUP
 	select DMA_DECLARE_COHERENT

arch/unicore32/include/asm/pgtable.h

@@ -198,8 +198,6 @@ static inline pte_t pte_mkspecial(pte_t pte) { return pte; }
 	__pgprot(pgprot_val(prot) & ~PTE_CACHEABLE)
 #define pgprot_writecombine(prot)	\
 	__pgprot(pgprot_val(prot) & ~PTE_CACHEABLE)
-#define pgprot_dmacoherent(prot)	\
-	__pgprot(pgprot_val(prot) & ~PTE_CACHEABLE)
 
 #define pmd_none(pmd)		(!pmd_val(pmd))
 #define pmd_present(pmd)	(pmd_val(pmd) & PMD_PRESENT)

arch/x86/include/asm/xen/page-coherent.h

@@ -21,18 +21,4 @@ static inline void xen_free_coherent_pages(struct device *hwdev, size_t size,
 	free_pages((unsigned long) cpu_addr, get_order(size));
 }
 
-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, unsigned long attrs) { }
-
-static inline void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
-		size_t size, enum dma_data_direction dir,
-		unsigned long 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) { }
-
-static inline void xen_dma_sync_single_for_device(struct device *hwdev,
-		dma_addr_t handle, size_t size, enum dma_data_direction dir) { }
-
 #endif /* _ASM_X86_XEN_PAGE_COHERENT_H */

arch/x86/kernel/amd_gart_64.c

@@ -677,7 +677,10 @@ static const struct dma_map_ops gart_dma_ops = {
 	.unmap_page			= gart_unmap_page,
 	.alloc				= gart_alloc_coherent,
 	.free				= gart_free_coherent,
+	.mmap				= dma_common_mmap,
+	.get_sgtable			= dma_common_get_sgtable,
 	.dma_supported			= dma_direct_supported,
+	.get_required_mask		= dma_direct_get_required_mask,
 };
 
 static void gart_iommu_shutdown(void)

arch/x86/kernel/pci-calgary_64.c

@@ -468,6 +468,8 @@ static const struct dma_map_ops calgary_dma_ops = {
 	.map_page = calgary_map_page,
 	.unmap_page = calgary_unmap_page,
 	.dma_supported = dma_direct_supported,
+	.mmap = dma_common_mmap,
+	.get_sgtable = dma_common_get_sgtable,
 };
 
 static inline void __iomem * busno_to_bbar(unsigned char num)

arch/x86/kernel/pci-swiotlb.c

 // SPDX-License-Identifier: GPL-2.0
-/* Glue code to lib/swiotlb.c */
 
 #include <linux/pci.h>
 #include <linux/cache.h>

arch/x86/kernel/setup.c

@@ -486,7 +486,7 @@ static int __init reserve_crashkernel_low(void)
 	ret = parse_crashkernel_low(boot_command_line, total_low_mem, &low_size, &base);
 	if (ret) {
 		/*
-		 * two parts from lib/swiotlb.c:
+		 * two parts from kernel/dma/swiotlb.c:
 		 * -swiotlb size: user-specified with swiotlb= or default.
 		 *
 		 * -swiotlb overflow buffer: now hardcoded to 32k. We round it

arch/x86/pci/sta2x11-fixup.c

 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * arch/x86/pci/sta2x11-fixup.c
- * glue code for lib/swiotlb.c and DMA translation between STA2x11
- * AMBA memory mapping and the X86 memory mapping
+ * DMA translation between STA2x11 AMBA memory mapping and the x86 memory mapping
  *
  * ST Microelectronics ConneXt (STA2X11/STA2X10)
  *

arch/x86/xen/mmu_pv.c

@@ -2625,7 +2625,6 @@ int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
 	*dma_handle = virt_to_machine(vstart).maddr;
 	return success ? 0 : -ENOMEM;
 }
-EXPORT_SYMBOL_GPL(xen_create_contiguous_region);
 
 void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
 {
@@ -2660,7 +2659,6 @@ void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
 
 	spin_unlock_irqrestore(&xen_reservation_lock, flags);
 }
-EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region);
 
 static noinline void xen_flush_tlb_all(void)
 {

arch/xtensa/Kconfig

@@ -5,7 +5,6 @@ config XTENSA
 	select ARCH_HAS_BINFMT_FLAT if !MMU
 	select ARCH_HAS_SYNC_DMA_FOR_CPU
 	select ARCH_HAS_SYNC_DMA_FOR_DEVICE
-	select ARCH_NO_COHERENT_DMA_MMAP if !MMU
 	select ARCH_USE_QUEUED_RWLOCKS
 	select ARCH_USE_QUEUED_SPINLOCKS
 	select ARCH_WANT_FRAME_POINTERS

arch/xtensa/kernel/pci-dma.c

@@ -167,7 +167,7 @@ void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
 	if (PageHighMem(page)) {
 		void *p;
 
-		p = dma_common_contiguous_remap(page, size, VM_MAP,
+		p = dma_common_contiguous_remap(page, size,
 						pgprot_noncached(PAGE_KERNEL),
 						__builtin_return_address(0));
 		if (!p) {
@@ -192,7 +192,7 @@ void arch_dma_free(struct device *dev, size_t size, void *vaddr,
 		page = virt_to_page(platform_vaddr_to_cached(vaddr));
 	} else {
 #ifdef CONFIG_MMU
-		dma_common_free_remap(vaddr, size, VM_MAP);
+		dma_common_free_remap(vaddr, size);
 #endif
 		page = pfn_to_page(PHYS_PFN(dma_to_phys(dev, dma_handle)));
 	}

block/blk-settings.c

@@ -12,6 +12,7 @@
 #include <linux/lcm.h>
 #include <linux/jiffies.h>
 #include <linux/gfp.h>
+#include <linux/dma-mapping.h>
 
 #include "blk.h"
 #include "blk-wbt.h"
@@ -848,6 +849,28 @@ void blk_queue_required_elevator_features(struct request_queue *q,
 }
 EXPORT_SYMBOL_GPL(blk_queue_required_elevator_features);
 
