// SPDX-License-Identifier: GPL-2.0
/*
 * HugeTLB Vmemmap Optimization (HVO)
 *
 * Copyright (c) 2020, ByteDance. All rights reserved.
 *
 *     Author: Muchun Song <songmuchun@bytedance.com>
 *
 * See Documentation/mm/vmemmap_dedup.rst
 */
#define pr_fmt(fmt)     "HugeTLB: " fmt

#include <linux/pgtable.h>
#include <linux/moduleparam.h>
#include <linux/bootmem_info.h>
#include <linux/mmdebug.h>
#include <linux/pagewalk.h>
#include <linux/pgalloc.h>

#include <asm/tlbflush.h>
#include "hugetlb_vmemmap.h"
#include "internal.h"

/**
 * struct vmemmap_remap_walk - walk vmemmap page table
 *
 * @remap_pte:          called for each lowest-level entry (PTE).
 * @nr_walked:          the number of walked pte.
 * @vmemmap_head:       the page to be installed as first in the vmemmap range
 * @vmemmap_tail:       the page to be installed as non-first in the vmemmap range
 * @vmemmap_pages:      the list head of the vmemmap pages that can be freed
 *                      or is mapped from.
 * @flags:              used to modify behavior in vmemmap page table walking
 *                      operations.
 */
struct vmemmap_remap_walk {
        void                    (*remap_pte)(pte_t *pte, unsigned long addr,
                                             struct vmemmap_remap_walk *walk);

        unsigned long           nr_walked;
        struct page             *vmemmap_head;
        struct page             *vmemmap_tail;
        struct list_head        *vmemmap_pages;


/* Skip the TLB flush when we split the PMD */
#define VMEMMAP_SPLIT_NO_TLB_FLUSH      BIT(0)
/* Skip the TLB flush when we remap the PTE */
#define VMEMMAP_REMAP_NO_TLB_FLUSH      BIT(1)
        unsigned long           flags;
};

static int vmemmap_split_pmd(pmd_t *pmd, struct page *head, unsigned long start,
                             struct vmemmap_remap_walk *walk)
{
        pmd_t __pmd;
        int i;
        unsigned long addr = start;
        pte_t *pgtable;

        pgtable = pte_alloc_one_kernel(&init_mm);
        if (!pgtable)
                return -ENOMEM;

        pmd_populate_kernel(&init_mm, &__pmd, pgtable);

        for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
                pte_t entry, *pte;
                pgprot_t pgprot = PAGE_KERNEL;

                entry = mk_pte(head + i, pgprot);
                pte = pte_offset_kernel(&__pmd, addr);
                set_pte_at(&init_mm, addr, pte, entry);
        }

        spin_lock(&init_mm.page_table_lock);
        if (likely(pmd_leaf(*pmd))) {
                /*
                 * Higher order allocations from buddy allocator must be able to
                 * be treated as independent small pages (as they can be freed
                 * individually).
                 */
                if (!PageReserved(head))
                        split_page(head, get_order(PMD_SIZE));

                /* Make pte visible before pmd. See comment in pmd_install(). */
                smp_wmb();
                pmd_populate_kernel(&init_mm, pmd, pgtable);
                if (!(walk->flags & VMEMMAP_SPLIT_NO_TLB_FLUSH))
                        flush_tlb_kernel_range(start, start + PMD_SIZE);
        } else {
                pte_free_kernel(&init_mm, pgtable);
        }
        spin_unlock(&init_mm.page_table_lock);

        return 0;
}

static int vmemmap_pmd_entry(pmd_t *pmd, unsigned long addr,
                             unsigned long next, struct mm_walk *walk)
{
        int ret = 0;
        struct page *head;
        struct vmemmap_remap_walk *vmemmap_walk = walk->private;

