1 // SPDX-License-Identifier: GPL-2.0
3 * This is a module to test the HMM (Heterogeneous Memory Management)
4 * mirror and zone device private memory migration APIs of the kernel.
5 * Userspace programs can register with the driver to mirror their own address
6 * space and can use the device to read/write any valid virtual address.
8 #include <linux/init.h>
11 #include <linux/module.h>
12 #include <linux/kernel.h>
13 #include <linux/cdev.h>
14 #include <linux/device.h>
15 #include <linux/mutex.h>
16 #include <linux/rwsem.h>
17 #include <linux/sched.h>
18 #include <linux/slab.h>
19 #include <linux/highmem.h>
20 #include <linux/delay.h>
21 #include <linux/pagemap.h>
22 #include <linux/hmm.h>
23 #include <linux/vmalloc.h>
24 #include <linux/swap.h>
25 #include <linux/swapops.h>
26 #include <linux/sched/mm.h>
27 #include <linux/platform_device.h>
29 #include "test_hmm_uapi.h"
31 #define DMIRROR_NDEVICES 2
32 #define DMIRROR_RANGE_FAULT_TIMEOUT 1000
33 #define DEVMEM_CHUNK_SIZE (256 * 1024 * 1024U)
34 #define DEVMEM_CHUNKS_RESERVE 16
36 static const struct dev_pagemap_ops dmirror_devmem_ops;
37 static const struct mmu_interval_notifier_ops dmirror_min_ops;
38 static dev_t dmirror_dev;
39 static struct page *dmirror_zero_page;
41 struct dmirror_device;
43 struct dmirror_bounce {
50 #define DPT_XA_TAG_WRITE 3UL
53 * Data structure to track address ranges and register for mmu interval
56 struct dmirror_interval {
57 struct mmu_interval_notifier notifier;
58 struct dmirror *dmirror;
62 * Data attached to the open device file.
63 * Note that it might be shared after a fork().
66 struct dmirror_device *mdevice;
68 struct mmu_interval_notifier notifier;
73 * ZONE_DEVICE pages for migration and simulating device memory.
75 struct dmirror_chunk {
76 struct dev_pagemap pagemap;
77 struct dmirror_device *mdevice;
83 struct dmirror_device {
85 struct hmm_devmem *devmem;
87 unsigned int devmem_capacity;
88 unsigned int devmem_count;
89 struct dmirror_chunk **devmem_chunks;
90 struct mutex devmem_lock; /* protects the above */
94 struct page *free_pages;
95 spinlock_t lock; /* protects the above */
98 static struct dmirror_device dmirror_devices[DMIRROR_NDEVICES];
100 static int dmirror_bounce_init(struct dmirror_bounce *bounce,
107 bounce->ptr = vmalloc(size);
113 static void dmirror_bounce_fini(struct dmirror_bounce *bounce)
118 static int dmirror_fops_open(struct inode *inode, struct file *filp)
120 struct cdev *cdev = inode->i_cdev;
121 struct dmirror *dmirror;
124 /* Mirror this process address space */
125 dmirror = kzalloc(sizeof(*dmirror), GFP_KERNEL);
129 dmirror->mdevice = container_of(cdev, struct dmirror_device, cdevice);
130 mutex_init(&dmirror->mutex);
131 xa_init(&dmirror->pt);
133 ret = mmu_interval_notifier_insert(&dmirror->notifier, current->mm,
134 0, ULONG_MAX & PAGE_MASK, &dmirror_min_ops);
140 filp->private_data = dmirror;
144 static int dmirror_fops_release(struct inode *inode, struct file *filp)
146 struct dmirror *dmirror = filp->private_data;
148 mmu_interval_notifier_remove(&dmirror->notifier);
149 xa_destroy(&dmirror->pt);
154 static struct dmirror_device *dmirror_page_to_device(struct page *page)
157 return container_of(page->pgmap, struct dmirror_chunk,
161 static int dmirror_do_fault(struct dmirror *dmirror, struct hmm_range *range)
163 unsigned long *pfns = range->hmm_pfns;
166 for (pfn = (range->start >> PAGE_SHIFT);
167 pfn < (range->end >> PAGE_SHIFT);
173 * Since we asked for hmm_range_fault() to populate pages,
174 * it shouldn't return an error entry on success.
