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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/memremap.h>
16#include <linux/mutex.h>
17#include <linux/rwsem.h>
18#include <linux/sched.h>
19#include <linux/slab.h>
20#include <linux/highmem.h>
21#include <linux/delay.h>
22#include <linux/pagemap.h>
23#include <linux/hmm.h>
24#include <linux/vmalloc.h>
25#include <linux/swap.h>
26#include <linux/swapops.h>
27#include <linux/sched/mm.h>
28#include <linux/platform_device.h>
29#include <linux/rmap.h>
30#include <linux/mmu_notifier.h>
31#include <linux/migrate.h>
32
33#include "test_hmm_uapi.h"
34
35#define DMIRROR_NDEVICES 4
36#define DMIRROR_RANGE_FAULT_TIMEOUT 1000
37#define DEVMEM_CHUNK_SIZE (256 * 1024 * 1024U)
38#define DEVMEM_CHUNKS_RESERVE 16
39
40/*
41 * For device_private pages, dpage is just a dummy struct page
42 * representing a piece of device memory. dmirror_devmem_alloc_page
43 * allocates a real system memory page as backing storage to fake a
44 * real device. zone_device_data points to that backing page. But
45 * for device_coherent memory, the struct page represents real
46 * physical CPU-accessible memory that we can use directly.
47 */
48#define BACKING_PAGE(page) (is_device_private_page((page)) ? \
49 (page)->zone_device_data : (page))
50
51static unsigned long spm_addr_dev0;
52module_param(spm_addr_dev0, long, 0644);
53MODULE_PARM_DESC(spm_addr_dev0,
54 "Specify start address for SPM (special purpose memory) used for device 0. By setting this Coherent device type will be used. Make sure spm_addr_dev1 is set too. Minimum SPM size should be DEVMEM_CHUNK_SIZE.");
55
56static unsigned long spm_addr_dev1;
57module_param(spm_addr_dev1, long, 0644);
58MODULE_PARM_DESC(spm_addr_dev1,
59 "Specify start address for SPM (special purpose memory) used for device 1. By setting this Coherent device type will be used. Make sure spm_addr_dev0 is set too. Minimum SPM size should be DEVMEM_CHUNK_SIZE.");
60
61static const struct dev_pagemap_ops dmirror_devmem_ops;
62static const struct mmu_interval_notifier_ops dmirror_min_ops;
63static dev_t dmirror_dev;
64
65struct dmirror_device;
66
67struct dmirror_bounce {
68 void *ptr;
69 unsigned long size;
70 unsigned long addr;
71 unsigned long cpages;
72};
73
74#define DPT_XA_TAG_ATOMIC 1UL
75#define DPT_XA_TAG_WRITE 3UL
76
77/*
78 * Data structure to track address ranges and register for mmu interval
79 * notifier updates.
80 */
81struct dmirror_interval {
82 struct mmu_interval_notifier notifier;
83 struct dmirror *dmirror;
84};
85
86/*
87 * Data attached to the open device file.
88 * Note that it might be shared after a fork().
89 */
90struct dmirror {
91 struct dmirror_device *mdevice;
92 struct xarray pt;
93 struct mmu_interval_notifier notifier;
94 struct mutex mutex;
95};
96
97/*
98 * ZONE_DEVICE pages for migration and simulating device memory.
99 */
100struct dmirror_chunk {
101 struct dev_pagemap pagemap;
102 struct dmirror_device *mdevice;
103 bool remove;
104};
105
106/*
107 * Per device data.
108 */
109struct dmirror_device {
110 struct cdev cdevice;
111 unsigned int zone_device_type;
112 struct device device;
113
114 unsigned int devmem_capacity;
115 unsigned int devmem_count;
116 struct dmirror_chunk **devmem_chunks;
117 struct mutex devmem_lock; /* protects the above */
118
119 unsigned long calloc;
120 unsigned long cfree;
121 struct page *free_pages;
122 spinlock_t lock; /* protects the above */
123};
124
125static struct dmirror_device dmirror_devices[DMIRROR_NDEVICES];
126
127static int dmirror_bounce_init(struct dmirror_bounce *bounce,
128 unsigned long addr,
129 unsigned long size)
130{
131 bounce->addr = addr;
132 bounce->size = size;
133 bounce->cpages = 0;
134 bounce->ptr = vmalloc(size);
135 if (!bounce->ptr)
136 return -ENOMEM;
137 return 0;
138}
139
140static bool dmirror_is_private_zone(struct dmirror_device *mdevice)
141{
142 return (mdevice->zone_device_type ==
143 HMM_DMIRROR_MEMORY_DEVICE_PRIVATE) ? true : false;
144}
145
146static enum migrate_vma_direction
147dmirror_select_device(struct dmirror *dmirror)
148{
149 return (dmirror->mdevice->zone_device_type ==
150 HMM_DMIRROR_MEMORY_DEVICE_PRIVATE) ?
151 MIGRATE_VMA_SELECT_DEVICE_PRIVATE :
152 MIGRATE_VMA_SELECT_DEVICE_COHERENT;
153}
154
155static void dmirror_bounce_fini(struct dmirror_bounce *bounce)
156{
157 vfree(bounce->ptr);
158}
159
160static int dmirror_fops_open(struct inode *inode, struct file *filp)
161{
162 struct cdev *cdev = inode->i_cdev;
163 struct dmirror *dmirror;
164 int ret;
165
166 /* Mirror this process address space */
167 dmirror = kzalloc(sizeof(*dmirror), GFP_KERNEL);
168 if (dmirror == NULL)
169 return -ENOMEM;
170
171 dmirror->mdevice = container_of(cdev, struct dmirror_device, cdevice);
172 mutex_init(&dmirror->mutex);
173 xa_init(&dmirror->pt);
174
175 ret = mmu_interval_notifier_insert(&dmirror->notifier, current->mm,
176 0, ULONG_MAX & PAGE_MASK, &dmirror_min_ops);
177 if (ret) {
178 kfree(dmirror);
179 return ret;
180 }
181
182 filp->private_data = dmirror;
183 return 0;
184}
185
186static int dmirror_fops_release(struct inode *inode, struct file *filp)
187{
188 struct dmirror *dmirror = filp->private_data;
189
190 mmu_interval_notifier_remove(&dmirror->notifier);
191 xa_destroy(&dmirror->pt);
192 kfree(dmirror);
193 return 0;
194}
195
196static struct dmirror_chunk *dmirror_page_to_chunk(struct page *page)
197{
198 return container_of(page->pgmap, struct dmirror_chunk, pagemap);
199}
200
201static struct dmirror_device *dmirror_page_to_device(struct page *page)
202
203{
204 return dmirror_page_to_chunk(page)->mdevice;
205}
206
207static int dmirror_do_fault(struct dmirror *dmirror, struct hmm_range *range)
208{
209 unsigned long *pfns = range->hmm_pfns;
210 unsigned long pfn;
211
212 for (pfn = (range->start >> PAGE_SHIFT);
213 pfn < (range->end >> PAGE_SHIFT);
214 pfn++, pfns++) {
215 struct page *page;
216 void *entry;
217
218 /*
219 * Since we asked for hmm_range_fault() to populate pages,
220 * it shouldn't return an error entry on success.
