rseq: Use get_user/put_user rather than __get_user/__put_user
[linux-2.6-microblaze.git] / mm / hmm.c
1 /*
2  * Copyright 2013 Red Hat Inc.
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License as published by
6  * the Free Software Foundation; either version 2 of the License, or
7  * (at your option) any later version.
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  *
14  * Authors: Jérôme Glisse <jglisse@redhat.com>
15  */
16 /*
17  * Refer to include/linux/hmm.h for information about heterogeneous memory
18  * management or HMM for short.
19  */
20 #include <linux/mm.h>
21 #include <linux/hmm.h>
22 #include <linux/init.h>
23 #include <linux/rmap.h>
24 #include <linux/swap.h>
25 #include <linux/slab.h>
26 #include <linux/sched.h>
27 #include <linux/mmzone.h>
28 #include <linux/pagemap.h>
29 #include <linux/swapops.h>
30 #include <linux/hugetlb.h>
31 #include <linux/memremap.h>
32 #include <linux/jump_label.h>
33 #include <linux/mmu_notifier.h>
34 #include <linux/memory_hotplug.h>
35
36 #define PA_SECTION_SIZE (1UL << PA_SECTION_SHIFT)
37
38 #if IS_ENABLED(CONFIG_HMM_MIRROR)
39 static const struct mmu_notifier_ops hmm_mmu_notifier_ops;
40
41 /*
42  * struct hmm - HMM per mm struct
43  *
44  * @mm: mm struct this HMM struct is bound to
45  * @lock: lock protecting ranges list
46  * @sequence: we track updates to the CPU page table with a sequence number
47  * @ranges: list of range being snapshotted
48  * @mirrors: list of mirrors for this mm
49  * @mmu_notifier: mmu notifier to track updates to CPU page table
50  * @mirrors_sem: read/write semaphore protecting the mirrors list
51  */
52 struct hmm {
53         struct mm_struct        *mm;
54         spinlock_t              lock;
55         atomic_t                sequence;
56         struct list_head        ranges;
57         struct list_head        mirrors;
58         struct mmu_notifier     mmu_notifier;
59         struct rw_semaphore     mirrors_sem;
60 };
61
62 /*
63  * hmm_register - register HMM against an mm (HMM internal)
64  *
65  * @mm: mm struct to attach to
66  *
67  * This is not intended to be used directly by device drivers. It allocates an
68  * HMM struct if mm does not have one, and initializes it.
69  */
70 static struct hmm *hmm_register(struct mm_struct *mm)
71 {
72         struct hmm *hmm = READ_ONCE(mm->hmm);
73         bool cleanup = false;
74
75         /*
76          * The hmm struct can only be freed once the mm_struct goes away,
77          * hence we should always have pre-allocated an new hmm struct
78          * above.
79          */
80         if (hmm)
81                 return hmm;
82
83         hmm = kmalloc(sizeof(*hmm), GFP_KERNEL);
84         if (!hmm)
85                 return NULL;
86         INIT_LIST_HEAD(&hmm->mirrors);
87         init_rwsem(&hmm->mirrors_sem);
88         atomic_set(&hmm->sequence, 0);
89         hmm->mmu_notifier.ops = NULL;
90         INIT_LIST_HEAD(&hmm->ranges);
91         spin_lock_init(&hmm->lock);
92         hmm->mm = mm;
93
94         /*
95          * We should only get here if hold the mmap_sem in write mode ie on
96          * registration of first mirror through hmm_mirror_register()
97          */
98         hmm->mmu_notifier.ops = &hmm_mmu_notifier_ops;
99         if (__mmu_notifier_register(&hmm->mmu_notifier, mm)) {
100                 kfree(hmm);
101                 return NULL;
102         }
103
104         spin_lock(&mm->page_table_lock);
105         if (!mm->hmm)
106                 mm->hmm = hmm;
107         else
108                 cleanup = true;
109         spin_unlock(&mm->page_table_lock);
110
111         if (cleanup) {
112                 mmu_notifier_unregister(&hmm->mmu_notifier, mm);
113                 kfree(hmm);
114         }
115
116         return mm->hmm;
117 }
118
119 void hmm_mm_destroy(struct mm_struct *mm)
120 {
121         kfree(mm->hmm);
122 }
123
124 static void hmm_invalidate_range(struct hmm *hmm,
125                                  enum hmm_update_type action,
126                                  unsigned long start,
127                                  unsigned long end)
128 {
129         struct hmm_mirror *mirror;
130         struct hmm_range *range;
131
132         spin_lock(&hmm->lock);
133         list_for_each_entry(range, &hmm->ranges, list) {
134                 unsigned long addr, idx, npages;
135
136                 if (end < range->start || start >= range->end)
137                         continue;
138
139                 range->valid = false;
140                 addr = max(start, range->start);
141                 idx = (addr - range->start) >> PAGE_SHIFT;
142                 npages = (min(range->end, end) - addr) >> PAGE_SHIFT;
143                 memset(&range->pfns[idx], 0, sizeof(*range->pfns) * npages);
144         }
145         spin_unlock(&hmm->lock);
146
147         down_read(&hmm->mirrors_sem);
148         list_for_each_entry(mirror, &hmm->mirrors, list)
149                 mirror->ops->sync_cpu_device_pagetables(mirror, action,
150                                                         start, end);
151         up_read(&hmm->mirrors_sem);
152 }
153
154 static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm)
155 {
156         struct hmm_mirror *mirror;
157         struct hmm *hmm = mm->hmm;
158
159         down_write(&hmm->mirrors_sem);
160         mirror = list_first_entry_or_null(&hmm->mirrors, struct hmm_mirror,
161                                           list);
162         while (mirror) {
163                 list_del_init(&mirror->list);
164                 if (mirror->ops->release) {
165                         /*
166                          * Drop mirrors_sem so callback can wait on any pending
167                          * work that might itself trigger mmu_notifier callback
168                          * and thus would deadlock with us.
