kernel/include/linux/memory_hotplug.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_MEMORY_HOTPLUG_H
#define __LINUX_MEMORY_HOTPLUG_H

#include <linux/mmzone.h>
#include <linux/spinlock.h>
#include <linux/notifier.h>
#include <linux/bug.h>

struct page;
struct zone;
struct pglist_data;
struct mem_section;
struct memory_group;
struct resource;
struct vmem_altmap;
struct dev_pagemap;

#ifdef CONFIG_MEMORY_HOTPLUG
struct page *pfn_to_online_page(unsigned long pfn);

/* Types for control the zone type of onlined and offlined memory */
enum {
	/* Offline the memory. */
	MMOP_OFFLINE = 0,
	/* Online the memory. Zone depends, see default_zone_for_pfn(). */
	MMOP_ONLINE,
	/* Online the memory to ZONE_NORMAL. */
	MMOP_ONLINE_KERNEL,
	/* Online the memory to ZONE_MOVABLE. */
	MMOP_ONLINE_MOVABLE,
};

/* Flags for add_memory() and friends to specify memory hotplug details. */
typedef int __bitwise mhp_t;

/* No special request */
#define MHP_NONE		((__force mhp_t)0)
/*
 * Allow merging of the added System RAM resource with adjacent,
 * mergeable resources. After a successful call to add_memory_resource()
 * with this flag set, the resource pointer must no longer be used as it
 * might be stale, or the resource might have changed.
 */
#define MHP_MERGE_RESOURCE	((__force mhp_t)BIT(0))

/*
 * We want memmap (struct page array) to be self contained.
 * To do so, we will use the beginning of the hot-added range to build
 * the page tables for the memmap array that describes the entire range.
 * Only selected architectures support it with SPARSE_VMEMMAP.
 * This is only a hint, the core kernel can decide to not do this based on
 * different alignment checks.
 */
#define MHP_MEMMAP_ON_MEMORY   ((__force mhp_t)BIT(1))
/*
 * The nid field specifies a memory group id (mgid) instead. The memory group
 * implies the node id (nid).
 */
#define MHP_NID_IS_MGID		((__force mhp_t)BIT(2))
/*
 * The hotplugged memory is completely inaccessible while the memory is
 * offline. The memory provider will handle MEM_PREPARE_ONLINE /
 * MEM_FINISH_OFFLINE notifications and make the memory accessible.
 *
 * This flag is only relevant when used along with MHP_MEMMAP_ON_MEMORY,
 * because the altmap cannot be written (e.g., poisoned) when adding
 * memory -- before it is set online.
 *
 * This allows for adding memory with an altmap that is not currently
 * made available by a hypervisor. When onlining that memory, the
 * hypervisor can be instructed to make that memory available, and
 * the onlining phase will not require any memory allocations, which is
 * helpful in low-memory situations.
 */
#define MHP_OFFLINE_INACCESSIBLE	((__force mhp_t)BIT(3))

/*
 * Extended parameters for memory hotplug:
 * altmap: alternative allocator for memmap array (optional)
 * pgprot: page protection flags to apply to newly created page tables
 *	(required)
 */
struct mhp_params {
	struct vmem_altmap *altmap;
	pgprot_t pgprot;
	struct dev_pagemap *pgmap;
};

bool mhp_range_allowed(u64 start, u64 size, bool need_mapping);
struct range mhp_get_pluggable_range(bool need_mapping);
bool mhp_supports_memmap_on_memory(void);