176 WARN_ON(*pfns & HMM_PFN_ERROR);
177 WARN_ON(!(*pfns & HMM_PFN_VALID));
179 page = hmm_pfn_to_page(*pfns);
183 if (*pfns & HMM_PFN_WRITE)
184 entry = xa_tag_pointer(entry, DPT_XA_TAG_WRITE);
185 else if (WARN_ON(range->default_flags & HMM_PFN_WRITE))
187 entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
188 if (xa_is_err(entry))
189 return xa_err(entry);
195 static void dmirror_do_update(struct dmirror *dmirror, unsigned long start,
202 * The XArray doesn't hold references to pages since it relies on
203 * the mmu notifier to clear page pointers when they become stale.
204 * Therefore, it is OK to just clear the entry.
206 xa_for_each_range(&dmirror->pt, pfn, entry, start >> PAGE_SHIFT,
208 xa_erase(&dmirror->pt, pfn);
211 static bool dmirror_interval_invalidate(struct mmu_interval_notifier *mni,
212 const struct mmu_notifier_range *range,
213 unsigned long cur_seq)
215 struct dmirror *dmirror = container_of(mni, struct dmirror, notifier);
217 if (mmu_notifier_range_blockable(range))
218 mutex_lock(&dmirror->mutex);
219 else if (!mutex_trylock(&dmirror->mutex))
222 mmu_interval_set_seq(mni, cur_seq);
223 dmirror_do_update(dmirror, range->start, range->end);
225 mutex_unlock(&dmirror->mutex);
229 static const struct mmu_interval_notifier_ops dmirror_min_ops = {
230 .invalidate = dmirror_interval_invalidate,
233 static int dmirror_range_fault(struct dmirror *dmirror,
234 struct hmm_range *range)
236 struct mm_struct *mm = dmirror->notifier.mm;
237 unsigned long timeout =
238 jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
242 if (time_after(jiffies, timeout)) {
247 range->notifier_seq = mmu_interval_read_begin(range->notifier);
249 ret = hmm_range_fault(range);
250 mmap_read_unlock(mm);
257 mutex_lock(&dmirror->mutex);
258 if (mmu_interval_read_retry(range->notifier,
259 range->notifier_seq)) {
260 mutex_unlock(&dmirror->mutex);
266 ret = dmirror_do_fault(dmirror, range);
268 mutex_unlock(&dmirror->mutex);
273 static int dmirror_fault(struct dmirror *dmirror, unsigned long start,
274 unsigned long end, bool write)
276 struct mm_struct *mm = dmirror->notifier.mm;
278 unsigned long pfns[64];
279 struct hmm_range range = {
280 .notifier = &dmirror->notifier,
284 HMM_PFN_REQ_FAULT | (write ? HMM_PFN_REQ_WRITE : 0),
285 .dev_private_owner = dmirror->mdevice,
289 /* Since the mm is for the mirrored process, get a reference first. */
290 if (!mmget_not_zero(mm))
293 for (addr = start; addr < end; addr = range.end) {
295 range.end = min(addr + (ARRAY_SIZE(pfns) << PAGE_SHIFT), end);
297 ret = dmirror_range_fault(dmirror, &range);
306 static int dmirror_do_read(struct dmirror *dmirror, unsigned long start,
307 unsigned long end, struct dmirror_bounce *bounce)
312 ptr = bounce->ptr + ((start - bounce->addr) & PAGE_MASK);
314 for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
319 entry = xa_load(&dmirror->pt, pfn);
320 page = xa_untag_pointer(entry);
325 memcpy(ptr, tmp, PAGE_SIZE);
335 static int dmirror_read(struct dmirror *dmirror, struct hmm_dmirror_cmd *cmd)
