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1// SPDX-License-Identifier: GPL-2.0
2/*
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.
7 */
8#include <linux/init.h>
9#include <linux/fs.h>
10#include <linux/mm.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>
28#include <linux/rmap.h>
29
30#include "test_hmm_uapi.h"
31
32#define DMIRROR_NDEVICES 2
33#define DMIRROR_RANGE_FAULT_TIMEOUT 1000
34#define DEVMEM_CHUNK_SIZE (256 * 1024 * 1024U)
35#define DEVMEM_CHUNKS_RESERVE 16
36
37static const struct dev_pagemap_ops dmirror_devmem_ops;
38static const struct mmu_interval_notifier_ops dmirror_min_ops;
39static dev_t dmirror_dev;
40
41struct dmirror_device;
42
43struct dmirror_bounce {
44 void *ptr;
45 unsigned long size;
46 unsigned long addr;
47 unsigned long cpages;
48};
49
50#define DPT_XA_TAG_ATOMIC 1UL
51#define DPT_XA_TAG_WRITE 3UL
52
53/*
54 * Data structure to track address ranges and register for mmu interval
55 * notifier updates.
56 */
57struct dmirror_interval {
58 struct mmu_interval_notifier notifier;
59 struct dmirror *dmirror;
60};
61
62/*
63 * Data attached to the open device file.
64 * Note that it might be shared after a fork().
65 */
66struct dmirror {
67 struct dmirror_device *mdevice;
68 struct xarray pt;
69 struct mmu_interval_notifier notifier;
70 struct mutex mutex;
71};
72
73/*
74 * ZONE_DEVICE pages for migration and simulating device memory.
75 */
76struct dmirror_chunk {
77 struct dev_pagemap pagemap;
78 struct dmirror_device *mdevice;
79};
80
81/*
82 * Per device data.
83 */
84struct dmirror_device {
85 struct cdev cdevice;
86 struct hmm_devmem *devmem;
87
88 unsigned int devmem_capacity;
89 unsigned int devmem_count;
90 struct dmirror_chunk **devmem_chunks;
91 struct mutex devmem_lock; /* protects the above */
92
93 unsigned long calloc;
94 unsigned long cfree;
95 struct page *free_pages;
96 spinlock_t lock; /* protects the above */
97};
98
99static struct dmirror_device dmirror_devices[DMIRROR_NDEVICES];
100
101static int dmirror_bounce_init(struct dmirror_bounce *bounce,
102 unsigned long addr,
103 unsigned long size)
104{
105 bounce->addr = addr;
106 bounce->size = size;
107 bounce->cpages = 0;
108 bounce->ptr = vmalloc(size);
109 if (!bounce->ptr)
110 return -ENOMEM;
111 return 0;
112}
113
114static void dmirror_bounce_fini(struct dmirror_bounce *bounce)
115{
116 vfree(bounce->ptr);
117}
118
119static int dmirror_fops_open(struct inode *inode, struct file *filp)
120{
121 struct cdev *cdev = inode->i_cdev;
122 struct dmirror *dmirror;
123 int ret;
124
125 /* Mirror this process address space */
126 dmirror = kzalloc(sizeof(*dmirror), GFP_KERNEL);
127 if (dmirror == NULL)
128 return -ENOMEM;
129
130 dmirror->mdevice = container_of(cdev, struct dmirror_device, cdevice);
131 mutex_init(&dmirror->mutex);
132 xa_init(&dmirror->pt);
133
134 ret = mmu_interval_notifier_insert(&dmirror->notifier, current->mm,
135 0, ULONG_MAX & PAGE_MASK, &dmirror_min_ops);
136 if (ret) {
137 kfree(dmirror);
138 return ret;
139 }
140
141 filp->private_data = dmirror;
142 return 0;
143}
144
145static int dmirror_fops_release(struct inode *inode, struct file *filp)
146{
147 struct dmirror *dmirror = filp->private_data;
148
149 mmu_interval_notifier_remove(&dmirror->notifier);
150 xa_destroy(&dmirror->pt);
151 kfree(dmirror);
152 return 0;
153}
154
155static struct dmirror_device *dmirror_page_to_device(struct page *page)
156
157{
158 return container_of(page->pgmap, struct dmirror_chunk,
159 pagemap)->mdevice;
160}
161
162static int dmirror_do_fault(struct dmirror *dmirror, struct hmm_range *range)
163{
164 unsigned long *pfns = range->hmm_pfns;
165 unsigned long pfn;
166
167 for (pfn = (range->start >> PAGE_SHIFT);
168 pfn < (range->end >> PAGE_SHIFT);
169 pfn++, pfns++) {
170 struct page *page;
171 void *entry;
172
173 /*
174 * Since we asked for hmm_range_fault() to populate pages,
175 * it shouldn't return an error entry on success.
176 */
177 WARN_ON(*pfns & HMM_PFN_ERROR);
178 WARN_ON(!(*pfns & HMM_PFN_VALID));
179
180 page = hmm_pfn_to_page(*pfns);
181 WARN_ON(!page);
182
183 entry = page;
184 if (*pfns & HMM_PFN_WRITE)
185 entry = xa_tag_pointer(entry, DPT_XA_TAG_WRITE);
186 else if (WARN_ON(range->default_flags & HMM_PFN_WRITE))
187 return -EFAULT;
188 entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
189 if (xa_is_err(entry))
190 return xa_err(entry);
191 }
192
193 return 0;
194}
195
196static void dmirror_do_update(struct dmirror *dmirror, unsigned long start,
197 unsigned long end)
198{
199 unsigned long pfn;
200 void *entry;
201
202 /*
203 * The XArray doesn't hold references to pages since it relies on
204 * the mmu notifier to clear page pointers when they become stale.
205 * Therefore, it is OK to just clear the entry.
206 */
207 xa_for_each_range(&dmirror->pt, pfn, entry, start >> PAGE_SHIFT,
208 end >> PAGE_SHIFT)
209 xa_erase(&dmirror->pt, pfn);
210}
211
212static bool dmirror_interval_invalidate(struct mmu_interval_notifier *mni,
213 const struct mmu_notifier_range *range,
214 unsigned long cur_seq)
215{
216 struct dmirror *dmirror = container_of(mni, struct dmirror, notifier);
217
218 /*
219 * Ignore invalidation callbacks for device private pages since
220 * the invalidation is handled as part of the migration process.
221 */
222 if (range->event == MMU_NOTIFY_MIGRATE &&
223 range->owner == dmirror->mdevice)
224 return true;
225
226 if (mmu_notifier_range_blockable(range))
227 mutex_lock(&dmirror->mutex);
228 else if (!mutex_trylock(&dmirror->mutex))
229 return false;
230
231 mmu_interval_set_seq(mni, cur_seq);
232 dmirror_do_update(dmirror, range->start, range->end);
233
234 mutex_unlock(&dmirror->mutex);
235 return true;
236}
237
238static const struct mmu_interval_notifier_ops dmirror_min_ops = {
239 .invalidate = dmirror_interval_invalidate,
240};
241
242static int dmirror_range_fault(struct dmirror *dmirror,
243 struct hmm_range *range)
244{
245 struct mm_struct *mm = dmirror->notifier.mm;
246 unsigned long timeout =
247 jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
248 int ret;
249
250 while (true) {
251 if (time_after(jiffies, timeout)) {
252 ret = -EBUSY;
253 goto out;
254 }
255
256 range->notifier_seq = mmu_interval_read_begin(range->notifier);
257 mmap_read_lock(mm);
258 ret = hmm_range_fault(range);
259 mmap_read_unlock(mm);
260 if (ret) {
261 if (ret == -EBUSY)
262 continue;
263 goto out;
264 }
265
266 mutex_lock(&dmirror->mutex);
267 if (mmu_interval_read_retry(range->notifier,
268 range->notifier_seq)) {
269 mutex_unlock(&dmirror->mutex);
270 continue;
271 }
272 break;
273 }
274
275 ret = dmirror_do_fault(dmirror, range);
276
277 mutex_unlock(&dmirror->mutex);
278out:
279 return ret;
280}
281
282static int dmirror_fault(struct dmirror *dmirror, unsigned long start,
283 unsigned long end, bool write)
284{
285 struct mm_struct *mm = dmirror->notifier.mm;
286 unsigned long addr;
287 unsigned long pfns[64];
288 struct hmm_range range = {
289 .notifier = &dmirror->notifier,
290 .hmm_pfns = pfns,
291 .pfn_flags_mask = 0,
292 .default_flags =
293 HMM_PFN_REQ_FAULT | (write ? HMM_PFN_REQ_WRITE : 0),
294 .dev_private_owner = dmirror->mdevice,
295 };
296 int ret = 0;
297
298 /* Since the mm is for the mirrored process, get a reference first. */
299 if (!mmget_not_zero(mm))
300 return 0;
301
302 for (addr = start; addr < end; addr = range.end) {
303 range.start = addr;
304 range.end = min(addr + (ARRAY_SIZE(pfns) << PAGE_SHIFT), end);
305
306 ret = dmirror_range_fault(dmirror, &range);
307 if (ret)
308 break;