        /* Only splitting, not remapping the vmemmap pages. */
        if (!vmemmap_walk->remap_pte)
                walk->action = ACTION_CONTINUE;

        spin_lock(&init_mm.page_table_lock);
        head = pmd_leaf(*pmd) ? pmd_page(*pmd) : NULL;
        /*
         * Due to HugeTLB alignment requirements and the vmemmap
         * pages being at the start of the hotplugged memory
         * region in memory_hotplug.memmap_on_memory case. Checking
         * the vmemmap page associated with the first vmemmap page
         * if it is self-hosted is sufficient.
         *
         * [                  hotplugged memory                  ]
         * [        section        ][...][        section        ]
         * [ vmemmap ][              usable memory               ]
         *   ^  | ^                        |
         *   +--+ |                        |
         *        +------------------------+
         */
        if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG) && unlikely(!vmemmap_walk->nr_walked)) {
                struct page *page = head ? head + pte_index(addr) :
                                    pte_page(ptep_get(pte_offset_kernel(pmd, addr)));

                if (PageVmemmapSelfHosted(page))
                        ret = -ENOTSUPP;
        }
        spin_unlock(&init_mm.page_table_lock);
        if (!head || ret)
                return ret;

        return vmemmap_split_pmd(pmd, head, addr & PMD_MASK, vmemmap_walk);
}

static int vmemmap_pte_entry(pte_t *pte, unsigned long addr,
                             unsigned long next, struct mm_walk *walk)
{
        struct vmemmap_remap_walk *vmemmap_walk = walk->private;

        vmemmap_walk->remap_pte(pte, addr, vmemmap_walk);
        vmemmap_walk->nr_walked++;

        return 0;
}

static const struct mm_walk_ops vmemmap_remap_ops = {
        .pmd_entry      = vmemmap_pmd_entry,
        .pte_entry      = vmemmap_pte_entry,
};

static int vmemmap_remap_range(unsigned long start, unsigned long end,
                               struct vmemmap_remap_walk *walk)
{
        int ret;

        VM_BUG_ON(!PAGE_ALIGNED(start | end));

        mmap_read_lock(&init_mm);
        ret = walk_kernel_page_table_range(start, end, &vmemmap_remap_ops,
                                    NULL, walk);
        mmap_read_unlock(&init_mm);
        if (ret)
                return ret;

        if (walk->remap_pte && !(walk->flags & VMEMMAP_REMAP_NO_TLB_FLUSH))
                flush_tlb_kernel_range(start, end);

        return 0;
}

/*
 * Free a vmemmap page. A vmemmap page can be allocated from the memblock
 * allocator or buddy allocator. If the PG_reserved flag is set, it means
 * that it allocated from the memblock allocator, just free it via the
 * free_bootmem_page(). Otherwise, use __free_page().
 */
static inline void free_vmemmap_page(struct page *page)
{
        if (PageReserved(page)) {
                memmap_boot_pages_add(-1);
                free_bootmem_page(page);
        } else {
                memmap_pages_add(-1);
                __free_page(page);
        }
}

/* Free a list of the vmemmap pages */
static void free_vmemmap_page_list(struct list_head *list)
{
        struct page *page, *next;

        list_for_each_entry_safe(page, next, list, lru)
                free_vmemmap_page(page);
}

static void vmemmap_remap_pte(pte_t *pte, unsigned long addr,
                              struct vmemmap_remap_walk *walk)
{
        struct page *page = pte_page(ptep_get(pte));
        pte_t entry;

        /* Remapping the head page requires r/w */
        if (unlikely(walk->nr_walked == 0 && walk->vmemmap_head)) {
                VM_WARN_ON_ONCE(!PageHead((const struct page *)addr));

                list_del(&walk->vmemmap_head->lru);

                /*
                 * Makes sure that preceding stores to the page contents from
                 * vmemmap_remap_free() become visible before the set_pte_at()
                 * write.
                 */
                smp_wmb();

                entry = mk_pte(walk->vmemmap_head, PAGE_KERNEL);
        } else {
                VM_WARN_ON_ONCE(!PageTail((const struct page *)addr));