337 struct dmirror_bounce bounce;
338 unsigned long start, end;
339 unsigned long size = cmd->npages << PAGE_SHIFT;
347 ret = dmirror_bounce_init(&bounce, start, size);
352 mutex_lock(&dmirror->mutex);
353 ret = dmirror_do_read(dmirror, start, end, &bounce);
354 mutex_unlock(&dmirror->mutex);
358 start = cmd->addr + (bounce.cpages << PAGE_SHIFT);
359 ret = dmirror_fault(dmirror, start, end, false);
366 if (copy_to_user(u64_to_user_ptr(cmd->ptr), bounce.ptr,
370 cmd->cpages = bounce.cpages;
371 dmirror_bounce_fini(&bounce);
375 static int dmirror_do_write(struct dmirror *dmirror, unsigned long start,
376 unsigned long end, struct dmirror_bounce *bounce)
381 ptr = bounce->ptr + ((start - bounce->addr) & PAGE_MASK);
383 for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
388 entry = xa_load(&dmirror->pt, pfn);
389 page = xa_untag_pointer(entry);
390 if (!page || xa_pointer_tag(entry) != DPT_XA_TAG_WRITE)
394 memcpy(tmp, ptr, PAGE_SIZE);
404 static int dmirror_write(struct dmirror *dmirror, struct hmm_dmirror_cmd *cmd)
406 struct dmirror_bounce bounce;
407 unsigned long start, end;
408 unsigned long size = cmd->npages << PAGE_SHIFT;
416 ret = dmirror_bounce_init(&bounce, start, size);
419 if (copy_from_user(bounce.ptr, u64_to_user_ptr(cmd->ptr),
426 mutex_lock(&dmirror->mutex);
427 ret = dmirror_do_write(dmirror, start, end, &bounce);
428 mutex_unlock(&dmirror->mutex);
432 start = cmd->addr + (bounce.cpages << PAGE_SHIFT);
433 ret = dmirror_fault(dmirror, start, end, true);
440 cmd->cpages = bounce.cpages;
441 dmirror_bounce_fini(&bounce);
445 static bool dmirror_allocate_chunk(struct dmirror_device *mdevice,
448 struct dmirror_chunk *devmem;
449 struct resource *res;
451 unsigned long pfn_first;
452 unsigned long pfn_last;
455 mutex_lock(&mdevice->devmem_lock);
457 if (mdevice->devmem_count == mdevice->devmem_capacity) {
458 struct dmirror_chunk **new_chunks;
459 unsigned int new_capacity;
461 new_capacity = mdevice->devmem_capacity +
462 DEVMEM_CHUNKS_RESERVE;
463 new_chunks = krealloc(mdevice->devmem_chunks,
464 sizeof(new_chunks[0]) * new_capacity,
468 mdevice->devmem_capacity = new_capacity;
469 mdevice->devmem_chunks = new_chunks;
472 res = request_free_mem_region(&iomem_resource, DEVMEM_CHUNK_SIZE,
477 devmem = kzalloc(sizeof(*devmem), GFP_KERNEL);
481 devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
482 devmem->pagemap.res = *res;
483 devmem->pagemap.ops = &dmirror_devmem_ops;
484 devmem->pagemap.owner = mdevice;
486 ptr = memremap_pages(&devmem->pagemap, numa_node_id());
490 devmem->mdevice = mdevice;
491 pfn_first = devmem->pagemap.res.start >> PAGE_SHIFT;
492 pfn_last = pfn_first +
493 (resource_size(&devmem->pagemap.res) >> PAGE_SHIFT);
494 mdevice->devmem_chunks[mdevice->devmem_count++] = devmem;
496 mutex_unlock(&mdevice->devmem_lock);
498 pr_info("added new %u MB chunk (total %u chunks, %u MB) PFNs [0x%lx 0x%lx)\n",
499 DEVMEM_CHUNK_SIZE / (1024 * 1024),
500 mdevice->devmem_count,
