/*-
 * Copyright (c) 2010 Isilon Systems, Inc.
 * Copyright (c) 2016 Matthew Macy (mmacy@mattmacy.io)
 * Copyright (c) 2017 Mellanox Technologies, Ltd.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice unmodified, this list of conditions, and the following
 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/rwlock.h>
#include <sys/proc.h>
#include <sys/sched.h>
#include <sys/memrange.h>

#include <machine/bus.h>

#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_param.h>
#include <vm/vm_kern.h>
#include <vm/vm_object.h>
#include <vm/vm_map.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_pager.h>
#include <vm/vm_radix.h>
#include <vm/vm_reserv.h>
#include <vm/vm_extern.h>

#include <vm/uma.h>
#include <vm/uma_int.h>

#include <linux/gfp.h>
#include <linux/mm.h>
#include <linux/preempt.h>
#include <linux/fs.h>
#include <linux/shmem_fs.h>
#include <linux/kernel.h>
#include <linux/idr.h>
#include <linux/io.h>
#include <linux/io-mapping.h>

#ifdef __i386__
DEFINE_IDR(mtrr_idr);
static MALLOC_DEFINE(M_LKMTRR, "idr", "Linux MTRR compat");
extern int pat_works;
#endif

void
si_meminfo(struct sysinfo *si)
{
        si->totalram = physmem;
        si->freeram = vm_free_count();
        si->totalhigh = 0;
        si->freehigh = 0;
        si->mem_unit = PAGE_SIZE;
}

void *
linux_page_address(const struct page *page)
{

        if (page->object != kernel_object) {
                return (PMAP_HAS_DMAP ?
                    ((void *)(uintptr_t)PHYS_TO_DMAP(page_to_phys(page))) :
                    NULL);
        }
        return ((void *)(uintptr_t)(VM_MIN_KERNEL_ADDRESS +
            IDX_TO_OFF(page->pindex)));
}

struct page *
linux_alloc_pages(gfp_t flags, unsigned int order)
{
        struct page *page;

        if (PMAP_HAS_DMAP) {
                unsigned long npages = 1UL << order;
                int req = VM_ALLOC_WIRED;

                if ((flags & M_ZERO) != 0)
                        req |= VM_ALLOC_ZERO;

                if (order == 0 && (flags & GFP_DMA32) == 0) {
                        page = vm_page_alloc_noobj(req);
                        if (page == NULL)
                                return (NULL);
                } else {
                        vm_paddr_t pmax = (flags & GFP_DMA32) ?
                            BUS_SPACE_MAXADDR_32BIT : BUS_SPACE_MAXADDR;

                        if ((flags & __GFP_NORETRY) != 0)
                                req |= VM_ALLOC_NORECLAIM;

                retry:
                        page = vm_page_alloc_noobj_contig(req, npages, 0, pmax,
                            PAGE_SIZE, 0, VM_MEMATTR_DEFAULT);
                        if (page == NULL) {
                                if ((flags & (M_WAITOK | __GFP_NORETRY)) ==
                                    M_WAITOK) {
                                        int err = vm_page_reclaim_contig(req,
                                            npages, 0, pmax, PAGE_SIZE, 0);
                                        if (err == ENOMEM)
                                                vm_wait(NULL);
                                        else if (err != 0)
                                                return (NULL);
                                        flags &= ~M_WAITOK;
                                        goto retry;
                                }
                                return (NULL);
                        }
                }
        } else {
                vm_offset_t vaddr;

                vaddr = linux_alloc_kmem(flags, order);
                if (vaddr == 0)
                        return (NULL);

                page = virt_to_page((void *)vaddr);

                KASSERT(vaddr == (vm_offset_t)page_address(page),
                    ("Page address mismatch"));
        }

        return (page);
}

static void
_linux_free_kmem(vm_offset_t addr, unsigned int order)
{
        size_t size = ((size_t)PAGE_SIZE) << order;

        kmem_free((void *)addr, size);
}

void
linux_free_pages(struct page *page, unsigned int order)
{
        if (PMAP_HAS_DMAP) {
                unsigned long npages = 1UL << order;
                unsigned long x;

                for (x = 0; x != npages; x++) {
                        vm_page_t pgo = page + x;

