Merge tag 'random_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel...

[mirror_ubuntu-zesty-kernel.git] / arch / s390 / mm / gmap.c

/*
 *  KVM guest address space mapping code
 *
 *    Copyright IBM Corp. 2007, 2016
 *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
 */

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/swapops.h>
#include <linux/ksm.h>
#include <linux/mman.h>

#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/gmap.h>
#include <asm/tlb.h>

/**
 * gmap_alloc - allocate a guest address space
 * @mm: pointer to the parent mm_struct
 * @limit: maximum address of the gmap address space
 *
 * Returns a guest address space structure.
 */
struct gmap *gmap_alloc(struct mm_struct *mm, unsigned long limit)
{
        struct gmap *gmap;
        struct page *page;
        unsigned long *table;
        unsigned long etype, atype;

        if (limit < (1UL << 31)) {
                limit = (1UL << 31) - 1;
                atype = _ASCE_TYPE_SEGMENT;
                etype = _SEGMENT_ENTRY_EMPTY;
        } else if (limit < (1UL << 42)) {
                limit = (1UL << 42) - 1;
                atype = _ASCE_TYPE_REGION3;
                etype = _REGION3_ENTRY_EMPTY;
        } else if (limit < (1UL << 53)) {
                limit = (1UL << 53) - 1;
                atype = _ASCE_TYPE_REGION2;
                etype = _REGION2_ENTRY_EMPTY;
        } else {
                limit = -1UL;
                atype = _ASCE_TYPE_REGION1;
                etype = _REGION1_ENTRY_EMPTY;
        }
        gmap = kzalloc(sizeof(struct gmap), GFP_KERNEL);
        if (!gmap)
                goto out;
        INIT_LIST_HEAD(&gmap->crst_list);
        INIT_RADIX_TREE(&gmap->guest_to_host, GFP_KERNEL);
        INIT_RADIX_TREE(&gmap->host_to_guest, GFP_ATOMIC);
        spin_lock_init(&gmap->guest_table_lock);
        gmap->mm = mm;
        page = alloc_pages(GFP_KERNEL, 2);
        if (!page)
                goto out_free;
        page->index = 0;
        list_add(&page->lru, &gmap->crst_list);
        table = (unsigned long *) page_to_phys(page);
        crst_table_init(table, etype);
        gmap->table = table;
        gmap->asce = atype | _ASCE_TABLE_LENGTH |
                _ASCE_USER_BITS | __pa(table);
        gmap->asce_end = limit;
        down_write(&mm->mmap_sem);
        list_add(&gmap->list, &mm->context.gmap_list);
        up_write(&mm->mmap_sem);
        return gmap;

out_free:
        kfree(gmap);
out:
        return NULL;
}
EXPORT_SYMBOL_GPL(gmap_alloc);

static void gmap_flush_tlb(struct gmap *gmap)
{
        if (MACHINE_HAS_IDTE)
                __tlb_flush_idte(gmap->asce);
        else
                __tlb_flush_global();
}

static void gmap_radix_tree_free(struct radix_tree_root *root)
{
        struct radix_tree_iter iter;
        unsigned long indices[16];
        unsigned long index;
        void **slot;
        int i, nr;

        /* A radix tree is freed by deleting all of its entries */
        index = 0;
        do {
                nr = 0;
                radix_tree_for_each_slot(slot, root, &iter, index) {
                        indices[nr] = iter.index;
                        if (++nr == 16)
                                break;
                }
                for (i = 0; i < nr; i++) {
                        index = indices[i];
                        radix_tree_delete(root, index);
                }
        } while (nr > 0);
}

/**
 * gmap_free - free a guest address space
 * @gmap: pointer to the guest address space structure
 */
void gmap_free(struct gmap *gmap)
{
        struct page *page, *next;

        /* Flush tlb. */
        if (MACHINE_HAS_IDTE)
                __tlb_flush_idte(gmap->asce);
        else
                __tlb_flush_global();