221 */
222 WARN_ON(*pfns & HMM_PFN_ERROR);
223 WARN_ON(!(*pfns & HMM_PFN_VALID));
224
225 page = hmm_pfn_to_page(*pfns);
226 WARN_ON(!page);
227
228 entry = page;
229 if (*pfns & HMM_PFN_WRITE)
230 entry = xa_tag_pointer(entry, DPT_XA_TAG_WRITE);
231 else if (WARN_ON(range->default_flags & HMM_PFN_WRITE))
232 return -EFAULT;
233 entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
234 if (xa_is_err(entry))
235 return xa_err(entry);
236 }
237
238 return 0;
239}
240
241static void dmirror_do_update(struct dmirror *dmirror, unsigned long start,
242 unsigned long end)
243{
244 unsigned long pfn;
245 void *entry;
246
247 /*
248 * The XArray doesn't hold references to pages since it relies on
249 * the mmu notifier to clear page pointers when they become stale.
250 * Therefore, it is OK to just clear the entry.
251 */
252 xa_for_each_range(&dmirror->pt, pfn, entry, start >> PAGE_SHIFT,
253 end >> PAGE_SHIFT)
254 xa_erase(&dmirror->pt, pfn);
255}
256
257static bool dmirror_interval_invalidate(struct mmu_interval_notifier *mni,
258 const struct mmu_notifier_range *range,
259 unsigned long cur_seq)
260{
261 struct dmirror *dmirror = container_of(mni, struct dmirror, notifier);
262
263 /*
264 * Ignore invalidation callbacks for device private pages since
265 * the invalidation is handled as part of the migration process.
266 */
267 if (range->event == MMU_NOTIFY_MIGRATE &&
268 range->owner == dmirror->mdevice)
269 return true;
270
271 if (mmu_notifier_range_blockable(range))
272 mutex_lock(&dmirror->mutex);
273 else if (!mutex_trylock(&dmirror->mutex))
274 return false;
275
276 mmu_interval_set_seq(mni, cur_seq);
277 dmirror_do_update(dmirror, range->start, range->end);
278
279 mutex_unlock(&dmirror->mutex);
280 return true;
281}
282
283static const struct mmu_interval_notifier_ops dmirror_min_ops = {
284 .invalidate = dmirror_interval_invalidate,
285};
286
287static int dmirror_range_fault(struct dmirror *dmirror,
288 struct hmm_range *range)
289{
290 struct mm_struct *mm = dmirror->notifier.mm;
291 unsigned long timeout =
292 jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
293 int ret;
294
295 while (true) {
296 if (time_after(jiffies, timeout)) {
297 ret = -EBUSY;
298 goto out;
299 }
300
301 range->notifier_seq = mmu_interval_read_begin(range->notifier);
302 mmap_read_lock(mm);
303 ret = hmm_range_fault(range);
304 mmap_read_unlock(mm);
305 if (ret) {
306 if (ret == -EBUSY)
307 continue;
308 goto out;
309 }
310
311 mutex_lock(&dmirror->mutex);
312 if (mmu_interval_read_retry(range->notifier,
313 range->notifier_seq)) {
314 mutex_unlock(&dmirror->mutex);
315 continue;
316 }
317 break;
318 }
319
320 ret = dmirror_do_fault(dmirror, range);
321
322 mutex_unlock(&dmirror->mutex);
323out:
324 return ret;
325}
326
327static int dmirror_fault(struct dmirror *dmirror, unsigned long start,
328 unsigned long end, bool write)
329{
330 struct mm_struct *mm = dmirror->notifier.mm;
331 unsigned long addr;
332 unsigned long pfns[64];
333 struct hmm_range range = {
334 .notifier = &dmirror->notifier,
335 .hmm_pfns = pfns,
336 .pfn_flags_mask = 0,
337 .default_flags =
338 HMM_PFN_REQ_FAULT | (write ? HMM_PFN_REQ_WRITE : 0),
339 .dev_private_owner = dmirror->mdevice,
340 };
341 int ret = 0;
342
343 /* Since the mm is for the mirrored process, get a reference first. */
344 if (!mmget_not_zero(mm))
345 return 0;
346
347 for (addr = start; addr < end; addr = range.end) {
348 range.start = addr;
349 range.end = min(addr + (ARRAY_SIZE(pfns) << PAGE_SHIFT), end);
350
351 ret = dmirror_range_fault(dmirror, &range);
352 if (ret)
353 break;
354 }
355
356 mmput(mm);
357 return ret;
358}
359
360static int dmirror_do_read(struct dmirror *dmirror, unsigned long start,
361 unsigned long end, struct dmirror_bounce *bounce)
362{
363 unsigned long pfn;
364 void *ptr;
365
366 ptr = bounce->ptr + ((start - bounce->addr) & PAGE_MASK);
367
368 for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
369 void *entry;
370 struct page *page;
371
372 entry = xa_load(&dmirror->pt, pfn);
373 page = xa_untag_pointer(entry);
374 if (!page)
375 return -ENOENT;
376
377 memcpy_from_page(ptr, page, 0, PAGE_SIZE);
378
379 ptr += PAGE_SIZE;
380 bounce->cpages++;
381 }
382
383 return 0;
384}
385
386static int dmirror_read(struct dmirror *dmirror, struct hmm_dmirror_cmd *cmd)
387{
388 struct dmirror_bounce bounce;
389 unsigned long start, end;
390 unsigned long size = cmd->npages << PAGE_SHIFT;
391 int ret;
392
393 start = cmd->addr;
394 end = start + size;
395 if (end < start)
396 return -EINVAL;
397
398 ret = dmirror_bounce_init(&bounce, start, size);
399 if (ret)
400 return ret;
401
402 while (1) {
403 mutex_lock(&dmirror->mutex);
404 ret = dmirror_do_read(dmirror, start, end, &bounce);
405 mutex_unlock(&dmirror->mutex);
406 if (ret != -ENOENT)
407 break;
408
409 start = cmd->addr + (bounce.cpages << PAGE_SHIFT);
410 ret = dmirror_fault(dmirror, start, end, false);
411 if (ret)
412 break;
413 cmd->faults++;
414 }
415
416 if (ret == 0) {
417 if (copy_to_user(u64_to_user_ptr(cmd->ptr), bounce.ptr,
418 bounce.size))
419 ret = -EFAULT;
420 }
