blob: 79c49e7f5c304fa5b98e039e9e077e2c85b0d061 [file] [log] [blame]
/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/range.h>
#include <linux/ioport.h>
#include <linux/percpu-refcount.h>
struct resource;
struct device;
* struct vmem_altmap - pre-allocated storage for vmemmap_populate
* @base_pfn: base of the entire dev_pagemap mapping
* @reserve: pages mapped, but reserved for driver use (relative to @base)
* @free: free pages set aside in the mapping for memmap storage
* @align: pages reserved to meet allocation alignments
* @alloc: track pages consumed, private to vmemmap_populate()
struct vmem_altmap {
const unsigned long base_pfn;
const unsigned long end_pfn;
const unsigned long reserve;
unsigned long free;
unsigned long align;
unsigned long alloc;
* Specialize ZONE_DEVICE memory into multiple types each having differents
* usage.
* Device memory that is not directly addressable by the CPU: CPU can neither
* read nor write private memory. In this case, we do still have struct pages
* backing the device memory. Doing so simplifies the implementation, but it is
* important to remember that there are certain points at which the struct page
* must be treated as an opaque object, rather than a "normal" struct page.
* A more complete discussion of unaddressable memory may be found in
* include/linux/hmm.h and Documentation/vm/hmm.rst.
* Host memory that has similar access semantics as System RAM i.e. DMA
* coherent and supports page pinning. In support of coordinating page
* pinning vs other operations MEMORY_DEVICE_FS_DAX arranges for a
* wakeup event whenever a page is unpinned and becomes idle. This
* wakeup is used to coordinate physical address space management (ex:
* fs truncate/hole punch) vs pinned pages (ex: device dma).
* Host memory that has similar access semantics as System RAM i.e. DMA
* coherent and supports page pinning. This is for example used by DAX devices
* that expose memory using a character device.
* Device memory residing in a PCI BAR intended for use with Peer-to-Peer
* transactions.
enum memory_type {
/* 0 is reserved to catch uninitialized type fields */
struct dev_pagemap_ops {
* Called once the page refcount reaches 1. (ZONE_DEVICE pages never
* reach 0 refcount unless there is a refcount bug. This allows the
* device driver to implement its own memory management.)
void (*page_free)(struct page *page);
* Transition the refcount in struct dev_pagemap to the dead state.
void (*kill)(struct dev_pagemap *pgmap);
* Wait for refcount in struct dev_pagemap to be idle and reap it.
void (*cleanup)(struct dev_pagemap *pgmap);
* Used for private (un-addressable) device memory only. Must migrate
* the page back to a CPU accessible page.
vm_fault_t (*migrate_to_ram)(struct vm_fault *vmf);
#define PGMAP_ALTMAP_VALID (1 << 0)
* struct dev_pagemap - metadata for ZONE_DEVICE mappings
* @altmap: pre-allocated/reserved memory for vmemmap allocations
* @ref: reference count that pins the devm_memremap_pages() mapping
* @internal_ref: internal reference if @ref is not provided by the caller
* @done: completion for @internal_ref
* @type: memory type: see MEMORY_* in memory_hotplug.h
* @flags: PGMAP_* flags to specify defailed behavior
* @ops: method table
* @owner: an opaque pointer identifying the entity that manages this
* instance. Used by various helpers to make sure that no
* foreign ZONE_DEVICE memory is accessed.
* @nr_range: number of ranges to be mapped
* @range: range to be mapped when nr_range == 1
* @ranges: array of ranges to be mapped when nr_range > 1
struct dev_pagemap {
struct vmem_altmap altmap;
struct percpu_ref *ref;
struct percpu_ref internal_ref;
struct completion done;
enum memory_type type;
unsigned int flags;
const struct dev_pagemap_ops *ops;
void *owner;
int nr_range;
union {
struct range range;
struct range ranges[0];
static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap)
if (pgmap->flags & PGMAP_ALTMAP_VALID)
return &pgmap->altmap;
return NULL;
void *memremap_pages(struct dev_pagemap *pgmap, int nid);
void memunmap_pages(struct dev_pagemap *pgmap);
void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap);
struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
struct dev_pagemap *pgmap);
unsigned long vmem_altmap_offset(struct vmem_altmap *altmap);
void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns);
unsigned long memremap_compat_align(void);
static inline void *devm_memremap_pages(struct device *dev,
struct dev_pagemap *pgmap)
* Fail attempts to call devm_memremap_pages() without
* ZONE_DEVICE support enabled, this requires callers to fall
* back to plain devm_memremap() based on config
return ERR_PTR(-ENXIO);
static inline void devm_memunmap_pages(struct device *dev,
struct dev_pagemap *pgmap)
static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
struct dev_pagemap *pgmap)
return NULL;
static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
return 0;
static inline void vmem_altmap_free(struct vmem_altmap *altmap,
unsigned long nr_pfns)
/* when memremap_pages() is disabled all archs can remap a single page */
static inline unsigned long memremap_compat_align(void)
return PAGE_SIZE;
static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
if (pgmap)
#endif /* _LINUX_MEMREMAP_H_ */