                        /*
                         * The "free page" function is used in several
                         * contexts.
                         *
                         * Some pages are allocated by `linux_alloc_pages()`
                         * above, but not all of them are. For instance in the
                         * DRM drivers, some pages come from
                         * `shmem_read_mapping_page_gfp()`.
                         *
                         * That's why we need to check if the page is managed
                         * or not here.
                         */
                        if ((pgo->oflags & VPO_UNMANAGED) == 0) {
                                vm_page_unwire(pgo, PQ_ACTIVE);
                        } else {
                                if (vm_page_unwire_noq(pgo))
                                        vm_page_free(pgo);
                        }
                }
        } else {
                vm_offset_t vaddr;

                vaddr = (vm_offset_t)page_address(page);

                _linux_free_kmem(vaddr, order);
        }
}

void
linux_release_pages(release_pages_arg arg, int nr)
{
        int i;

        CTASSERT(offsetof(struct folio, page) == 0);

        for (i = 0; i < nr; i++)
                __free_page(arg.pages[i]);
}

vm_offset_t
linux_alloc_kmem(gfp_t flags, unsigned int order)
{
        size_t size = ((size_t)PAGE_SIZE) << order;
        void *addr;

        addr = kmem_alloc_contig(size, flags & GFP_NATIVE_MASK, 0,
            ((flags & GFP_DMA32) == 0) ? -1UL : BUS_SPACE_MAXADDR_32BIT,
            PAGE_SIZE, 0, VM_MEMATTR_DEFAULT);

        return ((vm_offset_t)addr);
}

void
linux_free_kmem(vm_offset_t addr, unsigned int order)
{
        KASSERT((addr & ~PAGE_MASK) == 0,
            ("%s: addr %p is not page aligned", __func__, (void *)addr));

        if (addr >= VM_MIN_KERNEL_ADDRESS && addr < VM_MAX_KERNEL_ADDRESS) {
                _linux_free_kmem(addr, order);
        } else {
                vm_page_t page;

                page = PHYS_TO_VM_PAGE(DMAP_TO_PHYS(addr));
                linux_free_pages(page, order);
        }
}

static int
linux_get_user_pages_internal(vm_map_t map, unsigned long start, int nr_pages,
    int write, struct page **pages)
{
        vm_prot_t prot;
        size_t len;
        int count;

        prot = write ? (VM_PROT_READ | VM_PROT_WRITE) : VM_PROT_READ;
        len = ptoa((vm_offset_t)nr_pages);
        count = vm_fault_quick_hold_pages(map, start, len, prot, pages, nr_pages);
        return (count == -1 ? -EFAULT : nr_pages);
}

int
__get_user_pages_fast(unsigned long start, int nr_pages, int write,
    struct page **pages)
{
        vm_map_t map;
        vm_page_t *mp;
        vm_offset_t va;
        vm_offset_t end;
        vm_prot_t prot;
        int count;

        if (nr_pages == 0 || in_interrupt())
                return (0);

        MPASS(pages != NULL);
        map = &curthread->td_proc->p_vmspace->vm_map;
        end = start + ptoa((vm_offset_t)nr_pages);
        if (!vm_map_range_valid(map, start, end))
                return (-EINVAL);
        prot = write ? (VM_PROT_READ | VM_PROT_WRITE) : VM_PROT_READ;
        for (count = 0, mp = pages, va = start; va < end;
            mp++, va += PAGE_SIZE, count++) {
                *mp = pmap_extract_and_hold(map->pmap, va, prot);
                if (*mp == NULL)
                        break;

                if ((prot & VM_PROT_WRITE) != 0 &&
                    (*mp)->dirty != VM_PAGE_BITS_ALL) {
                        /*
                         * Explicitly dirty the physical page.  Otherwise, the
                         * caller's changes may go unnoticed because they are
                         * performed through an unmanaged mapping or by a DMA
                         * operation.
                         *
                         * The object lock is not held here.
                         * See vm_page_clear_dirty_mask().
                         */
                        vm_page_dirty(*mp);
                }
        }
        return (count);
}