421 cmd->cpages = bounce.cpages;
422 dmirror_bounce_fini(&bounce);
423 return ret;
424}
425
426static int dmirror_do_write(struct dmirror *dmirror, unsigned long start,
427 unsigned long end, struct dmirror_bounce *bounce)
428{
429 unsigned long pfn;
430 void *ptr;
431
432 ptr = bounce->ptr + ((start - bounce->addr) & PAGE_MASK);
433
434 for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
435 void *entry;
436 struct page *page;
437
438 entry = xa_load(&dmirror->pt, pfn);
439 page = xa_untag_pointer(entry);
440 if (!page || xa_pointer_tag(entry) != DPT_XA_TAG_WRITE)
441 return -ENOENT;
442
443 memcpy_to_page(page, 0, ptr, PAGE_SIZE);
444
445 ptr += PAGE_SIZE;
446 bounce->cpages++;
447 }
448
449 return 0;
450}
451
452static int dmirror_write(struct dmirror *dmirror, struct hmm_dmirror_cmd *cmd)
453{
454 struct dmirror_bounce bounce;
455 unsigned long start, end;
456 unsigned long size = cmd->npages << PAGE_SHIFT;
457 int ret;
458
459 start = cmd->addr;
460 end = start + size;
461 if (end < start)
462 return -EINVAL;
463
464 ret = dmirror_bounce_init(&bounce, start, size);
465 if (ret)
466 return ret;
467 if (copy_from_user(bounce.ptr, u64_to_user_ptr(cmd->ptr),
468 bounce.size)) {
469 ret = -EFAULT;
470 goto fini;
471 }
472
473 while (1) {
474 mutex_lock(&dmirror->mutex);
475 ret = dmirror_do_write(dmirror, start, end, &bounce);
476 mutex_unlock(&dmirror->mutex);
477 if (ret != -ENOENT)
478 break;
479
480 start = cmd->addr + (bounce.cpages << PAGE_SHIFT);
481 ret = dmirror_fault(dmirror, start, end, true);
482 if (ret)
483 break;
484 cmd->faults++;
485 }
486
487fini:
488 cmd->cpages = bounce.cpages;
489 dmirror_bounce_fini(&bounce);
490 return ret;
491}
492
493static int dmirror_allocate_chunk(struct dmirror_device *mdevice,
494 struct page **ppage)
495{
496 struct dmirror_chunk *devmem;
497 struct resource *res = NULL;
498 unsigned long pfn;
499 unsigned long pfn_first;
500 unsigned long pfn_last;
501 void *ptr;
502 int ret = -ENOMEM;
503
504 devmem = kzalloc(sizeof(*devmem), GFP_KERNEL);
505 if (!devmem)
506 return ret;
507
508 switch (mdevice->zone_device_type) {
509 case HMM_DMIRROR_MEMORY_DEVICE_PRIVATE:
510 res = request_free_mem_region(&iomem_resource, DEVMEM_CHUNK_SIZE,
511 "hmm_dmirror");
512 if (IS_ERR_OR_NULL(res))
513 goto err_devmem;
514 devmem->pagemap.range.start = res->start;
515 devmem->pagemap.range.end = res->end;
516 devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
517 break;
518 case HMM_DMIRROR_MEMORY_DEVICE_COHERENT:
519 devmem->pagemap.range.start = (MINOR(mdevice->cdevice.dev) - 2) ?
520 spm_addr_dev0 :
521 spm_addr_dev1;
522 devmem->pagemap.range.end = devmem->pagemap.range.start +
523 DEVMEM_CHUNK_SIZE - 1;
524 devmem->pagemap.type = MEMORY_DEVICE_COHERENT;
525 break;
526 default:
527 ret = -EINVAL;
528 goto err_devmem;
529 }
530
531 devmem->pagemap.nr_range = 1;
532 devmem->pagemap.ops = &dmirror_devmem_ops;
533 devmem->pagemap.owner = mdevice;
534
535 mutex_lock(&mdevice->devmem_lock);
536
537 if (mdevice->devmem_count == mdevice->devmem_capacity) {
538 struct dmirror_chunk **new_chunks;
539 unsigned int new_capacity;
540
541 new_capacity = mdevice->devmem_capacity +
542 DEVMEM_CHUNKS_RESERVE;
543 new_chunks = krealloc(mdevice->devmem_chunks,
544 sizeof(new_chunks[0]) * new_capacity,
545 GFP_KERNEL);
546 if (!new_chunks)
547 goto err_release;
548 mdevice->devmem_capacity = new_capacity;
549 mdevice->devmem_chunks = new_chunks;
550 }
551 ptr = memremap_pages(&devmem->pagemap, numa_node_id());
552 if (IS_ERR_OR_NULL(ptr)) {
553 if (ptr)
554 ret = PTR_ERR(ptr);
555 else
556 ret = -EFAULT;
557 goto err_release;
558 }
559
560 devmem->mdevice = mdevice;
561 pfn_first = devmem->pagemap.range.start >> PAGE_SHIFT;
562 pfn_last = pfn_first + (range_len(&devmem->pagemap.range) >> PAGE_SHIFT);
563 mdevice->devmem_chunks[mdevice->devmem_count++] = devmem;
564
565 mutex_unlock(&mdevice->devmem_lock);
566
567 pr_info("added new %u MB chunk (total %u chunks, %u MB) PFNs [0x%lx 0x%lx)\n",
568 DEVMEM_CHUNK_SIZE / (1024 * 1024),
569 mdevice->devmem_count,
570 mdevice->devmem_count * (DEVMEM_CHUNK_SIZE / (1024 * 1024)),
571 pfn_first, pfn_last);
572
573 spin_lock(&mdevice->lock);
574 for (pfn = pfn_first; pfn < pfn_last; pfn++) {
575 struct page *page = pfn_to_page(pfn);
576
577 page->zone_device_data = mdevice->free_pages;
578 mdevice->free_pages = page;
579 }
580 if (ppage) {
581 *ppage = mdevice->free_pages;
582 mdevice->free_pages = (*ppage)->zone_device_data;
583 mdevice->calloc++;
584 }
585 spin_unlock(&mdevice->lock);
586
587 return 0;
588
589err_release:
590 mutex_unlock(&mdevice->devmem_lock);
591 if (res && devmem->pagemap.type == MEMORY_DEVICE_PRIVATE)
592 release_mem_region(devmem->pagemap.range.start,
593 range_len(&devmem->pagemap.range));
594err_devmem:
595 kfree(devmem);
596
597 return ret;
598}
599
600static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
601{
602 struct page *dpage = NULL;
603 struct page *rpage = NULL;
604
605 /*
606 * For ZONE_DEVICE private type, this is a fake device so we allocate
607 * real system memory to store our device memory.