309 }
310
311 mmput(mm);
312 return ret;
313}
314
315static int dmirror_do_read(struct dmirror *dmirror, unsigned long start,
316 unsigned long end, struct dmirror_bounce *bounce)
317{
318 unsigned long pfn;
319 void *ptr;
320
321 ptr = bounce->ptr + ((start - bounce->addr) & PAGE_MASK);
322
323 for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
324 void *entry;
325 struct page *page;
326 void *tmp;
327
328 entry = xa_load(&dmirror->pt, pfn);
329 page = xa_untag_pointer(entry);
330 if (!page)
331 return -ENOENT;
332
333 tmp = kmap(page);
334 memcpy(ptr, tmp, PAGE_SIZE);
335 kunmap(page);
336
337 ptr += PAGE_SIZE;
338 bounce->cpages++;
339 }
340
341 return 0;
342}
343
344static int dmirror_read(struct dmirror *dmirror, struct hmm_dmirror_cmd *cmd)
345{
346 struct dmirror_bounce bounce;
347 unsigned long start, end;
348 unsigned long size = cmd->npages << PAGE_SHIFT;
349 int ret;
350
351 start = cmd->addr;
352 end = start + size;
353 if (end < start)
354 return -EINVAL;
355
356 ret = dmirror_bounce_init(&bounce, start, size);
357 if (ret)
358 return ret;
359
360 while (1) {
361 mutex_lock(&dmirror->mutex);
362 ret = dmirror_do_read(dmirror, start, end, &bounce);
363 mutex_unlock(&dmirror->mutex);
364 if (ret != -ENOENT)
365 break;
366
367 start = cmd->addr + (bounce.cpages << PAGE_SHIFT);
368 ret = dmirror_fault(dmirror, start, end, false);
369 if (ret)
370 break;
371 cmd->faults++;
372 }
373
374 if (ret == 0) {
375 if (copy_to_user(u64_to_user_ptr(cmd->ptr), bounce.ptr,
376 bounce.size))
377 ret = -EFAULT;
378 }
379 cmd->cpages = bounce.cpages;
380 dmirror_bounce_fini(&bounce);
381 return ret;
382}
383
384static int dmirror_do_write(struct dmirror *dmirror, unsigned long start,
385 unsigned long end, struct dmirror_bounce *bounce)
386{
387 unsigned long pfn;
388 void *ptr;
389
390 ptr = bounce->ptr + ((start - bounce->addr) & PAGE_MASK);
391
392 for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
393 void *entry;
394 struct page *page;
395 void *tmp;
396
397 entry = xa_load(&dmirror->pt, pfn);
398 page = xa_untag_pointer(entry);
399 if (!page || xa_pointer_tag(entry) != DPT_XA_TAG_WRITE)
400 return -ENOENT;
401
402 tmp = kmap(page);
403 memcpy(tmp, ptr, PAGE_SIZE);
404 kunmap(page);
405
406 ptr += PAGE_SIZE;
407 bounce->cpages++;
408 }
409
410 return 0;
411}
412
413static int dmirror_write(struct dmirror *dmirror, struct hmm_dmirror_cmd *cmd)
414{
415 struct dmirror_bounce bounce;
416 unsigned long start, end;
417 unsigned long size = cmd->npages << PAGE_SHIFT;
418 int ret;
419
420 start = cmd->addr;
421 end = start + size;
422 if (end < start)
423 return -EINVAL;
424
425 ret = dmirror_bounce_init(&bounce, start, size);
426 if (ret)
427 return ret;
428 if (copy_from_user(bounce.ptr, u64_to_user_ptr(cmd->ptr),
429 bounce.size)) {
430 ret = -EFAULT;
431 goto fini;
432 }
433
434 while (1) {
435 mutex_lock(&dmirror->mutex);
436 ret = dmirror_do_write(dmirror, start, end, &bounce);
437 mutex_unlock(&dmirror->mutex);
438 if (ret != -ENOENT)
439 break;
440
441 start = cmd->addr + (bounce.cpages << PAGE_SHIFT);
442 ret = dmirror_fault(dmirror, start, end, true);
443 if (ret)
444 break;
445 cmd->faults++;
446 }
447
448fini:
449 cmd->cpages = bounce.cpages;
450 dmirror_bounce_fini(&bounce);
451 return ret;
452}
453
454static bool dmirror_allocate_chunk(struct dmirror_device *mdevice,
455 struct page **ppage)
456{
457 struct dmirror_chunk *devmem;
458 struct resource *res;
459 unsigned long pfn;
460 unsigned long pfn_first;
461 unsigned long pfn_last;
462 void *ptr;
463
464 devmem = kzalloc(sizeof(*devmem), GFP_KERNEL);
465 if (!devmem)
466 return false;
467
468 res = request_free_mem_region(&iomem_resource, DEVMEM_CHUNK_SIZE,
469 "hmm_dmirror");
470 if (IS_ERR(res))
471 goto err_devmem;
472
473 devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
474 devmem->pagemap.range.start = res->start;
475 devmem->pagemap.range.end = res->end;
476 devmem->pagemap.nr_range = 1;
477 devmem->pagemap.ops = &dmirror_devmem_ops;
478 devmem->pagemap.owner = mdevice;
479
480 mutex_lock(&mdevice->devmem_lock);
481
482 if (mdevice->devmem_count == mdevice->devmem_capacity) {
483 struct dmirror_chunk **new_chunks;
484 unsigned int new_capacity;
485
486 new_capacity = mdevice->devmem_capacity +
487 DEVMEM_CHUNKS_RESERVE;
488 new_chunks = krealloc(mdevice->devmem_chunks,
489 sizeof(new_chunks[0]) * new_capacity,
490 GFP_KERNEL);
491 if (!new_chunks)
492 goto err_release;
493 mdevice->devmem_capacity = new_capacity;
494 mdevice->devmem_chunks = new_chunks;
495 }
496
497 ptr = memremap_pages(&devmem->pagemap, numa_node_id());
498 if (IS_ERR(ptr))
499 goto err_release;
500
501 devmem->mdevice = mdevice;
502 pfn_first = devmem->pagemap.range.start >> PAGE_SHIFT;
503 pfn_last = pfn_first + (range_len(&devmem->pagemap.range) >> PAGE_SHIFT);
504 mdevice->devmem_chunks[mdevice->devmem_count++] = devmem;
505
506 mutex_unlock(&mdevice->devmem_lock);
507
508 pr_info("added new %u MB chunk (total %u chunks, %u MB) PFNs [0x%lx 0x%lx)\n",
509 DEVMEM_CHUNK_SIZE / (1024 * 1024),
510 mdevice->devmem_count,
511 mdevice->devmem_count * (DEVMEM_CHUNK_SIZE / (1024 * 1024)),
512 pfn_first, pfn_last);
513
514 spin_lock(&mdevice->lock);
515 for (pfn = pfn_first; pfn < pfn_last; pfn++) {
516 struct page *page = pfn_to_page(pfn);
517
518 page->zone_device_data = mdevice->free_pages;
519 mdevice->free_pages = page;
520 }
521 if (ppage) {
522 *ppage = mdevice->free_pages;
523 mdevice->free_pages = (*ppage)->zone_device_data;
524 mdevice->calloc++;
525 }
526 spin_unlock(&mdevice->lock);
527
528 return true;
529
530err_release:
531 mutex_unlock(&mdevice->devmem_lock);
532 release_mem_region(devmem->pagemap.range.start, range_len(&devmem->pagemap.range));
533err_devmem:
534 kfree(devmem);
535
536 return false;
537}
538
539static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
540{
541 struct page *dpage = NULL;
542 struct page *rpage;
543
544 /*
545 * This is a fake device so we alloc real system memory to store
546 * our device memory.
547 */
548 rpage = alloc_page(GFP_HIGHUSER);
549 if (!rpage)
550 return NULL;
551
552 spin_lock(&mdevice->lock);
553
554 if (mdevice->free_pages) {
555 dpage = mdevice->free_pages;
556 mdevice->free_pages = dpage->zone_device_data;
557 mdevice->calloc++;
558 spin_unlock(&mdevice->lock);
559 } else {
560 spin_unlock(&mdevice->lock);
561 if (!dmirror_allocate_chunk(mdevice, &dpage))
562 goto error;
563 }
564
565 dpage->zone_device_data = rpage;
566 get_page(dpage);
567 lock_page(dpage);
568 return dpage;
569
570error:
571 __free_page(rpage);
572 return NULL;
573}
574
575static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
576 struct dmirror *dmirror)
577{
578 struct dmirror_device *mdevice = dmirror->mdevice;
579 const unsigned long *src = args->src;
580 unsigned long *dst = args->dst;
581 unsigned long addr;
582
583 for (addr = args->start; addr < args->end; addr += PAGE_SIZE,
584 src++, dst++) {
585 struct page *spage;
586 struct page *dpage;
587 struct page *rpage;
588
589 if (!(*src & MIGRATE_PFN_MIGRATE))
590 continue;
591
592 /*
593 * Note that spage might be NULL which is OK since it is an
594 * unallocated pte_none() or read-only zero page.
595 */
596 spage = migrate_pfn_to_page(*src);
597
598 dpage = dmirror_devmem_alloc_page(mdevice);
599 if (!dpage)
600 continue;
601
602 rpage = dpage->zone_device_data;
603 if (spage)
604 copy_highpage(rpage, spage);
605 else
606 clear_highpage(rpage);
607
608 /*
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
612 * to the mirror.
