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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_MEMREMAP_H_
#define _LINUX_MEMREMAP_H_
#include <linux/mmzone.h>
#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 {
unsigned long base_pfn;
const unsigned long end_pfn;
const unsigned long reserve;
unsigned long free;
unsigned long align;
unsigned long alloc;
bool inaccessible;
};
/*
* Specialize ZONE_DEVICE memory into multiple types each has a different
* usage.
*
* MEMORY_DEVICE_PRIVATE:
* 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/mm/hmm.rst.
*
* MEMORY_DEVICE_COHERENT:
* Device memory that is cache coherent from device and CPU point of view. This
* is used on platforms that have an advanced system bus (like CAPI or CXL). A
* driver can hotplug the device memory using ZONE_DEVICE and with that memory
* type. Any page of a process can be migrated to such memory. However no one
* should be allowed to pin such memory so that it can always be evicted.
*
* MEMORY_DEVICE_FS_DAX:
* 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).
*
* MEMORY_DEVICE_GENERIC:
* 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.
*
* MEMORY_DEVICE_PCI_P2PDMA:
* 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 */
MEMORY_DEVICE_PRIVATE = 1,
MEMORY_DEVICE_COHERENT,
MEMORY_DEVICE_FS_DAX,
MEMORY_DEVICE_GENERIC,
MEMORY_DEVICE_PCI_P2PDMA,
};
struct dev_pagemap_ops {
/*
* Called once the page refcount reaches 0. The reference count will be
* reset to one by the core code after the method is called to prepare
* for handing out the page again.
*/
void (*page_free)(struct page *page);
/*
* 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);
/*
* Handle the memory failure happens on a range of pfns. Notify the
* processes who are using these pfns, and try to recover the data on
* them if necessary. The mf_flags is finally passed to the recover
* function through the whole notify routine.
*
* When this is not implemented, or it returns -EOPNOTSUPP, the caller
* will fall back to a common handler called mf_generic_kill_procs().
*/
int (*memory_failure)(struct dev_pagemap *pgmap, unsigned long pfn,
unsigned long nr_pages, int mf_flags);
};
#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
* @done: completion for @ref
* @type: memory type: see MEMORY_* in memory_hotplug.h
* @flags: PGMAP_* flags to specify defailed behavior
* @vmemmap_shift: structural definition of how the vmemmap page metadata
* is populated, specifically the metadata page order.
* A zero value (default) uses base pages as the vmemmap metadata
* representation. A bigger value will set up compound struct pages
* of the requested order value.
* @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 completion done;
enum memory_type type;
unsigned int flags;
unsigned long vmemmap_shift;
const struct dev_pagemap_ops *ops;
void *owner;
int nr_range;
union {
struct range range;
DECLARE_FLEX_ARRAY(struct range, ranges);
};
};
static inline bool pgmap_has_memory_failure(struct dev_pagemap *pgmap)
{
return pgmap->ops && pgmap->ops->memory_failure;
}
static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap)
{
if (pgmap->flags & PGMAP_ALTMAP_VALID)
return &pgmap->altmap;
return NULL;
}
static inline unsigned long pgmap_vmemmap_nr(struct dev_pagemap *pgmap)
{
return 1 << pgmap->vmemmap_shift;
}
static inline bool is_device_private_page(const struct page *page)
{
return IS_ENABLED(CONFIG_DEVICE_PRIVATE) &&
is_zone_device_page(page) &&
page->pgmap->type == MEMORY_DEVICE_PRIVATE;
}
static inline bool folio_is_device_private(const struct folio *folio)
{
return is_device_private_page(&folio->page);
}
static inline bool is_pci_p2pdma_page(const struct page *page)
{
return IS_ENABLED(CONFIG_PCI_P2PDMA) &&
is_zone_device_page(page) &&
page->pgmap->type == MEMORY_DEVICE_PCI_P2PDMA;
}
static inline bool is_device_coherent_page(const struct page *page)
{
return is_zone_device_page(page) &&
page->pgmap->type == MEMORY_DEVICE_COHERENT;
}
static inline bool folio_is_device_coherent(const struct folio *folio)
{
return is_device_coherent_page(&folio->page);
}
#ifdef CONFIG_ZONE_DEVICE
void zone_device_page_init(struct page *page);
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);
bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn);
unsigned long memremap_compat_align(void);
#else
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
*/
WARN_ON_ONCE(1);
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 bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn)
{
return false;
}
/* when memremap_pages() is disabled all archs can remap a single page */
static inline unsigned long memremap_compat_align(void)
{
return PAGE_SIZE;
}
#endif /* CONFIG_ZONE_DEVICE */
static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
{
if (pgmap)
percpu_ref_put(&pgmap->ref);
}
#endif /* _LINUX_MEMREMAP_H_ */