        /* Free all segment & region tables. */
        list_for_each_entry_safe(page, next, &gmap->crst_list, lru)
                __free_pages(page, 2);
        gmap_radix_tree_free(&gmap->guest_to_host);
        gmap_radix_tree_free(&gmap->host_to_guest);
        down_write(&gmap->mm->mmap_sem);
        list_del(&gmap->list);
        up_write(&gmap->mm->mmap_sem);
        kfree(gmap);
}
EXPORT_SYMBOL_GPL(gmap_free);

/**
 * gmap_enable - switch primary space to the guest address space
 * @gmap: pointer to the guest address space structure
 */
void gmap_enable(struct gmap *gmap)
{
        S390_lowcore.gmap = (unsigned long) gmap;
}
EXPORT_SYMBOL_GPL(gmap_enable);

/**
 * gmap_disable - switch back to the standard primary address space
 * @gmap: pointer to the guest address space structure
 */
void gmap_disable(struct gmap *gmap)
{
        S390_lowcore.gmap = 0UL;
}
EXPORT_SYMBOL_GPL(gmap_disable);

/*
 * gmap_alloc_table is assumed to be called with mmap_sem held
 */
static int gmap_alloc_table(struct gmap *gmap, unsigned long *table,
                            unsigned long init, unsigned long gaddr)
{
        struct page *page;
        unsigned long *new;

        /* since we dont free the gmap table until gmap_free we can unlock */
        page = alloc_pages(GFP_KERNEL, 2);
        if (!page)
                return -ENOMEM;
        new = (unsigned long *) page_to_phys(page);
        crst_table_init(new, init);
        spin_lock(&gmap->mm->page_table_lock);
        if (*table & _REGION_ENTRY_INVALID) {
                list_add(&page->lru, &gmap->crst_list);
                *table = (unsigned long) new | _REGION_ENTRY_LENGTH |
                        (*table & _REGION_ENTRY_TYPE_MASK);
                page->index = gaddr;
                page = NULL;
        }
        spin_unlock(&gmap->mm->page_table_lock);
        if (page)
                __free_pages(page, 2);
        return 0;
}

/**
 * __gmap_segment_gaddr - find virtual address from segment pointer
 * @entry: pointer to a segment table entry in the guest address space
 *
 * Returns the virtual address in the guest address space for the segment
 */
static unsigned long __gmap_segment_gaddr(unsigned long *entry)
{
        struct page *page;
        unsigned long offset, mask;

        offset = (unsigned long) entry / sizeof(unsigned long);
        offset = (offset & (PTRS_PER_PMD - 1)) * PMD_SIZE;
        mask = ~(PTRS_PER_PMD * sizeof(pmd_t) - 1);
        page = virt_to_page((void *)((unsigned long) entry & mask));
        return page->index + offset;
}

/**
 * __gmap_unlink_by_vmaddr - unlink a single segment via a host address
 * @gmap: pointer to the guest address space structure
 * @vmaddr: address in the host process address space
 *
 * Returns 1 if a TLB flush is required
 */
static int __gmap_unlink_by_vmaddr(struct gmap *gmap, unsigned long vmaddr)
{
        unsigned long *entry;
        int flush = 0;

        spin_lock(&gmap->guest_table_lock);
        entry = radix_tree_delete(&gmap->host_to_guest, vmaddr >> PMD_SHIFT);
        if (entry) {
                flush = (*entry != _SEGMENT_ENTRY_INVALID);
                *entry = _SEGMENT_ENTRY_INVALID;
        }
        spin_unlock(&gmap->guest_table_lock);
        return flush;
}

/**
 * __gmap_unmap_by_gaddr - unmap a single segment via a guest address
 * @gmap: pointer to the guest address space structure
 * @gaddr: address in the guest address space
 *
 * Returns 1 if a TLB flush is required
 */
static int __gmap_unmap_by_gaddr(struct gmap *gmap, unsigned long gaddr)
{
        unsigned long vmaddr;

        vmaddr = (unsigned long) radix_tree_delete(&gmap->guest_to_host,
                                                   gaddr >> PMD_SHIFT);
        return vmaddr ? __gmap_unlink_by_vmaddr(gmap, vmaddr) : 0;
}