+/**
+ * blk_queue_can_use_dma_map_merging - configure queue for merging segments.
+ * @q:		the request queue for the device
+ * @dev:	the device pointer for dma
+ *
+ * Tell the block layer about merging the segments by dma map of @q.
+ */
+bool blk_queue_can_use_dma_map_merging(struct request_queue *q,
+				       struct device *dev)
+{
+	unsigned long boundary = dma_get_merge_boundary(dev);
+
+	if (!boundary)
+		return false;
+
+	/* No need to update max_segment_size. see blk_queue_virt_boundary() */
+	blk_queue_virt_boundary(q, boundary);
+
+	return true;
+}
+EXPORT_SYMBOL_GPL(blk_queue_can_use_dma_map_merging);
+
 static int __init blk_settings_init(void)
 {
 	blk_max_low_pfn = max_low_pfn - 1;

drivers/gpu/drm/omapdrm/dss/dispc.c

@@ -4609,11 +4609,10 @@ static int dispc_errata_i734_wa_init(struct dispc_device *dispc)
 	i734_buf.size = i734.ovli.width * i734.ovli.height *
 		color_mode_to_bpp(i734.ovli.fourcc) / 8;
 
-	i734_buf.vaddr = dma_alloc_writecombine(&dispc->pdev->dev,
-						i734_buf.size, &i734_buf.paddr,
-						GFP_KERNEL);
+	i734_buf.vaddr = dma_alloc_wc(&dispc->pdev->dev, i734_buf.size,
+				      &i734_buf.paddr, GFP_KERNEL);
 	if (!i734_buf.vaddr) {
-		dev_err(&dispc->pdev->dev, "%s: dma_alloc_writecombine failed\n",
+		dev_err(&dispc->pdev->dev, "%s: dma_alloc_wc failed\n",
 			__func__);
 		return -ENOMEM;
 	}
@@ -4626,8 +4625,8 @@ static void dispc_errata_i734_wa_fini(struct dispc_device *dispc)
 	if (!dispc->feat->has_gamma_i734_bug)
 		return;
 
-	dma_free_writecombine(&dispc->pdev->dev, i734_buf.size, i734_buf.vaddr,
-			      i734_buf.paddr);
+	dma_free_wc(&dispc->pdev->dev, i734_buf.size, i734_buf.vaddr,
+		    i734_buf.paddr);
 }
 
 static void dispc_errata_i734_wa(struct dispc_device *dispc)

drivers/iommu/amd_iommu.c

@@ -2754,6 +2754,8 @@ static const struct dma_map_ops amd_iommu_dma_ops = {
 	.map_sg		= map_sg,
 	.unmap_sg	= unmap_sg,
 	.dma_supported	= amd_iommu_dma_supported,
+	.mmap		= dma_common_mmap,
+	.get_sgtable	= dma_common_get_sgtable,
 };
 
 static int init_reserved_iova_ranges(void)

drivers/iommu/dma-iommu.c

@@ -548,15 +548,6 @@ static struct page **__iommu_dma_alloc_pages(struct device *dev,
 	return pages;
 }
 
-static struct page **__iommu_dma_get_pages(void *cpu_addr)
-{
-	struct vm_struct *area = find_vm_area(cpu_addr);
-
-	if (!area || !area->pages)
-		return NULL;
-	return area->pages;
-}
-
 /**
  * iommu_dma_alloc_remap - Allocate and map a buffer contiguous in IOVA space
  * @dev: Device to allocate memory for. Must be a real device
@@ -624,7 +615,7 @@ static void *iommu_dma_alloc_remap(struct device *dev, size_t size,
 			< size)
 		goto out_free_sg;
 
-	vaddr = dma_common_pages_remap(pages, size, VM_USERMAP, prot,
+	vaddr = dma_common_pages_remap(pages, size, prot,
 			__builtin_return_address(0));
 	if (!vaddr)
 		goto out_unmap;
@@ -945,10 +936,10 @@ static void __iommu_dma_free(struct device *dev, size_t size, void *cpu_addr)
 		 * If it the address is remapped, then it's either non-coherent
 		 * or highmem CMA, or an iommu_dma_alloc_remap() construction.
 		 */
-		pages = __iommu_dma_get_pages(cpu_addr);
+		pages = dma_common_find_pages(cpu_addr);
 		if (!pages)
 			page = vmalloc_to_page(cpu_addr);
-		dma_common_free_remap(cpu_addr, alloc_size, VM_USERMAP);
+		dma_common_free_remap(cpu_addr, alloc_size);
 	} else {
 		/* Lowmem means a coherent atomic or CMA allocation */
 		page = virt_to_page(cpu_addr);
@@ -986,7 +977,7 @@ static void *iommu_dma_alloc_pages(struct device *dev, size_t size,
 		pgprot_t prot = dma_pgprot(dev, PAGE_KERNEL, attrs);
 
 		cpu_addr = dma_common_contiguous_remap(page, alloc_size,
-				VM_USERMAP, prot, __builtin_return_address(0));
+				prot, __builtin_return_address(0));
 		if (!cpu_addr)
 			goto out_free_pages;
 
@@ -1052,7 +1043,7 @@ static int iommu_dma_mmap(struct device *dev, struct vm_area_struct *vma,
 		return -ENXIO;
 
 	if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr)) {
-		struct page **pages = __iommu_dma_get_pages(cpu_addr);
+		struct page **pages = dma_common_find_pages(cpu_addr);
 
 		if (pages)
 			return __iommu_dma_mmap(pages, size, vma);
@@ -1074,7 +1065,7 @@ static int iommu_dma_get_sgtable(struct device *dev, struct sg_table *sgt,
 	int ret;
 
 	if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr)) {
-		struct page **pages = __iommu_dma_get_pages(cpu_addr);
+		struct page **pages = dma_common_find_pages(cpu_addr);
 
 		if (pages) {
 			return sg_alloc_table_from_pages(sgt, pages,
@@ -1093,6 +1084,13 @@ static int iommu_dma_get_sgtable(struct device *dev, struct sg_table *sgt,
 	return ret;
 }
 
+static unsigned long iommu_dma_get_merge_boundary(struct device *dev)
+{
+	struct iommu_domain *domain = iommu_get_dma_domain(dev);
+
+	return (1UL << __ffs(domain->pgsize_bitmap)) - 1;
+}
+
 static const struct dma_map_ops iommu_dma_ops = {
 	.alloc			= iommu_dma_alloc,
 	.free			= iommu_dma_free,
@@ -1108,6 +1106,7 @@ static const struct dma_map_ops iommu_dma_ops = {
 	.sync_sg_for_device	= iommu_dma_sync_sg_for_device,
 	.map_resource		= iommu_dma_map_resource,
 	.unmap_resource		= iommu_dma_unmap_resource,
+	.get_merge_boundary	= iommu_dma_get_merge_boundary,
 };
 
 /*

drivers/iommu/intel-iommu.c

@@ -3785,6 +3785,8 @@ static const struct dma_map_ops intel_dma_ops = {
 	.map_resource = intel_map_resource,
 	.unmap_resource = intel_unmap_resource,
 	.dma_supported = dma_direct_supported,
+	.mmap = dma_common_mmap,
+	.get_sgtable = dma_common_get_sgtable,
 };
 
 static void

drivers/mmc/core/queue.c

@@ -21,6 +21,8 @@
 #include "card.h"
 #include "host.h"
 