608 * For ZONE_DEVICE coherent type we use the actual dpage to store the
609 * data and ignore rpage.
610 */
611 if (dmirror_is_private_zone(mdevice)) {
612 rpage = alloc_page(GFP_HIGHUSER);
613 if (!rpage)
614 return NULL;
615 }
616 spin_lock(&mdevice->lock);
617
618 if (mdevice->free_pages) {
619 dpage = mdevice->free_pages;
620 mdevice->free_pages = dpage->zone_device_data;
621 mdevice->calloc++;
622 spin_unlock(&mdevice->lock);
623 } else {
624 spin_unlock(&mdevice->lock);
625 if (dmirror_allocate_chunk(mdevice, &dpage))
626 goto error;
627 }
628
629 zone_device_page_init(dpage);
630 dpage->zone_device_data = rpage;
631 return dpage;
632
633error:
634 if (rpage)
635 __free_page(rpage);
636 return NULL;
637}
638
639static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
640 struct dmirror *dmirror)
641{
642 struct dmirror_device *mdevice = dmirror->mdevice;
643 const unsigned long *src = args->src;
644 unsigned long *dst = args->dst;
645 unsigned long addr;
646
647 for (addr = args->start; addr < args->end; addr += PAGE_SIZE,
648 src++, dst++) {
649 struct page *spage;
650 struct page *dpage;
651 struct page *rpage;
652
653 if (!(*src & MIGRATE_PFN_MIGRATE))
654 continue;
655
656 /*
657 * Note that spage might be NULL which is OK since it is an
658 * unallocated pte_none() or read-only zero page.
659 */
660 spage = migrate_pfn_to_page(*src);
661 if (WARN(spage && is_zone_device_page(spage),
662 "page already in device spage pfn: 0x%lx\n",
663 page_to_pfn(spage)))
664 continue;
665
666 dpage = dmirror_devmem_alloc_page(mdevice);
667 if (!dpage)
668 continue;
669
670 rpage = BACKING_PAGE(dpage);
671 if (spage)
672 copy_highpage(rpage, spage);
673 else
674 clear_highpage(rpage);
675
676 /*
677 * Normally, a device would use the page->zone_device_data to
678 * point to the mirror but here we use it to hold the page for
679 * the simulated device memory and that page holds the pointer
680 * to the mirror.
681 */
682 rpage->zone_device_data = dmirror;
683
684 pr_debug("migrating from sys to dev pfn src: 0x%lx pfn dst: 0x%lx\n",
685 page_to_pfn(spage), page_to_pfn(dpage));
686 *dst = migrate_pfn(page_to_pfn(dpage));
687 if ((*src & MIGRATE_PFN_WRITE) ||
688 (!spage && args->vma->vm_flags & VM_WRITE))
689 *dst |= MIGRATE_PFN_WRITE;
690 }
691}
692
693static int dmirror_check_atomic(struct dmirror *dmirror, unsigned long start,
694 unsigned long end)
695{
696 unsigned long pfn;
697
698 for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
699 void *entry;
700
701 entry = xa_load(&dmirror->pt, pfn);
702 if (xa_pointer_tag(entry) == DPT_XA_TAG_ATOMIC)
703 return -EPERM;
704 }
705
706 return 0;
707}
708
709static int dmirror_atomic_map(unsigned long start, unsigned long end,
710 struct page **pages, struct dmirror *dmirror)
711{
712 unsigned long pfn, mapped = 0;
713 int i;
714
715 /* Map the migrated pages into the device's page tables. */
716 mutex_lock(&dmirror->mutex);
717
718 for (i = 0, pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++, i++) {
719 void *entry;
720
721 if (!pages[i])
722 continue;
723
724 entry = pages[i];
725 entry = xa_tag_pointer(entry, DPT_XA_TAG_ATOMIC);
726 entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
727 if (xa_is_err(entry)) {
728 mutex_unlock(&dmirror->mutex);
729 return xa_err(entry);
730 }
731
732 mapped++;
733 }
734
735 mutex_unlock(&dmirror->mutex);
736 return mapped;
737}
738
739static int dmirror_migrate_finalize_and_map(struct migrate_vma *args,
740 struct dmirror *dmirror)
741{
742 unsigned long start = args->start;
743 unsigned long end = args->end;
744 const unsigned long *src = args->src;
745 const unsigned long *dst = args->dst;
746 unsigned long pfn;
747
748 /* Map the migrated pages into the device's page tables. */
749 mutex_lock(&dmirror->mutex);
750
751 for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++,
752 src++, dst++) {
753 struct page *dpage;
754 void *entry;
755
756 if (!(*src & MIGRATE_PFN_MIGRATE))
757 continue;
758
759 dpage = migrate_pfn_to_page(*dst);
760 if (!dpage)
761 continue;
762
763 entry = BACKING_PAGE(dpage);
764 if (*dst & MIGRATE_PFN_WRITE)
765 entry = xa_tag_pointer(entry, DPT_XA_TAG_WRITE);
766 entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
767 if (xa_is_err(entry)) {
768 mutex_unlock(&dmirror->mutex);
769 return xa_err(entry);
770 }
771 }
772
773 mutex_unlock(&dmirror->mutex);
774 return 0;
775}
776
777static int dmirror_exclusive(struct dmirror *dmirror,
778 struct hmm_dmirror_cmd *cmd)
779{
780 unsigned long start, end, addr;
781 unsigned long size = cmd->npages << PAGE_SHIFT;
782 struct mm_struct *mm = dmirror->notifier.mm;
783 struct page *pages[64];
784 struct dmirror_bounce bounce;
785 unsigned long next;
786 int ret;
787
788 start = cmd->addr;
789 end = start + size;
790 if (end < start)
791 return -EINVAL;
792
793 /* Since the mm is for the mirrored process, get a reference first. */
794 if (!mmget_not_zero(mm))
795 return -EINVAL;
796
797 mmap_read_lock(mm);
798 for (addr = start; addr < end; addr = next) {
799 unsigned long mapped = 0;
800 int i;
801
802 if (end < addr + (ARRAY_SIZE(pages) << PAGE_SHIFT))
803 next = end;
804 else
805 next = addr + (ARRAY_SIZE(pages) << PAGE_SHIFT);
806
807 ret = make_device_exclusive_range(mm, addr, next, pages, NULL);
808 /*
809 * Do dmirror_atomic_map() iff all pages are marked for
810 * exclusive access to avoid accessing uninitialized
811 * fields of pages.