long
get_user_pages_remote(struct task_struct *task, struct mm_struct *mm,
    unsigned long start, unsigned long nr_pages, unsigned int gup_flags,
    struct page **pages, struct vm_area_struct **vmas)
{
        vm_map_t map;

        map = &task->task_thread->td_proc->p_vmspace->vm_map;
        return (linux_get_user_pages_internal(map, start, nr_pages,
            !!(gup_flags & FOLL_WRITE), pages));
}

long
lkpi_get_user_pages(unsigned long start, unsigned long nr_pages,
    unsigned int gup_flags, struct page **pages)
{
        vm_map_t map;

        map = &curthread->td_proc->p_vmspace->vm_map;
        return (linux_get_user_pages_internal(map, start, nr_pages,
            !!(gup_flags & FOLL_WRITE), pages));
}

/*
 * Hash of vmmap addresses.  This is infrequently accessed and does not
 * need to be particularly large.  This is done because we must store the
 * caller's idea of the map size to properly unmap.
 */
struct vmmap {
        LIST_ENTRY(vmmap)       vm_next;
        void                    *vm_addr;
        unsigned long           vm_size;
};

struct vmmaphd {
        struct vmmap *lh_first;
};
#define VMMAP_HASH_SIZE 64
#define VMMAP_HASH_MASK (VMMAP_HASH_SIZE - 1)
#define VM_HASH(addr)   ((uintptr_t)(addr) >> PAGE_SHIFT) & VMMAP_HASH_MASK
static struct vmmaphd vmmaphead[VMMAP_HASH_SIZE];
static struct mtx vmmaplock;

int
is_vmalloc_addr(const void *addr)
{
        struct vmmap *vmmap;

        mtx_lock(&vmmaplock);
        LIST_FOREACH(vmmap, &vmmaphead[VM_HASH(addr)], vm_next)
                if (addr == vmmap->vm_addr)
                        break;
        mtx_unlock(&vmmaplock);
        if (vmmap != NULL)
                return (1);

        return (vtoslab((vm_offset_t)addr & ~UMA_SLAB_MASK) != NULL);
}

static void
vmmap_add(void *addr, unsigned long size)
{
        struct vmmap *vmmap;

        vmmap = kmalloc(sizeof(*vmmap), GFP_KERNEL);
        mtx_lock(&vmmaplock);
        vmmap->vm_size = size;
        vmmap->vm_addr = addr;
        LIST_INSERT_HEAD(&vmmaphead[VM_HASH(addr)], vmmap, vm_next);
        mtx_unlock(&vmmaplock);
}

static struct vmmap *
vmmap_remove(void *addr)
{
        struct vmmap *vmmap;

        mtx_lock(&vmmaplock);
        LIST_FOREACH(vmmap, &vmmaphead[VM_HASH(addr)], vm_next)
                if (vmmap->vm_addr == addr)
                        break;
        if (vmmap)
                LIST_REMOVE(vmmap, vm_next);
        mtx_unlock(&vmmaplock);

        return (vmmap);
}

#if defined(__i386__) || defined(__amd64__) || defined(__powerpc__) || defined(__aarch64__) || defined(__riscv)
void *
_ioremap_attr(vm_paddr_t phys_addr, unsigned long size, int attr)
{
        void *addr;

        addr = pmap_mapdev_attr(phys_addr, size, attr);
        if (addr == NULL)
                return (NULL);
        vmmap_add(addr, size);

        return (addr);
}
#endif

void
iounmap(void *addr)
{
        struct vmmap *vmmap;

        vmmap = vmmap_remove(addr);
        if (vmmap == NULL)
                return;
#if defined(__i386__) || defined(__amd64__) || defined(__powerpc__) || defined(__aarch64__) || defined(__riscv)
        pmap_unmapdev(addr, vmmap->vm_size);
#endif
        kfree(vmmap);
}