                /*
                 * Remap the tail pages as read-only to catch illegal write
                 * operation to the tail pages.
                 */
                entry = mk_pte(walk->vmemmap_tail, PAGE_KERNEL_RO);
        }

        list_add(&page->lru, walk->vmemmap_pages);
        set_pte_at(&init_mm, addr, pte, entry);
}

static void vmemmap_restore_pte(pte_t *pte, unsigned long addr,
                                struct vmemmap_remap_walk *walk)
{
        struct page *src = pte_page(ptep_get(pte)), *dst;

        /*
         * When rolling back vmemmap_remap_free(), keep the copied head page
         * mapping and restore only PTEs currently pointing at the shared tail
         * page.
         */
        if (walk->vmemmap_tail && walk->vmemmap_tail != src)
                return;

        VM_WARN_ON_ONCE(PageHead((const struct page *)addr));

        dst = list_first_entry(walk->vmemmap_pages, struct page, lru);
        list_del(&dst->lru);
        copy_page(page_to_virt(dst), page_to_virt(src));

        /*
         * Makes sure that preceding stores to the page contents become visible
         * before the set_pte_at() write.
         */
        smp_wmb();
        set_pte_at(&init_mm, addr, pte, mk_pte(dst, PAGE_KERNEL));
}

/**
 * vmemmap_remap_split - split the vmemmap virtual address range [@start, @end)
 *                      backing PMDs of the directmap into PTEs
 * @start:     start address of the vmemmap virtual address range that we want
 *             to remap.
 * @end:       end address of the vmemmap virtual address range that we want to
 *             remap.
 * Return: %0 on success, negative error code otherwise.
 */
static int vmemmap_remap_split(unsigned long start, unsigned long end)
{
        struct vmemmap_remap_walk walk = {
                .remap_pte      = NULL,
                .flags          = VMEMMAP_SPLIT_NO_TLB_FLUSH,
        };

        return vmemmap_remap_range(start, end, &walk);
}

/**
 * vmemmap_remap_free - remap the vmemmap virtual address range [@start, @end)
 *                      to use @vmemmap_head/tail, then free vmemmap which
 *                      the range are mapped to.
 * @start:      start address of the vmemmap virtual address range that we want
 *              to remap.
 * @end:        end address of the vmemmap virtual address range that we want to
 *              remap.
 * @vmemmap_head: the page to be installed as first in the vmemmap range
 * @vmemmap_tail: the page to be installed as non-first in the vmemmap range
 * @vmemmap_pages: list to deposit vmemmap pages to be freed.  It is callers
 *              responsibility to free pages.
 * @flags:      modifications to vmemmap_remap_walk flags
 *
 * Return: %0 on success, negative error code otherwise.
 */
static int vmemmap_remap_free(unsigned long start, unsigned long end,
                              struct page *vmemmap_head,
                              struct page *vmemmap_tail,
                              struct list_head *vmemmap_pages,
                              unsigned long flags)
{
        int ret;
        struct vmemmap_remap_walk walk = {
                .remap_pte      = vmemmap_remap_pte,
                .vmemmap_head   = vmemmap_head,
                .vmemmap_tail   = vmemmap_tail,
                .vmemmap_pages  = vmemmap_pages,
                .flags          = flags,
        };

        ret = vmemmap_remap_range(start, end, &walk);
        if (!ret || !walk.nr_walked)
                return ret;

        end = start + walk.nr_walked * PAGE_SIZE;

        /*
         * vmemmap_pages contains pages from the previous vmemmap_remap_range()
         * call which failed.  These are pages which were removed from
         * the vmemmap. They will be restored in the following call.
         */
        walk = (struct vmemmap_remap_walk) {
                .remap_pte      = vmemmap_restore_pte,
                .vmemmap_tail   = vmemmap_tail,
                .vmemmap_pages  = vmemmap_pages,
                .flags          = 0,
        };

        vmemmap_remap_range(start, end, &walk);

        return ret;
}

static int alloc_vmemmap_page_list(unsigned long start, unsigned long end,
                                   struct list_head *list)
{
        gfp_t gfp_mask = GFP_KERNEL | __GFP_RETRY_MAYFAIL;
        unsigned long nr_pages = (end - start) >> PAGE_SHIFT;
        int nid = page_to_nid((struct page *)start);
        struct page *page, *next;
        int i;

        for (i = 0; i < nr_pages; i++) {
                page = alloc_pages_node(nid, gfp_mask, 0);
                if (!page)
                        goto out;
                list_add(&page->lru, list);
        }
        memmap_pages_add(nr_pages);

        return 0;
out:
        list_for_each_entry_safe(page, next, list, lru)
                __free_page(page);
        return -ENOMEM;
}