613 */
614 rpage->zone_device_data = dmirror;
615
616 *dst = migrate_pfn(page_to_pfn(dpage)) |
617 MIGRATE_PFN_LOCKED;
618 if ((*src & MIGRATE_PFN_WRITE) ||
619 (!spage && args->vma->vm_flags & VM_WRITE))
620 *dst |= MIGRATE_PFN_WRITE;
621 }
622}
623
624static int dmirror_check_atomic(struct dmirror *dmirror, unsigned long start,
625 unsigned long end)
626{
627 unsigned long pfn;
628
629 for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
630 void *entry;
631
632 entry = xa_load(&dmirror->pt, pfn);
633 if (xa_pointer_tag(entry) == DPT_XA_TAG_ATOMIC)
634 return -EPERM;
635 }
636
637 return 0;
638}
639
640static int dmirror_atomic_map(unsigned long start, unsigned long end,
641 struct page **pages, struct dmirror *dmirror)
642{
643 unsigned long pfn, mapped = 0;
644 int i;
645
646 /* Map the migrated pages into the device's page tables. */
647 mutex_lock(&dmirror->mutex);
648
649 for (i = 0, pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++, i++) {
650 void *entry;
651
652 if (!pages[i])
653 continue;
654
655 entry = pages[i];
656 entry = xa_tag_pointer(entry, DPT_XA_TAG_ATOMIC);
657 entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
658 if (xa_is_err(entry)) {
659 mutex_unlock(&dmirror->mutex);
660 return xa_err(entry);
661 }
662
663 mapped++;
664 }
665
666 mutex_unlock(&dmirror->mutex);
667 return mapped;
668}
669
670static int dmirror_migrate_finalize_and_map(struct migrate_vma *args,
671 struct dmirror *dmirror)
672{
673 unsigned long start = args->start;
674 unsigned long end = args->end;
675 const unsigned long *src = args->src;
676 const unsigned long *dst = args->dst;
677 unsigned long pfn;
678
679 /* Map the migrated pages into the device's page tables. */
680 mutex_lock(&dmirror->mutex);
681
682 for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++,
683 src++, dst++) {
684 struct page *dpage;
685 void *entry;
686
687 if (!(*src & MIGRATE_PFN_MIGRATE))
688 continue;
689
690 dpage = migrate_pfn_to_page(*dst);
691 if (!dpage)
692 continue;
693
694 /*
695 * Store the page that holds the data so the page table
696 * doesn't have to deal with ZONE_DEVICE private pages.
697 */
698 entry = dpage->zone_device_data;
699 if (*dst & MIGRATE_PFN_WRITE)
700 entry = xa_tag_pointer(entry, DPT_XA_TAG_WRITE);
701 entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
702 if (xa_is_err(entry)) {
703 mutex_unlock(&dmirror->mutex);
704 return xa_err(entry);
705 }
706 }
707
708 mutex_unlock(&dmirror->mutex);
709 return 0;
710}
711
712static int dmirror_exclusive(struct dmirror *dmirror,
713 struct hmm_dmirror_cmd *cmd)
714{
715 unsigned long start, end, addr;
716 unsigned long size = cmd->npages << PAGE_SHIFT;
717 struct mm_struct *mm = dmirror->notifier.mm;
718 struct page *pages[64];
719 struct dmirror_bounce bounce;
720 unsigned long next;
721 int ret;
722
723 start = cmd->addr;
724 end = start + size;
725 if (end < start)
726 return -EINVAL;
727
728 /* Since the mm is for the mirrored process, get a reference first. */
729 if (!mmget_not_zero(mm))
730 return -EINVAL;
731
732 mmap_read_lock(mm);
733 for (addr = start; addr < end; addr = next) {
734 unsigned long mapped;
735 int i;
736
737 if (end < addr + (ARRAY_SIZE(pages) << PAGE_SHIFT))
738 next = end;
739 else
740 next = addr + (ARRAY_SIZE(pages) << PAGE_SHIFT);
741
742 ret = make_device_exclusive_range(mm, addr, next, pages, NULL);
743 mapped = dmirror_atomic_map(addr, next, pages, dmirror);
744 for (i = 0; i < ret; i++) {
745 if (pages[i]) {
746 unlock_page(pages[i]);
747 put_page(pages[i]);
748 }
749 }
750
751 if (addr + (mapped << PAGE_SHIFT) < next) {
752 mmap_read_unlock(mm);
753 mmput(mm);
754 return -EBUSY;
755 }
756 }
757 mmap_read_unlock(mm);
758 mmput(mm);
759
760 /* Return the migrated data for verification. */
761 ret = dmirror_bounce_init(&bounce, start, size);
762 if (ret)
763 return ret;
764 mutex_lock(&dmirror->mutex);
765 ret = dmirror_do_read(dmirror, start, end, &bounce);
766 mutex_unlock(&dmirror->mutex);
767 if (ret == 0) {
768 if (copy_to_user(u64_to_user_ptr(cmd->ptr), bounce.ptr,
769 bounce.size))
770 ret = -EFAULT;
771 }
772
773 cmd->cpages = bounce.cpages;
774 dmirror_bounce_fini(&bounce);
775 return ret;
776}
777
778static int dmirror_migrate(struct dmirror *dmirror,
779 struct hmm_dmirror_cmd *cmd)
780{
781 unsigned long start, end, addr;
782 unsigned long size = cmd->npages << PAGE_SHIFT;
783 struct mm_struct *mm = dmirror->notifier.mm;
784 struct vm_area_struct *vma;
785 unsigned long src_pfns[64];
786 unsigned long dst_pfns[64];
787 struct dmirror_bounce bounce;
788 struct migrate_vma args;
789 unsigned long next;
790 int ret;
791
792 start = cmd->addr;
793 end = start + size;
794 if (end < start)
795 return -EINVAL;
796
797 /* Since the mm is for the mirrored process, get a reference first. */
798 if (!mmget_not_zero(mm))
799 return -EINVAL;
800
801 mmap_read_lock(mm);
802 for (addr = start; addr < end; addr = next) {
803 vma = vma_lookup(mm, addr);
804 if (!vma || !(vma->vm_flags & VM_READ)) {
805 ret = -EINVAL;
806 goto out;
807 }
808 next = min(end, addr + (ARRAY_SIZE(src_pfns) << PAGE_SHIFT));
809 if (next > vma->vm_end)
810 next = vma->vm_end;
811
812 args.vma = vma;
813 args.src = src_pfns;
814 args.dst = dst_pfns;
815 args.start = addr;
816 args.end = next;
817 args.pgmap_owner = dmirror->mdevice;
818 args.flags = MIGRATE_VMA_SELECT_SYSTEM;
819 ret = migrate_vma_setup(&args);
820 if (ret)
821 goto out;
822
823 dmirror_migrate_alloc_and_copy(&args, dmirror);
824 migrate_vma_pages(&args);
825 dmirror_migrate_finalize_and_map(&args, dmirror);
826 migrate_vma_finalize(&args);
827 }
828 mmap_read_unlock(mm);
829 mmput(mm);
830
831 /* Return the migrated data for verification. */
832 ret = dmirror_bounce_init(&bounce, start, size);
833 if (ret)
834 return ret;
835 mutex_lock(&dmirror->mutex);
836 ret = dmirror_do_read(dmirror, start, end, &bounce);
837 mutex_unlock(&dmirror->mutex);
838 if (ret == 0) {
839 if (copy_to_user(u64_to_user_ptr(cmd->ptr), bounce.ptr,
840 bounce.size))
841 ret = -EFAULT;
842 }
843 cmd->cpages = bounce.cpages;
844 dmirror_bounce_fini(&bounce);
845 return ret;
846
847out:
848 mmap_read_unlock(mm);
849 mmput(mm);
850 return ret;
851}
852
853static void dmirror_mkentry(struct dmirror *dmirror, struct hmm_range *range,
854 unsigned char *perm, unsigned long entry)
855{
856 struct page *page;
857
858 if (entry & HMM_PFN_ERROR) {
859 *perm = HMM_DMIRROR_PROT_ERROR;
860 return;
861 }
862 if (!(entry & HMM_PFN_VALID)) {
863 *perm = HMM_DMIRROR_PROT_NONE;
864 return;
865 }
866
867 page = hmm_pfn_to_page(entry);
868 if (is_device_private_page(page)) {
869 /* Is the page migrated to this device or some other? */
870 if (dmirror->mdevice == dmirror_page_to_device(page))
871 *perm = HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL;
872 else
873 *perm = HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE;
874 } else if (is_zero_pfn(page_to_pfn(page)))
875 *perm = HMM_DMIRROR_PROT_ZERO;
876 else
877 *perm = HMM_DMIRROR_PROT_NONE;
878 if (entry & HMM_PFN_WRITE)
879 *perm |= HMM_DMIRROR_PROT_WRITE;
880 else
881 *perm |= HMM_DMIRROR_PROT_READ;
882 if (hmm_pfn_to_map_order(entry) + PAGE_SHIFT == PMD_SHIFT)
883 *perm |= HMM_DMIRROR_PROT_PMD;
884 else if (hmm_pfn_to_map_order(entry) + PAGE_SHIFT == PUD_SHIFT)
885 *perm |= HMM_DMIRROR_PROT_PUD;
886}
887
888static bool dmirror_snapshot_invalidate(struct mmu_interval_notifier *mni,
889 const struct mmu_notifier_range *range,
890 unsigned long cur_seq)
891{
892 struct dmirror_interval *dmi =
893 container_of(mni, struct dmirror_interval, notifier);
894 struct dmirror *dmirror = dmi->dmirror;
895
896 if (mmu_notifier_range_blockable(range))
897 mutex_lock(&dmirror->mutex);
898 else if (!mutex_trylock(&dmirror->mutex))
899 return false;
900
901 /*
902 * Snapshots only need to set the sequence number since any
903 * invalidation in the interval invalidates the whole snapshot.