/**
 * gmap_unmap_segment - unmap segment from the guest address space
 * @gmap: pointer to the guest address space structure
 * @to: address in the guest address space
 * @len: length of the memory area to unmap
 *
 * Returns 0 if the unmap succeeded, -EINVAL if not.
 */
int gmap_unmap_segment(struct gmap *gmap, unsigned long to, unsigned long len)
{
        unsigned long off;
        int flush;

        if ((to | len) & (PMD_SIZE - 1))
                return -EINVAL;
        if (len == 0 || to + len < to)
                return -EINVAL;

        flush = 0;
        down_write(&gmap->mm->mmap_sem);
        for (off = 0; off < len; off += PMD_SIZE)
                flush |= __gmap_unmap_by_gaddr(gmap, to + off);
        up_write(&gmap->mm->mmap_sem);
        if (flush)
                gmap_flush_tlb(gmap);
        return 0;
}
EXPORT_SYMBOL_GPL(gmap_unmap_segment);

/**
 * gmap_map_segment - map a segment to the guest address space
 * @gmap: pointer to the guest address space structure
 * @from: source address in the parent address space
 * @to: target address in the guest address space
 * @len: length of the memory area to map
 *
 * Returns 0 if the mmap succeeded, -EINVAL or -ENOMEM if not.
 */
int gmap_map_segment(struct gmap *gmap, unsigned long from,
                     unsigned long to, unsigned long len)
{
        unsigned long off;
        int flush;

        if ((from | to | len) & (PMD_SIZE - 1))
                return -EINVAL;
        if (len == 0 || from + len < from || to + len < to ||
            from + len - 1 > TASK_MAX_SIZE || to + len - 1 > gmap->asce_end)
                return -EINVAL;

        flush = 0;
        down_write(&gmap->mm->mmap_sem);
        for (off = 0; off < len; off += PMD_SIZE) {
                /* Remove old translation */
                flush |= __gmap_unmap_by_gaddr(gmap, to + off);
                /* Store new translation */
                if (radix_tree_insert(&gmap->guest_to_host,
                                      (to + off) >> PMD_SHIFT,
                                      (void *) from + off))
                        break;
        }
        up_write(&gmap->mm->mmap_sem);
        if (flush)
                gmap_flush_tlb(gmap);
        if (off >= len)
                return 0;
        gmap_unmap_segment(gmap, to, len);
        return -ENOMEM;
}
EXPORT_SYMBOL_GPL(gmap_map_segment);

/**
 * __gmap_translate - translate a guest address to a user space address
 * @gmap: pointer to guest mapping meta data structure
 * @gaddr: guest address
 *
 * Returns user space address which corresponds to the guest address or
 * -EFAULT if no such mapping exists.
 * This function does not establish potentially missing page table entries.
 * The mmap_sem of the mm that belongs to the address space must be held
 * when this function gets called.
 */
unsigned long __gmap_translate(struct gmap *gmap, unsigned long gaddr)
{
        unsigned long vmaddr;

        vmaddr = (unsigned long)
                radix_tree_lookup(&gmap->guest_to_host, gaddr >> PMD_SHIFT);
        return vmaddr ? (vmaddr | (gaddr & ~PMD_MASK)) : -EFAULT;
}
EXPORT_SYMBOL_GPL(__gmap_translate);