/**
 * vmemmap_remap_alloc - remap the vmemmap virtual address range [@start, end)
 *                       to the page which is from the @vmemmap_pages
 *                       respectively.
 * @start:      start address of the vmemmap virtual address range that we want
 *              to remap.
 * @end:        end address of the vmemmap virtual address range that we want to
 *              remap.
 * @flags:      modifications to vmemmap_remap_walk flags
 *
 * Return: %0 on success, negative error code otherwise.
 */
static int vmemmap_remap_alloc(unsigned long start, unsigned long end,
                               unsigned long flags)
{
        LIST_HEAD(vmemmap_pages);
        struct vmemmap_remap_walk walk = {
                .remap_pte      = vmemmap_restore_pte,
                .vmemmap_pages  = &vmemmap_pages,
                .flags          = flags,
        };

        if (alloc_vmemmap_page_list(start, end, &vmemmap_pages))
                return -ENOMEM;

        return vmemmap_remap_range(start, end, &walk);
}

static bool vmemmap_optimize_enabled = IS_ENABLED(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON);
static int __init hugetlb_vmemmap_optimize_param(char *buf)
{
        return kstrtobool(buf, &vmemmap_optimize_enabled);
}
early_param("hugetlb_free_vmemmap", hugetlb_vmemmap_optimize_param);

static int __hugetlb_vmemmap_restore_folio(const struct hstate *h,
                                           struct folio *folio, unsigned long flags)
{
        int ret;
        unsigned long vmemmap_start, vmemmap_end;

        VM_WARN_ON_ONCE_FOLIO(!folio_test_hugetlb(folio), folio);
        VM_WARN_ON_ONCE_FOLIO(folio_ref_count(folio), folio);

        if (!folio_test_hugetlb_vmemmap_optimized(folio))
                return 0;

        vmemmap_start   = (unsigned long)&folio->page;
        vmemmap_end     = vmemmap_start + hugetlb_vmemmap_size(h);

        vmemmap_start   += HUGETLB_VMEMMAP_RESERVE_SIZE;

        /*
         * The pages which the vmemmap virtual address range [@vmemmap_start,
         * @vmemmap_end) are mapped to are freed to the buddy allocator.
         * When a HugeTLB page is freed to the buddy allocator, previously
         * discarded vmemmap pages must be allocated and remapping.
         */
        ret = vmemmap_remap_alloc(vmemmap_start, vmemmap_end, flags);
        if (!ret)
                folio_clear_hugetlb_vmemmap_optimized(folio);

        return ret;
}

/**
 * hugetlb_vmemmap_restore_folio - restore previously optimized (by
 *                              hugetlb_vmemmap_optimize_folio()) vmemmap pages which
 *                              will be reallocated and remapped.
 * @h:          struct hstate.
 * @folio:     the folio whose vmemmap pages will be restored.
 *
 * Return: %0 if @folio's vmemmap pages have been reallocated and remapped,
 * negative error code otherwise.
 */
int hugetlb_vmemmap_restore_folio(const struct hstate *h, struct folio *folio)
{
        return __hugetlb_vmemmap_restore_folio(h, folio, 0);
}