904 */
905 mmu_interval_set_seq(mni, cur_seq);
906
907 mutex_unlock(&dmirror->mutex);
908 return true;
909}
910
911static const struct mmu_interval_notifier_ops dmirror_mrn_ops = {
912 .invalidate = dmirror_snapshot_invalidate,
913};
914
915static int dmirror_range_snapshot(struct dmirror *dmirror,
916 struct hmm_range *range,
917 unsigned char *perm)
918{
919 struct mm_struct *mm = dmirror->notifier.mm;
920 struct dmirror_interval notifier;
921 unsigned long timeout =
922 jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
923 unsigned long i;
924 unsigned long n;
925 int ret = 0;
926
927 notifier.dmirror = dmirror;
928 range->notifier = ¬ifier.notifier;
929
930 ret = mmu_interval_notifier_insert(range->notifier, mm,
931 range->start, range->end - range->start,
932 &dmirror_mrn_ops);
933 if (ret)
934 return ret;
935
936 while (true) {
937 if (time_after(jiffies, timeout)) {
938 ret = -EBUSY;
939 goto out;
940 }
941
942 range->notifier_seq = mmu_interval_read_begin(range->notifier);
943
944 mmap_read_lock(mm);
945 ret = hmm_range_fault(range);
946 mmap_read_unlock(mm);
947 if (ret) {
948 if (ret == -EBUSY)
949 continue;
950 goto out;
951 }
952
953 mutex_lock(&dmirror->mutex);
954 if (mmu_interval_read_retry(range->notifier,
955 range->notifier_seq)) {
956 mutex_unlock(&dmirror->mutex);
957 continue;
958 }
959 break;
960 }
961
962 n = (range->end - range->start) >> PAGE_SHIFT;
963 for (i = 0; i < n; i++)
964 dmirror_mkentry(dmirror, range, perm + i, range->hmm_pfns[i]);
965
966 mutex_unlock(&dmirror->mutex);
967out:
968 mmu_interval_notifier_remove(range->notifier);
969 return ret;
970}
971
972static int dmirror_snapshot(struct dmirror *dmirror,
973 struct hmm_dmirror_cmd *cmd)
974{
975 struct mm_struct *mm = dmirror->notifier.mm;
976 unsigned long start, end;
977 unsigned long size = cmd->npages << PAGE_SHIFT;
978 unsigned long addr;
979 unsigned long next;
980 unsigned long pfns[64];
981 unsigned char perm[64];
982 char __user *uptr;
983 struct hmm_range range = {
984 .hmm_pfns = pfns,
985 .dev_private_owner = dmirror->mdevice,
986 };
987 int ret = 0;
988
989 start = cmd->addr;
990 end = start + size;
991 if (end < start)
992 return -EINVAL;
993
994 /* Since the mm is for the mirrored process, get a reference first. */
995 if (!mmget_not_zero(mm))
996 return -EINVAL;
997
998 /*
999 * Register a temporary notifier to detect invalidations even if it
1000 * overlaps with other mmu_interval_notifiers.
1001 */
1002 uptr = u64_to_user_ptr(cmd->ptr);
1003 for (addr = start; addr < end; addr = next) {
1004 unsigned long n;
1005
1006 next = min(addr + (ARRAY_SIZE(pfns) << PAGE_SHIFT), end);
1007 range.start = addr;
1008 range.end = next;
1009
1010 ret = dmirror_range_snapshot(dmirror, &range, perm);
1011 if (ret)
1012 break;
1013
1014 n = (range.end - range.start) >> PAGE_SHIFT;
1015 if (copy_to_user(uptr, perm, n)) {
1016 ret = -EFAULT;
1017 break;
1018 }
1019
1020 cmd->cpages += n;
1021 uptr += n;
1022 }
1023 mmput(mm);
1024
1025 return ret;
1026}
1027
1028static long dmirror_fops_unlocked_ioctl(struct file *filp,
1029 unsigned int command,
1030 unsigned long arg)
1031{
1032 void __user *uarg = (void __user *)arg;
1033 struct hmm_dmirror_cmd cmd;
1034 struct dmirror *dmirror;
1035 int ret;
1036
1037 dmirror = filp->private_data;
1038 if (!dmirror)
1039 return -EINVAL;
1040
1041 if (copy_from_user(&cmd, uarg, sizeof(cmd)))
1042 return -EFAULT;
1043
1044 if (cmd.addr & ~PAGE_MASK)
1045 return -EINVAL;
1046 if (cmd.addr >= (cmd.addr + (cmd.npages << PAGE_SHIFT)))
1047 return -EINVAL;
1048
1049 cmd.cpages = 0;
1050 cmd.faults = 0;
1051
1052 switch (command) {
1053 case HMM_DMIRROR_READ:
1054 ret = dmirror_read(dmirror, &cmd);
1055 break;
1056
1057 case HMM_DMIRROR_WRITE:
1058 ret = dmirror_write(dmirror, &cmd);
1059 break;
1060
1061 case HMM_DMIRROR_MIGRATE:
1062 ret = dmirror_migrate(dmirror, &cmd);
1063 break;
1064
1065 case HMM_DMIRROR_EXCLUSIVE:
1066 ret = dmirror_exclusive(dmirror, &cmd);
1067 break;
1068
1069 case HMM_DMIRROR_CHECK_EXCLUSIVE:
1070 ret = dmirror_check_atomic(dmirror, cmd.addr,
1071 cmd.addr + (cmd.npages << PAGE_SHIFT));
1072 break;
1073
1074 case HMM_DMIRROR_SNAPSHOT:
1075 ret = dmirror_snapshot(dmirror, &cmd);
1076 break;
1077
1078 default:
1079 return -EINVAL;
1080 }
1081 if (ret)
1082 return ret;
1083
1084 if (copy_to_user(uarg, &cmd, sizeof(cmd)))
1085 return -EFAULT;
1086
1087 return 0;
1088}
1089
1090static const struct file_operations dmirror_fops = {
1091 .open = dmirror_fops_open,
1092 .release = dmirror_fops_release,
1093 .unlocked_ioctl = dmirror_fops_unlocked_ioctl,
1094 .llseek = default_llseek,
1095 .owner = THIS_MODULE,
1096};
1097
1098static void dmirror_devmem_free(struct page *page)
1099{
1100 struct page *rpage = page->zone_device_data;
1101 struct dmirror_device *mdevice;
1102
1103 if (rpage)
1104 __free_page(rpage);
1105
1106 mdevice = dmirror_page_to_device(page);
1107
1108 spin_lock(&mdevice->lock);
1109 mdevice->cfree++;
1110 page->zone_device_data = mdevice->free_pages;
1111 mdevice->free_pages = page;
1112 spin_unlock(&mdevice->lock);
1113}
1114
1115static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
1116 struct dmirror *dmirror)
1117{
1118 const unsigned long *src = args->src;
1119 unsigned long *dst = args->dst;
1120 unsigned long start = args->start;
1121 unsigned long end = args->end;
1122 unsigned long addr;
1123
1124 for (addr = start; addr < end; addr += PAGE_SIZE,
1125 src++, dst++) {
1126 struct page *dpage, *spage;
1127
1128 spage = migrate_pfn_to_page(*src);
1129 if (!spage || !(*src & MIGRATE_PFN_MIGRATE))
1130 continue;
1131 spage = spage->zone_device_data;
1132
1133 dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr);
1134 if (!dpage)
1135 continue;
1136
1137 lock_page(dpage);
1138 xa_erase(&dmirror->pt, addr >> PAGE_SHIFT);
1139 copy_highpage(dpage, spage);
1140 *dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
1141 if (*src & MIGRATE_PFN_WRITE)
1142 *dst |= MIGRATE_PFN_WRITE;
1143 }
1144 return 0;
1145}
1146
1147static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
1148{
1149 struct migrate_vma args;
1150 unsigned long src_pfns;
1151 unsigned long dst_pfns;
1152 struct page *rpage;
1153 struct dmirror *dmirror;
1154 vm_fault_t ret;
1155
1156 /*
1157 * Normally, a device would use the page->zone_device_data to point to
1158 * the mirror but here we use it to hold the page for the simulated
1159 * device memory and that page holds the pointer to the mirror.
1160 */
1161 rpage = vmf->page->zone_device_data;
1162 dmirror = rpage->zone_device_data;
1163
1164 /* FIXME demonstrate how we can adjust migrate range */
1165 args.vma = vmf->vma;
1166 args.start = vmf->address;
1167 args.end = args.start + PAGE_SIZE;
1168 args.src = &src_pfns;
1169 args.dst = &dst_pfns;
1170 args.pgmap_owner = dmirror->mdevice;
1171 args.flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
1172
1173 if (migrate_vma_setup(&args))
1174 return VM_FAULT_SIGBUS;
1175
1176 ret = dmirror_devmem_fault_alloc_and_copy(&args, dmirror);
1177 if (ret)
1178 return ret;
1179 migrate_vma_pages(&args);
1180 /*
1181 * No device finalize step is needed since
1182 * dmirror_devmem_fault_alloc_and_copy() will have already
1183 * invalidated the device page table.
