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Diffstat (limited to 'include/linux/memremap.h')
| -rw-r--r-- | include/linux/memremap.h | 254 |
1 files changed, 254 insertions, 0 deletions
diff --git a/include/linux/memremap.h b/include/linux/memremap.h new file mode 100644 index 000000000..1314d9c5f --- /dev/null +++ b/include/linux/memremap.h @@ -0,0 +1,254 @@ +/* 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; +}; + +/* + * 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 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); +#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; +} + +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; +} +#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_ */ |