/**
 * hugetlb_vmemmap_restore_folios - restore vmemmap for every folio on the list.
 * @h:                  hstate.
 * @folio_list:         list of folios.
 * @non_hvo_folios:     Output list of folios for which vmemmap exists.
 *
 * Return: number of folios for which vmemmap was restored, or an error code
 *              if an error was encountered restoring vmemmap for a folio.
 *              Folios that have vmemmap are moved to the non_hvo_folios
 *              list.  Processing of entries stops when the first error is
 *              encountered. The folio that experienced the error and all
 *              non-processed folios will remain on folio_list.
 */
long hugetlb_vmemmap_restore_folios(const struct hstate *h,
                                        struct list_head *folio_list,
                                        struct list_head *non_hvo_folios)
{
        struct folio *folio, *t_folio;
        long restored = 0;
        long ret = 0;
        unsigned long flags = VMEMMAP_REMAP_NO_TLB_FLUSH;

        list_for_each_entry_safe(folio, t_folio, folio_list, lru) {
                if (folio_test_hugetlb_vmemmap_optimized(folio)) {
                        ret = __hugetlb_vmemmap_restore_folio(h, folio, flags);
                        if (ret)
                                break;
                        restored++;
                }

                /* Add non-optimized folios to output list */
                list_move(&folio->lru, non_hvo_folios);
        }

        if (restored)
                flush_tlb_all();
        if (!ret)
                ret = restored;
        return ret;
}

/* Return true iff a HugeTLB whose vmemmap should and can be optimized. */
static bool vmemmap_should_optimize_folio(const struct hstate *h, struct folio *folio)
{
        if (folio_test_hugetlb_vmemmap_optimized(folio))
                return false;

        if (!READ_ONCE(vmemmap_optimize_enabled))
                return false;

        if (!hugetlb_vmemmap_optimizable(h))
                return false;

        return true;
}

static struct page *vmemmap_get_tail(unsigned int order, struct zone *zone)
{
        const unsigned int idx = order - VMEMMAP_TAIL_MIN_ORDER;
        struct page *tail, *p;
        int node = zone_to_nid(zone);

        tail = READ_ONCE(zone->vmemmap_tails[idx]);
        if (likely(tail))
                return tail;

        tail = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
        if (!tail)
                return NULL;

        p = page_to_virt(tail);
        for (int i = 0; i < PAGE_SIZE / sizeof(struct page); i++)
                init_compound_tail(p + i, NULL, order, zone);

        if (cmpxchg(&zone->vmemmap_tails[idx], NULL, tail)) {
                __free_page(tail);
                tail = READ_ONCE(zone->vmemmap_tails[idx]);
        }

        return tail;
}

static int __hugetlb_vmemmap_optimize_folio(const struct hstate *h,
                                            struct folio *folio,
                                            struct list_head *vmemmap_pages,
                                            unsigned long flags)
{
        unsigned long vmemmap_start, vmemmap_end;
        struct page *vmemmap_head, *vmemmap_tail;
        int nid, ret = 0;

        VM_WARN_ON_ONCE_FOLIO(!folio_test_hugetlb(folio), folio);
        VM_WARN_ON_ONCE_FOLIO(folio_ref_count(folio), folio);

        if (!vmemmap_should_optimize_folio(h, folio))
                return ret;

        nid = folio_nid(folio);
        vmemmap_tail = vmemmap_get_tail(h->order, folio_zone(folio));
        if (!vmemmap_tail)
                return -ENOMEM;

        /*
         * Very Subtle
         * If VMEMMAP_REMAP_NO_TLB_FLUSH is set, TLB flushing is not performed
         * immediately after remapping.  As a result, subsequent accesses
         * and modifications to struct pages associated with the hugetlb
         * page could be to the OLD struct pages.  Set the vmemmap optimized
         * flag here so that it is copied to the new head page.  This keeps
         * the old and new struct pages in sync.
         * If there is an error during optimization, we will immediately FLUSH
         * the TLB and clear the flag below.
         */
        folio_set_hugetlb_vmemmap_optimized(folio);

        vmemmap_head = alloc_pages_node(nid, GFP_KERNEL, 0);
        if (!vmemmap_head) {
                ret = -ENOMEM;
                goto out;
        }

        copy_page(page_to_virt(vmemmap_head), folio);
        list_add(&vmemmap_head->lru, vmemmap_pages);
        memmap_pages_add(1);

        vmemmap_start   = (unsigned long)&folio->page;
        vmemmap_end     = vmemmap_start + hugetlb_vmemmap_size(h);