+#define MMC_DMA_MAP_MERGE_SEGMENTS	512
+
 static inline bool mmc_cqe_dcmd_busy(struct mmc_queue *mq)
 {
 	/* Allow only 1 DCMD at a time */
@@ -193,6 +195,12 @@ static void mmc_queue_setup_discard(struct request_queue *q,
 		blk_queue_flag_set(QUEUE_FLAG_SECERASE, q);
 }
 
+static unsigned int mmc_get_max_segments(struct mmc_host *host)
+{
+	return host->can_dma_map_merge ? MMC_DMA_MAP_MERGE_SEGMENTS :
+					 host->max_segs;
+}
+
 /**
  * mmc_init_request() - initialize the MMC-specific per-request data
  * @q: the request queue
@@ -206,7 +214,7 @@ static int __mmc_init_request(struct mmc_queue *mq, struct request *req,
 	struct mmc_card *card = mq->card;
 	struct mmc_host *host = card->host;
 
-	mq_rq->sg = mmc_alloc_sg(host->max_segs, gfp);
+	mq_rq->sg = mmc_alloc_sg(mmc_get_max_segments(host), gfp);
 	if (!mq_rq->sg)
 		return -ENOMEM;
 
@@ -362,13 +370,23 @@ static void mmc_setup_queue(struct mmc_queue *mq, struct mmc_card *card)
 		blk_queue_bounce_limit(mq->queue, BLK_BOUNCE_HIGH);
 	blk_queue_max_hw_sectors(mq->queue,
 		min(host->max_blk_count, host->max_req_size / 512));
-	blk_queue_max_segments(mq->queue, host->max_segs);
+	if (host->can_dma_map_merge)
+		WARN(!blk_queue_can_use_dma_map_merging(mq->queue,
+							mmc_dev(host)),
+		     "merging was advertised but not possible");
+	blk_queue_max_segments(mq->queue, mmc_get_max_segments(host));
 
 	if (mmc_card_mmc(card))
 		block_size = card->ext_csd.data_sector_size;
 
 	blk_queue_logical_block_size(mq->queue, block_size);
-	blk_queue_max_segment_size(mq->queue,
+	/*
+	 * After blk_queue_can_use_dma_map_merging() was called with succeed,
+	 * since it calls blk_queue_virt_boundary(), the mmc should not call
+	 * both blk_queue_max_segment_size().
+	 */
+	if (!host->can_dma_map_merge)
+		blk_queue_max_segment_size(mq->queue,
 			round_down(host->max_seg_size, block_size));
 
 	dma_set_max_seg_size(mmc_dev(host), queue_max_segment_size(mq->queue));
@@ -381,6 +399,11 @@ static void mmc_setup_queue(struct mmc_queue *mq, struct mmc_card *card)
 	init_waitqueue_head(&mq->wait);
 }
 
+static inline bool mmc_merge_capable(struct mmc_host *host)
+{
+	return host->caps2 & MMC_CAP2_MERGE_CAPABLE;
+}
+
 /* Set queue depth to get a reasonable value for q->nr_requests */
 #define MMC_QUEUE_DEPTH 64
 
@@ -418,6 +441,18 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card)
 	mq->tag_set.cmd_size = sizeof(struct mmc_queue_req);
 	mq->tag_set.driver_data = mq;
 
+	/*
+	 * Since blk_mq_alloc_tag_set() calls .init_request() of mmc_mq_ops,
+	 * the host->can_dma_map_merge should be set before to get max_segs
+	 * from mmc_get_max_segments().
+	 */
+	if (mmc_merge_capable(host) &&
+	    host->max_segs < MMC_DMA_MAP_MERGE_SEGMENTS &&
+	    dma_get_merge_boundary(mmc_dev(host)))
+		host->can_dma_map_merge = 1;
+	else
+		host->can_dma_map_merge = 0;
+
 	ret = blk_mq_alloc_tag_set(&mq->tag_set);
 	if (ret)
 		return ret;

drivers/mmc/host/renesas_sdhi_internal_dmac.c

@@ -106,7 +106,7 @@ static const struct renesas_sdhi_of_data of_rcar_gen3_compatible = {
 			  TMIO_MMC_HAVE_CBSY | TMIO_MMC_MIN_RCAR2,
 	.capabilities	= MMC_CAP_SD_HIGHSPEED | MMC_CAP_SDIO_IRQ |
 			  MMC_CAP_CMD23,
-	.capabilities2	= MMC_CAP2_NO_WRITE_PROTECT,
+	.capabilities2	= MMC_CAP2_NO_WRITE_PROTECT | MMC_CAP2_MERGE_CAPABLE,
 	.bus_shift	= 2,
 	.scc_offset	= 0x1000,
 	.taps		= rcar_gen3_scc_taps,

drivers/parisc/ccio-dma.c

@@ -1024,6 +1024,7 @@ static const struct dma_map_ops ccio_ops = {
 	.unmap_page =		ccio_unmap_page,
 	.map_sg = 		ccio_map_sg,
 	.unmap_sg = 		ccio_unmap_sg,
+	.get_sgtable =		dma_common_get_sgtable,
 };
 
 #ifdef CONFIG_PROC_FS

drivers/parisc/sba_iommu.c

@@ -1084,6 +1084,7 @@ static const struct dma_map_ops sba_ops = {
 	.unmap_page =		sba_unmap_page,
 	.map_sg =		sba_map_sg,
 	.unmap_sg =		sba_unmap_sg,
+	.get_sgtable =		dma_common_get_sgtable,
 };
 
 

drivers/remoteproc/Kconfig

@@ -2,7 +2,7 @@
 menu "Remoteproc drivers"
 
 config REMOTEPROC
-	tristate "Support for Remote Processor subsystem"
+	bool "Support for Remote Processor subsystem"
 	depends on HAS_DMA
 	select CRC32
 	select FW_LOADER

drivers/xen/swiotlb-xen.c

@@ -28,6 +28,7 @@
 
 #include <linux/memblock.h>
 #include <linux/dma-direct.h>
+#include <linux/dma-noncoherent.h>
 #include <linux/export.h>
 #include <xen/swiotlb-xen.h>
 #include <xen/page.h>
@@ -391,6 +392,7 @@ static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
 	if (map == (phys_addr_t)DMA_MAPPING_ERROR)
 		return DMA_MAPPING_ERROR;
 