812 */
813 if (ret == (next - addr) >> PAGE_SHIFT)
814 mapped = dmirror_atomic_map(addr, next, pages, dmirror);
815 for (i = 0; i < ret; i++) {
816 if (pages[i]) {
817 unlock_page(pages[i]);
818 put_page(pages[i]);
819 }
820 }
821
822 if (addr + (mapped << PAGE_SHIFT) < next) {
823 mmap_read_unlock(mm);
824 mmput(mm);
825 return -EBUSY;
826 }
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
844 cmd->cpages = bounce.cpages;
845 dmirror_bounce_fini(&bounce);
846 return ret;
847}
848
849static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
850 struct dmirror *dmirror)
851{
852 const unsigned long *src = args->src;
853 unsigned long *dst = args->dst;
854 unsigned long start = args->start;
855 unsigned long end = args->end;
856 unsigned long addr;
857
858 for (addr = start; addr < end; addr += PAGE_SIZE,
859 src++, dst++) {
860 struct page *dpage, *spage;
861
862 spage = migrate_pfn_to_page(*src);
863 if (!spage || !(*src & MIGRATE_PFN_MIGRATE))
864 continue;
865
866 if (WARN_ON(!is_device_private_page(spage) &&
867 !is_device_coherent_page(spage)))
868 continue;
869 spage = BACKING_PAGE(spage);
870 dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr);
871 if (!dpage)
872 continue;
873 pr_debug("migrating from dev to sys pfn src: 0x%lx pfn dst: 0x%lx\n",
874 page_to_pfn(spage), page_to_pfn(dpage));
875
876 lock_page(dpage);
877 xa_erase(&dmirror->pt, addr >> PAGE_SHIFT);
878 copy_highpage(dpage, spage);
879 *dst = migrate_pfn(page_to_pfn(dpage));
880 if (*src & MIGRATE_PFN_WRITE)
881 *dst |= MIGRATE_PFN_WRITE;
882 }
883 return 0;
884}
885
886static unsigned long
887dmirror_successful_migrated_pages(struct migrate_vma *migrate)
888{
889 unsigned long cpages = 0;
890 unsigned long i;
891
892 for (i = 0; i < migrate->npages; i++) {
893 if (migrate->src[i] & MIGRATE_PFN_VALID &&
894 migrate->src[i] & MIGRATE_PFN_MIGRATE)
895 cpages++;
896 }
897 return cpages;
898}
899
900static int dmirror_migrate_to_system(struct dmirror *dmirror,
901 struct hmm_dmirror_cmd *cmd)
902{
903 unsigned long start, end, addr;
904 unsigned long size = cmd->npages << PAGE_SHIFT;
905 struct mm_struct *mm = dmirror->notifier.mm;
906 struct vm_area_struct *vma;
907 unsigned long src_pfns[64] = { 0 };
908 unsigned long dst_pfns[64] = { 0 };
909 struct migrate_vma args = { 0 };
910 unsigned long next;
911 int ret;
912
913 start = cmd->addr;
914 end = start + size;
915 if (end < start)
916 return -EINVAL;
917
918 /* Since the mm is for the mirrored process, get a reference first. */
919 if (!mmget_not_zero(mm))
920 return -EINVAL;
921
922 cmd->cpages = 0;
923 mmap_read_lock(mm);
924 for (addr = start; addr < end; addr = next) {
925 vma = vma_lookup(mm, addr);
926 if (!vma || !(vma->vm_flags & VM_READ)) {
927 ret = -EINVAL;
928 goto out;
929 }
930 next = min(end, addr + (ARRAY_SIZE(src_pfns) << PAGE_SHIFT));
931 if (next > vma->vm_end)
932 next = vma->vm_end;
933
934 args.vma = vma;
935 args.src = src_pfns;
936 args.dst = dst_pfns;
937 args.start = addr;
938 args.end = next;
939 args.pgmap_owner = dmirror->mdevice;
940 args.flags = dmirror_select_device(dmirror);
941
942 ret = migrate_vma_setup(&args);
943 if (ret)
944 goto out;
945
946 pr_debug("Migrating from device mem to sys mem\n");
947 dmirror_devmem_fault_alloc_and_copy(&args, dmirror);
948
949 migrate_vma_pages(&args);
950 cmd->cpages += dmirror_successful_migrated_pages(&args);
951 migrate_vma_finalize(&args);
952 }
953out:
954 mmap_read_unlock(mm);
955 mmput(mm);
956
957 return ret;
958}
959
960static int dmirror_migrate_to_device(struct dmirror *dmirror,
961 struct hmm_dmirror_cmd *cmd)
962{
963 unsigned long start, end, addr;
964 unsigned long size = cmd->npages << PAGE_SHIFT;
965 struct mm_struct *mm = dmirror->notifier.mm;
966 struct vm_area_struct *vma;
967 unsigned long src_pfns[64] = { 0 };
968 unsigned long dst_pfns[64] = { 0 };
969 struct dmirror_bounce bounce;
970 struct migrate_vma args = { 0 };
971 unsigned long next;
972 int ret;
973
974 start = cmd->addr;
975 end = start + size;
976 if (end < start)
977 return -EINVAL;
978
979 /* Since the mm is for the mirrored process, get a reference first. */
980 if (!mmget_not_zero(mm))
981 return -EINVAL;
982
983 mmap_read_lock(mm);
984 for (addr = start; addr < end; addr = next) {
985 vma = vma_lookup(mm, addr);
986 if (!vma || !(vma->vm_flags & VM_READ)) {
987 ret = -EINVAL;
988 goto out;
989 }
990 next = min(end, addr + (ARRAY_SIZE(src_pfns) << PAGE_SHIFT));
991 if (next > vma->vm_end)
992 next = vma->vm_end;
993
994 args.vma = vma;
995 args.src = src_pfns;
996 args.dst = dst_pfns;
997 args.start = addr;
998 args.end = next;
999 args.pgmap_owner = dmirror->mdevice;
1000 args.flags = MIGRATE_VMA_SELECT_SYSTEM;
1001 ret = migrate_vma_setup(&args);
1002 if (ret)
1003 goto out;
1004
1005 pr_debug("Migrating from sys mem to device mem\n");
1006 dmirror_migrate_alloc_and_copy(&args, dmirror);
1007 migrate_vma_pages(&args);
1008 dmirror_migrate_finalize_and_map(&args, dmirror);
1009 migrate_vma_finalize(&args);
1010 }
1011 mmap_read_unlock(mm);
1012 mmput(mm);
1013
1014 /*
1015 * Return the migrated data for verification.