501 mdevice->devmem_count * (DEVMEM_CHUNK_SIZE / (1024 * 1024)),
502 pfn_first, pfn_last);
504 spin_lock(&mdevice->lock);
505 for (pfn = pfn_first; pfn < pfn_last; pfn++) {
506 struct page *page = pfn_to_page(pfn);
508 page->zone_device_data = mdevice->free_pages;
509 mdevice->free_pages = page;
512 *ppage = mdevice->free_pages;
513 mdevice->free_pages = (*ppage)->zone_device_data;
516 spin_unlock(&mdevice->lock);
523 release_mem_region(devmem->pagemap.res.start,
524 resource_size(&devmem->pagemap.res));
526 mutex_unlock(&mdevice->devmem_lock);
530 static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
532 struct page *dpage = NULL;
536 * This is a fake device so we alloc real system memory to store
539 rpage = alloc_page(GFP_HIGHUSER);
543 spin_lock(&mdevice->lock);
545 if (mdevice->free_pages) {
546 dpage = mdevice->free_pages;
547 mdevice->free_pages = dpage->zone_device_data;
549 spin_unlock(&mdevice->lock);
551 spin_unlock(&mdevice->lock);
552 if (!dmirror_allocate_chunk(mdevice, &dpage))
556 dpage->zone_device_data = rpage;
566 static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
567 struct dmirror *dmirror)
569 struct dmirror_device *mdevice = dmirror->mdevice;
570 const unsigned long *src = args->src;
571 unsigned long *dst = args->dst;
574 for (addr = args->start; addr < args->end; addr += PAGE_SIZE,
580 if (!(*src & MIGRATE_PFN_MIGRATE))
584 * Note that spage might be NULL which is OK since it is an
585 * unallocated pte_none() or read-only zero page.
587 spage = migrate_pfn_to_page(*src);
590 * Don't migrate device private pages from our own driver or
591 * others. For our own we would do a device private memory copy
592 * not a migration and for others, we would need to fault the
593 * other device's page into system memory first.
595 if (spage && is_zone_device_page(spage))
598 dpage = dmirror_devmem_alloc_page(mdevice);
602 rpage = dpage->zone_device_data;
604 copy_highpage(rpage, spage);
606 clear_highpage(rpage);
609 * Normally, a device would use the page->zone_device_data to
610 * point to the mirror but here we use it to hold the page for
611 * the simulated device memory and that page holds the pointer
614 rpage->zone_device_data = dmirror;
616 *dst = migrate_pfn(page_to_pfn(dpage)) |
618 if ((*src & MIGRATE_PFN_WRITE) ||
619 (!spage && args->vma->vm_flags & VM_WRITE))
620 *dst |= MIGRATE_PFN_WRITE;
624 static int dmirror_migrate_finalize_and_map(struct migrate_vma *args,
625 struct dmirror *dmirror)
627 unsigned long start = args->start;
628 unsigned long end = args->end;
629 const unsigned long *src = args->src;
630 const unsigned long *dst = args->dst;
633 /* Map the migrated pages into the device's page tables. */
634 mutex_lock(&dmirror->mutex);
636 for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++,
641 if (!(*src & MIGRATE_PFN_MIGRATE))
644 dpage = migrate_pfn_to_page(*dst);
649 * Store the page that holds the data so the page table
650 * doesn't have to deal with ZONE_DEVICE private pages.