+	phys = map;
 	dev_addr = xen_phys_to_bus(map);
 
 	/*
@@ -402,14 +404,9 @@ static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
 		return DMA_MAPPING_ERROR;
 	}
 
-	page = pfn_to_page(map >> PAGE_SHIFT);
-	offset = map & ~PAGE_MASK;
 done:
-	/*
-	 * we are not interested in the dma_addr returned by xen_dma_map_page,
-	 * only in the potential cache flushes executed by the function.
-	 */
-	xen_dma_map_page(dev, page, dev_addr, offset, size, dir, attrs);
+	if (!dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		xen_dma_sync_for_device(dev, dev_addr, phys, size, dir);
 	return dev_addr;
 }
 
@@ -421,35 +418,29 @@ static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
  * After this call, reads by the cpu to the buffer are guaranteed to see
  * whatever the device wrote there.
  */
-static void xen_unmap_single(struct device *hwdev, dma_addr_t dev_addr,
-			     size_t size, enum dma_data_direction dir,
-			     unsigned long attrs)
+static void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
+		size_t size, enum dma_data_direction dir, unsigned long attrs)
 {
 	phys_addr_t paddr = xen_bus_to_phys(dev_addr);
 
 	BUG_ON(dir == DMA_NONE);
 
-	xen_dma_unmap_page(hwdev, dev_addr, size, dir, attrs);
+	if (!dev_is_dma_coherent(hwdev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		xen_dma_sync_for_cpu(hwdev, dev_addr, paddr, size, dir);
 
 	/* NOTE: We use dev_addr here, not paddr! */
 	if (is_xen_swiotlb_buffer(dev_addr))
 		swiotlb_tbl_unmap_single(hwdev, paddr, size, size, dir, attrs);
 }
 
-static void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
-			    size_t size, enum dma_data_direction dir,
-			    unsigned long attrs)
-{
-	xen_unmap_single(hwdev, dev_addr, size, dir, attrs);
-}
-
 static void
 xen_swiotlb_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr,
 		size_t size, enum dma_data_direction dir)
 {
 	phys_addr_t paddr = xen_bus_to_phys(dma_addr);
 
-	xen_dma_sync_single_for_cpu(dev, dma_addr, size, dir);
+	if (!dev_is_dma_coherent(dev))
+		xen_dma_sync_for_cpu(dev, dma_addr, paddr, size, dir);
 
 	if (is_xen_swiotlb_buffer(dma_addr))
 		swiotlb_tbl_sync_single(dev, paddr, size, dir, SYNC_FOR_CPU);
@@ -464,7 +455,8 @@ xen_swiotlb_sync_single_for_device(struct device *dev, dma_addr_t dma_addr,
 	if (is_xen_swiotlb_buffer(dma_addr))
 		swiotlb_tbl_sync_single(dev, paddr, size, dir, SYNC_FOR_DEVICE);
 
-	xen_dma_sync_single_for_device(dev, dma_addr, size, dir);
+	if (!dev_is_dma_coherent(dev))
+		xen_dma_sync_for_device(dev, dma_addr, paddr, size, dir);
 }
 
 /*
@@ -481,7 +473,8 @@ xen_swiotlb_unmap_sg(struct device *hwdev, struct scatterlist *sgl, int nelems,
 	BUG_ON(dir == DMA_NONE);
 
 	for_each_sg(sgl, sg, nelems, i)
-		xen_unmap_single(hwdev, sg->dma_address, sg_dma_len(sg), dir, attrs);
+		xen_swiotlb_unmap_page(hwdev, sg->dma_address, sg_dma_len(sg),
+				dir, attrs);
 
 }
 
@@ -547,51 +540,6 @@ xen_swiotlb_dma_supported(struct device *hwdev, u64 mask)
 	return xen_virt_to_bus(xen_io_tlb_end - 1) <= mask;
 }
 
-/*
- * Create userspace mapping for the DMA-coherent memory.
- * This function should be called with the pages from the current domain only,
- * passing pages mapped from other domains would lead to memory corruption.
- */
-static int
-xen_swiotlb_dma_mmap(struct device *dev, struct vm_area_struct *vma,
-		     void *cpu_addr, dma_addr_t dma_addr, size_t size,
-		     unsigned long attrs)
-{
-#ifdef CONFIG_ARM
-	if (xen_get_dma_ops(dev)->mmap)
-		return xen_get_dma_ops(dev)->mmap(dev, vma, cpu_addr,
-						    dma_addr, size, attrs);
-#endif
-	return dma_common_mmap(dev, vma, cpu_addr, dma_addr, size, attrs);
-}
-
-/*
- * This function should be called with the pages from the current domain only,
- * passing pages mapped from other domains would lead to memory corruption.
- */
-static int
-xen_swiotlb_get_sgtable(struct device *dev, struct sg_table *sgt,
-			void *cpu_addr, dma_addr_t handle, size_t size,
-			unsigned long attrs)
-{
-#ifdef CONFIG_ARM
-	if (xen_get_dma_ops(dev)->get_sgtable) {
-#if 0
-	/*
-	 * This check verifies that the page belongs to the current domain and
-	 * is not one mapped from another domain.
-	 * This check is for debug only, and should not go to production build
-	 */
-		unsigned long bfn = PHYS_PFN(dma_to_phys(dev, handle));
-		BUG_ON (!page_is_ram(bfn));
-#endif
-		return xen_get_dma_ops(dev)->get_sgtable(dev, sgt, cpu_addr,
-							   handle, size, attrs);
-	}
-#endif
-	return dma_common_get_sgtable(dev, sgt, cpu_addr, handle, size, attrs);
-}
-
 const struct dma_map_ops xen_swiotlb_dma_ops = {
 	.alloc = xen_swiotlb_alloc_coherent,
 	.free = xen_swiotlb_free_coherent,
@@ -604,6 +552,6 @@ const struct dma_map_ops xen_swiotlb_dma_ops = {
 	.map_page = xen_swiotlb_map_page,
 	.unmap_page = xen_swiotlb_unmap_page,
 	.dma_supported = xen_swiotlb_dma_supported,
-	.mmap = xen_swiotlb_dma_mmap,
-	.get_sgtable = xen_swiotlb_get_sgtable,
+	.mmap = dma_common_mmap,
+	.get_sgtable = dma_common_get_sgtable,
 };

include/linux/blkdev.h

@@ -1110,6 +1110,8 @@ extern void blk_queue_rq_timeout(struct request_queue *, unsigned int);
 extern void blk_queue_write_cache(struct request_queue *q, bool enabled, bool fua);
 extern void blk_queue_required_elevator_features(struct request_queue *q,
 						 unsigned int features);
+extern bool blk_queue_can_use_dma_map_merging(struct request_queue *q,
+					      struct device *dev);
 