1184 */
1185 migrate_vma_finalize(&args);
1186 return 0;
1187}
1188
1189static const struct dev_pagemap_ops dmirror_devmem_ops = {
1190 .page_free = dmirror_devmem_free,
1191 .migrate_to_ram = dmirror_devmem_fault,
1192};
1193
1194static int dmirror_device_init(struct dmirror_device *mdevice, int id)
1195{
1196 dev_t dev;
1197 int ret;
1198
1199 dev = MKDEV(MAJOR(dmirror_dev), id);
1200 mutex_init(&mdevice->devmem_lock);
1201 spin_lock_init(&mdevice->lock);
1202
1203 cdev_init(&mdevice->cdevice, &dmirror_fops);
1204 mdevice->cdevice.owner = THIS_MODULE;
1205 ret = cdev_add(&mdevice->cdevice, dev, 1);
1206 if (ret)
1207 return ret;
1208
1209 /* Build a list of free ZONE_DEVICE private struct pages */
1210 dmirror_allocate_chunk(mdevice, NULL);
1211
1212 return 0;
1213}
1214
1215static void dmirror_device_remove(struct dmirror_device *mdevice)
1216{
1217 unsigned int i;
1218
1219 if (mdevice->devmem_chunks) {
1220 for (i = 0; i < mdevice->devmem_count; i++) {
1221 struct dmirror_chunk *devmem =
1222 mdevice->devmem_chunks[i];
1223
1224 memunmap_pages(&devmem->pagemap);
1225 release_mem_region(devmem->pagemap.range.start,
1226 range_len(&devmem->pagemap.range));
1227 kfree(devmem);
1228 }
1229 kfree(mdevice->devmem_chunks);
1230 }
1231
1232 cdev_del(&mdevice->cdevice);
1233}
1234
1235static int __init hmm_dmirror_init(void)
1236{
1237 int ret;
1238 int id;
1239
1240 ret = alloc_chrdev_region(&dmirror_dev, 0, DMIRROR_NDEVICES,
1241 "HMM_DMIRROR");
1242 if (ret)
1243 goto err_unreg;
1244
1245 for (id = 0; id < DMIRROR_NDEVICES; id++) {
1246 ret = dmirror_device_init(dmirror_devices + id, id);
1247 if (ret)
1248 goto err_chrdev;
1249 }
1250
1251 pr_info("HMM test module loaded. This is only for testing HMM.\n");
1252 return 0;
1253
1254err_chrdev:
1255 while (--id >= 0)
1256 dmirror_device_remove(dmirror_devices + id);
1257 unregister_chrdev_region(dmirror_dev, DMIRROR_NDEVICES);
1258err_unreg:
1259 return ret;
1260}
1261
1262static void __exit hmm_dmirror_exit(void)
1263{
1264 int id;
1265
1266 for (id = 0; id < DMIRROR_NDEVICES; id++)
1267 dmirror_device_remove(dmirror_devices + id);
1268 unregister_chrdev_region(dmirror_dev, DMIRROR_NDEVICES);
1269}
1270
1271module_init(hmm_dmirror_init);
1272module_exit(hmm_dmirror_exit);
1273MODULE_LICENSE("GPL");
1// SPDX-License-Identifier: GPL-2.0
2/*
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.
7 */
8#include <linux/init.h>
9#include <linux/fs.h>
10#include <linux/mm.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>
28
29#include "test_hmm_uapi.h"
30
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
35
36static const struct dev_pagemap_ops dmirror_devmem_ops;
37static const struct mmu_interval_notifier_ops dmirror_min_ops;
38static dev_t dmirror_dev;
39static struct page *dmirror_zero_page;
40
41struct dmirror_device;
42
43struct dmirror_bounce {
44 void *ptr;
45 unsigned long size;
46 unsigned long addr;
47 unsigned long cpages;
48};
49
50#define DPT_XA_TAG_WRITE 3UL
51
52/*
53 * Data structure to track address ranges and register for mmu interval
54 * notifier updates.
55 */
56struct dmirror_interval {
57 struct mmu_interval_notifier notifier;
58 struct dmirror *dmirror;
59};
60
61/*
62 * Data attached to the open device file.
63 * Note that it might be shared after a fork().
64 */
65struct dmirror {
66 struct dmirror_device *mdevice;
67 struct xarray pt;
68 struct mmu_interval_notifier notifier;
69 struct mutex mutex;
70};
71
72/*
73 * ZONE_DEVICE pages for migration and simulating device memory.
74 */
75struct dmirror_chunk {
76 struct dev_pagemap pagemap;
77 struct dmirror_device *mdevice;
78};
79
80/*
81 * Per device data.
82 */
83struct dmirror_device {
84 struct cdev cdevice;
85 struct hmm_devmem *devmem;
86
87 unsigned int devmem_capacity;
88 unsigned int devmem_count;
89 struct dmirror_chunk **devmem_chunks;
90 struct mutex devmem_lock; /* protects the above */
91
92 unsigned long calloc;
93 unsigned long cfree;
94 struct page *free_pages;
95 spinlock_t lock; /* protects the above */
96};
97
98static struct dmirror_device dmirror_devices[DMIRROR_NDEVICES];
99
100static int dmirror_bounce_init(struct dmirror_bounce *bounce,
101 unsigned long addr,
102 unsigned long size)
103{
104 bounce->addr = addr;
105 bounce->size = size;
106 bounce->cpages = 0;
107 bounce->ptr = vmalloc(size);
108 if (!bounce->ptr)
109 return -ENOMEM;
110 return 0;
111}
112
113static void dmirror_bounce_fini(struct dmirror_bounce *bounce)
114{
115 vfree(bounce->ptr);
116}
117
118static int dmirror_fops_open(struct inode *inode, struct file *filp)
119{
120 struct cdev *cdev = inode->i_cdev;
121 struct dmirror *dmirror;
122 int ret;
123
124 /* Mirror this process address space */
125 dmirror = kzalloc(sizeof(*dmirror), GFP_KERNEL);
126 if (dmirror == NULL)
127 return -ENOMEM;
128
129 dmirror->mdevice = container_of(cdev, struct dmirror_device, cdevice);
130 mutex_init(&dmirror->mutex);
131 xa_init(&dmirror->pt);
132
133 ret = mmu_interval_notifier_insert(&dmirror->notifier, current->mm,
134 0, ULONG_MAX & PAGE_MASK, &dmirror_min_ops);
135 if (ret) {
136 kfree(dmirror);
137 return ret;
138 }
139
140 filp->private_data = dmirror;
141 return 0;
142}
143
144static int dmirror_fops_release(struct inode *inode, struct file *filp)
145{
146 struct dmirror *dmirror = filp->private_data;
147
148 mmu_interval_notifier_remove(&dmirror->notifier);
149 xa_destroy(&dmirror->pt);
150 kfree(dmirror);
151 return 0;
152}
153
154static struct dmirror_device *dmirror_page_to_device(struct page *page)
155
156{
157 return container_of(page->pgmap, struct dmirror_chunk,
158 pagemap)->mdevice;
159}
160
161static int dmirror_do_fault(struct dmirror *dmirror, struct hmm_range *range)
162{
163 unsigned long *pfns = range->hmm_pfns;
164 unsigned long pfn;
165
166 for (pfn = (range->start >> PAGE_SHIFT);
167 pfn < (range->end >> PAGE_SHIFT);
168 pfn++, pfns++) {
169 struct page *page;
170 void *entry;
171
172 /*
173 * Since we asked for hmm_range_fault() to populate pages,
174 * it shouldn't return an error entry on success.
175 */
176 WARN_ON(*pfns & HMM_PFN_ERROR);
177 WARN_ON(!(*pfns & HMM_PFN_VALID));
178
179 page = hmm_pfn_to_page(*pfns);
180 WARN_ON(!page);
181
182 entry = page;
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))
186 return -EFAULT;
187 entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
188 if (xa_is_err(entry))
189 return xa_err(entry);
190 }
191
192 return 0;
193}
194
195static void dmirror_do_update(struct dmirror *dmirror, unsigned long start,
196 unsigned long end)
197{
198 unsigned long pfn;
199 void *entry;
200
201 /*
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.
205 */
206 xa_for_each_range(&dmirror->pt, pfn, entry, start >> PAGE_SHIFT,
207 end >> PAGE_SHIFT)
208 xa_erase(&dmirror->pt, pfn);
209}
210
211static bool dmirror_interval_invalidate(struct mmu_interval_notifier *mni,
212 const struct mmu_notifier_range *range,
213 unsigned long cur_seq)
214{
215 struct dmirror *dmirror = container_of(mni, struct dmirror, notifier);
216
217 /*
218 * Ignore invalidation callbacks for device private pages since
219 * the invalidation is handled as part of the migration process.