652 entry = dpage->zone_device_data;
653 if (*dst & MIGRATE_PFN_WRITE)
654 entry = xa_tag_pointer(entry, DPT_XA_TAG_WRITE);
655 entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
656 if (xa_is_err(entry)) {
657 mutex_unlock(&dmirror->mutex);
658 return xa_err(entry);
662 mutex_unlock(&dmirror->mutex);
666 static int dmirror_migrate(struct dmirror *dmirror,
667 struct hmm_dmirror_cmd *cmd)
669 unsigned long start, end, addr;
670 unsigned long size = cmd->npages << PAGE_SHIFT;
671 struct mm_struct *mm = dmirror->notifier.mm;
672 struct vm_area_struct *vma;
673 unsigned long src_pfns[64];
674 unsigned long dst_pfns[64];
675 struct dmirror_bounce bounce;
676 struct migrate_vma args;
685 /* Since the mm is for the mirrored process, get a reference first. */
686 if (!mmget_not_zero(mm))
690 for (addr = start; addr < end; addr = next) {
691 vma = find_vma(mm, addr);
692 if (!vma || addr < vma->vm_start ||
693 !(vma->vm_flags & VM_READ)) {
697 next = min(end, addr + (ARRAY_SIZE(src_pfns) << PAGE_SHIFT));
698 if (next > vma->vm_end)
706 args.src_owner = NULL;
707 ret = migrate_vma_setup(&args);
711 dmirror_migrate_alloc_and_copy(&args, dmirror);
712 migrate_vma_pages(&args);
713 dmirror_migrate_finalize_and_map(&args, dmirror);
714 migrate_vma_finalize(&args);
716 mmap_read_unlock(mm);
719 /* Return the migrated data for verification. */
720 ret = dmirror_bounce_init(&bounce, start, size);
723 mutex_lock(&dmirror->mutex);
724 ret = dmirror_do_read(dmirror, start, end, &bounce);
725 mutex_unlock(&dmirror->mutex);
727 if (copy_to_user(u64_to_user_ptr(cmd->ptr), bounce.ptr,
731 cmd->cpages = bounce.cpages;
732 dmirror_bounce_fini(&bounce);
736 mmap_read_unlock(mm);
741 static void dmirror_mkentry(struct dmirror *dmirror, struct hmm_range *range,
742 unsigned char *perm, unsigned long entry)
746 if (entry & HMM_PFN_ERROR) {
747 *perm = HMM_DMIRROR_PROT_ERROR;
750 if (!(entry & HMM_PFN_VALID)) {
751 *perm = HMM_DMIRROR_PROT_NONE;
755 page = hmm_pfn_to_page(entry);
756 if (is_device_private_page(page)) {
757 /* Is the page migrated to this device or some other? */
758 if (dmirror->mdevice == dmirror_page_to_device(page))
759 *perm = HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL;
761 *perm = HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE;
762 } else if (is_zero_pfn(page_to_pfn(page)))
763 *perm = HMM_DMIRROR_PROT_ZERO;
765 *perm = HMM_DMIRROR_PROT_NONE;
766 if (entry & HMM_PFN_WRITE)
767 *perm |= HMM_DMIRROR_PROT_WRITE;
769 *perm |= HMM_DMIRROR_PROT_READ;
772 static bool dmirror_snapshot_invalidate(struct mmu_interval_notifier *mni,
773 const struct mmu_notifier_range *range,
774 unsigned long cur_seq)
776 struct dmirror_interval *dmi =
777 container_of(mni, struct dmirror_interval, notifier);
778 struct dmirror *dmirror = dmi->dmirror;
780 if (mmu_notifier_range_blockable(range))
781 mutex_lock(&dmirror->mutex);
782 else if (!mutex_trylock(&dmirror->mutex))
786 * Snapshots only need to set the sequence number since any
787 * invalidation in the interval invalidates the whole snapshot.
789 mmu_interval_set_seq(mni, cur_seq);
791 mutex_unlock(&dmirror->mutex);
795 static const struct mmu_interval_notifier_ops dmirror_mrn_ops = {
796 .invalidate = dmirror_snapshot_invalidate,
799 static int dmirror_range_snapshot(struct dmirror *dmirror,
800 struct hmm_range *range,
803 struct mm_struct *mm = dmirror->notifier.mm;
804 struct dmirror_interval notifier;
805 unsigned long timeout =
806 jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
811 notifier.dmirror = dmirror;
812 range->notifier = ¬ifier.notifier;
814 ret = mmu_interval_notifier_insert(range->notifier, mm,
815 range->start, range->end - range->start,
821 if (time_after(jiffies, timeout)) {
826 range->notifier_seq = mmu_interval_read_begin(range->notifier);
829 ret = hmm_range_fault(range);
830 mmap_read_unlock(mm);
837 mutex_lock(&dmirror->mutex);
838 if (mmu_interval_read_retry(range->notifier,
839 range->notifier_seq)) {
840 mutex_unlock(&dmirror->mutex);
846 n = (range->end - range->start) >> PAGE_SHIFT;
847 for (i = 0; i < n; i++)
848 dmirror_mkentry(dmirror, range, perm + i, range->hmm_pfns[i]);
850 mutex_unlock(&dmirror->mutex);
852 mmu_interval_notifier_remove(range->notifier);
856 static int dmirror_snapshot(struct dmirror *dmirror,
857 struct hmm_dmirror_cmd *cmd)
859 struct mm_struct *mm = dmirror->notifier.mm;
860 unsigned long start, end;
861 unsigned long size = cmd->npages << PAGE_SHIFT;
864 unsigned long pfns[64];
865 unsigned char perm[64];
867 struct hmm_range range = {
869 .dev_private_owner = dmirror->mdevice,
878 /* Since the mm is for the mirrored process, get a reference first. */
879 if (!mmget_not_zero(mm))
883 * Register a temporary notifier to detect invalidations even if it
884 * overlaps with other mmu_interval_notifiers.