/**
 * gmap_translate - translate a guest address to a user space address
 * @gmap: pointer to guest mapping meta data structure
 * @gaddr: guest address
 *
 * Returns user space address which corresponds to the guest address or
 * -EFAULT if no such mapping exists.
 * This function does not establish potentially missing page table entries.
 */
unsigned long gmap_translate(struct gmap *gmap, unsigned long gaddr)
{
        unsigned long rc;

        down_read(&gmap->mm->mmap_sem);
        rc = __gmap_translate(gmap, gaddr);
        up_read(&gmap->mm->mmap_sem);
        return rc;
}
EXPORT_SYMBOL_GPL(gmap_translate);

/**
 * gmap_unlink - disconnect a page table from the gmap shadow tables
 * @gmap: pointer to guest mapping meta data structure
 * @table: pointer to the host page table
 * @vmaddr: vm address associated with the host page table
 */
void gmap_unlink(struct mm_struct *mm, unsigned long *table,
                 unsigned long vmaddr)
{
        struct gmap *gmap;
        int flush;

        list_for_each_entry(gmap, &mm->context.gmap_list, list) {
                flush = __gmap_unlink_by_vmaddr(gmap, vmaddr);
                if (flush)
                        gmap_flush_tlb(gmap);
        }
}

/**
 * gmap_link - set up shadow page tables to connect a host to a guest address
 * @gmap: pointer to guest mapping meta data structure
 * @gaddr: guest address
 * @vmaddr: vm address
 *
 * Returns 0 on success, -ENOMEM for out of memory conditions, and -EFAULT
 * if the vm address is already mapped to a different guest segment.
 * The mmap_sem of the mm that belongs to the address space must be held
 * when this function gets called.
 */
int __gmap_link(struct gmap *gmap, unsigned long gaddr, unsigned long vmaddr)
{
        struct mm_struct *mm;
        unsigned long *table;
        spinlock_t *ptl;
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;
        int rc;

        /* Create higher level tables in the gmap page table */
        table = gmap->table;
        if ((gmap->asce & _ASCE_TYPE_MASK) >= _ASCE_TYPE_REGION1) {
                table += (gaddr >> 53) & 0x7ff;
                if ((*table & _REGION_ENTRY_INVALID) &&
                    gmap_alloc_table(gmap, table, _REGION2_ENTRY_EMPTY,
                                     gaddr & 0xffe0000000000000UL))
                        return -ENOMEM;
                table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
        }
        if ((gmap->asce & _ASCE_TYPE_MASK) >= _ASCE_TYPE_REGION2) {
                table += (gaddr >> 42) & 0x7ff;
                if ((*table & _REGION_ENTRY_INVALID) &&
                    gmap_alloc_table(gmap, table, _REGION3_ENTRY_EMPTY,
                                     gaddr & 0xfffffc0000000000UL))
                        return -ENOMEM;
                table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
        }
        if ((gmap->asce & _ASCE_TYPE_MASK) >= _ASCE_TYPE_REGION3) {
                table += (gaddr >> 31) & 0x7ff;
                if ((*table & _REGION_ENTRY_INVALID) &&
                    gmap_alloc_table(gmap, table, _SEGMENT_ENTRY_EMPTY,
                                     gaddr & 0xffffffff80000000UL))
                        return -ENOMEM;
                table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
        }
        table += (gaddr >> 20) & 0x7ff;
        /* Walk the parent mm page table */
        mm = gmap->mm;
        pgd = pgd_offset(mm, vmaddr);
        VM_BUG_ON(pgd_none(*pgd));
        pud = pud_offset(pgd, vmaddr);
        VM_BUG_ON(pud_none(*pud));
        /* large puds cannot yet be handled */
        if (pud_large(*pud))
                return -EFAULT;
        pmd = pmd_offset(pud, vmaddr);
        VM_BUG_ON(pmd_none(*pmd));
        /* large pmds cannot yet be handled */
        if (pmd_large(*pmd))
                return -EFAULT;
        /* Link gmap segment table entry location to page table. */
        rc = radix_tree_preload(GFP_KERNEL);
        if (rc)
                return rc;
        ptl = pmd_lock(mm, pmd);
        spin_lock(&gmap->guest_table_lock);
        if (*table == _SEGMENT_ENTRY_INVALID) {
                rc = radix_tree_insert(&gmap->host_to_guest,
                                       vmaddr >> PMD_SHIFT, table);
                if (!rc)
                        *table = pmd_val(*pmd);
        } else
                rc = 0;
        spin_unlock(&gmap->guest_table_lock);
        spin_unlock(ptl);
        radix_tree_preload_end();
        return rc;
}