        /*
         * Remap the vmemmap virtual address range [@vmemmap_start, @vmemmap_end).
         * Add pages previously mapping the range to vmemmap_pages list so that
         * they can be freed by the caller.
         */
        ret = vmemmap_remap_free(vmemmap_start, vmemmap_end,
                                 vmemmap_head, vmemmap_tail,
                                 vmemmap_pages, flags);
out:
        if (ret)
                folio_clear_hugetlb_vmemmap_optimized(folio);

        return ret;
}

/**
 * hugetlb_vmemmap_optimize_folio - optimize @folio's vmemmap pages.
 * @h:          struct hstate.
 * @folio:     the folio whose vmemmap pages will be optimized.
 *
 * This function only tries to optimize @folio's vmemmap pages and does not
 * guarantee that the optimization will succeed after it returns. The caller
 * can use folio_test_hugetlb_vmemmap_optimized(@folio) to detect if @folio's
 * vmemmap pages have been optimized.
 */
void hugetlb_vmemmap_optimize_folio(const struct hstate *h, struct folio *folio)
{
        LIST_HEAD(vmemmap_pages);

        __hugetlb_vmemmap_optimize_folio(h, folio, &vmemmap_pages, 0);
        free_vmemmap_page_list(&vmemmap_pages);
}

static int hugetlb_vmemmap_split_folio(const struct hstate *h, struct folio *folio)
{
        unsigned long vmemmap_start, vmemmap_end;

        if (!vmemmap_should_optimize_folio(h, folio))
                return 0;

        vmemmap_start   = (unsigned long)&folio->page;
        vmemmap_end     = vmemmap_start + hugetlb_vmemmap_size(h);

        /*
         * Split PMDs on the vmemmap virtual address range [@vmemmap_start,
         * @vmemmap_end]
         */
        return vmemmap_remap_split(vmemmap_start, vmemmap_end);
}

static void __hugetlb_vmemmap_optimize_folios(struct hstate *h,
                                              struct list_head *folio_list,
                                              bool boot)
{
        struct folio *folio;
        int nr_to_optimize;
        LIST_HEAD(vmemmap_pages);
        unsigned long flags = VMEMMAP_REMAP_NO_TLB_FLUSH;

        nr_to_optimize = 0;
        list_for_each_entry(folio, folio_list, lru) {
                int ret;
                unsigned long spfn, epfn;

                if (boot && folio_test_hugetlb_vmemmap_optimized(folio)) {
                        /*
                         * Already optimized by pre-HVO, just map the
                         * mirrored tail page structs RO.
                         */
                        spfn = (unsigned long)&folio->page;
                        epfn = spfn + pages_per_huge_page(h);
                        vmemmap_wrprotect_hvo(spfn, epfn, folio_nid(folio),
                                        HUGETLB_VMEMMAP_RESERVE_SIZE);
                        register_page_bootmem_memmap(pfn_to_section_nr(spfn),
                                        &folio->page,
                                        HUGETLB_VMEMMAP_RESERVE_SIZE);
                        continue;
                }

                nr_to_optimize++;

                ret = hugetlb_vmemmap_split_folio(h, folio);

                /*
                 * Splitting the PMD requires allocating a page, thus let's fail
                 * early once we encounter the first OOM. No point in retrying
                 * as it can be dynamically done on remap with the memory
                 * we get back from the vmemmap deduplication.
                 */
                if (ret == -ENOMEM)
                        break;
        }

        if (!nr_to_optimize)
                /*
                 * All pre-HVO folios, nothing left to do. It's ok if
                 * there is a mix of pre-HVO and not yet HVO-ed folios
                 * here, as __hugetlb_vmemmap_optimize_folio() will
                 * skip any folios that already have the optimized flag
                 * set, see vmemmap_should_optimize_folio().
                 */
                goto out;

        flush_tlb_all();

        list_for_each_entry(folio, folio_list, lru) {
                int ret;

                ret = __hugetlb_vmemmap_optimize_folio(h, folio, &vmemmap_pages, flags);