886 uptr = u64_to_user_ptr(cmd->ptr);
887 for (addr = start; addr < end; addr = next) {
890 next = min(addr + (ARRAY_SIZE(pfns) << PAGE_SHIFT), end);
894 ret = dmirror_range_snapshot(dmirror, &range, perm);
898 n = (range.end - range.start) >> PAGE_SHIFT;
899 if (copy_to_user(uptr, perm, n)) {
912 static long dmirror_fops_unlocked_ioctl(struct file *filp,
913 unsigned int command,
916 void __user *uarg = (void __user *)arg;
917 struct hmm_dmirror_cmd cmd;
918 struct dmirror *dmirror;
921 dmirror = filp->private_data;
925 if (copy_from_user(&cmd, uarg, sizeof(cmd)))
928 if (cmd.addr & ~PAGE_MASK)
930 if (cmd.addr >= (cmd.addr + (cmd.npages << PAGE_SHIFT)))
937 case HMM_DMIRROR_READ:
938 ret = dmirror_read(dmirror, &cmd);
941 case HMM_DMIRROR_WRITE:
942 ret = dmirror_write(dmirror, &cmd);
945 case HMM_DMIRROR_MIGRATE:
946 ret = dmirror_migrate(dmirror, &cmd);
949 case HMM_DMIRROR_SNAPSHOT:
950 ret = dmirror_snapshot(dmirror, &cmd);
959 if (copy_to_user(uarg, &cmd, sizeof(cmd)))
965 static const struct file_operations dmirror_fops = {
966 .open = dmirror_fops_open,
967 .release = dmirror_fops_release,
968 .unlocked_ioctl = dmirror_fops_unlocked_ioctl,
969 .llseek = default_llseek,
970 .owner = THIS_MODULE,
973 static void dmirror_devmem_free(struct page *page)
975 struct page *rpage = page->zone_device_data;
976 struct dmirror_device *mdevice;
981 mdevice = dmirror_page_to_device(page);
983 spin_lock(&mdevice->lock);
985 page->zone_device_data = mdevice->free_pages;
986 mdevice->free_pages = page;
987 spin_unlock(&mdevice->lock);
990 static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
991 struct dmirror_device *mdevice)
993 const unsigned long *src = args->src;
994 unsigned long *dst = args->dst;
995 unsigned long start = args->start;
996 unsigned long end = args->end;
999 for (addr = start; addr < end; addr += PAGE_SIZE,
1001 struct page *dpage, *spage;
1003 spage = migrate_pfn_to_page(*src);
1004 if (!spage || !(*src & MIGRATE_PFN_MIGRATE))
1006 spage = spage->zone_device_data;
1008 dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr);
1013 copy_highpage(dpage, spage);
1014 *dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
1015 if (*src & MIGRATE_PFN_WRITE)
1016 *dst |= MIGRATE_PFN_WRITE;
1021 static void dmirror_devmem_fault_finalize_and_map(struct migrate_vma *args,
1022 struct dmirror *dmirror)
1024 /* Invalidate the device's page table mapping. */
1025 mutex_lock(&dmirror->mutex);
1026 dmirror_do_update(dmirror, args->start, args->end);
1027 mutex_unlock(&dmirror->mutex);
1030 static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
1032 struct migrate_vma args;
1033 unsigned long src_pfns;
1034 unsigned long dst_pfns;
1036 struct dmirror *dmirror;
1040 * Normally, a device would use the page->zone_device_data to point to
1041 * the mirror but here we use it to hold the page for the simulated
1042 * device memory and that page holds the pointer to the mirror.