169                          */
170                         up_write(&hmm->mirrors_sem);
171                         mirror->ops->release(mirror);
172                         down_write(&hmm->mirrors_sem);
173                 }
174                 mirror = list_first_entry_or_null(&hmm->mirrors,
175                                                   struct hmm_mirror, list);
176         }
177         up_write(&hmm->mirrors_sem);
178 }
179
180 static void hmm_invalidate_range_start(struct mmu_notifier *mn,
181                                        struct mm_struct *mm,
182                                        unsigned long start,
183                                        unsigned long end)
184 {
185         struct hmm *hmm = mm->hmm;
186
187         VM_BUG_ON(!hmm);
188
189         atomic_inc(&hmm->sequence);
190 }
191
192 static void hmm_invalidate_range_end(struct mmu_notifier *mn,
193                                      struct mm_struct *mm,
194                                      unsigned long start,
195                                      unsigned long end)
196 {
197         struct hmm *hmm = mm->hmm;
198
199         VM_BUG_ON(!hmm);
200
201         hmm_invalidate_range(mm->hmm, HMM_UPDATE_INVALIDATE, start, end);
202 }
203
204 static const struct mmu_notifier_ops hmm_mmu_notifier_ops = {
205         .release                = hmm_release,
206         .invalidate_range_start = hmm_invalidate_range_start,
207         .invalidate_range_end   = hmm_invalidate_range_end,
208 };
209
210 /*
211  * hmm_mirror_register() - register a mirror against an mm
212  *
213  * @mirror: new mirror struct to register
214  * @mm: mm to register against
215  *
216  * To start mirroring a process address space, the device driver must register
217  * an HMM mirror struct.
218  *
219  * THE mm->mmap_sem MUST BE HELD IN WRITE MODE !
220  */
221 int hmm_mirror_register(struct hmm_mirror *mirror, struct mm_struct *mm)
222 {
223         /* Sanity check */
224         if (!mm || !mirror || !mirror->ops)
225                 return -EINVAL;
226
227 again:
228         mirror->hmm = hmm_register(mm);
229         if (!mirror->hmm)
230                 return -ENOMEM;
231
232         down_write(&mirror->hmm->mirrors_sem);
233         if (mirror->hmm->mm == NULL) {
234                 /*
235                  * A racing hmm_mirror_unregister() is about to destroy the hmm
236                  * struct. Try again to allocate a new one.
237                  */
238                 up_write(&mirror->hmm->mirrors_sem);
239                 mirror->hmm = NULL;
240                 goto again;
241         } else {
242                 list_add(&mirror->list, &mirror->hmm->mirrors);
243                 up_write(&mirror->hmm->mirrors_sem);
244         }
245
246         return 0;
247 }
248 EXPORT_SYMBOL(hmm_mirror_register);
249
250 /*
251  * hmm_mirror_unregister() - unregister a mirror
252  *
253  * @mirror: new mirror struct to register
254  *
255  * Stop mirroring a process address space, and cleanup.
256  */
257 void hmm_mirror_unregister(struct hmm_mirror *mirror)
258 {
259         bool should_unregister = false;
260         struct mm_struct *mm;
261         struct hmm *hmm;
262
263         if (mirror->hmm == NULL)
264                 return;
265
266         hmm = mirror->hmm;
267         down_write(&hmm->mirrors_sem);
268         list_del_init(&mirror->list);
269         should_unregister = list_empty(&hmm->mirrors);
270         mirror->hmm = NULL;
271         mm = hmm->mm;
272         hmm->mm = NULL;
273         up_write(&hmm->mirrors_sem);
274
275         if (!should_unregister || mm == NULL)
276                 return;
277
278         spin_lock(&mm->page_table_lock);
279         if (mm->hmm == hmm)
280                 mm->hmm = NULL;
281         spin_unlock(&mm->page_table_lock);
282
283         mmu_notifier_unregister_no_release(&hmm->mmu_notifier, mm);
284         kfree(hmm);
285 }
286 EXPORT_SYMBOL(hmm_mirror_unregister);
287
288 struct hmm_vma_walk {
289         struct hmm_range        *range;
290         unsigned long           last;
291         bool                    fault;
292         bool                    block;
293 };
294
295 static int hmm_vma_do_fault(struct mm_walk *walk, unsigned long addr,
296                             bool write_fault, uint64_t *pfn)
297 {
298         unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_REMOTE;
299         struct hmm_vma_walk *hmm_vma_walk = walk->private;
300         struct hmm_range *range = hmm_vma_walk->range;
301         struct vm_area_struct *vma = walk->vma;
302         int r;
303
304         flags |= hmm_vma_walk->block ? 0 : FAULT_FLAG_ALLOW_RETRY;
305         flags |= write_fault ? FAULT_FLAG_WRITE : 0;
306         r = handle_mm_fault(vma, addr, flags);
307         if (r & VM_FAULT_RETRY)
308                 return -EBUSY;
309         if (r & VM_FAULT_ERROR) {
310                 *pfn = range->values[HMM_PFN_ERROR];
311                 return -EFAULT;
312         }
313
314         return -EAGAIN;
315 }
316
317 static int hmm_pfns_bad(unsigned long addr,
318                         unsigned long end,
319                         struct mm_walk *walk)
320 {
321         struct hmm_vma_walk *hmm_vma_walk = walk->private;
322         struct hmm_range *range = hmm_vma_walk->range;
323         uint64_t *pfns = range->pfns;
324         unsigned long i;
325
326         i = (addr - range->start) >> PAGE_SHIFT;
327         for (; addr < end; addr += PAGE_SIZE, i++)
328                 pfns[i] = range->values[HMM_PFN_ERROR];
329
330         return 0;
331 }
332
333 /*
334  * hmm_vma_walk_hole() - handle a range lacking valid pmd or pte(s)
335  * @start: range virtual start address (inclusive)
336  * @end: range virtual end address (exclusive)
337  * @fault: should we fault or not ?
338  * @write_fault: write fault ?
339  * @walk: mm_walk structure
340  * Returns: 0 on success, -EAGAIN after page fault, or page fault error
341  *
342  * This function will be called whenever pmd_none() or pte_none() returns true,
343  * or whenever there is no page directory covering the virtual address range.