/**
 * gmap_fault - resolve a fault on a guest address
 * @gmap: pointer to guest mapping meta data structure
 * @gaddr: guest address
 * @fault_flags: flags to pass down to handle_mm_fault()
 *
 * Returns 0 on success, -ENOMEM for out of memory conditions, and -EFAULT
 * if the vm address is already mapped to a different guest segment.
 */
int gmap_fault(struct gmap *gmap, unsigned long gaddr,
               unsigned int fault_flags)
{
        unsigned long vmaddr;
        int rc;
        bool unlocked;

        down_read(&gmap->mm->mmap_sem);

retry:
        unlocked = false;
        vmaddr = __gmap_translate(gmap, gaddr);
        if (IS_ERR_VALUE(vmaddr)) {
                rc = vmaddr;
                goto out_up;
        }
        if (fixup_user_fault(current, gmap->mm, vmaddr, fault_flags,
                             &unlocked)) {
                rc = -EFAULT;
                goto out_up;
        }
        /*
         * In the case that fixup_user_fault unlocked the mmap_sem during
         * faultin redo __gmap_translate to not race with a map/unmap_segment.
         */
        if (unlocked)
                goto retry;

        rc = __gmap_link(gmap, gaddr, vmaddr);
out_up:
        up_read(&gmap->mm->mmap_sem);
        return rc;
}
EXPORT_SYMBOL_GPL(gmap_fault);

/*
 * this function is assumed to be called with mmap_sem held
 */
void __gmap_zap(struct gmap *gmap, unsigned long gaddr)
{
        unsigned long vmaddr;
        spinlock_t *ptl;
        pte_t *ptep;

        /* Find the vm address for the guest address */
        vmaddr = (unsigned long) radix_tree_lookup(&gmap->guest_to_host,
                                                   gaddr >> PMD_SHIFT);
        if (vmaddr) {
                vmaddr |= gaddr & ~PMD_MASK;
                /* Get pointer to the page table entry */
                ptep = get_locked_pte(gmap->mm, vmaddr, &ptl);
                if (likely(ptep))
                        ptep_zap_unused(gmap->mm, vmaddr, ptep, 0);
                pte_unmap_unlock(ptep, ptl);
        }
}
EXPORT_SYMBOL_GPL(__gmap_zap);

void gmap_discard(struct gmap *gmap, unsigned long from, unsigned long to)
{
        unsigned long gaddr, vmaddr, size;
        struct vm_area_struct *vma;

        down_read(&gmap->mm->mmap_sem);
        for (gaddr = from; gaddr < to;
             gaddr = (gaddr + PMD_SIZE) & PMD_MASK) {
                /* Find the vm address for the guest address */
                vmaddr = (unsigned long)
                        radix_tree_lookup(&gmap->guest_to_host,
                                          gaddr >> PMD_SHIFT);
                if (!vmaddr)
                        continue;
                vmaddr |= gaddr & ~PMD_MASK;
                /* Find vma in the parent mm */
                vma = find_vma(gmap->mm, vmaddr);
                size = min(to - gaddr, PMD_SIZE - (gaddr & ~PMD_MASK));
                zap_page_range(vma, vmaddr, size, NULL);
        }
        up_read(&gmap->mm->mmap_sem);
}
EXPORT_SYMBOL_GPL(gmap_discard);

static LIST_HEAD(gmap_notifier_list);
static DEFINE_SPINLOCK(gmap_notifier_lock);