 /*
  * Number of physical segments as sent to the device.

include/linux/dma-mapping.h

@@ -131,6 +131,7 @@ struct dma_map_ops {
 	int (*dma_supported)(struct device *dev, u64 mask);
 	u64 (*get_required_mask)(struct device *dev);
 	size_t (*max_mapping_size)(struct device *dev);
+	unsigned long (*get_merge_boundary)(struct device *dev);
 };
 
 #define DMA_MAPPING_ERROR		(~(dma_addr_t)0)
@@ -457,11 +458,13 @@ int dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt,
 int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
 		void *cpu_addr, dma_addr_t dma_addr, size_t size,
 		unsigned long attrs);
+bool dma_can_mmap(struct device *dev);
 int dma_supported(struct device *dev, u64 mask);
 int dma_set_mask(struct device *dev, u64 mask);
 int dma_set_coherent_mask(struct device *dev, u64 mask);
 u64 dma_get_required_mask(struct device *dev);
 size_t dma_max_mapping_size(struct device *dev);
+unsigned long dma_get_merge_boundary(struct device *dev);
 #else /* CONFIG_HAS_DMA */
 static inline dma_addr_t dma_map_page_attrs(struct device *dev,
 		struct page *page, size_t offset, size_t size,
@@ -547,6 +550,10 @@ static inline int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
 {
 	return -ENXIO;
 }
+static inline bool dma_can_mmap(struct device *dev)
+{
+	return false;
+}
 static inline int dma_supported(struct device *dev, u64 mask)
 {
 	return 0;
@@ -567,6 +574,10 @@ static inline size_t dma_max_mapping_size(struct device *dev)
 {
 	return 0;
 }
+static inline unsigned long dma_get_merge_boundary(struct device *dev)
+{
+	return 0;
+}
 #endif /* CONFIG_HAS_DMA */
 
 static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr,
@@ -610,16 +621,14 @@ extern int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
 		void *cpu_addr, dma_addr_t dma_addr, size_t size,
 		unsigned long attrs);
 
+struct page **dma_common_find_pages(void *cpu_addr);
 void *dma_common_contiguous_remap(struct page *page, size_t size,
-			unsigned long vm_flags,
 			pgprot_t prot, const void *caller);
 
 void *dma_common_pages_remap(struct page **pages, size_t size,
-			unsigned long vm_flags, pgprot_t prot,
-			const void *caller);
-void dma_common_free_remap(void *cpu_addr, size_t size, unsigned long vm_flags);
+			pgprot_t prot, const void *caller);
+void dma_common_free_remap(void *cpu_addr, size_t size);
 
-int __init dma_atomic_pool_init(gfp_t gfp, pgprot_t prot);
 bool dma_in_atomic_pool(void *start, size_t size);
 void *dma_alloc_from_pool(size_t size, struct page **ret_page, gfp_t flags);
 bool dma_free_from_pool(void *start, size_t size);
@@ -749,7 +758,6 @@ static inline int dma_get_cache_alignment(void)
 #ifdef CONFIG_DMA_DECLARE_COHERENT
 int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
 				dma_addr_t device_addr, size_t size);
-void dma_release_declared_memory(struct device *dev);
 #else
 static inline int
 dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
@@ -757,11 +765,6 @@ dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
 {
 	return -ENOSYS;
 }
-
-static inline void
-dma_release_declared_memory(struct device *dev)
-{
-}
 #endif /* CONFIG_DMA_DECLARE_COHERENT */
 
 static inline void *dmam_alloc_coherent(struct device *dev, size_t size,
@@ -781,9 +784,6 @@ static inline void *dma_alloc_wc(struct device *dev, size_t size,
 
 	return dma_alloc_attrs(dev, size, dma_addr, gfp, attrs);
 }
-#ifndef dma_alloc_writecombine
-#define dma_alloc_writecombine dma_alloc_wc
-#endif
 
 static inline void dma_free_wc(struct device *dev, size_t size,
 			       void *cpu_addr, dma_addr_t dma_addr)
@@ -791,9 +791,6 @@ static inline void dma_free_wc(struct device *dev, size_t size,
 	return dma_free_attrs(dev, size, cpu_addr, dma_addr,
 			      DMA_ATTR_WRITE_COMBINE);
 }
-#ifndef dma_free_writecombine
-#define dma_free_writecombine dma_free_wc
-#endif
 
 static inline int dma_mmap_wc(struct device *dev,
 			      struct vm_area_struct *vma,
@@ -803,9 +800,6 @@ static inline int dma_mmap_wc(struct device *dev,
 	return dma_mmap_attrs(dev, vma, cpu_addr, dma_addr, size,
 			      DMA_ATTR_WRITE_COMBINE);
 }
-#ifndef dma_mmap_writecombine
-#define dma_mmap_writecombine dma_mmap_wc
-#endif
 
 #ifdef CONFIG_NEED_DMA_MAP_STATE
 #define DEFINE_DMA_UNMAP_ADDR(ADDR_NAME)        dma_addr_t ADDR_NAME

include/linux/dma-noncoherent.h

@@ -3,6 +3,7 @@
 #define _LINUX_DMA_NONCOHERENT_H 1
 
 #include <linux/dma-mapping.h>
+#include <asm/pgtable.h>
 
 #ifdef CONFIG_ARCH_HAS_DMA_COHERENCE_H
 #include <asm/dma-coherence.h>
@@ -42,10 +43,18 @@ void arch_dma_free(struct device *dev, size_t size, void *cpu_addr,
 		dma_addr_t dma_addr, unsigned long attrs);
 long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr,
 		dma_addr_t dma_addr);
-pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
-		unsigned long attrs);
 