220 */
221 if (range->event == MMU_NOTIFY_MIGRATE &&
222 range->migrate_pgmap_owner == dmirror->mdevice)
223 return true;
224
225 if (mmu_notifier_range_blockable(range))
226 mutex_lock(&dmirror->mutex);
227 else if (!mutex_trylock(&dmirror->mutex))
228 return false;
229
230 mmu_interval_set_seq(mni, cur_seq);
231 dmirror_do_update(dmirror, range->start, range->end);
232
233 mutex_unlock(&dmirror->mutex);
234 return true;
235}
236
237static const struct mmu_interval_notifier_ops dmirror_min_ops = {
238 .invalidate = dmirror_interval_invalidate,
239};
240
241static int dmirror_range_fault(struct dmirror *dmirror,
242 struct hmm_range *range)
243{
244 struct mm_struct *mm = dmirror->notifier.mm;
245 unsigned long timeout =
246 jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
247 int ret;
248
249 while (true) {
250 if (time_after(jiffies, timeout)) {
251 ret = -EBUSY;
252 goto out;
253 }
254
255 range->notifier_seq = mmu_interval_read_begin(range->notifier);
256 mmap_read_lock(mm);
257 ret = hmm_range_fault(range);
258 mmap_read_unlock(mm);
259 if (ret) {
260 if (ret == -EBUSY)
261 continue;
262 goto out;
263 }
264
265 mutex_lock(&dmirror->mutex);
266 if (mmu_interval_read_retry(range->notifier,
267 range->notifier_seq)) {
268 mutex_unlock(&dmirror->mutex);
269 continue;
270 }
271 break;
272 }
273
274 ret = dmirror_do_fault(dmirror, range);
275
276 mutex_unlock(&dmirror->mutex);
277out:
278 return ret;
279}
280
281static int dmirror_fault(struct dmirror *dmirror, unsigned long start,
282 unsigned long end, bool write)
283{
284 struct mm_struct *mm = dmirror->notifier.mm;
285 unsigned long addr;
286 unsigned long pfns[64];
287 struct hmm_range range = {
288 .notifier = &dmirror->notifier,
289 .hmm_pfns = pfns,
290 .pfn_flags_mask = 0,
291 .default_flags =
292 HMM_PFN_REQ_FAULT | (write ? HMM_PFN_REQ_WRITE : 0),
293 .dev_private_owner = dmirror->mdevice,
294 };
295 int ret = 0;
296
297 /* Since the mm is for the mirrored process, get a reference first. */
298 if (!mmget_not_zero(mm))
299 return 0;
300
301 for (addr = start; addr < end; addr = range.end) {
302 range.start = addr;
303 range.end = min(addr + (ARRAY_SIZE(pfns) << PAGE_SHIFT), end);
304
305 ret = dmirror_range_fault(dmirror, &range);
306 if (ret)
307 break;
308 }
309
310 mmput(mm);
311 return ret;
312}
313
314static int dmirror_do_read(struct dmirror *dmirror, unsigned long start,
315 unsigned long end, struct dmirror_bounce *bounce)
316{
317 unsigned long pfn;
318 void *ptr;
319
320 ptr = bounce->ptr + ((start - bounce->addr) & PAGE_MASK);
321
322 for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
323 void *entry;
324 struct page *page;
325 void *tmp;
326
327 entry = xa_load(&dmirror->pt, pfn);
328 page = xa_untag_pointer(entry);
329 if (!page)
330 return -ENOENT;
331
332 tmp = kmap(page);
333 memcpy(ptr, tmp, PAGE_SIZE);
334 kunmap(page);
335
336 ptr += PAGE_SIZE;
337 bounce->cpages++;
338 }
339
340 return 0;
341}
342
343static int dmirror_read(struct dmirror *dmirror, struct hmm_dmirror_cmd *cmd)
344{
345 struct dmirror_bounce bounce;
346 unsigned long start, end;
347 unsigned long size = cmd->npages << PAGE_SHIFT;
348 int ret;
349
350 start = cmd->addr;
351 end = start + size;
352 if (end < start)
353 return -EINVAL;
354
355 ret = dmirror_bounce_init(&bounce, start, size);
356 if (ret)
357 return ret;
358
359 while (1) {
360 mutex_lock(&dmirror->mutex);
361 ret = dmirror_do_read(dmirror, start, end, &bounce);
362 mutex_unlock(&dmirror->mutex);
363 if (ret != -ENOENT)
364 break;
365
366 start = cmd->addr + (bounce.cpages << PAGE_SHIFT);
367 ret = dmirror_fault(dmirror, start, end, false);
368 if (ret)
369 break;
370 cmd->faults++;
371 }
372
373 if (ret == 0) {
374 if (copy_to_user(u64_to_user_ptr(cmd->ptr), bounce.ptr,
375 bounce.size))
376 ret = -EFAULT;
377 }
378 cmd->cpages = bounce.cpages;
379 dmirror_bounce_fini(&bounce);
380 return ret;
381}
382
383static int dmirror_do_write(struct dmirror *dmirror, unsigned long start,
384 unsigned long end, struct dmirror_bounce *bounce)
385{
386 unsigned long pfn;
387 void *ptr;
388
389 ptr = bounce->ptr + ((start - bounce->addr) & PAGE_MASK);
390
391 for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
392 void *entry;
393 struct page *page;
394 void *tmp;
395
396 entry = xa_load(&dmirror->pt, pfn);
397 page = xa_untag_pointer(entry);
398 if (!page || xa_pointer_tag(entry) != DPT_XA_TAG_WRITE)
399 return -ENOENT;
400
401 tmp = kmap(page);
402 memcpy(tmp, ptr, PAGE_SIZE);
403 kunmap(page);
404
405 ptr += PAGE_SIZE;
406 bounce->cpages++;
407 }
408
409 return 0;
410}
411
412static int dmirror_write(struct dmirror *dmirror, struct hmm_dmirror_cmd *cmd)
413{
414 struct dmirror_bounce bounce;
415 unsigned long start, end;
416 unsigned long size = cmd->npages << PAGE_SHIFT;
417 int ret;
418
419 start = cmd->addr;
420 end = start + size;
421 if (end < start)
422 return -EINVAL;
423
424 ret = dmirror_bounce_init(&bounce, start, size);
425 if (ret)
426 return ret;
427 if (copy_from_user(bounce.ptr, u64_to_user_ptr(cmd->ptr),
428 bounce.size)) {
429 ret = -EFAULT;
430 goto fini;
431 }
432
433 while (1) {
434 mutex_lock(&dmirror->mutex);
435 ret = dmirror_do_write(dmirror, start, end, &bounce);
436 mutex_unlock(&dmirror->mutex);
437 if (ret != -ENOENT)
438 break;
439
440 start = cmd->addr + (bounce.cpages << PAGE_SHIFT);
441 ret = dmirror_fault(dmirror, start, end, true);
442 if (ret)
443 break;
444 cmd->faults++;
445 }
446
447fini:
448 cmd->cpages = bounce.cpages;
449 dmirror_bounce_fini(&bounce);
450 return ret;
451}
452
453static bool dmirror_allocate_chunk(struct dmirror_device *mdevice,
454 struct page **ppage)
455{
456 struct dmirror_chunk *devmem;
457 struct resource *res;
458 unsigned long pfn;
459 unsigned long pfn_first;
460 unsigned long pfn_last;
461 void *ptr;
462
463 mutex_lock(&mdevice->devmem_lock);
464
465 if (mdevice->devmem_count == mdevice->devmem_capacity) {
466 struct dmirror_chunk **new_chunks;
467 unsigned int new_capacity;
468
469 new_capacity = mdevice->devmem_capacity +
470 DEVMEM_CHUNKS_RESERVE;
471 new_chunks = krealloc(mdevice->devmem_chunks,
472 sizeof(new_chunks[0]) * new_capacity,
473 GFP_KERNEL);
474 if (!new_chunks)
475 goto err;
476 mdevice->devmem_capacity = new_capacity;
477 mdevice->devmem_chunks = new_chunks;
478 }
479
480 res = request_free_mem_region(&iomem_resource, DEVMEM_CHUNK_SIZE,
481 "hmm_dmirror");
482 if (IS_ERR(res))
483 goto err;
484
485 devmem = kzalloc(sizeof(*devmem), GFP_KERNEL);
486 if (!devmem)
487 goto err_release;
488
489 devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
490 devmem->pagemap.res = *res;
491 devmem->pagemap.ops = &dmirror_devmem_ops;
492 devmem->pagemap.owner = mdevice;
493
494 ptr = memremap_pages(&devmem->pagemap, numa_node_id());
495 if (IS_ERR(ptr))
496 goto err_free;
497
498 devmem->mdevice = mdevice;
499 pfn_first = devmem->pagemap.res.start >> PAGE_SHIFT;
500 pfn_last = pfn_first +
501 (resource_size(&devmem->pagemap.res) >> PAGE_SHIFT);
502 mdevice->devmem_chunks[mdevice->devmem_count++] = devmem;
503
504 mutex_unlock(&mdevice->devmem_lock);
505
506 pr_info("added new %u MB chunk (total %u chunks, %u MB) PFNs [0x%lx 0x%lx)\n",
507 DEVMEM_CHUNK_SIZE / (1024 * 1024),
508 mdevice->devmem_count,
509 mdevice->devmem_count * (DEVMEM_CHUNK_SIZE / (1024 * 1024)),
510 pfn_first, pfn_last);
511
512 spin_lock(&mdevice->lock);
513 for (pfn = pfn_first; pfn < pfn_last; pfn++) {
514 struct page *page = pfn_to_page(pfn);
515
516 page->zone_device_data = mdevice->free_pages;
517 mdevice->free_pages = page;
518 }
519 if (ppage) {
520 *ppage = mdevice->free_pages;
521 mdevice->free_pages = (*ppage)->zone_device_data;
522 mdevice->calloc++;
523 }
524 spin_unlock(&mdevice->lock);
525
526 return true;
527
528err_free:
529 kfree(devmem);
530err_release:
531 release_mem_region(res->start, resource_size(res));
532err:
533 mutex_unlock(&mdevice->devmem_lock);
534 return false;
535}
536
537static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
538{
539 struct page *dpage = NULL;
540 struct page *rpage;
541
542 /*
543 * This is a fake device so we alloc real system memory to store
544 * our device memory.
545 */
546 rpage = alloc_page(GFP_HIGHUSER);
547 if (!rpage)
548 return NULL;
549
550 spin_lock(&mdevice->lock);
551
552 if (mdevice->free_pages) {
553 dpage = mdevice->free_pages;
554 mdevice->free_pages = dpage->zone_device_data;
555 mdevice->calloc++;
556 spin_unlock(&mdevice->lock);
557 } else {
558 spin_unlock(&mdevice->lock);
559 if (!dmirror_allocate_chunk(mdevice, &dpage))
560 goto error;
561 }
562
563 dpage->zone_device_data = rpage;
564 get_page(dpage);
565 lock_page(dpage);
566 return dpage;
567
568error:
569 __free_page(rpage);
570 return NULL;
571}
572
573static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
574 struct dmirror *dmirror)
575{
576 struct dmirror_device *mdevice = dmirror->mdevice;
577 const unsigned long *src = args->src;
578 unsigned long *dst = args->dst;
579 unsigned long addr;
580
581 for (addr = args->start; addr < args->end; addr += PAGE_SIZE,
582 src++, dst++) {
583 struct page *spage;
584 struct page *dpage;
585 struct page *rpage;
586
587 if (!(*src & MIGRATE_PFN_MIGRATE))
588 continue;
589
590 /*
591 * Note that spage might be NULL which is OK since it is an
592 * unallocated pte_none() or read-only zero page.