/**
 * gmap_register_ipte_notifier - register a pte invalidation callback
 * @nb: pointer to the gmap notifier block
 */
void gmap_register_ipte_notifier(struct gmap_notifier *nb)
{
        spin_lock(&gmap_notifier_lock);
        list_add(&nb->list, &gmap_notifier_list);
        spin_unlock(&gmap_notifier_lock);
}
EXPORT_SYMBOL_GPL(gmap_register_ipte_notifier);

/**
 * gmap_unregister_ipte_notifier - remove a pte invalidation callback
 * @nb: pointer to the gmap notifier block
 */
void gmap_unregister_ipte_notifier(struct gmap_notifier *nb)
{
        spin_lock(&gmap_notifier_lock);
        list_del_init(&nb->list);
        spin_unlock(&gmap_notifier_lock);
}
EXPORT_SYMBOL_GPL(gmap_unregister_ipte_notifier);

/**
 * gmap_ipte_notify - mark a range of ptes for invalidation notification
 * @gmap: pointer to guest mapping meta data structure
 * @gaddr: virtual address in the guest address space
 * @len: size of area
 *
 * Returns 0 if for each page in the given range a gmap mapping exists and
 * the invalidation notification could be set. If the gmap mapping is missing
 * for one or more pages -EFAULT is returned. If no memory could be allocated
 * -ENOMEM is returned. This function establishes missing page table entries.
 */
int gmap_ipte_notify(struct gmap *gmap, unsigned long gaddr, unsigned long len)
{
        unsigned long addr;
        spinlock_t *ptl;
        pte_t *ptep;
        bool unlocked;
        int rc = 0;

        if ((gaddr & ~PAGE_MASK) || (len & ~PAGE_MASK))
                return -EINVAL;
        down_read(&gmap->mm->mmap_sem);
        while (len) {
                unlocked = false;
                /* Convert gmap address and connect the page tables */
                addr = __gmap_translate(gmap, gaddr);
                if (IS_ERR_VALUE(addr)) {
                        rc = addr;
                        break;
                }
                /* Get the page mapped */
                if (fixup_user_fault(current, gmap->mm, addr, FAULT_FLAG_WRITE,
                                     &unlocked)) {
                        rc = -EFAULT;
                        break;
                }
                /* While trying to map mmap_sem got unlocked. Let us retry */
                if (unlocked)
                        continue;
                rc = __gmap_link(gmap, gaddr, addr);
                if (rc)
                        break;
                /* Walk the process page table, lock and get pte pointer */
                ptep = get_locked_pte(gmap->mm, addr, &ptl);
                VM_BUG_ON(!ptep);
                /* Set notification bit in the pgste of the pte */
                if ((pte_val(*ptep) & (_PAGE_INVALID | _PAGE_PROTECT)) == 0) {
                        ptep_set_notify(gmap->mm, addr, ptep);
                        gaddr += PAGE_SIZE;
                        len -= PAGE_SIZE;
                }
                pte_unmap_unlock(ptep, ptl);
        }
        up_read(&gmap->mm->mmap_sem);
        return rc;
}
EXPORT_SYMBOL_GPL(gmap_ipte_notify);

/**
 * ptep_notify - call all invalidation callbacks for a specific pte.
 * @mm: pointer to the process mm_struct
 * @addr: virtual address in the process address space
 * @pte: pointer to the page table entry
 *
 * This function is assumed to be called with the page table lock held
 * for the pte to notify.
 */
void ptep_notify(struct mm_struct *mm, unsigned long vmaddr, pte_t *pte)
{
        unsigned long offset, gaddr;
        unsigned long *table;
        struct gmap_notifier *nb;
        struct gmap *gmap;