                /*
                 * Pages to be freed may have been accumulated.  If we
                 * encounter an ENOMEM,  free what we have and try again.
                 * This can occur in the case that both splitting fails
                 * halfway and head page allocation also failed. In this
                 * case __hugetlb_vmemmap_optimize_folio() would free memory
                 * allowing more vmemmap remaps to occur.
                 */
                if (ret == -ENOMEM && !list_empty(&vmemmap_pages)) {
                        flush_tlb_all();
                        free_vmemmap_page_list(&vmemmap_pages);
                        INIT_LIST_HEAD(&vmemmap_pages);
                        __hugetlb_vmemmap_optimize_folio(h, folio, &vmemmap_pages, flags);
                }
        }

out:
        flush_tlb_all();
        free_vmemmap_page_list(&vmemmap_pages);
}

void hugetlb_vmemmap_optimize_folios(struct hstate *h, struct list_head *folio_list)
{
        __hugetlb_vmemmap_optimize_folios(h, folio_list, false);
}

void hugetlb_vmemmap_optimize_bootmem_folios(struct hstate *h, struct list_head *folio_list)
{
        __hugetlb_vmemmap_optimize_folios(h, folio_list, true);
}

#ifdef CONFIG_SPARSEMEM_VMEMMAP_PREINIT

/* Return true of a bootmem allocated HugeTLB page should be pre-HVO-ed */
static bool vmemmap_should_optimize_bootmem_page(struct huge_bootmem_page *m)
{
        unsigned long section_size, psize, pmd_vmemmap_size;
        phys_addr_t paddr;

        if (!READ_ONCE(vmemmap_optimize_enabled))
                return false;

        if (!hugetlb_vmemmap_optimizable(m->hstate))
                return false;

        psize = huge_page_size(m->hstate);
        paddr = virt_to_phys(m);

        /*
         * Pre-HVO only works if the bootmem huge page
         * is aligned to the section size.
         */
        section_size = (1UL << PA_SECTION_SHIFT);
        if (!IS_ALIGNED(paddr, section_size) ||
            !IS_ALIGNED(psize, section_size))
                return false;

        /*
         * The pre-HVO code does not deal with splitting PMDS,
         * so the bootmem page must be aligned to the number
         * of base pages that can be mapped with one vmemmap PMD.
         */
        pmd_vmemmap_size = (PMD_SIZE / (sizeof(struct page))) << PAGE_SHIFT;
        if (!IS_ALIGNED(paddr, pmd_vmemmap_size) ||
            !IS_ALIGNED(psize, pmd_vmemmap_size))
                return false;

        return true;
}

/*
 * Initialize memmap section for a gigantic page, HVO-style.
 */
void __init hugetlb_vmemmap_init_early(int nid)
{
        unsigned long psize, paddr, section_size;
        unsigned long ns, i, pnum, pfn, nr_pages;
        struct huge_bootmem_page *m = NULL;
        void *map;

        if (!READ_ONCE(vmemmap_optimize_enabled))
                return;

        section_size = (1UL << PA_SECTION_SHIFT);

        list_for_each_entry(m, &huge_boot_pages[nid], list) {
                if (!vmemmap_should_optimize_bootmem_page(m))
                        continue;

                nr_pages = pages_per_huge_page(m->hstate);
                psize = nr_pages << PAGE_SHIFT;
                paddr = virt_to_phys(m);
                pfn = PHYS_PFN(paddr);
                map = pfn_to_page(pfn);

                pnum = pfn_to_section_nr(pfn);
                ns = psize / section_size;

                for (i = 0; i < ns; i++) {
                        sparse_init_early_section(nid, map, pnum,
                                        SECTION_IS_VMEMMAP_PREINIT);
                        map += section_map_size();
                        pnum++;
                }