1044 rpage = vmf->page->zone_device_data;
1045 dmirror = rpage->zone_device_data;
1047 /* FIXME demonstrate how we can adjust migrate range */
1048 args.vma = vmf->vma;
1049 args.start = vmf->address;
1050 args.end = args.start + PAGE_SIZE;
1051 args.src = &src_pfns;
1052 args.dst = &dst_pfns;
1053 args.src_owner = dmirror->mdevice;
1055 if (migrate_vma_setup(&args))
1056 return VM_FAULT_SIGBUS;
1058 ret = dmirror_devmem_fault_alloc_and_copy(&args, dmirror->mdevice);
1061 migrate_vma_pages(&args);
1062 dmirror_devmem_fault_finalize_and_map(&args, dmirror);
1063 migrate_vma_finalize(&args);
1067 static const struct dev_pagemap_ops dmirror_devmem_ops = {
1068 .page_free = dmirror_devmem_free,
1069 .migrate_to_ram = dmirror_devmem_fault,
1072 static int dmirror_device_init(struct dmirror_device *mdevice, int id)
1077 dev = MKDEV(MAJOR(dmirror_dev), id);
1078 mutex_init(&mdevice->devmem_lock);
1079 spin_lock_init(&mdevice->lock);
1081 cdev_init(&mdevice->cdevice, &dmirror_fops);
1082 mdevice->cdevice.owner = THIS_MODULE;
1083 ret = cdev_add(&mdevice->cdevice, dev, 1);
1087 /* Build a list of free ZONE_DEVICE private struct pages */
1088 dmirror_allocate_chunk(mdevice, NULL);
1093 static void dmirror_device_remove(struct dmirror_device *mdevice)
1097 if (mdevice->devmem_chunks) {
1098 for (i = 0; i < mdevice->devmem_count; i++) {
1099 struct dmirror_chunk *devmem =
1100 mdevice->devmem_chunks[i];
1102 memunmap_pages(&devmem->pagemap);
1103 release_mem_region(devmem->pagemap.res.start,
1104 resource_size(&devmem->pagemap.res));
1107 kfree(mdevice->devmem_chunks);
1110 cdev_del(&mdevice->cdevice);
1113 static int __init hmm_dmirror_init(void)
1118 ret = alloc_chrdev_region(&dmirror_dev, 0, DMIRROR_NDEVICES,
1123 for (id = 0; id < DMIRROR_NDEVICES; id++) {
1124 ret = dmirror_device_init(dmirror_devices + id, id);
1130 * Allocate a zero page to simulate a reserved page of device private
1131 * memory which is always zero. The zero_pfn page isn't used just to
1132 * make the code here simpler (i.e., we need a struct page for it).
1134 dmirror_zero_page = alloc_page(GFP_HIGHUSER | __GFP_ZERO);
1135 if (!dmirror_zero_page) {
1140 pr_info("HMM test module loaded. This is only for testing HMM.\n");
1145 dmirror_device_remove(dmirror_devices + id);
1146 unregister_chrdev_region(dmirror_dev, DMIRROR_NDEVICES);
1151 static void __exit hmm_dmirror_exit(void)
1155 if (dmirror_zero_page)
1156 __free_page(dmirror_zero_page);
1157 for (id = 0; id < DMIRROR_NDEVICES; id++)
1158 dmirror_device_remove(dmirror_devices + id);
1159 unregister_chrdev_region(dmirror_dev, DMIRROR_NDEVICES);
1162 module_init(hmm_dmirror_init);
1163 module_exit(hmm_dmirror_exit);
1164 MODULE_LICENSE("GPL");