        offset = ((unsigned long) pte) & (255 * sizeof(pte_t));
        offset = offset * (4096 / sizeof(pte_t));
        spin_lock(&gmap_notifier_lock);
        list_for_each_entry(gmap, &mm->context.gmap_list, list) {
                table = radix_tree_lookup(&gmap->host_to_guest,
                                          vmaddr >> PMD_SHIFT);
                if (!table)
                        continue;
                gaddr = __gmap_segment_gaddr(table) + offset;
                list_for_each_entry(nb, &gmap_notifier_list, list)
                        nb->notifier_call(gmap, gaddr);
        }
        spin_unlock(&gmap_notifier_lock);
}
EXPORT_SYMBOL_GPL(ptep_notify);

static inline void thp_split_mm(struct mm_struct *mm)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
        struct vm_area_struct *vma;
        unsigned long addr;

        for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
                for (addr = vma->vm_start;
                     addr < vma->vm_end;
                     addr += PAGE_SIZE)
                        follow_page(vma, addr, FOLL_SPLIT);
                vma->vm_flags &= ~VM_HUGEPAGE;
                vma->vm_flags |= VM_NOHUGEPAGE;
        }
        mm->def_flags |= VM_NOHUGEPAGE;
#endif
}

/*
 * switch on pgstes for its userspace process (for kvm)
 */
int s390_enable_sie(void)
{
        struct mm_struct *mm = current->mm;

        /* Do we have pgstes? if yes, we are done */
        if (mm_has_pgste(mm))
                return 0;
        /* Fail if the page tables are 2K */
        if (!mm_alloc_pgste(mm))
                return -EINVAL;
        down_write(&mm->mmap_sem);
        mm->context.has_pgste = 1;
        /* split thp mappings and disable thp for future mappings */
        thp_split_mm(mm);
        up_write(&mm->mmap_sem);
        return 0;
}
EXPORT_SYMBOL_GPL(s390_enable_sie);

/*
 * Enable storage key handling from now on and initialize the storage
 * keys with the default key.
 */
static int __s390_enable_skey(pte_t *pte, unsigned long addr,
                              unsigned long next, struct mm_walk *walk)
{
        /*
         * Remove all zero page mappings,
         * after establishing a policy to forbid zero page mappings
         * following faults for that page will get fresh anonymous pages
         */
        if (is_zero_pfn(pte_pfn(*pte)))
                ptep_xchg_direct(walk->mm, addr, pte, __pte(_PAGE_INVALID));
        /* Clear storage key */
        ptep_zap_key(walk->mm, addr, pte);
        return 0;
}

int s390_enable_skey(void)
{
        struct mm_walk walk = { .pte_entry = __s390_enable_skey };
        struct mm_struct *mm = current->mm;
        struct vm_area_struct *vma;
        int rc = 0;

        down_write(&mm->mmap_sem);
        if (mm_use_skey(mm))
                goto out_up;

        mm->context.use_skey = 1;
        for (vma = mm->mmap; vma; vma = vma->vm_next) {
                if (ksm_madvise(vma, vma->vm_start, vma->vm_end,
                                MADV_UNMERGEABLE, &vma->vm_flags)) {
                        mm->context.use_skey = 0;
                        rc = -ENOMEM;
                        goto out_up;
                }
        }
        mm->def_flags &= ~VM_MERGEABLE;

        walk.mm = mm;
        walk_page_range(0, TASK_SIZE, &walk);

out_up:
        up_write(&mm->mmap_sem);
        return rc;
}
EXPORT_SYMBOL_GPL(s390_enable_skey);

/*
 * Reset CMMA state, make all pages stable again.
 */
static int __s390_reset_cmma(pte_t *pte, unsigned long addr,
                             unsigned long next, struct mm_walk *walk)
{
        ptep_zap_unused(walk->mm, addr, pte, 1);
        return 0;
}

void s390_reset_cmma(struct mm_struct *mm)
{
        struct mm_walk walk = { .pte_entry = __s390_reset_cmma };

        down_write(&mm->mmap_sem);
        walk.mm = mm;
        walk_page_range(0, TASK_SIZE, &walk);
        up_write(&mm->mmap_sem);
}
EXPORT_SYMBOL_GPL(s390_reset_cmma);