344  */
345 static int hmm_vma_walk_hole_(unsigned long addr, unsigned long end,
346                               bool fault, bool write_fault,
347                               struct mm_walk *walk)
348 {
349         struct hmm_vma_walk *hmm_vma_walk = walk->private;
350         struct hmm_range *range = hmm_vma_walk->range;
351         uint64_t *pfns = range->pfns;
352         unsigned long i;
353
354         hmm_vma_walk->last = addr;
355         i = (addr - range->start) >> PAGE_SHIFT;
356         for (; addr < end; addr += PAGE_SIZE, i++) {
357                 pfns[i] = range->values[HMM_PFN_NONE];
358                 if (fault || write_fault) {
359                         int ret;
360
361                         ret = hmm_vma_do_fault(walk, addr, write_fault,
362                                                &pfns[i]);
363                         if (ret != -EAGAIN)
364                                 return ret;
365                 }
366         }
367
368         return (fault || write_fault) ? -EAGAIN : 0;
369 }
370
371 static inline void hmm_pte_need_fault(const struct hmm_vma_walk *hmm_vma_walk,
372                                       uint64_t pfns, uint64_t cpu_flags,
373                                       bool *fault, bool *write_fault)
374 {
375         struct hmm_range *range = hmm_vma_walk->range;
376
377         *fault = *write_fault = false;
378         if (!hmm_vma_walk->fault)
379                 return;
380
381         /* We aren't ask to do anything ... */
382         if (!(pfns & range->flags[HMM_PFN_VALID]))
383                 return;
384         /* If this is device memory than only fault if explicitly requested */
385         if ((cpu_flags & range->flags[HMM_PFN_DEVICE_PRIVATE])) {
386                 /* Do we fault on device memory ? */
387                 if (pfns & range->flags[HMM_PFN_DEVICE_PRIVATE]) {
388                         *write_fault = pfns & range->flags[HMM_PFN_WRITE];
389                         *fault = true;
390                 }
391                 return;
392         }
393
394         /* If CPU page table is not valid then we need to fault */
395         *fault = !(cpu_flags & range->flags[HMM_PFN_VALID]);
396         /* Need to write fault ? */
397         if ((pfns & range->flags[HMM_PFN_WRITE]) &&
398             !(cpu_flags & range->flags[HMM_PFN_WRITE])) {
399                 *write_fault = true;
400                 *fault = true;
401         }
402 }
403
404 static void hmm_range_need_fault(const struct hmm_vma_walk *hmm_vma_walk,
405                                  const uint64_t *pfns, unsigned long npages,
406                                  uint64_t cpu_flags, bool *fault,
407                                  bool *write_fault)
408 {
409         unsigned long i;
410
411         if (!hmm_vma_walk->fault) {
412                 *fault = *write_fault = false;
413                 return;
414         }
415
416         for (i = 0; i < npages; ++i) {
417                 hmm_pte_need_fault(hmm_vma_walk, pfns[i], cpu_flags,
418                                    fault, write_fault);
419                 if ((*fault) || (*write_fault))
420                         return;
421         }
422 }
423
424 static int hmm_vma_walk_hole(unsigned long addr, unsigned long end,
425                              struct mm_walk *walk)
426 {
427         struct hmm_vma_walk *hmm_vma_walk = walk->private;
428         struct hmm_range *range = hmm_vma_walk->range;
429         bool fault, write_fault;
430         unsigned long i, npages;
431         uint64_t *pfns;
432
433         i = (addr - range->start) >> PAGE_SHIFT;
434         npages = (end - addr) >> PAGE_SHIFT;
435         pfns = &range->pfns[i];
436         hmm_range_need_fault(hmm_vma_walk, pfns, npages,
437                              0, &fault, &write_fault);
438         return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk);
439 }
440
441 static inline uint64_t pmd_to_hmm_pfn_flags(struct hmm_range *range, pmd_t pmd)
442 {
443         if (pmd_protnone(pmd))
444                 return 0;
445         return pmd_write(pmd) ? range->flags[HMM_PFN_VALID] |
446                                 range->flags[HMM_PFN_WRITE] :
447                                 range->flags[HMM_PFN_VALID];
448 }
449
450 static int hmm_vma_handle_pmd(struct mm_walk *walk,
451                               unsigned long addr,
452                               unsigned long end,
453                               uint64_t *pfns,
454                               pmd_t pmd)
455 {
456         struct hmm_vma_walk *hmm_vma_walk = walk->private;
457         struct hmm_range *range = hmm_vma_walk->range;
458         unsigned long pfn, npages, i;
459         bool fault, write_fault;
460         uint64_t cpu_flags;
461
462         npages = (end - addr) >> PAGE_SHIFT;
463         cpu_flags = pmd_to_hmm_pfn_flags(range, pmd);
464         hmm_range_need_fault(hmm_vma_walk, pfns, npages, cpu_flags,
465                              &fault, &write_fault);
466
467         if (pmd_protnone(pmd) || fault || write_fault)
468                 return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk);
469
470         pfn = pmd_pfn(pmd) + pte_index(addr);
471         for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++)
472                 pfns[i] = hmm_pfn_from_pfn(range, pfn) | cpu_flags;
473         hmm_vma_walk->last = end;
474         return 0;
475 }
476
477 static inline uint64_t pte_to_hmm_pfn_flags(struct hmm_range *range, pte_t pte)
478 {
479         if (pte_none(pte) || !pte_present(pte))
480                 return 0;
481         return pte_write(pte) ? range->flags[HMM_PFN_VALID] |
482                                 range->flags[HMM_PFN_WRITE] :
483                                 range->flags[HMM_PFN_VALID];
484 }
485
486 static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
487                               unsigned long end, pmd_t *pmdp, pte_t *ptep,
488                               uint64_t *pfn)
489 {
490         struct hmm_vma_walk *hmm_vma_walk = walk->private;
491         struct hmm_range *range = hmm_vma_walk->range;
492         struct vm_area_struct *vma = walk->vma;
493         bool fault, write_fault;
494         uint64_t cpu_flags;
495         pte_t pte = *ptep;
496         uint64_t orig_pfn = *pfn;
497
498         *pfn = range->values[HMM_PFN_NONE];
499         cpu_flags = pte_to_hmm_pfn_flags(range, pte);
500         hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
501                            &fault, &write_fault);
502
503         if (pte_none(pte)) {
504                 if (fault || write_fault)
505                         goto fault;
506                 return 0;
507         }
508
509         if (!pte_present(pte)) {
510                 swp_entry_t entry = pte_to_swp_entry(pte);
511
512                 if (!non_swap_entry(entry)) {
513                         if (fault || write_fault)
514                                 goto fault;
515                         return 0;
516                 }
517
518                 /*
519                  * This is a special swap entry, ignore migration, use
520                  * device and report anything else as error.
521                  */
522                 if (is_device_private_entry(entry)) {
523                         cpu_flags = range->flags[HMM_PFN_VALID] |
524                                 range->flags[HMM_PFN_DEVICE_PRIVATE];
525                         cpu_flags |= is_write_device_private_entry(entry) ?