/*
 * Zone resizing functions
 *
 * Note: any attempt to resize a zone should has pgdat_resize_lock()
 * zone_span_writelock() both held. This ensure the size of a zone
 * can't be changed while pgdat_resize_lock() held.
 */
static inline unsigned zone_span_seqbegin(struct zone *zone)
{
	return read_seqbegin(&zone->span_seqlock);
}
static inline int zone_span_seqretry(struct zone *zone, unsigned iv)
{
	return read_seqretry(&zone->span_seqlock, iv);
}
static inline void zone_span_writelock(struct zone *zone)
{
	write_seqlock(&zone->span_seqlock);
}
static inline void zone_span_writeunlock(struct zone *zone)
{
	write_sequnlock(&zone->span_seqlock);
}
static inline void zone_seqlock_init(struct zone *zone)
{
	seqlock_init(&zone->span_seqlock);
}
extern void adjust_present_page_count(struct page *page,
				      struct memory_group *group,
				      long nr_pages);
/* VM interface that may be used by firmware interface */
extern int mhp_init_memmap_on_memory(unsigned long pfn, unsigned long nr_pages,
				     struct zone *zone, bool mhp_off_inaccessible);
extern void mhp_deinit_memmap_on_memory(unsigned long pfn, unsigned long nr_pages);
extern int online_pages(unsigned long pfn, unsigned long nr_pages,
			struct zone *zone, struct memory_group *group);
extern unsigned long __offline_isolated_pages(unsigned long start_pfn,
		unsigned long end_pfn);

typedef void (*online_page_callback_t)(struct page *page, unsigned int order);

extern void generic_online_page(struct page *page, unsigned int order);
extern int set_online_page_callback(online_page_callback_t callback);
extern int restore_online_page_callback(online_page_callback_t callback);

extern int try_online_node(int nid);

extern int arch_add_memory(int nid, u64 start, u64 size,
			   struct mhp_params *params);
extern u64 max_mem_size;

extern int mhp_online_type_from_str(const char *str);

/* Default online_type (MMOP_*) when new memory blocks are added. */
extern int mhp_default_online_type;
/* If movable_node boot option specified */
extern bool movable_node_enabled;
static inline bool movable_node_is_enabled(void)
{
	return movable_node_enabled;
}

extern void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap);
extern void __remove_pages(unsigned long start_pfn, unsigned long nr_pages,
			   struct vmem_altmap *altmap);

/* reasonably generic interface to expand the physical pages */
extern int __add_pages(int nid, unsigned long start_pfn, unsigned long nr_pages,
		       struct mhp_params *params);

#ifndef CONFIG_ARCH_HAS_ADD_PAGES
static inline int add_pages(int nid, unsigned long start_pfn,
		unsigned long nr_pages, struct mhp_params *params)
{
	return __add_pages(nid, start_pfn, nr_pages, params);
}
#else /* ARCH_HAS_ADD_PAGES */
int add_pages(int nid, unsigned long start_pfn, unsigned long nr_pages,
	      struct mhp_params *params);
#endif /* ARCH_HAS_ADD_PAGES */

void get_online_mems(void);
void put_online_mems(void);

void mem_hotplug_begin(void);
void mem_hotplug_done(void);

/* See kswapd_is_running() */
static inline void pgdat_kswapd_lock(pg_data_t *pgdat)
{
	mutex_lock(&pgdat->kswapd_lock);
}

static inline void pgdat_kswapd_unlock(pg_data_t *pgdat)
{
	mutex_unlock(&pgdat->kswapd_lock);
}

static inline void pgdat_kswapd_lock_init(pg_data_t *pgdat)
{
	mutex_init(&pgdat->kswapd_lock);
}

#else /* ! CONFIG_MEMORY_HOTPLUG */
#define pfn_to_online_page(pfn)			\
({						\
	struct page *___page = NULL;		\
	if (pfn_valid(pfn))			\
		___page = pfn_to_page(pfn);	\
	___page;				\
 })

static inline unsigned zone_span_seqbegin(struct zone *zone)
{
	return 0;
}
static inline int zone_span_seqretry(struct zone *zone, unsigned iv)
{
	return 0;
}
static inline void zone_span_writelock(struct zone *zone) {}
static inline void zone_span_writeunlock(struct zone *zone) {}
static inline void zone_seqlock_init(struct zone *zone) {}

static inline int try_online_node(int nid)
{
	return 0;
}

static inline void get_online_mems(void) {}
static inline void put_online_mems(void) {}

static inline void mem_hotplug_begin(void) {}
static inline void mem_hotplug_done(void) {}

static inline bool movable_node_is_enabled(void)
{
	return false;
}

static inline bool mhp_supports_memmap_on_memory(void)
{
	return false;
}

static inline void pgdat_kswapd_lock(pg_data_t *pgdat) {}
static inline void pgdat_kswapd_unlock(pg_data_t *pgdat) {}
static inline void pgdat_kswapd_lock_init(pg_data_t *pgdat) {}
#endif /* ! CONFIG_MEMORY_HOTPLUG */