1016 * Only for pages in device zone
1017 */
1018 ret = dmirror_bounce_init(&bounce, start, size);
1019 if (ret)
1020 return ret;
1021 mutex_lock(&dmirror->mutex);
1022 ret = dmirror_do_read(dmirror, start, end, &bounce);
1023 mutex_unlock(&dmirror->mutex);
1024 if (ret == 0) {
1025 if (copy_to_user(u64_to_user_ptr(cmd->ptr), bounce.ptr,
1026 bounce.size))
1027 ret = -EFAULT;
1028 }
1029 cmd->cpages = bounce.cpages;
1030 dmirror_bounce_fini(&bounce);
1031 return ret;
1032
1033out:
1034 mmap_read_unlock(mm);
1035 mmput(mm);
1036 return ret;
1037}
1038
1039static void dmirror_mkentry(struct dmirror *dmirror, struct hmm_range *range,
1040 unsigned char *perm, unsigned long entry)
1041{
1042 struct page *page;
1043
1044 if (entry & HMM_PFN_ERROR) {
1045 *perm = HMM_DMIRROR_PROT_ERROR;
1046 return;
1047 }
1048 if (!(entry & HMM_PFN_VALID)) {
1049 *perm = HMM_DMIRROR_PROT_NONE;
1050 return;
1051 }
1052
1053 page = hmm_pfn_to_page(entry);
1054 if (is_device_private_page(page)) {
1055 /* Is the page migrated to this device or some other? */
1056 if (dmirror->mdevice == dmirror_page_to_device(page))
1057 *perm = HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL;
1058 else
1059 *perm = HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE;
1060 } else if (is_device_coherent_page(page)) {
1061 /* Is the page migrated to this device or some other? */
1062 if (dmirror->mdevice == dmirror_page_to_device(page))
1063 *perm = HMM_DMIRROR_PROT_DEV_COHERENT_LOCAL;
1064 else
1065 *perm = HMM_DMIRROR_PROT_DEV_COHERENT_REMOTE;
1066 } else if (is_zero_pfn(page_to_pfn(page)))
1067 *perm = HMM_DMIRROR_PROT_ZERO;
1068 else
1069 *perm = HMM_DMIRROR_PROT_NONE;
1070 if (entry & HMM_PFN_WRITE)
1071 *perm |= HMM_DMIRROR_PROT_WRITE;
1072 else
1073 *perm |= HMM_DMIRROR_PROT_READ;
1074 if (hmm_pfn_to_map_order(entry) + PAGE_SHIFT == PMD_SHIFT)
1075 *perm |= HMM_DMIRROR_PROT_PMD;
1076 else if (hmm_pfn_to_map_order(entry) + PAGE_SHIFT == PUD_SHIFT)
1077 *perm |= HMM_DMIRROR_PROT_PUD;
1078}
1079
1080static bool dmirror_snapshot_invalidate(struct mmu_interval_notifier *mni,
1081 const struct mmu_notifier_range *range,
1082 unsigned long cur_seq)
1083{
1084 struct dmirror_interval *dmi =
1085 container_of(mni, struct dmirror_interval, notifier);
1086 struct dmirror *dmirror = dmi->dmirror;
1087
1088 if (mmu_notifier_range_blockable(range))
1089 mutex_lock(&dmirror->mutex);
1090 else if (!mutex_trylock(&dmirror->mutex))
1091 return false;
1092
1093 /*
1094 * Snapshots only need to set the sequence number since any
1095 * invalidation in the interval invalidates the whole snapshot.
1096 */
1097 mmu_interval_set_seq(mni, cur_seq);
1098
1099 mutex_unlock(&dmirror->mutex);
1100 return true;
1101}
1102
1103static const struct mmu_interval_notifier_ops dmirror_mrn_ops = {
1104 .invalidate = dmirror_snapshot_invalidate,
1105};
1106
1107static int dmirror_range_snapshot(struct dmirror *dmirror,
1108 struct hmm_range *range,
1109 unsigned char *perm)
1110{
1111 struct mm_struct *mm = dmirror->notifier.mm;
1112 struct dmirror_interval notifier;
1113 unsigned long timeout =
1114 jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
1115 unsigned long i;
1116 unsigned long n;
1117 int ret = 0;
1118
1119 notifier.dmirror = dmirror;
1120 range->notifier = ¬ifier.notifier;
1121
1122 ret = mmu_interval_notifier_insert(range->notifier, mm,
1123 range->start, range->end - range->start,
1124 &dmirror_mrn_ops);
1125 if (ret)
1126 return ret;
1127
1128 while (true) {
1129 if (time_after(jiffies, timeout)) {
1130 ret = -EBUSY;
1131 goto out;
1132 }
1133
1134 range->notifier_seq = mmu_interval_read_begin(range->notifier);
1135
1136 mmap_read_lock(mm);
1137 ret = hmm_range_fault(range);
1138 mmap_read_unlock(mm);
1139 if (ret) {
1140 if (ret == -EBUSY)
1141 continue;
1142 goto out;
1143 }
1144
1145 mutex_lock(&dmirror->mutex);
1146 if (mmu_interval_read_retry(range->notifier,
1147 range->notifier_seq)) {
1148 mutex_unlock(&dmirror->mutex);
1149 continue;
1150 }
1151 break;
1152 }
1153
1154 n = (range->end - range->start) >> PAGE_SHIFT;
1155 for (i = 0; i < n; i++)
1156 dmirror_mkentry(dmirror, range, perm + i, range->hmm_pfns[i]);
1157
1158 mutex_unlock(&dmirror->mutex);
1159out:
1160 mmu_interval_notifier_remove(range->notifier);
1161 return ret;
1162}
1163
1164static int dmirror_snapshot(struct dmirror *dmirror,
1165 struct hmm_dmirror_cmd *cmd)
1166{
1167 struct mm_struct *mm = dmirror->notifier.mm;
1168 unsigned long start, end;
1169 unsigned long size = cmd->npages << PAGE_SHIFT;
1170 unsigned long addr;
1171 unsigned long next;
1172 unsigned long pfns[64];
1173 unsigned char perm[64];
1174 char __user *uptr;
1175 struct hmm_range range = {
1176 .hmm_pfns = pfns,
1177 .dev_private_owner = dmirror->mdevice,
1178 };
1179 int ret = 0;
1180
1181 start = cmd->addr;
1182 end = start + size;
1183 if (end < start)
1184 return -EINVAL;
1185
1186 /* Since the mm is for the mirrored process, get a reference first. */
1187 if (!mmget_not_zero(mm))
1188 return -EINVAL;
1189
1190 /*
1191 * Register a temporary notifier to detect invalidations even if it
1192 * overlaps with other mmu_interval_notifiers.