 #ifdef CONFIG_MMU
+/*
+ * Page protection so that devices that can't snoop CPU caches can use the
+ * memory coherently.  We default to pgprot_noncached which is usually used
+ * for ioremap as a safe bet, but architectures can override this with less
+ * strict semantics if possible.
+ */
+#ifndef pgprot_dmacoherent
+#define pgprot_dmacoherent(prot)	pgprot_noncached(prot)
+#endif
+
 pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs);
 #else
 static inline pgprot_t dma_pgprot(struct device *dev, pgprot_t prot,

include/linux/mmc/host.h

@@ -368,6 +368,7 @@ struct mmc_host {
 #define MMC_CAP2_CQE		(1 << 23)	/* Has eMMC command queue engine */
 #define MMC_CAP2_CQE_DCMD	(1 << 24)	/* CQE can issue a direct command */
 #define MMC_CAP2_AVOID_3_3V	(1 << 25)	/* Host must negotiate down from 3.3V */
+#define MMC_CAP2_MERGE_CAPABLE	(1 << 26)	/* Host can merge a segment over the segment size */
 
 	int			fixed_drv_type;	/* fixed driver type for non-removable media */
 
@@ -397,6 +398,7 @@ struct mmc_host {
 	unsigned int		retune_paused:1; /* re-tuning is temporarily disabled */
 	unsigned int		use_blk_mq:1;	/* use blk-mq */
 	unsigned int		retune_crc_disable:1; /* don't trigger retune upon crc */
+	unsigned int		can_dma_map_merge:1; /* merging can be used */
 
 	int			rescan_disable;	/* disable card detection */
 	int			rescan_entered;	/* used with nonremovable devices */

include/linux/vmalloc.h

@@ -18,6 +18,7 @@ struct notifier_block;		/* in notifier.h */
 #define VM_ALLOC		0x00000002	/* vmalloc() */
 #define VM_MAP			0x00000004	/* vmap()ed pages */
 #define VM_USERMAP		0x00000008	/* suitable for remap_vmalloc_range */
+#define VM_DMA_COHERENT		0x00000010	/* dma_alloc_coherent */
 #define VM_UNINITIALIZED	0x00000020	/* vm_struct is not fully initialized */
 #define VM_NO_GUARD		0x00000040      /* don't add guard page */
 #define VM_KASAN		0x00000080      /* has allocated kasan shadow memory */
@@ -26,6 +27,7 @@ struct notifier_block;		/* in notifier.h */
  * vfree_atomic().
  */
 #define VM_FLUSH_RESET_PERMS	0x00000100      /* Reset direct map and flush TLB on unmap */
+
 /* bits [20..32] reserved for arch specific ioremap internals */
 
 /*

include/xen/arm/hypervisor.h

@@ -19,8 +19,6 @@ static inline enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
 	return PARAVIRT_LAZY_NONE;
 }
 
-extern const struct dma_map_ops *xen_dma_ops;
-
 #ifdef CONFIG_XEN
 void __init xen_early_init(void);
 #else

include/xen/arm/page-coherent.h

@@ -2,15 +2,19 @@
 #ifndef _XEN_ARM_PAGE_COHERENT_H
 #define _XEN_ARM_PAGE_COHERENT_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, unsigned long attrs);
-void __xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
-		size_t size, enum dma_data_direction dir,
-		unsigned long attrs);
-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);
+#include <linux/dma-mapping.h>
+#include <asm/page.h>
+
+static inline void *xen_alloc_coherent_pages(struct device *hwdev, size_t size,
+		dma_addr_t *dma_handle, gfp_t flags, unsigned long attrs)
+{
+	return dma_direct_alloc(hwdev, size, dma_handle, flags, attrs);
+}
+
+static inline void xen_free_coherent_pages(struct device *hwdev, size_t size,
+		void *cpu_addr, dma_addr_t dma_handle, unsigned long attrs)
+{
+	dma_direct_free(hwdev, size, cpu_addr, dma_handle, attrs);
+}
 
 #endif /* _XEN_ARM_PAGE_COHERENT_H */

include/xen/swiotlb-xen.h

@@ -4,6 +4,11 @@
 
 #include <linux/swiotlb.h>
 
+void xen_dma_sync_for_cpu(struct device *dev, dma_addr_t handle,
+		phys_addr_t paddr, size_t size, enum dma_data_direction dir);
+void xen_dma_sync_for_device(struct device *dev, dma_addr_t handle,
+		phys_addr_t paddr, size_t size, enum dma_data_direction dir);
+
 extern int xen_swiotlb_init(int verbose, bool early);
 extern const struct dma_map_ops xen_swiotlb_dma_ops;
 

kernel/dma/Kconfig

@@ -20,6 +20,15 @@ config ARCH_HAS_DMA_COHERENCE_H
 config ARCH_HAS_DMA_SET_MASK
 	bool
 
+#
+# Select this option if the architecture needs special handling for
+# DMA_ATTR_WRITE_COMBINE.  Normally the "uncached" mapping should be what
+# people thing of when saying write combine, so very few platforms should
+# need to enable this.
+#
+config ARCH_HAS_DMA_WRITE_COMBINE
+	bool
+
 config DMA_DECLARE_COHERENT
 	bool
 
@@ -45,9 +54,6 @@ config ARCH_HAS_DMA_PREP_COHERENT
 config ARCH_HAS_DMA_COHERENT_TO_PFN
 	bool
 
-config ARCH_HAS_DMA_MMAP_PGPROT
-	bool
-
 config ARCH_HAS_FORCE_DMA_UNENCRYPTED
 	bool
 

kernel/dma/coherent.c

@@ -122,18 +122,6 @@ int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
 		dma_release_coherent_memory(mem);
 	return ret;
 }
-EXPORT_SYMBOL(dma_declare_coherent_memory);
-
-void dma_release_declared_memory(struct device *dev)
-{
-	struct dma_coherent_mem *mem = dev->dma_mem;
-
-	if (!mem)
-		return;
-	dma_release_coherent_memory(mem);
-	dev->dma_mem = NULL;
-}
-EXPORT_SYMBOL(dma_release_declared_memory);
 
 static void *__dma_alloc_from_coherent(struct dma_coherent_mem *mem,
 		ssize_t size, dma_addr_t *dma_handle)
@@ -288,7 +276,6 @@ int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma,
 
 	return __dma_mmap_from_coherent(mem, vma, vaddr, size, ret);
 }
-EXPORT_SYMBOL(dma_mmap_from_dev_coherent);
 
 int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *vaddr,
 				   size_t size, int *ret)

kernel/dma/mapping.c

@@ -136,17 +136,29 @@ int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
 	return ret;
 }
 
+/*
+ * The whole dma_get_sgtable() idea is fundamentally unsafe - it seems
+ * that the intention is to allow exporting memory allocated via the
+ * coherent DMA APIs through the dma_buf API, which only accepts a
+ * scattertable.  This presents a couple of problems:
+ * 1. Not all memory allocated via the coherent DMA APIs is backed by
+ *    a struct page
+ * 2. Passing coherent DMA memory into the streaming APIs is not allowed
+ *    as we will try to flush the memory through a different alias to that
+ *    actually being used (and the flushes are redundant.)
+ */
 int dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt,
 		void *cpu_addr, dma_addr_t dma_addr, size_t size,
 		unsigned long attrs)
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
 