void *
vmap(struct page **pages, unsigned int count, unsigned long flags, int prot)
{
        vm_offset_t off;
        size_t size;

        size = count * PAGE_SIZE;
        off = kva_alloc(size);
        if (off == 0)
                return (NULL);
        vmmap_add((void *)off, size);
        pmap_qenter(off, pages, count);

        return ((void *)off);
}

#define VMAP_MAX_CHUNK_SIZE (65536U / sizeof(struct vm_page)) /* KMEM_ZMAX */

void *
linuxkpi_vmap_pfn(unsigned long *pfns, unsigned int count, int prot)
{
        vm_page_t m, *ma, fma;
        vm_offset_t off, coff;
        vm_paddr_t pa;
        vm_memattr_t attr;
        size_t size;
        unsigned int i, c, chunk;

        size = ptoa(count);
        off = kva_alloc(size);
        if (off == 0)
                return (NULL);
        vmmap_add((void *)off, size);

        chunk = MIN(count, VMAP_MAX_CHUNK_SIZE);
        attr = pgprot2cachemode(prot);
        ma = malloc(chunk * sizeof(vm_page_t), M_TEMP, M_WAITOK | M_ZERO);
        fma = NULL;
        c = 0;
        coff = off;
        for (i = 0; i < count; i++) {
                pa = IDX_TO_OFF(pfns[i]);
                m = PHYS_TO_VM_PAGE(pa);
                if (m == NULL) {
                        if (fma == NULL)
                                fma = malloc(chunk * sizeof(struct vm_page),
                                    M_TEMP, M_WAITOK | M_ZERO);
                        m = fma + c;
                        vm_page_initfake(m, pa, attr);
                } else {
                        pmap_page_set_memattr(m, attr);
                }
                ma[c] = m;
                c++;
                if (c == chunk || i == count - 1) {
                        pmap_qenter(coff, ma, c);
                        if (i == count - 1)
                                break;
                        coff += ptoa(c);
                        c = 0;
                        memset(ma, 0, chunk * sizeof(vm_page_t));
                        if (fma != NULL)
                                memset(fma, 0, chunk * sizeof(struct vm_page));
                }
        }
        free(fma, M_TEMP);
        free(ma, M_TEMP);

        return ((void *)off);
}

void
vunmap(void *addr)
{
        struct vmmap *vmmap;

        vmmap = vmmap_remove(addr);
        if (vmmap == NULL)
                return;
        pmap_qremove((vm_offset_t)addr, vmmap->vm_size / PAGE_SIZE);
        kva_free((vm_offset_t)addr, vmmap->vm_size);
        kfree(vmmap);
}

vm_fault_t
lkpi_vmf_insert_pfn_prot_locked(struct vm_area_struct *vma, unsigned long addr,
    unsigned long pfn, pgprot_t prot)
{
        struct pctrie_iter pages;
        vm_object_t vm_obj = vma->vm_obj;
        vm_object_t tmp_obj;
        vm_page_t page;
        vm_pindex_t pindex;

        VM_OBJECT_ASSERT_WLOCKED(vm_obj);
        vm_page_iter_init(&pages, vm_obj);
        pindex = OFF_TO_IDX(addr - vma->vm_start);
        if (vma->vm_pfn_count == 0)
                vma->vm_pfn_first = pindex;
        MPASS(pindex <= OFF_TO_IDX(vma->vm_end));