526                                 range->flags[HMM_PFN_WRITE] : 0;
527                         hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
528                                            &fault, &write_fault);
529                         if (fault || write_fault)
530                                 goto fault;
531                         *pfn = hmm_pfn_from_pfn(range, swp_offset(entry));
532                         *pfn |= cpu_flags;
533                         return 0;
534                 }
535
536                 if (is_migration_entry(entry)) {
537                         if (fault || write_fault) {
538                                 pte_unmap(ptep);
539                                 hmm_vma_walk->last = addr;
540                                 migration_entry_wait(vma->vm_mm,
541                                                      pmdp, addr);
542                                 return -EAGAIN;
543                         }
544                         return 0;
545                 }
546
547                 /* Report error for everything else */
548                 *pfn = range->values[HMM_PFN_ERROR];
549                 return -EFAULT;
550         }
551
552         if (fault || write_fault)
553                 goto fault;
554
555         *pfn = hmm_pfn_from_pfn(range, pte_pfn(pte)) | cpu_flags;
556         return 0;
557
558 fault:
559         pte_unmap(ptep);
560         /* Fault any virtual address we were asked to fault */
561         return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk);
562 }
563
564 static int hmm_vma_walk_pmd(pmd_t *pmdp,
565                             unsigned long start,
566                             unsigned long end,
567                             struct mm_walk *walk)
568 {
569         struct hmm_vma_walk *hmm_vma_walk = walk->private;
570         struct hmm_range *range = hmm_vma_walk->range;
571         uint64_t *pfns = range->pfns;
572         unsigned long addr = start, i;
573         pte_t *ptep;
574
575         i = (addr - range->start) >> PAGE_SHIFT;
576
577 again:
578         if (pmd_none(*pmdp))
579                 return hmm_vma_walk_hole(start, end, walk);
580
581         if (pmd_huge(*pmdp) && (range->vma->vm_flags & VM_HUGETLB))
582                 return hmm_pfns_bad(start, end, walk);
583
584         if (pmd_devmap(*pmdp) || pmd_trans_huge(*pmdp)) {
585                 pmd_t pmd;
586
587                 /*
588                  * No need to take pmd_lock here, even if some other threads
589                  * is splitting the huge pmd we will get that event through
590                  * mmu_notifier callback.
591                  *
592                  * So just read pmd value and check again its a transparent
593                  * huge or device mapping one and compute corresponding pfn
594                  * values.
595                  */
596                 pmd = pmd_read_atomic(pmdp);
597                 barrier();
598                 if (!pmd_devmap(pmd) && !pmd_trans_huge(pmd))
599                         goto again;
600
601                 return hmm_vma_handle_pmd(walk, addr, end, &pfns[i], pmd);
602         }
603
604         if (pmd_bad(*pmdp))
605                 return hmm_pfns_bad(start, end, walk);
606
607         ptep = pte_offset_map(pmdp, addr);
608         for (; addr < end; addr += PAGE_SIZE, ptep++, i++) {
609                 int r;
610
611                 r = hmm_vma_handle_pte(walk, addr, end, pmdp, ptep, &pfns[i]);
612                 if (r) {
613                         /* hmm_vma_handle_pte() did unmap pte directory */
614                         hmm_vma_walk->last = addr;
615                         return r;
616                 }
617         }
618         pte_unmap(ptep - 1);
619
620         hmm_vma_walk->last = addr;
621         return 0;
622 }
623
624 static void hmm_pfns_clear(struct hmm_range *range,
625                            uint64_t *pfns,
626                            unsigned long addr,
627                            unsigned long end)
628 {
629         for (; addr < end; addr += PAGE_SIZE, pfns++)
630                 *pfns = range->values[HMM_PFN_NONE];
631 }
632
633 static void hmm_pfns_special(struct hmm_range *range)
634 {
635         unsigned long addr = range->start, i = 0;
636
637         for (; addr < range->end; addr += PAGE_SIZE, i++)
638                 range->pfns[i] = range->values[HMM_PFN_SPECIAL];
639 }
640
641 /*
642  * hmm_vma_get_pfns() - snapshot CPU page table for a range of virtual addresses
643  * @range: range being snapshotted
644  * Returns: -EINVAL if invalid argument, -ENOMEM out of memory, -EPERM invalid
645  *          vma permission, 0 success
646  *
647  * This snapshots the CPU page table for a range of virtual addresses. Snapshot
648  * validity is tracked by range struct. See hmm_vma_range_done() for further
649  * information.
650  *
651  * The range struct is initialized here. It tracks the CPU page table, but only
652  * if the function returns success (0), in which case the caller must then call
653  * hmm_vma_range_done() to stop CPU page table update tracking on this range.
654  *
655  * NOT CALLING hmm_vma_range_done() IF FUNCTION RETURNS 0 WILL LEAD TO SERIOUS
656  * MEMORY CORRUPTION ! YOU HAVE BEEN WARNED !
657  */
658 int hmm_vma_get_pfns(struct hmm_range *range)
659 {
660         struct vm_area_struct *vma = range->vma;
661         struct hmm_vma_walk hmm_vma_walk;
662         struct mm_walk mm_walk;
663         struct hmm *hmm;
664
665         /* Sanity check, this really should not happen ! */
666         if (range->start < vma->vm_start || range->start >= vma->vm_end)
667                 return -EINVAL;
668         if (range->end < vma->vm_start || range->end > vma->vm_end)
669                 return -EINVAL;
670
671         hmm = hmm_register(vma->vm_mm);
672         if (!hmm)
673                 return -ENOMEM;
674         /* Caller must have registered a mirror, via hmm_mirror_register() ! */
675         if (!hmm->mmu_notifier.ops)
676                 return -EINVAL;
677
678         /* FIXME support hugetlb fs */
679         if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) {
680                 hmm_pfns_special(range);
681                 return -EINVAL;
682         }
683
684         if (!(vma->vm_flags & VM_READ)) {
685                 /*
686                  * If vma do not allow read access, then assume that it does
687                  * not allow write access, either. Architecture that allow
688                  * write without read access are not supported by HMM, because
689                  * operations such has atomic access would not work.
690                  */
691                 hmm_pfns_clear(range, range->pfns, range->start, range->end);
692                 return -EPERM;
693         }
694
695         /* Initialize range to track CPU page table update */
696         spin_lock(&hmm->lock);
697         range->valid = true;
698         list_add_rcu(&range->list, &hmm->ranges);
699         spin_unlock(&hmm->lock);
700
701         hmm_vma_walk.fault = false;
702         hmm_vma_walk.range = range;
703         mm_walk.private = &hmm_vma_walk;
704
705         mm_walk.vma = vma;
706         mm_walk.mm = vma->vm_mm;
707         mm_walk.pte_entry = NULL;
708         mm_walk.test_walk = NULL;
709         mm_walk.hugetlb_entry = NULL;
710         mm_walk.pmd_entry = hmm_vma_walk_pmd;
711         mm_walk.pte_hole = hmm_vma_walk_hole;
712
713         walk_page_range(range->start, range->end, &mm_walk);
714         return 0;
715 }
716 EXPORT_SYMBOL(hmm_vma_get_pfns);
717
718 /*
719  * hmm_vma_range_done() - stop tracking change to CPU page table over a range
720  * @range: range being tracked
721  * Returns: false if range data has been invalidated, true otherwise
722  *
723  * Range struct is used to track updates to the CPU page table after a call to
724  * either hmm_vma_get_pfns() or hmm_vma_fault(). Once the device driver is done
725  * using the data,  or wants to lock updates to the data it got from those
726  * functions, it must call the hmm_vma_range_done() function, which will then
727  * stop tracking CPU page table updates.