-	if (!dma_is_direct(ops) && ops->get_sgtable)
-		return ops->get_sgtable(dev, sgt, cpu_addr, dma_addr, size,
-					attrs);
-	return dma_common_get_sgtable(dev, sgt, cpu_addr, dma_addr, size,
-			attrs);
+	if (dma_is_direct(ops))
+		return dma_common_get_sgtable(dev, sgt, cpu_addr, dma_addr,
+				size, attrs);
+	if (!ops->get_sgtable)
+		return -ENXIO;
+	return ops->get_sgtable(dev, sgt, cpu_addr, dma_addr, size, attrs);
 }
 EXPORT_SYMBOL(dma_get_sgtable_attrs);
 
@@ -161,9 +173,11 @@ pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs)
 	    (IS_ENABLED(CONFIG_DMA_NONCOHERENT_CACHE_SYNC) &&
              (attrs & DMA_ATTR_NON_CONSISTENT)))
 		return prot;
-	if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_MMAP_PGPROT))
-		return arch_dma_mmap_pgprot(dev, prot, attrs);
-	return pgprot_noncached(prot);
+#ifdef CONFIG_ARCH_HAS_DMA_WRITE_COMBINE
+	if (attrs & DMA_ATTR_WRITE_COMBINE)
+		return pgprot_writecombine(prot);
+#endif
+	return pgprot_dmacoherent(prot);
 }
 #endif /* CONFIG_MMU */
 
@@ -174,7 +188,7 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
 		void *cpu_addr, dma_addr_t dma_addr, size_t size,
 		unsigned long attrs)
 {
-#ifndef CONFIG_ARCH_NO_COHERENT_DMA_MMAP
+#ifdef CONFIG_MMU
 	unsigned long user_count = vma_pages(vma);
 	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 	unsigned long off = vma->vm_pgoff;
@@ -205,8 +219,29 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
 			user_count << PAGE_SHIFT, vma->vm_page_prot);
 #else
 	return -ENXIO;
-#endif /* !CONFIG_ARCH_NO_COHERENT_DMA_MMAP */
+#endif /* CONFIG_MMU */
+}
+
+/**
+ * dma_can_mmap - check if a given device supports dma_mmap_*
+ * @dev: device to check
+ *
+ * Returns %true if @dev supports dma_mmap_coherent() and dma_mmap_attrs() to
+ * map DMA allocations to userspace.
+ */
+bool dma_can_mmap(struct device *dev)
+{
+	const struct dma_map_ops *ops = get_dma_ops(dev);
+
+	if (dma_is_direct(ops)) {
+		return IS_ENABLED(CONFIG_MMU) &&
+		       (dev_is_dma_coherent(dev) ||
+			IS_ENABLED(CONFIG_ARCH_HAS_DMA_COHERENT_TO_PFN));
+	}
+
+	return ops->mmap != NULL;
 }
+EXPORT_SYMBOL_GPL(dma_can_mmap);
 
 /**
  * dma_mmap_attrs - map a coherent DMA allocation into user space
@@ -227,31 +262,15 @@ int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
 
-	if (!dma_is_direct(ops) && ops->mmap)
-		return ops->mmap(dev, vma, cpu_addr, dma_addr, size, attrs);
-	return dma_common_mmap(dev, vma, cpu_addr, dma_addr, size, attrs);
+	if (dma_is_direct(ops))
+		return dma_common_mmap(dev, vma, cpu_addr, dma_addr, size,
+				attrs);
+	if (!ops->mmap)
+		return -ENXIO;
+	return ops->mmap(dev, vma, cpu_addr, dma_addr, size, attrs);
 }
 EXPORT_SYMBOL(dma_mmap_attrs);
 
-static u64 dma_default_get_required_mask(struct device *dev)
-{
-	u32 low_totalram = ((max_pfn - 1) << PAGE_SHIFT);
-	u32 high_totalram = ((max_pfn - 1) >> (32 - PAGE_SHIFT));
-	u64 mask;
-
-	if (!high_totalram) {
-		/* convert to mask just covering totalram */
-		low_totalram = (1 << (fls(low_totalram) - 1));
-		low_totalram += low_totalram - 1;
-		mask = low_totalram;
-	} else {
-		high_totalram = (1 << (fls(high_totalram) - 1));
-		high_totalram += high_totalram - 1;
-		mask = (((u64)high_totalram) << 32) + 0xffffffff;
-	}
-	return mask;
-}
-
 u64 dma_get_required_mask(struct device *dev)
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
@@ -260,7 +279,16 @@ u64 dma_get_required_mask(struct device *dev)
 		return dma_direct_get_required_mask(dev);
 	if (ops->get_required_mask)
 		return ops->get_required_mask(dev);
-	return dma_default_get_required_mask(dev);
+
+	/*
+	 * We require every DMA ops implementation to at least support a 32-bit
+	 * DMA mask (and use bounce buffering if that isn't supported in
+	 * hardware).  As the direct mapping code has its own routine to
+	 * actually report an optimal mask we default to 32-bit here as that
+	 * is the right thing for most IOMMUs, and at least not actively
+	 * harmful in general.
+	 */
+	return DMA_BIT_MASK(32);
 }
 EXPORT_SYMBOL_GPL(dma_get_required_mask);
 
@@ -405,3 +433,14 @@ size_t dma_max_mapping_size(struct device *dev)
 	return size;
 }
 EXPORT_SYMBOL_GPL(dma_max_mapping_size);
+
+unsigned long dma_get_merge_boundary(struct device *dev)
+{
+	const struct dma_map_ops *ops = get_dma_ops(dev);
+
+	if (!ops || !ops->get_merge_boundary)
+		return 0;	/* can't merge */
+
+	return ops->get_merge_boundary(dev);
+}
+EXPORT_SYMBOL_GPL(dma_get_merge_boundary);

kernel/dma/remap.c

@@ -11,13 +11,21 @@
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 
+struct page **dma_common_find_pages(void *cpu_addr)
+{
+	struct vm_struct *area = find_vm_area(cpu_addr);
+
+	if (!area || area->flags != VM_DMA_COHERENT)
+		return NULL;
+	return area->pages;
+}
+
 static struct vm_struct *__dma_common_pages_remap(struct page **pages,
-			size_t size, unsigned long vm_flags, pgprot_t prot,
-			const void *caller)
+			size_t size, pgprot_t prot, const void *caller)
 {
 	struct vm_struct *area;
 
-	area = get_vm_area_caller(size, vm_flags, caller);
+	area = get_vm_area_caller(size, VM_DMA_COHERENT, caller);
 	if (!area)
 		return NULL;
 