                m->flags |= HUGE_BOOTMEM_HVO;
        }
}

static struct zone *pfn_to_zone(unsigned nid, unsigned long pfn)
{
        struct zone *zone;
        enum zone_type zone_type;

        for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++) {
                zone = &NODE_DATA(nid)->node_zones[zone_type];
                if (zone_spans_pfn(zone, pfn))
                        return zone;
        }

        return NULL;
}

void __init hugetlb_vmemmap_init_late(int nid)
{
        struct huge_bootmem_page *m, *tm;
        unsigned long phys, nr_pages, start, end;
        unsigned long pfn, nr_mmap;
        struct zone *zone = NULL;
        struct hstate *h;
        void *map;

        if (!READ_ONCE(vmemmap_optimize_enabled))
                return;

        list_for_each_entry_safe(m, tm, &huge_boot_pages[nid], list) {
                if (!(m->flags & HUGE_BOOTMEM_HVO))
                        continue;

                phys = virt_to_phys(m);
                h = m->hstate;
                pfn = PHYS_PFN(phys);
                nr_pages = pages_per_huge_page(h);
                map = pfn_to_page(pfn);
                start = (unsigned long)map;
                end = start + nr_pages * sizeof(struct page);

                if (!hugetlb_bootmem_page_zones_valid(nid, m)) {
                        /*
                         * Oops, the hugetlb page spans multiple zones.
                         * Remove it from the list, and populate it normally.
                         */
                        list_del(&m->list);

                        vmemmap_populate(start, end, nid, NULL);
                        nr_mmap = end - start;
                        memmap_boot_pages_add(DIV_ROUND_UP(nr_mmap, PAGE_SIZE));

                        memblock_phys_free(phys, huge_page_size(h));
                        continue;
                }

                if (!zone || !zone_spans_pfn(zone, pfn))
                        zone = pfn_to_zone(nid, pfn);
                if (WARN_ON_ONCE(!zone))
                        continue;

                if (vmemmap_populate_hvo(start, end, huge_page_order(h), zone,
                                         HUGETLB_VMEMMAP_RESERVE_SIZE) < 0) {
                        /* Fallback if HVO population fails */
                        vmemmap_populate(start, end, nid, NULL);
                        nr_mmap = end - start;
                } else {
                        m->flags |= HUGE_BOOTMEM_ZONES_VALID;
                        nr_mmap = HUGETLB_VMEMMAP_RESERVE_SIZE;
                }

                memmap_boot_pages_add(DIV_ROUND_UP(nr_mmap, PAGE_SIZE));
        }
}
#endif

static const struct ctl_table hugetlb_vmemmap_sysctls[] = {
        {
                .procname       = "hugetlb_optimize_vmemmap",
                .data           = &vmemmap_optimize_enabled,
                .maxlen         = sizeof(vmemmap_optimize_enabled),
                .mode           = 0644,
                .proc_handler   = proc_dobool,
        },
};

static int __init hugetlb_vmemmap_init(void)
{
        const struct hstate *h;
        struct zone *zone;

        /* HUGETLB_VMEMMAP_RESERVE_SIZE should cover all used struct pages */
        BUILD_BUG_ON(__NR_USED_SUBPAGE > HUGETLB_VMEMMAP_RESERVE_PAGES);

        for_each_zone(zone) {
                for (int i = 0; i < NR_VMEMMAP_TAILS; i++) {
                        struct page *tail, *p;
                        unsigned int order;

                        tail = zone->vmemmap_tails[i];
                        if (!tail)
                                continue;

                        order = i + VMEMMAP_TAIL_MIN_ORDER;
                        p = page_to_virt(tail);
                        for (int j = 0; j < PAGE_SIZE / sizeof(struct page); j++)
                                init_compound_tail(p + j, NULL, order, zone);
                }
        }

        for_each_hstate(h) {
                if (hugetlb_vmemmap_optimizable(h)) {
                        register_sysctl_init("vm", hugetlb_vmemmap_sysctls);
                        break;
                }
        }
        return 0;
}
late_initcall(hugetlb_vmemmap_init);