728  *
729  * Note that device driver must still implement general CPU page table update
730  * tracking either by using hmm_mirror (see hmm_mirror_register()) or by using
731  * the mmu_notifier API directly.
732  *
733  * CPU page table update tracking done through hmm_range is only temporary and
734  * to be used while trying to duplicate CPU page table contents for a range of
735  * virtual addresses.
736  *
737  * There are two ways to use this :
738  * again:
739  *   hmm_vma_get_pfns(range); or hmm_vma_fault(...);
740  *   trans = device_build_page_table_update_transaction(pfns);
741  *   device_page_table_lock();
742  *   if (!hmm_vma_range_done(range)) {
743  *     device_page_table_unlock();
744  *     goto again;
745  *   }
746  *   device_commit_transaction(trans);
747  *   device_page_table_unlock();
748  *
749  * Or:
750  *   hmm_vma_get_pfns(range); or hmm_vma_fault(...);
751  *   device_page_table_lock();
752  *   hmm_vma_range_done(range);
753  *   device_update_page_table(range->pfns);
754  *   device_page_table_unlock();
755  */
756 bool hmm_vma_range_done(struct hmm_range *range)
757 {
758         unsigned long npages = (range->end - range->start) >> PAGE_SHIFT;
759         struct hmm *hmm;
760
761         if (range->end <= range->start) {
762                 BUG();
763                 return false;
764         }
765
766         hmm = hmm_register(range->vma->vm_mm);
767         if (!hmm) {
768                 memset(range->pfns, 0, sizeof(*range->pfns) * npages);
769                 return false;
770         }
771
772         spin_lock(&hmm->lock);
773         list_del_rcu(&range->list);
774         spin_unlock(&hmm->lock);
775
776         return range->valid;
777 }
778 EXPORT_SYMBOL(hmm_vma_range_done);
779
780 /*
781  * hmm_vma_fault() - try to fault some address in a virtual address range
782  * @range: range being faulted
783  * @block: allow blocking on fault (if true it sleeps and do not drop mmap_sem)
784  * Returns: 0 success, error otherwise (-EAGAIN means mmap_sem have been drop)
785  *
786  * This is similar to a regular CPU page fault except that it will not trigger
787  * any memory migration if the memory being faulted is not accessible by CPUs.
788  *
789  * On error, for one virtual address in the range, the function will mark the
790  * corresponding HMM pfn entry with an error flag.
791  *
792  * Expected use pattern:
793  * retry:
794  *   down_read(&mm->mmap_sem);
795  *   // Find vma and address device wants to fault, initialize hmm_pfn_t
796  *   // array accordingly
797  *   ret = hmm_vma_fault(range, write, block);
798  *   switch (ret) {
799  *   case -EAGAIN:
800  *     hmm_vma_range_done(range);
801  *     // You might want to rate limit or yield to play nicely, you may
802  *     // also commit any valid pfn in the array assuming that you are
803  *     // getting true from hmm_vma_range_monitor_end()
804  *     goto retry;
805  *   case 0:
806  *     break;
807  *   case -ENOMEM:
808  *   case -EINVAL:
809  *   case -EPERM:
810  *   default:
811  *     // Handle error !
812  *     up_read(&mm->mmap_sem)
813  *     return;
814  *   }
815  *   // Take device driver lock that serialize device page table update
816  *   driver_lock_device_page_table_update();
817  *   hmm_vma_range_done(range);
818  *   // Commit pfns we got from hmm_vma_fault()
819  *   driver_unlock_device_page_table_update();
820  *   up_read(&mm->mmap_sem)
821  *
822  * YOU MUST CALL hmm_vma_range_done() AFTER THIS FUNCTION RETURN SUCCESS (0)
823  * BEFORE FREEING THE range struct OR YOU WILL HAVE SERIOUS MEMORY CORRUPTION !
824  *
825  * YOU HAVE BEEN WARNED !
826  */
827 int hmm_vma_fault(struct hmm_range *range, bool block)
828 {
829         struct vm_area_struct *vma = range->vma;
830         unsigned long start = range->start;
831         struct hmm_vma_walk hmm_vma_walk;
832         struct mm_walk mm_walk;
833         struct hmm *hmm;
834         int ret;
835
836         /* Sanity check, this really should not happen ! */
837         if (range->start < vma->vm_start || range->start >= vma->vm_end)
838                 return -EINVAL;
839         if (range->end < vma->vm_start || range->end > vma->vm_end)
840                 return -EINVAL;
841
842         hmm = hmm_register(vma->vm_mm);
843         if (!hmm) {
844                 hmm_pfns_clear(range, range->pfns, range->start, range->end);
845                 return -ENOMEM;
846         }
847         /* Caller must have registered a mirror using hmm_mirror_register() */
848         if (!hmm->mmu_notifier.ops)
849                 return -EINVAL;
850
851         /* FIXME support hugetlb fs */
852         if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) {
853                 hmm_pfns_special(range);
854                 return -EINVAL;
855         }
856
857         if (!(vma->vm_flags & VM_READ)) {
858                 /*
859                  * If vma do not allow read access, then assume that it does
860                  * not allow write access, either. Architecture that allow
861                  * write without read access are not supported by HMM, because
862                  * operations such has atomic access would not work.