@@ -34,12 +42,11 @@ static struct vm_struct *__dma_common_pages_remap(struct page **pages,
  * Cannot be used in non-sleeping contexts
  */
 void *dma_common_pages_remap(struct page **pages, size_t size,
-			unsigned long vm_flags, pgprot_t prot,
-			const void *caller)
+			 pgprot_t prot, const void *caller)
 {
 	struct vm_struct *area;
 
-	area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller);
+	area = __dma_common_pages_remap(pages, size, prot, caller);
 	if (!area)
 		return NULL;
 
@@ -53,7 +60,6 @@ void *dma_common_pages_remap(struct page **pages, size_t size,
  * Cannot be used in non-sleeping contexts
  */
 void *dma_common_contiguous_remap(struct page *page, size_t size,
-			unsigned long vm_flags,
 			pgprot_t prot, const void *caller)
 {
 	int i;
@@ -67,7 +73,7 @@ void *dma_common_contiguous_remap(struct page *page, size_t size,
 	for (i = 0; i < (size >> PAGE_SHIFT); i++)
 		pages[i] = nth_page(page, i);
 
-	area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller);
+	area = __dma_common_pages_remap(pages, size, prot, caller);
 
 	kfree(pages);
 
@@ -79,11 +85,11 @@ void *dma_common_contiguous_remap(struct page *page, size_t size,
 /*
  * Unmaps a range previously mapped by dma_common_*_remap
  */
-void dma_common_free_remap(void *cpu_addr, size_t size, unsigned long vm_flags)
+void dma_common_free_remap(void *cpu_addr, size_t size)
 {
-	struct vm_struct *area = find_vm_area(cpu_addr);
+	struct page **pages = dma_common_find_pages(cpu_addr);
 
-	if (!area || (area->flags & vm_flags) != vm_flags) {
+	if (!pages) {
 		WARN(1, "trying to free invalid coherent area: %p\n", cpu_addr);
 		return;
 	}
@@ -105,7 +111,16 @@ static int __init early_coherent_pool(char *p)
 }
 early_param("coherent_pool", early_coherent_pool);
 
-int __init dma_atomic_pool_init(gfp_t gfp, pgprot_t prot)
+static gfp_t dma_atomic_pool_gfp(void)
+{
+	if (IS_ENABLED(CONFIG_ZONE_DMA))
+		return GFP_DMA;
+	if (IS_ENABLED(CONFIG_ZONE_DMA32))
+		return GFP_DMA32;
+	return GFP_KERNEL;
+}
+
+static int __init dma_atomic_pool_init(void)
 {
 	unsigned int pool_size_order = get_order(atomic_pool_size);
 	unsigned long nr_pages = atomic_pool_size >> PAGE_SHIFT;
@@ -117,7 +132,7 @@ int __init dma_atomic_pool_init(gfp_t gfp, pgprot_t prot)
 		page = dma_alloc_from_contiguous(NULL, nr_pages,
 						 pool_size_order, false);
 	else
-		page = alloc_pages(gfp, pool_size_order);
+		page = alloc_pages(dma_atomic_pool_gfp(), pool_size_order);
 	if (!page)
 		goto out;
 
@@ -127,8 +142,9 @@ int __init dma_atomic_pool_init(gfp_t gfp, pgprot_t prot)
 	if (!atomic_pool)
 		goto free_page;
 
-	addr = dma_common_contiguous_remap(page, atomic_pool_size, VM_USERMAP,
-					   prot, __builtin_return_address(0));
+	addr = dma_common_contiguous_remap(page, atomic_pool_size,
+					   pgprot_dmacoherent(PAGE_KERNEL),
+					   __builtin_return_address(0));
 	if (!addr)
 		goto destroy_genpool;
 
@@ -143,7 +159,7 @@ int __init dma_atomic_pool_init(gfp_t gfp, pgprot_t prot)
 	return 0;
 
 remove_mapping:
-	dma_common_free_remap(addr, atomic_pool_size, VM_USERMAP);
+	dma_common_free_remap(addr, atomic_pool_size);
 destroy_genpool:
 	gen_pool_destroy(atomic_pool);
 	atomic_pool = NULL;
@@ -155,6 +171,7 @@ int __init dma_atomic_pool_init(gfp_t gfp, pgprot_t prot)
 		atomic_pool_size / 1024);
 	return -ENOMEM;
 }
+postcore_initcall(dma_atomic_pool_init);
 
 bool dma_in_atomic_pool(void *start, size_t size)
 {
@@ -217,7 +234,7 @@ void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
 	arch_dma_prep_coherent(page, size);
 
 	/* create a coherent mapping */
-	ret = dma_common_contiguous_remap(page, size, VM_USERMAP,
+	ret = dma_common_contiguous_remap(page, size,
 			dma_pgprot(dev, PAGE_KERNEL, attrs),
 			__builtin_return_address(0));
 	if (!ret) {

mm/vmalloc.c

@@ -2993,7 +2993,7 @@ int remap_vmalloc_range_partial(struct vm_area_struct *vma, unsigned long uaddr,
 	if (!area)
 		return -EINVAL;
 
-	if (!(area->flags & VM_USERMAP))
+	if (!(area->flags & (VM_USERMAP | VM_DMA_COHERENT)))
 		return -EINVAL;
 
 	if (kaddr + size > area->addr + get_vm_area_size(area))
@@ -3496,6 +3496,9 @@ static int s_show(struct seq_file *m, void *p)
 	if (v->flags & VM_USERMAP)
 		seq_puts(m, " user");
 
+	if (v->flags & VM_DMA_COHERENT)
+		seq_puts(m, " dma-coherent");
+
 	if (is_vmalloc_addr(v->pages))
 		seq_puts(m, " vpages");
 

sound/core/pcm_native.c

@@ -220,13 +220,12 @@ static bool hw_support_mmap(struct snd_pcm_substream *substream)
 {
 	if (!(substream->runtime->hw.info & SNDRV_PCM_INFO_MMAP))
 		return false;
-	/* architecture supports dma_mmap_coherent()? */
-#if defined(CONFIG_ARCH_NO_COHERENT_DMA_MMAP) || !defined(CONFIG_HAS_DMA)
-	if (!substream->ops->mmap &&
-	    substream->dma_buffer.dev.type == SNDRV_DMA_TYPE_DEV)
-		return false;
-#endif
-	return true;
+
+	if (substream->ops->mmap ||
+	    substream->dma_buffer.dev.type != SNDRV_DMA_TYPE_DEV)
+		return true;
+
+	return dma_can_mmap(substream->dma_buffer.dev.dev);
 }
 
 static int constrain_mask_params(struct snd_pcm_substream *substream,