retry:
        page = vm_page_grab_iter(vm_obj, pindex, VM_ALLOC_NOCREAT, &pages);
        if (page == NULL) {
                page = PHYS_TO_VM_PAGE(IDX_TO_OFF(pfn));
                if (page == NULL)
                        return (VM_FAULT_SIGBUS);
                if (!vm_page_busy_acquire(page, VM_ALLOC_WAITFAIL)) {
                        pctrie_iter_reset(&pages);
                        goto retry;
                }
                if (page->object != NULL) {
                        tmp_obj = page->object;
                        vm_page_xunbusy(page);
                        VM_OBJECT_WUNLOCK(vm_obj);
                        VM_OBJECT_WLOCK(tmp_obj);
                        if (page->object == tmp_obj &&
                            vm_page_busy_acquire(page, VM_ALLOC_WAITFAIL)) {
                                KASSERT(page->object == tmp_obj,
                                    ("page has changed identity"));
                                KASSERT((page->oflags & VPO_UNMANAGED) == 0,
                                    ("page does not belong to shmem"));
                                vm_pager_page_unswapped(page);
                                if (pmap_page_is_mapped(page)) {
                                        vm_page_xunbusy(page);
                                        VM_OBJECT_WUNLOCK(tmp_obj);
                                        printf("%s: page rename failed: page "
                                            "is mapped\n", __func__);
                                        VM_OBJECT_WLOCK(vm_obj);
                                        return (VM_FAULT_NOPAGE);
                                }
                                vm_page_remove(page);
                        }
                        VM_OBJECT_WUNLOCK(tmp_obj);
                        pctrie_iter_reset(&pages);
                        VM_OBJECT_WLOCK(vm_obj);
                        goto retry;
                }
                if (vm_page_iter_insert(page, vm_obj, pindex, &pages) != 0) {
                        vm_page_xunbusy(page);
                        return (VM_FAULT_OOM);
                }
                vm_page_valid(page);
        }
        pmap_page_set_memattr(page, pgprot2cachemode(prot));
        vma->vm_pfn_count++;

        return (VM_FAULT_NOPAGE);
}

int
lkpi_remap_pfn_range(struct vm_area_struct *vma, unsigned long start_addr,
    unsigned long start_pfn, unsigned long size, pgprot_t prot)
{
        vm_object_t vm_obj;
        unsigned long addr, pfn;
        int err = 0;

        vm_obj = vma->vm_obj;

        VM_OBJECT_WLOCK(vm_obj);
        for (addr = start_addr, pfn = start_pfn;
            addr < start_addr + size;
            addr += PAGE_SIZE) {
                vm_fault_t ret;
retry:
                ret = lkpi_vmf_insert_pfn_prot_locked(vma, addr, pfn, prot);

                if ((ret & VM_FAULT_OOM) != 0) {
                        VM_OBJECT_WUNLOCK(vm_obj);
                        vm_wait(NULL);
                        VM_OBJECT_WLOCK(vm_obj);
                        goto retry;
                }

                if ((ret & VM_FAULT_ERROR) != 0) {
                        err = -EFAULT;
                        break;
                }

                pfn++;
        }
        VM_OBJECT_WUNLOCK(vm_obj);

        if (unlikely(err)) {
                zap_vma_ptes(vma, start_addr,
                    (pfn - start_pfn) << PAGE_SHIFT);
                return (err);
        }

        return (0);
}

int
lkpi_io_mapping_map_user(struct io_mapping *iomap,
    struct vm_area_struct *vma, unsigned long addr,
    unsigned long pfn, unsigned long size)
{
        pgprot_t prot;
        int ret;

        prot = cachemode2protval(iomap->attr);
        ret = lkpi_remap_pfn_range(vma, addr, pfn, size, prot);

        return (ret);
}

/*
 * Although FreeBSD version of unmap_mapping_range has semantics and types of
 * parameters compatible with Linux version, the values passed in are different
 * @obj should match to vm_private_data field of vm_area_struct returned by
 *      mmap file operation handler, see linux_file_mmap_single() sources
 * @holelen should match to size of area to be munmapped.
 */
void
lkpi_unmap_mapping_range(void *obj, loff_t const holebegin __unused,
    loff_t const holelen __unused, int even_cows __unused)
{
        vm_object_t devobj;

        devobj = cdev_pager_lookup(obj);
        if (devobj != NULL) {
                cdev_mgtdev_pager_free_pages(devobj);
                vm_object_deallocate(devobj);
        }
}

int
lkpi_arch_phys_wc_add(unsigned long base, unsigned long size)
{
#ifdef __i386__
        struct mem_range_desc *mrdesc;
        int error, id, act;