863                  */
864                 hmm_pfns_clear(range, range->pfns, range->start, range->end);
865                 return -EPERM;
866         }
867
868         /* Initialize range to track CPU page table update */
869         spin_lock(&hmm->lock);
870         range->valid = true;
871         list_add_rcu(&range->list, &hmm->ranges);
872         spin_unlock(&hmm->lock);
873
874         hmm_vma_walk.fault = true;
875         hmm_vma_walk.block = block;
876         hmm_vma_walk.range = range;
877         mm_walk.private = &hmm_vma_walk;
878         hmm_vma_walk.last = range->start;
879
880         mm_walk.vma = vma;
881         mm_walk.mm = vma->vm_mm;
882         mm_walk.pte_entry = NULL;
883         mm_walk.test_walk = NULL;
884         mm_walk.hugetlb_entry = NULL;
885         mm_walk.pmd_entry = hmm_vma_walk_pmd;
886         mm_walk.pte_hole = hmm_vma_walk_hole;
887
888         do {
889                 ret = walk_page_range(start, range->end, &mm_walk);
890                 start = hmm_vma_walk.last;
891         } while (ret == -EAGAIN);
892
893         if (ret) {
894                 unsigned long i;
895
896                 i = (hmm_vma_walk.last - range->start) >> PAGE_SHIFT;
897                 hmm_pfns_clear(range, &range->pfns[i], hmm_vma_walk.last,
898                                range->end);
899                 hmm_vma_range_done(range);
900         }
901         return ret;
902 }
903 EXPORT_SYMBOL(hmm_vma_fault);
904 #endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */
905
906
907 #if IS_ENABLED(CONFIG_DEVICE_PRIVATE) ||  IS_ENABLED(CONFIG_DEVICE_PUBLIC)
908 struct page *hmm_vma_alloc_locked_page(struct vm_area_struct *vma,
909                                        unsigned long addr)
910 {
911         struct page *page;
912
913         page = alloc_page_vma(GFP_HIGHUSER, vma, addr);
914         if (!page)
915                 return NULL;
916         lock_page(page);
917         return page;
918 }
919 EXPORT_SYMBOL(hmm_vma_alloc_locked_page);
920
921
922 static void hmm_devmem_ref_release(struct percpu_ref *ref)
923 {
924         struct hmm_devmem *devmem;
925
926         devmem = container_of(ref, struct hmm_devmem, ref);
927         complete(&devmem->completion);
928 }
929
930 static void hmm_devmem_ref_exit(void *data)
931 {
932         struct percpu_ref *ref = data;
933         struct hmm_devmem *devmem;
934
935         devmem = container_of(ref, struct hmm_devmem, ref);
936         percpu_ref_exit(ref);
937         devm_remove_action(devmem->device, &hmm_devmem_ref_exit, data);
938 }
939
940 static void hmm_devmem_ref_kill(void *data)
941 {
942         struct percpu_ref *ref = data;
943         struct hmm_devmem *devmem;
944
945         devmem = container_of(ref, struct hmm_devmem, ref);
946         percpu_ref_kill(ref);
947         wait_for_completion(&devmem->completion);
948         devm_remove_action(devmem->device, &hmm_devmem_ref_kill, data);
949 }
950
951 static int hmm_devmem_fault(struct vm_area_struct *vma,
952                             unsigned long addr,
953                             const struct page *page,
954                             unsigned int flags,
955                             pmd_t *pmdp)
956 {
957         struct hmm_devmem *devmem = page->pgmap->data;
958
959         return devmem->ops->fault(devmem, vma, addr, page, flags, pmdp);
960 }
961
962 static void hmm_devmem_free(struct page *page, void *data)
963 {
964         struct hmm_devmem *devmem = data;
965
966         devmem->ops->free(devmem, page);
967 }
968
969 static DEFINE_MUTEX(hmm_devmem_lock);
970 static RADIX_TREE(hmm_devmem_radix, GFP_KERNEL);
971
972 static void hmm_devmem_radix_release(struct resource *resource)
973 {
974         resource_size_t key, align_start, align_size;
975
976         align_start = resource->start & ~(PA_SECTION_SIZE - 1);
977         align_size = ALIGN(resource_size(resource), PA_SECTION_SIZE);
978
979         mutex_lock(&hmm_devmem_lock);
980         for (key = resource->start;
981              key <= resource->end;
982              key += PA_SECTION_SIZE)
983                 radix_tree_delete(&hmm_devmem_radix, key >> PA_SECTION_SHIFT);
984         mutex_unlock(&hmm_devmem_lock);
985 }
986
987 static void hmm_devmem_release(struct device *dev, void *data)
988 {
989         struct hmm_devmem *devmem = data;
990         struct resource *resource = devmem->resource;
991         unsigned long start_pfn, npages;
992         struct zone *zone;
993         struct page *page;
994
995         if (percpu_ref_tryget_live(&devmem->ref)) {
996                 dev_WARN(dev, "%s: page mapping is still live!\n", __func__);
997                 percpu_ref_put(&devmem->ref);
998         }
999
1000         /* pages are dead and unused, undo the arch mapping */
1001         start_pfn = (resource->start & ~(PA_SECTION_SIZE - 1)) >> PAGE_SHIFT;
1002         npages = ALIGN(resource_size(resource), PA_SECTION_SIZE) >> PAGE_SHIFT;
1003
1004         page = pfn_to_page(start_pfn);
1005         zone = page_zone(page);
1006
1007         mem_hotplug_begin();
1008         if (resource->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY)
1009                 __remove_pages(zone, start_pfn, npages, NULL);
1010         else
1011                 arch_remove_memory(start_pfn << PAGE_SHIFT,
1012                                    npages << PAGE_SHIFT, NULL);
1013         mem_hotplug_done();
1014
1015         hmm_devmem_radix_release(resource);
1016 }
1017
1018 static int hmm_devmem_pages_create(struct hmm_devmem *devmem)
1019 {
1020         resource_size_t key, align_start, align_size, align_end;
1021         struct device *device = devmem->device;
1022         int ret, nid, is_ram;
1023         unsigned long pfn;
1024
1025         align_start = devmem->resource->start & ~(PA_SECTION_SIZE - 1);
1026         align_size = ALIGN(devmem->resource->start +
1027                            resource_size(devmem->resource),
1028                            PA_SECTION_SIZE) - align_start;
1029
1030         is_ram = region_intersects(align_start, align_size,
1031                                    IORESOURCE_SYSTEM_RAM,
1032                                    IORES_DESC_NONE);
1033         if (is_ram == REGION_MIXED) {
1034                 WARN_ONCE(1, "%s attempted on mixed region %pr\n",
1035                                 __func__, devmem->resource);
1036                 return -ENXIO;
1037         }
1038         if (is_ram == REGION_INTERSECTS)
1039                 return -ENXIO;
1040
1041         if (devmem->resource->desc == IORES_DESC_DEVICE_PUBLIC_MEMORY)
1042                 devmem->pagemap.type = MEMORY_DEVICE_PUBLIC;
1043         else
1044                 devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
1045
1046         devmem->pagemap.res = *devmem->resource;
1047         devmem->pagemap.page_fault = hmm_devmem_fault;
1048         devmem->pagemap.page_free = hmm_devmem_free;
1049         devmem->pagemap.dev = devmem->device;
1050         devmem->pagemap.ref = &devmem->ref;
1051         devmem->pagemap.data = devmem;
1052
1053         mutex_lock(&hmm_devmem_lock);
1054         align_end = align_start + align_size - 1;
1055         for (key = align_start; key <= align_end; key += PA_SECTION_SIZE) {
1056                 struct hmm_devmem *dup;
1057
1058                 dup = radix_tree_lookup(&hmm_devmem_radix,
1059                                         key >> PA_SECTION_SHIFT);
1060                 if (dup) {
1061                         dev_err(device, "%s: collides with mapping for %s\n",
1062                                 __func__, dev_name(dup->device));
1063                         mutex_unlock(&hmm_devmem_lock);
1064                         ret = -EBUSY;
1065                         goto error;
1066                 }
1067                 ret = radix_tree_insert(&hmm_devmem_radix,
1068                                         key >> PA_SECTION_SHIFT,
1069                                         devmem);
1070                 if (ret) {
1071                         dev_err(device, "%s: failed: %d\n", __func__, ret);
1072                         mutex_unlock(&hmm_devmem_lock);
1073                         goto error_radix;
1074                 }
1075         }
1076         mutex_unlock(&hmm_devmem_lock);
1077
1078         nid = dev_to_node(device);
1079         if (nid < 0)
1080                 nid = numa_mem_id();
1081
1082         mem_hotplug_begin();
1083         /*
1084          * For device private memory we call add_pages() as we only need to
1085          * allocate and initialize struct page for the device memory. More-
1086          * over the device memory is un-accessible thus we do not want to
1087          * create a linear mapping for the memory like arch_add_memory()
1088          * would do.