593 */
594 spage = migrate_pfn_to_page(*src);
595
596 dpage = dmirror_devmem_alloc_page(mdevice);
597 if (!dpage)
598 continue;
599
600 rpage = dpage->zone_device_data;
601 if (spage)
602 copy_highpage(rpage, spage);
603 else
604 clear_highpage(rpage);
605
606 /*
607 * Normally, a device would use the page->zone_device_data to
608 * point to the mirror but here we use it to hold the page for
609 * the simulated device memory and that page holds the pointer
610 * to the mirror.
611 */
612 rpage->zone_device_data = dmirror;
613
614 *dst = migrate_pfn(page_to_pfn(dpage)) |
615 MIGRATE_PFN_LOCKED;
616 if ((*src & MIGRATE_PFN_WRITE) ||
617 (!spage && args->vma->vm_flags & VM_WRITE))
618 *dst |= MIGRATE_PFN_WRITE;
619 }
620}
621
622static int dmirror_migrate_finalize_and_map(struct migrate_vma *args,
623 struct dmirror *dmirror)
624{
625 unsigned long start = args->start;
626 unsigned long end = args->end;
627 const unsigned long *src = args->src;
628 const unsigned long *dst = args->dst;
629 unsigned long pfn;
630
631 /* Map the migrated pages into the device's page tables. */
632 mutex_lock(&dmirror->mutex);
633
634 for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++,
635 src++, dst++) {
636 struct page *dpage;
637 void *entry;
638
639 if (!(*src & MIGRATE_PFN_MIGRATE))
640 continue;
641
642 dpage = migrate_pfn_to_page(*dst);
643 if (!dpage)
644 continue;
645
646 /*
647 * Store the page that holds the data so the page table
648 * doesn't have to deal with ZONE_DEVICE private pages.
649 */
650 entry = dpage->zone_device_data;
651 if (*dst & MIGRATE_PFN_WRITE)
652 entry = xa_tag_pointer(entry, DPT_XA_TAG_WRITE);
653 entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
654 if (xa_is_err(entry)) {
655 mutex_unlock(&dmirror->mutex);
656 return xa_err(entry);
657 }
658 }
659
660 mutex_unlock(&dmirror->mutex);
661 return 0;
662}
663
664static int dmirror_migrate(struct dmirror *dmirror,
665 struct hmm_dmirror_cmd *cmd)
666{
667 unsigned long start, end, addr;
668 unsigned long size = cmd->npages << PAGE_SHIFT;
669 struct mm_struct *mm = dmirror->notifier.mm;
670 struct vm_area_struct *vma;
671 unsigned long src_pfns[64];
672 unsigned long dst_pfns[64];
673 struct dmirror_bounce bounce;
674 struct migrate_vma args;
675 unsigned long next;
676 int ret;
677
678 start = cmd->addr;
679 end = start + size;
680 if (end < start)
681 return -EINVAL;
682
683 /* Since the mm is for the mirrored process, get a reference first. */
684 if (!mmget_not_zero(mm))
685 return -EINVAL;
686
687 mmap_read_lock(mm);
688 for (addr = start; addr < end; addr = next) {
689 vma = find_vma(mm, addr);
690 if (!vma || addr < vma->vm_start ||
691 !(vma->vm_flags & VM_READ)) {
692 ret = -EINVAL;
693 goto out;
694 }
695 next = min(end, addr + (ARRAY_SIZE(src_pfns) << PAGE_SHIFT));
696 if (next > vma->vm_end)
697 next = vma->vm_end;
698
699 args.vma = vma;
700 args.src = src_pfns;
701 args.dst = dst_pfns;
702 args.start = addr;
703 args.end = next;
704 args.pgmap_owner = dmirror->mdevice;
705 args.flags = MIGRATE_VMA_SELECT_SYSTEM;
706 ret = migrate_vma_setup(&args);
707 if (ret)
708 goto out;
709
710 dmirror_migrate_alloc_and_copy(&args, dmirror);
711 migrate_vma_pages(&args);
712 dmirror_migrate_finalize_and_map(&args, dmirror);
713 migrate_vma_finalize(&args);
714 }
715 mmap_read_unlock(mm);
716 mmput(mm);
717
718 /* Return the migrated data for verification. */
719 ret = dmirror_bounce_init(&bounce, start, size);
720 if (ret)
721 return ret;
722 mutex_lock(&dmirror->mutex);
723 ret = dmirror_do_read(dmirror, start, end, &bounce);
724 mutex_unlock(&dmirror->mutex);
725 if (ret == 0) {
726 if (copy_to_user(u64_to_user_ptr(cmd->ptr), bounce.ptr,
727 bounce.size))
728 ret = -EFAULT;
729 }
730 cmd->cpages = bounce.cpages;
731 dmirror_bounce_fini(&bounce);
732 return ret;
733
734out:
735 mmap_read_unlock(mm);
736 mmput(mm);
737 return ret;
738}
739
740static void dmirror_mkentry(struct dmirror *dmirror, struct hmm_range *range,
741 unsigned char *perm, unsigned long entry)
742{
743 struct page *page;
744
745 if (entry & HMM_PFN_ERROR) {
746 *perm = HMM_DMIRROR_PROT_ERROR;
747 return;
748 }
749 if (!(entry & HMM_PFN_VALID)) {
750 *perm = HMM_DMIRROR_PROT_NONE;
751 return;
752 }
753
754 page = hmm_pfn_to_page(entry);
755 if (is_device_private_page(page)) {
756 /* Is the page migrated to this device or some other? */
757 if (dmirror->mdevice == dmirror_page_to_device(page))
758 *perm = HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL;
759 else
760 *perm = HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE;
761 } else if (is_zero_pfn(page_to_pfn(page)))
762 *perm = HMM_DMIRROR_PROT_ZERO;
763 else
764 *perm = HMM_DMIRROR_PROT_NONE;
765 if (entry & HMM_PFN_WRITE)
766 *perm |= HMM_DMIRROR_PROT_WRITE;
767 else
768 *perm |= HMM_DMIRROR_PROT_READ;
769 if (hmm_pfn_to_map_order(entry) + PAGE_SHIFT == PMD_SHIFT)
770 *perm |= HMM_DMIRROR_PROT_PMD;
771 else if (hmm_pfn_to_map_order(entry) + PAGE_SHIFT == PUD_SHIFT)
772 *perm |= HMM_DMIRROR_PROT_PUD;
773}
774
775static bool dmirror_snapshot_invalidate(struct mmu_interval_notifier *mni,
776 const struct mmu_notifier_range *range,
777 unsigned long cur_seq)
778{
779 struct dmirror_interval *dmi =
780 container_of(mni, struct dmirror_interval, notifier);
781 struct dmirror *dmirror = dmi->dmirror;
782
783 if (mmu_notifier_range_blockable(range))
784 mutex_lock(&dmirror->mutex);
785 else if (!mutex_trylock(&dmirror->mutex))
786 return false;
787
788 /*
789 * Snapshots only need to set the sequence number since any
790 * invalidation in the interval invalidates the whole snapshot.
791 */
792 mmu_interval_set_seq(mni, cur_seq);
793
794 mutex_unlock(&dmirror->mutex);
795 return true;
796}
797
798static const struct mmu_interval_notifier_ops dmirror_mrn_ops = {
799 .invalidate = dmirror_snapshot_invalidate,
800};
801
802static int dmirror_range_snapshot(struct dmirror *dmirror,
803 struct hmm_range *range,
804 unsigned char *perm)
805{
806 struct mm_struct *mm = dmirror->notifier.mm;
807 struct dmirror_interval notifier;
808 unsigned long timeout =
809 jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
810 unsigned long i;
811 unsigned long n;
812 int ret = 0;
813
814 notifier.dmirror = dmirror;
815 range->notifier = ¬ifier.notifier;
816
817 ret = mmu_interval_notifier_insert(range->notifier, mm,
818 range->start, range->end - range->start,
819 &dmirror_mrn_ops);
820 if (ret)
821 return ret;
822
823 while (true) {
824 if (time_after(jiffies, timeout)) {
825 ret = -EBUSY;
826 goto out;
827 }
828
829 range->notifier_seq = mmu_interval_read_begin(range->notifier);
830
831 mmap_read_lock(mm);
832 ret = hmm_range_fault(range);
833 mmap_read_unlock(mm);
834 if (ret) {
835 if (ret == -EBUSY)
836 continue;
837 goto out;
838 }
839
840 mutex_lock(&dmirror->mutex);
841 if (mmu_interval_read_retry(range->notifier,
842 range->notifier_seq)) {
843 mutex_unlock(&dmirror->mutex);
844 continue;
845 }
846 break;
847 }
848
849 n = (range->end - range->start) >> PAGE_SHIFT;
850 for (i = 0; i < n; i++)
851 dmirror_mkentry(dmirror, range, perm + i, range->hmm_pfns[i]);
852
853 mutex_unlock(&dmirror->mutex);
854out:
855 mmu_interval_notifier_remove(range->notifier);
856 return ret;
857}
858
859static int dmirror_snapshot(struct dmirror *dmirror,
860 struct hmm_dmirror_cmd *cmd)
861{
862 struct mm_struct *mm = dmirror->notifier.mm;
863 unsigned long start, end;
864 unsigned long size = cmd->npages << PAGE_SHIFT;
865 unsigned long addr;
866 unsigned long next;
867 unsigned long pfns[64];
868 unsigned char perm[64];
869 char __user *uptr;
870 struct hmm_range range = {
871 .hmm_pfns = pfns,
872 .dev_private_owner = dmirror->mdevice,
873 };
874 int ret = 0;
875
876 start = cmd->addr;
877 end = start + size;
878 if (end < start)
879 return -EINVAL;
880
881 /* Since the mm is for the mirrored process, get a reference first. */
882 if (!mmget_not_zero(mm))
883 return -EINVAL;
884
885 /*
886 * Register a temporary notifier to detect invalidations even if it
887 * overlaps with other mmu_interval_notifiers.