/*
 * Keep this declaration outside CONFIG_MEMORY_HOTPLUG as some
 * platforms might override and use arch_get_mappable_range()
 * for internal non memory hotplug purposes.
 */
struct range arch_get_mappable_range(void);

#if defined(CONFIG_MEMORY_HOTPLUG) || defined(CONFIG_DEFERRED_STRUCT_PAGE_INIT)
/*
 * pgdat resizing functions
 */
static inline
void pgdat_resize_lock(struct pglist_data *pgdat, unsigned long *flags)
{
	spin_lock_irqsave(&pgdat->node_size_lock, *flags);
}
static inline
void pgdat_resize_unlock(struct pglist_data *pgdat, unsigned long *flags)
{
	spin_unlock_irqrestore(&pgdat->node_size_lock, *flags);
}
static inline
void pgdat_resize_init(struct pglist_data *pgdat)
{
	spin_lock_init(&pgdat->node_size_lock);
}
#else /* !(CONFIG_MEMORY_HOTPLUG || CONFIG_DEFERRED_STRUCT_PAGE_INIT) */
/*
 * Stub functions for when hotplug is off
 */
static inline void pgdat_resize_lock(struct pglist_data *p, unsigned long *f) {}
static inline void pgdat_resize_unlock(struct pglist_data *p, unsigned long *f) {}
static inline void pgdat_resize_init(struct pglist_data *pgdat) {}
#endif /* !(CONFIG_MEMORY_HOTPLUG || CONFIG_DEFERRED_STRUCT_PAGE_INIT) */

#ifdef CONFIG_MEMORY_HOTREMOVE

extern void try_offline_node(int nid);
extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages,
			 struct zone *zone, struct memory_group *group);
extern int remove_memory(u64 start, u64 size);
extern void __remove_memory(u64 start, u64 size);
extern int offline_and_remove_memory(u64 start, u64 size);

#else
static inline void try_offline_node(int nid) {}

static inline int offline_pages(unsigned long start_pfn, unsigned long nr_pages,
				struct zone *zone, struct memory_group *group)
{
	return -EINVAL;
}

static inline int remove_memory(u64 start, u64 size)
{
	return -EBUSY;
}

static inline void __remove_memory(u64 start, u64 size) {}
#endif /* CONFIG_MEMORY_HOTREMOVE */

#ifdef CONFIG_MEMORY_HOTPLUG
extern void __ref free_area_init_core_hotplug(struct pglist_data *pgdat);
extern int __add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags);
extern int add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags);
extern int add_memory_resource(int nid, struct resource *resource,
			       mhp_t mhp_flags);
extern int add_memory_driver_managed(int nid, u64 start, u64 size,
				     const char *resource_name,
				     mhp_t mhp_flags);
extern void move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
				   unsigned long nr_pages,
				   struct vmem_altmap *altmap, int migratetype);
extern void remove_pfn_range_from_zone(struct zone *zone,
				       unsigned long start_pfn,
				       unsigned long nr_pages);
extern int sparse_add_section(int nid, unsigned long pfn,
		unsigned long nr_pages, struct vmem_altmap *altmap,
		struct dev_pagemap *pgmap);
extern void sparse_remove_section(unsigned long pfn, unsigned long nr_pages,
				  struct vmem_altmap *altmap);
extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,
					  unsigned long pnum);
extern struct zone *zone_for_pfn_range(int online_type, int nid,
		struct memory_group *group, unsigned long start_pfn,
		unsigned long nr_pages);
extern int arch_create_linear_mapping(int nid, u64 start, u64 size,
				      struct mhp_params *params);
void arch_remove_linear_mapping(u64 start, u64 size);
#endif /* CONFIG_MEMORY_HOTPLUG */

#endif /* __LINUX_MEMORY_HOTPLUG_H */