1193 */
1194 uptr = u64_to_user_ptr(cmd->ptr);
1195 for (addr = start; addr < end; addr = next) {
1196 unsigned long n;
1197
1198 next = min(addr + (ARRAY_SIZE(pfns) << PAGE_SHIFT), end);
1199 range.start = addr;
1200 range.end = next;
1201
1202 ret = dmirror_range_snapshot(dmirror, &range, perm);
1203 if (ret)
1204 break;
1205
1206 n = (range.end - range.start) >> PAGE_SHIFT;
1207 if (copy_to_user(uptr, perm, n)) {
1208 ret = -EFAULT;
1209 break;
1210 }
1211
1212 cmd->cpages += n;
1213 uptr += n;
1214 }
1215 mmput(mm);
1216
1217 return ret;
1218}
1219
1220static void dmirror_device_evict_chunk(struct dmirror_chunk *chunk)
1221{
1222 unsigned long start_pfn = chunk->pagemap.range.start >> PAGE_SHIFT;
1223 unsigned long end_pfn = chunk->pagemap.range.end >> PAGE_SHIFT;
1224 unsigned long npages = end_pfn - start_pfn + 1;
1225 unsigned long i;
1226 unsigned long *src_pfns;
1227 unsigned long *dst_pfns;
1228
1229 src_pfns = kcalloc(npages, sizeof(*src_pfns), GFP_KERNEL);
1230 dst_pfns = kcalloc(npages, sizeof(*dst_pfns), GFP_KERNEL);
1231
1232 migrate_device_range(src_pfns, start_pfn, npages);
1233 for (i = 0; i < npages; i++) {
1234 struct page *dpage, *spage;
1235
1236 spage = migrate_pfn_to_page(src_pfns[i]);
1237 if (!spage || !(src_pfns[i] & MIGRATE_PFN_MIGRATE))
1238 continue;
1239
1240 if (WARN_ON(!is_device_private_page(spage) &&
1241 !is_device_coherent_page(spage)))
1242 continue;
1243 spage = BACKING_PAGE(spage);
1244 dpage = alloc_page(GFP_HIGHUSER_MOVABLE | __GFP_NOFAIL);
1245 lock_page(dpage);
1246 copy_highpage(dpage, spage);
1247 dst_pfns[i] = migrate_pfn(page_to_pfn(dpage));
1248 if (src_pfns[i] & MIGRATE_PFN_WRITE)
1249 dst_pfns[i] |= MIGRATE_PFN_WRITE;
1250 }
1251 migrate_device_pages(src_pfns, dst_pfns, npages);
1252 migrate_device_finalize(src_pfns, dst_pfns, npages);
1253 kfree(src_pfns);
1254 kfree(dst_pfns);
1255}
1256
1257/* Removes free pages from the free list so they can't be re-allocated */
1258static void dmirror_remove_free_pages(struct dmirror_chunk *devmem)
1259{
1260 struct dmirror_device *mdevice = devmem->mdevice;
1261 struct page *page;
1262
1263 for (page = mdevice->free_pages; page; page = page->zone_device_data)
1264 if (dmirror_page_to_chunk(page) == devmem)
1265 mdevice->free_pages = page->zone_device_data;
1266}
1267
1268static void dmirror_device_remove_chunks(struct dmirror_device *mdevice)
1269{
1270 unsigned int i;
1271
1272 mutex_lock(&mdevice->devmem_lock);
1273 if (mdevice->devmem_chunks) {
1274 for (i = 0; i < mdevice->devmem_count; i++) {
1275 struct dmirror_chunk *devmem =
1276 mdevice->devmem_chunks[i];
1277
1278 spin_lock(&mdevice->lock);
1279 devmem->remove = true;
1280 dmirror_remove_free_pages(devmem);
1281 spin_unlock(&mdevice->lock);
1282
1283 dmirror_device_evict_chunk(devmem);
1284 memunmap_pages(&devmem->pagemap);
1285 if (devmem->pagemap.type == MEMORY_DEVICE_PRIVATE)
1286 release_mem_region(devmem->pagemap.range.start,
1287 range_len(&devmem->pagemap.range));
1288 kfree(devmem);
1289 }
1290 mdevice->devmem_count = 0;
1291 mdevice->devmem_capacity = 0;
1292 mdevice->free_pages = NULL;
1293 kfree(mdevice->devmem_chunks);
1294 mdevice->devmem_chunks = NULL;
1295 }
1296 mutex_unlock(&mdevice->devmem_lock);
1297}
1298
1299static long dmirror_fops_unlocked_ioctl(struct file *filp,
1300 unsigned int command,
1301 unsigned long arg)
1302{
1303 void __user *uarg = (void __user *)arg;
1304 struct hmm_dmirror_cmd cmd;
1305 struct dmirror *dmirror;
1306 int ret;
1307
1308 dmirror = filp->private_data;
1309 if (!dmirror)
1310 return -EINVAL;
1311
1312 if (copy_from_user(&cmd, uarg, sizeof(cmd)))
1313 return -EFAULT;
1314
1315 if (cmd.addr & ~PAGE_MASK)
1316 return -EINVAL;
1317 if (cmd.addr >= (cmd.addr + (cmd.npages << PAGE_SHIFT)))
1318 return -EINVAL;
1319
1320 cmd.cpages = 0;
1321 cmd.faults = 0;
1322
1323 switch (command) {
1324 case HMM_DMIRROR_READ:
1325 ret = dmirror_read(dmirror, &cmd);
1326 break;
1327
1328 case HMM_DMIRROR_WRITE:
1329 ret = dmirror_write(dmirror, &cmd);
1330 break;
1331
1332 case HMM_DMIRROR_MIGRATE_TO_DEV:
1333 ret = dmirror_migrate_to_device(dmirror, &cmd);
1334 break;
1335
1336 case HMM_DMIRROR_MIGRATE_TO_SYS:
1337 ret = dmirror_migrate_to_system(dmirror, &cmd);
1338 break;
1339
1340 case HMM_DMIRROR_EXCLUSIVE:
1341 ret = dmirror_exclusive(dmirror, &cmd);
1342 break;
1343
1344 case HMM_DMIRROR_CHECK_EXCLUSIVE:
1345 ret = dmirror_check_atomic(dmirror, cmd.addr,
1346 cmd.addr + (cmd.npages << PAGE_SHIFT));
1347 break;
1348
1349 case HMM_DMIRROR_SNAPSHOT:
1350 ret = dmirror_snapshot(dmirror, &cmd);
1351 break;
1352
1353 case HMM_DMIRROR_RELEASE:
1354 dmirror_device_remove_chunks(dmirror->mdevice);
1355 ret = 0;
1356 break;
1357
1358 default:
1359 return -EINVAL;
1360 }
1361 if (ret)
1362 return ret;
1363
1364 if (copy_to_user(uarg, &cmd, sizeof(cmd)))
1365 return -EFAULT;
1366
1367 return 0;
1368}
1369
1370static int dmirror_fops_mmap(struct file *file, struct vm_area_struct *vma)
1371{
1372 unsigned long addr;
1373
1374 for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE) {
1375 struct page *page;
1376 int ret;
1377
1378 page = alloc_page(GFP_KERNEL | __GFP_ZERO);
1379 if (!page)
1380 return -ENOMEM;
1381
1382 ret = vm_insert_page(vma, addr, page);
1383 if (ret) {
1384 __free_page(page);
1385 return ret;
1386 }
1387 put_page(page);
1388 }
1389
1390 return 0;
1391}
1392
1393static const struct file_operations dmirror_fops = {
1394 .open = dmirror_fops_open,
1395 .release = dmirror_fops_release,
1396 .mmap = dmirror_fops_mmap,
1397 .unlocked_ioctl = dmirror_fops_unlocked_ioctl,
1398 .llseek = default_llseek,
1399 .owner = THIS_MODULE,
1400};
1401
1402static void dmirror_devmem_free(struct page *page)
1403{
1404 struct page *rpage = BACKING_PAGE(page);
1405 struct dmirror_device *mdevice;
1406
1407 if (rpage != page)
1408 __free_page(rpage);
1409
1410 mdevice = dmirror_page_to_device(page);
1411 spin_lock(&mdevice->lock);
1412
1413 /* Return page to our allocator if not freeing the chunk */
1414 if (!dmirror_page_to_chunk(page)->remove) {
1415 mdevice->cfree++;
1416 page->zone_device_data = mdevice->free_pages;
1417 mdevice->free_pages = page;
1418 }
1419 spin_unlock(&mdevice->lock);
1420}
1421
1422static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
1423{
1424 struct migrate_vma args = { 0 };
1425 unsigned long src_pfns = 0;
1426 unsigned long dst_pfns = 0;
1427 struct page *rpage;
1428 struct dmirror *dmirror;
1429 vm_fault_t ret;
1430
1431 /*
1432 * Normally, a device would use the page->zone_device_data to point to
1433 * the mirror but here we use it to hold the page for the simulated
1434 * device memory and that page holds the pointer to the mirror.