888 */
889 uptr = u64_to_user_ptr(cmd->ptr);
890 for (addr = start; addr < end; addr = next) {
891 unsigned long n;
892
893 next = min(addr + (ARRAY_SIZE(pfns) << PAGE_SHIFT), end);
894 range.start = addr;
895 range.end = next;
896
897 ret = dmirror_range_snapshot(dmirror, &range, perm);
898 if (ret)
899 break;
900
901 n = (range.end - range.start) >> PAGE_SHIFT;
902 if (copy_to_user(uptr, perm, n)) {
903 ret = -EFAULT;
904 break;
905 }
906
907 cmd->cpages += n;
908 uptr += n;
909 }
910 mmput(mm);
911
912 return ret;
913}
914
915static long dmirror_fops_unlocked_ioctl(struct file *filp,
916 unsigned int command,
917 unsigned long arg)
918{
919 void __user *uarg = (void __user *)arg;
920 struct hmm_dmirror_cmd cmd;
921 struct dmirror *dmirror;
922 int ret;
923
924 dmirror = filp->private_data;
925 if (!dmirror)
926 return -EINVAL;
927
928 if (copy_from_user(&cmd, uarg, sizeof(cmd)))
929 return -EFAULT;
930
931 if (cmd.addr & ~PAGE_MASK)
932 return -EINVAL;
933 if (cmd.addr >= (cmd.addr + (cmd.npages << PAGE_SHIFT)))
934 return -EINVAL;
935
936 cmd.cpages = 0;
937 cmd.faults = 0;
938
939 switch (command) {
940 case HMM_DMIRROR_READ:
941 ret = dmirror_read(dmirror, &cmd);
942 break;
943
944 case HMM_DMIRROR_WRITE:
945 ret = dmirror_write(dmirror, &cmd);
946 break;
947
948 case HMM_DMIRROR_MIGRATE:
949 ret = dmirror_migrate(dmirror, &cmd);
950 break;
951
952 case HMM_DMIRROR_SNAPSHOT:
953 ret = dmirror_snapshot(dmirror, &cmd);
954 break;
955
956 default:
957 return -EINVAL;
958 }
959 if (ret)
960 return ret;
961
962 if (copy_to_user(uarg, &cmd, sizeof(cmd)))
963 return -EFAULT;
964
965 return 0;
966}
967
968static const struct file_operations dmirror_fops = {
969 .open = dmirror_fops_open,
970 .release = dmirror_fops_release,
971 .unlocked_ioctl = dmirror_fops_unlocked_ioctl,
972 .llseek = default_llseek,
973 .owner = THIS_MODULE,
974};
975
976static void dmirror_devmem_free(struct page *page)
977{
978 struct page *rpage = page->zone_device_data;
979 struct dmirror_device *mdevice;
980
981 if (rpage)
982 __free_page(rpage);
983
984 mdevice = dmirror_page_to_device(page);
985
986 spin_lock(&mdevice->lock);
987 mdevice->cfree++;
988 page->zone_device_data = mdevice->free_pages;
989 mdevice->free_pages = page;
990 spin_unlock(&mdevice->lock);
991}
992
993static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
994 struct dmirror *dmirror)
995{
996 const unsigned long *src = args->src;
997 unsigned long *dst = args->dst;
998 unsigned long start = args->start;
999 unsigned long end = args->end;
1000 unsigned long addr;
1001
1002 for (addr = start; addr < end; addr += PAGE_SIZE,
1003 src++, dst++) {
1004 struct page *dpage, *spage;
1005
1006 spage = migrate_pfn_to_page(*src);
1007 if (!spage || !(*src & MIGRATE_PFN_MIGRATE))
1008 continue;
1009 spage = spage->zone_device_data;
1010
1011 dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr);
1012 if (!dpage)
1013 continue;
1014
1015 lock_page(dpage);
1016 xa_erase(&dmirror->pt, addr >> PAGE_SHIFT);
1017 copy_highpage(dpage, spage);
1018 *dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
1019 if (*src & MIGRATE_PFN_WRITE)
1020 *dst |= MIGRATE_PFN_WRITE;
1021 }
1022 return 0;
1023}
1024
1025static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
1026{
1027 struct migrate_vma args;
1028 unsigned long src_pfns;
1029 unsigned long dst_pfns;
1030 struct page *rpage;
1031 struct dmirror *dmirror;
1032 vm_fault_t ret;
1033
1034 /*
1035 * Normally, a device would use the page->zone_device_data to point to
1036 * the mirror but here we use it to hold the page for the simulated
1037 * device memory and that page holds the pointer to the mirror.
1038 */
1039 rpage = vmf->page->zone_device_data;
1040 dmirror = rpage->zone_device_data;
1041
1042 /* FIXME demonstrate how we can adjust migrate range */
1043 args.vma = vmf->vma;
1044 args.start = vmf->address;
1045 args.end = args.start + PAGE_SIZE;
1046 args.src = &src_pfns;
1047 args.dst = &dst_pfns;
1048 args.pgmap_owner = dmirror->mdevice;
1049 args.flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
1050
1051 if (migrate_vma_setup(&args))
1052 return VM_FAULT_SIGBUS;
1053
1054 ret = dmirror_devmem_fault_alloc_and_copy(&args, dmirror);
1055 if (ret)
1056 return ret;
1057 migrate_vma_pages(&args);
1058 /*
1059 * No device finalize step is needed since
1060 * dmirror_devmem_fault_alloc_and_copy() will have already
1061 * invalidated the device page table.
1062 */
1063 migrate_vma_finalize(&args);
1064 return 0;
1065}
1066
1067static const struct dev_pagemap_ops dmirror_devmem_ops = {
1068 .page_free = dmirror_devmem_free,
1069 .migrate_to_ram = dmirror_devmem_fault,
1070};
1071
1072static int dmirror_device_init(struct dmirror_device *mdevice, int id)
1073{
1074 dev_t dev;
1075 int ret;
1076
1077 dev = MKDEV(MAJOR(dmirror_dev), id);
1078 mutex_init(&mdevice->devmem_lock);
1079 spin_lock_init(&mdevice->lock);
1080
1081 cdev_init(&mdevice->cdevice, &dmirror_fops);
1082 mdevice->cdevice.owner = THIS_MODULE;
1083 ret = cdev_add(&mdevice->cdevice, dev, 1);
1084 if (ret)
1085 return ret;
1086
1087 /* Build a list of free ZONE_DEVICE private struct pages */
1088 dmirror_allocate_chunk(mdevice, NULL);
1089
1090 return 0;
1091}
1092
1093static void dmirror_device_remove(struct dmirror_device *mdevice)
1094{
1095 unsigned int i;
1096
1097 if (mdevice->devmem_chunks) {
1098 for (i = 0; i < mdevice->devmem_count; i++) {
1099 struct dmirror_chunk *devmem =
1100 mdevice->devmem_chunks[i];
1101
1102 memunmap_pages(&devmem->pagemap);
1103 release_mem_region(devmem->pagemap.res.start,
1104 resource_size(&devmem->pagemap.res));
1105 kfree(devmem);
1106 }
1107 kfree(mdevice->devmem_chunks);
1108 }
1109
1110 cdev_del(&mdevice->cdevice);
1111}
1112
1113static int __init hmm_dmirror_init(void)
1114{
1115 int ret;
1116 int id;
1117
1118 ret = alloc_chrdev_region(&dmirror_dev, 0, DMIRROR_NDEVICES,
1119 "HMM_DMIRROR");
1120 if (ret)
1121 goto err_unreg;
1122
1123 for (id = 0; id < DMIRROR_NDEVICES; id++) {
1124 ret = dmirror_device_init(dmirror_devices + id, id);
1125 if (ret)
1126 goto err_chrdev;
1127 }
1128
1129 /*
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).
1133 */
1134 dmirror_zero_page = alloc_page(GFP_HIGHUSER | __GFP_ZERO);
1135 if (!dmirror_zero_page) {
1136 ret = -ENOMEM;
1137 goto err_chrdev;
1138 }
1139
1140 pr_info("HMM test module loaded. This is only for testing HMM.\n");
1141 return 0;
1142
1143err_chrdev:
1144 while (--id >= 0)
1145 dmirror_device_remove(dmirror_devices + id);
1146 unregister_chrdev_region(dmirror_dev, DMIRROR_NDEVICES);
1147err_unreg:
1148 return ret;
1149}
1150
1151static void __exit hmm_dmirror_exit(void)
1152{
1153 int id;
1154
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);
1160}
1161
1162module_init(hmm_dmirror_init);
1163module_exit(hmm_dmirror_exit);
1164MODULE_LICENSE("GPL");