1089          *
1090          * For device public memory, which is accesible by the CPU, we do
1091          * want the linear mapping and thus use arch_add_memory().
1092          */
1093         if (devmem->pagemap.type == MEMORY_DEVICE_PUBLIC)
1094                 ret = arch_add_memory(nid, align_start, align_size, NULL,
1095                                 false);
1096         else
1097                 ret = add_pages(nid, align_start >> PAGE_SHIFT,
1098                                 align_size >> PAGE_SHIFT, NULL, false);
1099         if (ret) {
1100                 mem_hotplug_done();
1101                 goto error_add_memory;
1102         }
1103         move_pfn_range_to_zone(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
1104                                 align_start >> PAGE_SHIFT,
1105                                 align_size >> PAGE_SHIFT, NULL);
1106         mem_hotplug_done();
1107
1108         for (pfn = devmem->pfn_first; pfn < devmem->pfn_last; pfn++) {
1109                 struct page *page = pfn_to_page(pfn);
1110
1111                 page->pgmap = &devmem->pagemap;
1112         }
1113         return 0;
1114
1115 error_add_memory:
1116         untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
1117 error_radix:
1118         hmm_devmem_radix_release(devmem->resource);
1119 error:
1120         return ret;
1121 }
1122
1123 static int hmm_devmem_match(struct device *dev, void *data, void *match_data)
1124 {
1125         struct hmm_devmem *devmem = data;
1126
1127         return devmem->resource == match_data;
1128 }
1129
1130 static void hmm_devmem_pages_remove(struct hmm_devmem *devmem)
1131 {
1132         devres_release(devmem->device, &hmm_devmem_release,
1133                        &hmm_devmem_match, devmem->resource);
1134 }
1135
1136 /*
1137  * hmm_devmem_add() - hotplug ZONE_DEVICE memory for device memory
1138  *
1139  * @ops: memory event device driver callback (see struct hmm_devmem_ops)
1140  * @device: device struct to bind the resource too
1141  * @size: size in bytes of the device memory to add
1142  * Returns: pointer to new hmm_devmem struct ERR_PTR otherwise
1143  *
1144  * This function first finds an empty range of physical address big enough to
1145  * contain the new resource, and then hotplugs it as ZONE_DEVICE memory, which
1146  * in turn allocates struct pages. It does not do anything beyond that; all
1147  * events affecting the memory will go through the various callbacks provided
1148  * by hmm_devmem_ops struct.
1149  *
1150  * Device driver should call this function during device initialization and
1151  * is then responsible of memory management. HMM only provides helpers.
1152  */
1153 struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
1154                                   struct device *device,
1155                                   unsigned long size)
1156 {
1157         struct hmm_devmem *devmem;
1158         resource_size_t addr;
1159         int ret;
1160
1161         dev_pagemap_get_ops();
1162
1163         devmem = devres_alloc_node(&hmm_devmem_release, sizeof(*devmem),
1164                                    GFP_KERNEL, dev_to_node(device));
1165         if (!devmem)
1166                 return ERR_PTR(-ENOMEM);
1167
1168         init_completion(&devmem->completion);
1169         devmem->pfn_first = -1UL;
1170         devmem->pfn_last = -1UL;
1171         devmem->resource = NULL;
1172         devmem->device = device;
1173         devmem->ops = ops;
1174
1175         ret = percpu_ref_init(&devmem->ref, &hmm_devmem_ref_release,
1176                               0, GFP_KERNEL);
1177         if (ret)
1178                 goto error_percpu_ref;
1179
1180         ret = devm_add_action(device, hmm_devmem_ref_exit, &devmem->ref);
1181         if (ret)
1182                 goto error_devm_add_action;
1183
1184         size = ALIGN(size, PA_SECTION_SIZE);
1185         addr = min((unsigned long)iomem_resource.end,
1186                    (1UL << MAX_PHYSMEM_BITS) - 1);
1187         addr = addr - size + 1UL;
1188
1189         /*
1190          * FIXME add a new helper to quickly walk resource tree and find free
1191          * range
1192          *
1193          * FIXME what about ioport_resource resource ?