        /* If PAT is available, do nothing */
        if (pat_works)
                return (0);

        mrdesc = malloc(sizeof(*mrdesc), M_LKMTRR, M_WAITOK);
        mrdesc->mr_base = base;
        mrdesc->mr_len = size;
        mrdesc->mr_flags = MDF_WRITECOMBINE;
        strlcpy(mrdesc->mr_owner, "drm", sizeof(mrdesc->mr_owner));
        act = MEMRANGE_SET_UPDATE;
        error = mem_range_attr_set(mrdesc, &act);
        if (error == 0) {
                error = idr_get_new(&mtrr_idr, mrdesc, &id);
                MPASS(idr_find(&mtrr_idr, id) == mrdesc);
                if (error != 0) {
                        act = MEMRANGE_SET_REMOVE;
                        mem_range_attr_set(mrdesc, &act);
                }
        }
        if (error != 0) {
                free(mrdesc, M_LKMTRR);
                pr_warn(
                    "Failed to add WC MTRR for [%p-%p]: %d; "
                    "performance may suffer\n",
                    (void *)base, (void *)(base + size - 1), error);
        } else
                pr_warn("Successfully added WC MTRR for [%p-%p]\n",
                    (void *)base, (void *)(base + size - 1));

        return (error != 0 ? -error : id + __MTRR_ID_BASE);
#else
        return (0);
#endif
}

void
lkpi_arch_phys_wc_del(int reg)
{
#ifdef __i386__
        struct mem_range_desc *mrdesc;
        int act;

        /* Check if arch_phys_wc_add() failed. */
        if (reg < __MTRR_ID_BASE)
                return;

        mrdesc = idr_find(&mtrr_idr, reg - __MTRR_ID_BASE);
        MPASS(mrdesc != NULL);
        idr_remove(&mtrr_idr, reg - __MTRR_ID_BASE);
        act = MEMRANGE_SET_REMOVE;
        mem_range_attr_set(mrdesc, &act);
        free(mrdesc, M_LKMTRR);
#endif
}

/*
 * This is a highly simplified version of the Linux page_frag_cache.
 * We only support up-to 1 single page as fragment size and we will
 * always return a full page.  This may be wasteful on small objects
 * but the only known consumer (mt76) is either asking for a half-page
 * or a full page.  If this was to become a problem we can implement
 * a more elaborate version.
 */
void *
linuxkpi_page_frag_alloc(struct page_frag_cache *pfc,
    size_t fragsz, gfp_t gfp)
{
        vm_page_t pages;

        if (fragsz == 0)
                return (NULL);

        KASSERT(fragsz <= PAGE_SIZE, ("%s: fragsz %zu > PAGE_SIZE not yet "
            "supported", __func__, fragsz));

        pages = alloc_pages(gfp, flsl(howmany(fragsz, PAGE_SIZE) - 1));
        if (pages == NULL)
                return (NULL);
        pfc->va = linux_page_address(pages);

        /* Passed in as "count" to __page_frag_cache_drain(). Unused by us. */
        pfc->pagecnt_bias = 0;

        return (pfc->va);
}

void
linuxkpi_page_frag_free(void *addr)
{
        vm_page_t page;

        page = virt_to_page(addr);
        linux_free_pages(page, 0);
}

void
linuxkpi__page_frag_cache_drain(struct page *page, size_t count __unused)
{

        linux_free_pages(page, 0);
}

static void
lkpi_page_init(void *arg)
{
        int i;

        mtx_init(&vmmaplock, "IO Map lock", NULL, MTX_DEF);
        for (i = 0; i < VMMAP_HASH_SIZE; i++)
                LIST_INIT(&vmmaphead[i]);
}
SYSINIT(lkpi_page, SI_SUB_DRIVERS, SI_ORDER_SECOND, lkpi_page_init, NULL);

static void
lkpi_page_uninit(void *arg)
{
        mtx_destroy(&vmmaplock);
}
SYSUNINIT(lkpi_page, SI_SUB_DRIVERS, SI_ORDER_SECOND, lkpi_page_uninit, NULL);