1435 */
1436 rpage = vmf->page->zone_device_data;
1437 dmirror = rpage->zone_device_data;
1438
1439 /* FIXME demonstrate how we can adjust migrate range */
1440 args.vma = vmf->vma;
1441 args.start = vmf->address;
1442 args.end = args.start + PAGE_SIZE;
1443 args.src = &src_pfns;
1444 args.dst = &dst_pfns;
1445 args.pgmap_owner = dmirror->mdevice;
1446 args.flags = dmirror_select_device(dmirror);
1447 args.fault_page = vmf->page;
1448
1449 if (migrate_vma_setup(&args))
1450 return VM_FAULT_SIGBUS;
1451
1452 ret = dmirror_devmem_fault_alloc_and_copy(&args, dmirror);
1453 if (ret)
1454 return ret;
1455 migrate_vma_pages(&args);
1456 /*
1457 * No device finalize step is needed since
1458 * dmirror_devmem_fault_alloc_and_copy() will have already
1459 * invalidated the device page table.
1460 */
1461 migrate_vma_finalize(&args);
1462 return 0;
1463}
1464
1465static const struct dev_pagemap_ops dmirror_devmem_ops = {
1466 .page_free = dmirror_devmem_free,
1467 .migrate_to_ram = dmirror_devmem_fault,
1468};
1469
1470static int dmirror_device_init(struct dmirror_device *mdevice, int id)
1471{
1472 dev_t dev;
1473 int ret;
1474
1475 dev = MKDEV(MAJOR(dmirror_dev), id);
1476 mutex_init(&mdevice->devmem_lock);
1477 spin_lock_init(&mdevice->lock);
1478
1479 cdev_init(&mdevice->cdevice, &dmirror_fops);
1480 mdevice->cdevice.owner = THIS_MODULE;
1481 device_initialize(&mdevice->device);
1482 mdevice->device.devt = dev;
1483
1484 ret = dev_set_name(&mdevice->device, "hmm_dmirror%u", id);
1485 if (ret)
1486 return ret;
1487
1488 ret = cdev_device_add(&mdevice->cdevice, &mdevice->device);
1489 if (ret)
1490 return ret;
1491
1492 /* Build a list of free ZONE_DEVICE struct pages */
1493 return dmirror_allocate_chunk(mdevice, NULL);
1494}
1495
1496static void dmirror_device_remove(struct dmirror_device *mdevice)
1497{
1498 dmirror_device_remove_chunks(mdevice);
1499 cdev_device_del(&mdevice->cdevice, &mdevice->device);
1500}
1501
1502static int __init hmm_dmirror_init(void)
1503{
1504 int ret;
1505 int id = 0;
1506 int ndevices = 0;
1507
1508 ret = alloc_chrdev_region(&dmirror_dev, 0, DMIRROR_NDEVICES,
1509 "HMM_DMIRROR");
1510 if (ret)
1511 goto err_unreg;
1512
1513 memset(dmirror_devices, 0, DMIRROR_NDEVICES * sizeof(dmirror_devices[0]));
1514 dmirror_devices[ndevices++].zone_device_type =
1515 HMM_DMIRROR_MEMORY_DEVICE_PRIVATE;
1516 dmirror_devices[ndevices++].zone_device_type =
1517 HMM_DMIRROR_MEMORY_DEVICE_PRIVATE;
1518 if (spm_addr_dev0 && spm_addr_dev1) {
1519 dmirror_devices[ndevices++].zone_device_type =
1520 HMM_DMIRROR_MEMORY_DEVICE_COHERENT;
1521 dmirror_devices[ndevices++].zone_device_type =
1522 HMM_DMIRROR_MEMORY_DEVICE_COHERENT;
1523 }
1524 for (id = 0; id < ndevices; id++) {
1525 ret = dmirror_device_init(dmirror_devices + id, id);
1526 if (ret)
1527 goto err_chrdev;
1528 }
1529
1530 pr_info("HMM test module loaded. This is only for testing HMM.\n");
1531 return 0;
1532
1533err_chrdev:
1534 while (--id >= 0)
1535 dmirror_device_remove(dmirror_devices + id);
1536 unregister_chrdev_region(dmirror_dev, DMIRROR_NDEVICES);
1537err_unreg:
1538 return ret;
1539}
1540
1541static void __exit hmm_dmirror_exit(void)
1542{
1543 int id;
1544
1545 for (id = 0; id < DMIRROR_NDEVICES; id++)
1546 if (dmirror_devices[id].zone_device_type)
1547 dmirror_device_remove(dmirror_devices + id);
1548 unregister_chrdev_region(dmirror_dev, DMIRROR_NDEVICES);
1549}
1550
1551module_init(hmm_dmirror_init);
1552module_exit(hmm_dmirror_exit);
1553MODULE_LICENSE("GPL");