1194          */
1195         for (; addr > size && addr >= iomem_resource.start; addr -= size) {
1196                 ret = region_intersects(addr, size, 0, IORES_DESC_NONE);
1197                 if (ret != REGION_DISJOINT)
1198                         continue;
1199
1200                 devmem->resource = devm_request_mem_region(device, addr, size,
1201                                                            dev_name(device));
1202                 if (!devmem->resource) {
1203                         ret = -ENOMEM;
1204                         goto error_no_resource;
1205                 }
1206                 break;
1207         }
1208         if (!devmem->resource) {
1209                 ret = -ERANGE;
1210                 goto error_no_resource;
1211         }
1212
1213         devmem->resource->desc = IORES_DESC_DEVICE_PRIVATE_MEMORY;
1214         devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT;
1215         devmem->pfn_last = devmem->pfn_first +
1216                            (resource_size(devmem->resource) >> PAGE_SHIFT);
1217
1218         ret = hmm_devmem_pages_create(devmem);
1219         if (ret)
1220                 goto error_pages;
1221
1222         devres_add(device, devmem);
1223
1224         ret = devm_add_action(device, hmm_devmem_ref_kill, &devmem->ref);
1225         if (ret) {
1226                 hmm_devmem_remove(devmem);
1227                 return ERR_PTR(ret);
1228         }
1229
1230         return devmem;
1231
1232 error_pages:
1233         devm_release_mem_region(device, devmem->resource->start,
1234                                 resource_size(devmem->resource));
1235 error_no_resource:
1236 error_devm_add_action:
1237         hmm_devmem_ref_kill(&devmem->ref);
1238         hmm_devmem_ref_exit(&devmem->ref);
1239 error_percpu_ref:
1240         devres_free(devmem);
1241         return ERR_PTR(ret);
1242 }
1243 EXPORT_SYMBOL(hmm_devmem_add);
1244
1245 struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops,
1246                                            struct device *device,
1247                                            struct resource *res)
1248 {
1249         struct hmm_devmem *devmem;
1250         int ret;
1251
1252         if (res->desc != IORES_DESC_DEVICE_PUBLIC_MEMORY)
1253                 return ERR_PTR(-EINVAL);
1254
1255         dev_pagemap_get_ops();
1256
1257         devmem = devres_alloc_node(&hmm_devmem_release, sizeof(*devmem),
1258                                    GFP_KERNEL, dev_to_node(device));
1259         if (!devmem)
1260                 return ERR_PTR(-ENOMEM);
1261
1262         init_completion(&devmem->completion);
1263         devmem->pfn_first = -1UL;
1264         devmem->pfn_last = -1UL;
1265         devmem->resource = res;
1266         devmem->device = device;
1267         devmem->ops = ops;
1268
1269         ret = percpu_ref_init(&devmem->ref, &hmm_devmem_ref_release,
1270                               0, GFP_KERNEL);
1271         if (ret)
1272                 goto error_percpu_ref;
1273
1274         ret = devm_add_action(device, hmm_devmem_ref_exit, &devmem->ref);
1275         if (ret)
1276                 goto error_devm_add_action;
1277
1278
1279         devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT;
1280         devmem->pfn_last = devmem->pfn_first +
1281                            (resource_size(devmem->resource) >> PAGE_SHIFT);
1282
1283         ret = hmm_devmem_pages_create(devmem);
1284         if (ret)
1285                 goto error_devm_add_action;
1286
1287         devres_add(device, devmem);
1288
1289         ret = devm_add_action(device, hmm_devmem_ref_kill, &devmem->ref);
1290         if (ret) {
1291                 hmm_devmem_remove(devmem);
1292                 return ERR_PTR(ret);
1293         }
1294
1295         return devmem;
1296
1297 error_devm_add_action:
1298         hmm_devmem_ref_kill(&devmem->ref);
1299         hmm_devmem_ref_exit(&devmem->ref);
1300 error_percpu_ref:
1301         devres_free(devmem);
1302         return ERR_PTR(ret);
1303 }
1304 EXPORT_SYMBOL(hmm_devmem_add_resource);
1305
1306 /*
1307  * hmm_devmem_remove() - remove device memory (kill and free ZONE_DEVICE)
1308  *
1309  * @devmem: hmm_devmem struct use to track and manage the ZONE_DEVICE memory
1310  *
1311  * This will hot-unplug memory that was hotplugged by hmm_devmem_add on behalf
1312  * of the device driver. It will free struct page and remove the resource that
1313  * reserved the physical address range for this device memory.
1314  */
1315 void hmm_devmem_remove(struct hmm_devmem *devmem)
1316 {
1317         resource_size_t start, size;
1318         struct device *device;
1319         bool cdm = false;
1320
1321         if (!devmem)
1322                 return;
1323
1324         device = devmem->device;
1325         start = devmem->resource->start;
1326         size = resource_size(devmem->resource);
1327
1328         cdm = devmem->resource->desc == IORES_DESC_DEVICE_PUBLIC_MEMORY;
1329         hmm_devmem_ref_kill(&devmem->ref);
1330         hmm_devmem_ref_exit(&devmem->ref);
1331         hmm_devmem_pages_remove(devmem);
1332
1333         if (!cdm)
1334                 devm_release_mem_region(device, start, size);
1335 }
1336 EXPORT_SYMBOL(hmm_devmem_remove);
1337
1338 /*
1339  * A device driver that wants to handle multiple devices memory through a
1340  * single fake device can use hmm_device to do so. This is purely a helper
1341  * and it is not needed to make use of any HMM functionality.
1342  */
1343 #define HMM_DEVICE_MAX 256
1344
1345 static DECLARE_BITMAP(hmm_device_mask, HMM_DEVICE_MAX);
1346 static DEFINE_SPINLOCK(hmm_device_lock);
1347 static struct class *hmm_device_class;
1348 static dev_t hmm_device_devt;
1349
1350 static void hmm_device_release(struct device *device)
1351 {
1352         struct hmm_device *hmm_device;
1353
1354         hmm_device = container_of(device, struct hmm_device, device);
1355         spin_lock(&hmm_device_lock);
1356         clear_bit(hmm_device->minor, hmm_device_mask);
1357         spin_unlock(&hmm_device_lock);
1358
1359         kfree(hmm_device);
1360 }
1361
1362 struct hmm_device *hmm_device_new(void *drvdata)
1363 {
1364         struct hmm_device *hmm_device;
1365
1366         hmm_device = kzalloc(sizeof(*hmm_device), GFP_KERNEL);
1367         if (!hmm_device)
1368                 return ERR_PTR(-ENOMEM);
1369
1370         spin_lock(&hmm_device_lock);
1371         hmm_device->minor = find_first_zero_bit(hmm_device_mask, HMM_DEVICE_MAX);
1372         if (hmm_device->minor >= HMM_DEVICE_MAX) {
1373                 spin_unlock(&hmm_device_lock);
1374                 kfree(hmm_device);
1375                 return ERR_PTR(-EBUSY);
1376         }
1377         set_bit(hmm_device->minor, hmm_device_mask);
1378         spin_unlock(&hmm_device_lock);
1379
1380         dev_set_name(&hmm_device->device, "hmm_device%d", hmm_device->minor);
1381         hmm_device->device.devt = MKDEV(MAJOR(hmm_device_devt),
1382                                         hmm_device->minor);
1383         hmm_device->device.release = hmm_device_release;
1384         dev_set_drvdata(&hmm_device->device, drvdata);
1385         hmm_device->device.class = hmm_device_class;
1386         device_initialize(&hmm_device->device);
1387
1388         return hmm_device;
1389 }
1390 EXPORT_SYMBOL(hmm_device_new);
1391
1392 void hmm_device_put(struct hmm_device *hmm_device)
1393 {
1394         put_device(&hmm_device->device);
1395 }
1396 EXPORT_SYMBOL(hmm_device_put);
1397
1398 static int __init hmm_init(void)
1399 {
1400         int ret;
1401
1402         ret = alloc_chrdev_region(&hmm_device_devt, 0,
1403                                   HMM_DEVICE_MAX,
1404                                   "hmm_device");
1405         if (ret)
1406                 return ret;
1407
1408         hmm_device_class = class_create(THIS_MODULE, "hmm_device");
1409         if (IS_ERR(hmm_device_class)) {
1410                 unregister_chrdev_region(hmm_device_devt, HMM_DEVICE_MAX);
1411                 return PTR_ERR(hmm_device_class);
1412         }
1413         return 0;
1414 }
1415
1416 device_initcall(hmm_init);
1417 #endif /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */