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11#include <linux/pagewalk.h>
12#include <linux/hmm.h>
13#include <linux/init.h>
14#include <linux/rmap.h>
15#include <linux/swap.h>
16#include <linux/slab.h>
17#include <linux/sched.h>
18#include <linux/mmzone.h>
19#include <linux/pagemap.h>
20#include <linux/swapops.h>
21#include <linux/hugetlb.h>
22#include <linux/memremap.h>
23#include <linux/sched/mm.h>
24#include <linux/jump_label.h>
25#include <linux/dma-mapping.h>
26#include <linux/mmu_notifier.h>
27#include <linux/memory_hotplug.h>
28
29#include "internal.h"
30
31struct hmm_vma_walk {
32 struct hmm_range *range;
33 unsigned long last;
34};
35
36enum {
37 HMM_NEED_FAULT = 1 << 0,
38 HMM_NEED_WRITE_FAULT = 1 << 1,
39 HMM_NEED_ALL_BITS = HMM_NEED_FAULT | HMM_NEED_WRITE_FAULT,
40};
41
42static int hmm_pfns_fill(unsigned long addr, unsigned long end,
43 struct hmm_range *range, unsigned long cpu_flags)
44{
45 unsigned long i = (addr - range->start) >> PAGE_SHIFT;
46
47 for (; addr < end; addr += PAGE_SIZE, i++)
48 range->hmm_pfns[i] = cpu_flags;
49 return 0;
50}
51
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61
62
63static int hmm_vma_fault(unsigned long addr, unsigned long end,
64 unsigned int required_fault, struct mm_walk *walk)
65{
66 struct hmm_vma_walk *hmm_vma_walk = walk->private;
67 struct vm_area_struct *vma = walk->vma;
68 unsigned int fault_flags = FAULT_FLAG_REMOTE;
69
70 WARN_ON_ONCE(!required_fault);
71 hmm_vma_walk->last = addr;
72
73 if (required_fault & HMM_NEED_WRITE_FAULT) {
74 if (!(vma->vm_flags & VM_WRITE))
75 return -EPERM;
76 fault_flags |= FAULT_FLAG_WRITE;
77 }
78
79 for (; addr < end; addr += PAGE_SIZE)
80 if (handle_mm_fault(vma, addr, fault_flags, NULL) &
81 VM_FAULT_ERROR)
82 return -EFAULT;
83 return -EBUSY;
84}
85
86static unsigned int hmm_pte_need_fault(const struct hmm_vma_walk *hmm_vma_walk,
87 unsigned long pfn_req_flags,
88 unsigned long cpu_flags)
89{
90 struct hmm_range *range = hmm_vma_walk->range;
91
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100
101
102 pfn_req_flags &= range->pfn_flags_mask;
103 pfn_req_flags |= range->default_flags;
104
105
106 if (!(pfn_req_flags & HMM_PFN_REQ_FAULT))
107 return 0;
108
109
110 if ((pfn_req_flags & HMM_PFN_REQ_WRITE) &&
111 !(cpu_flags & HMM_PFN_WRITE))
112 return HMM_NEED_FAULT | HMM_NEED_WRITE_FAULT;
113
114
115 if (!(cpu_flags & HMM_PFN_VALID))
116 return HMM_NEED_FAULT;
117 return 0;
118}
119
120static unsigned int
121hmm_range_need_fault(const struct hmm_vma_walk *hmm_vma_walk,
122 const unsigned long hmm_pfns[], unsigned long npages,
123 unsigned long cpu_flags)
124{
125 struct hmm_range *range = hmm_vma_walk->range;
126 unsigned int required_fault = 0;
127 unsigned long i;
128
129
130
131
132
133
134 if (!((range->default_flags | range->pfn_flags_mask) &
135 HMM_PFN_REQ_FAULT))
136 return 0;
137
138 for (i = 0; i < npages; ++i) {
139 required_fault |= hmm_pte_need_fault(hmm_vma_walk, hmm_pfns[i],
140 cpu_flags);
141 if (required_fault == HMM_NEED_ALL_BITS)
142 return required_fault;
143 }
144 return required_fault;
145}
146
147static int hmm_vma_walk_hole(unsigned long addr, unsigned long end,
148 __always_unused int depth, struct mm_walk *walk)
149{
150 struct hmm_vma_walk *hmm_vma_walk = walk->private;
151 struct hmm_range *range = hmm_vma_walk->range;
152 unsigned int required_fault;
153 unsigned long i, npages;
154 unsigned long *hmm_pfns;
155
156 i = (addr - range->start) >> PAGE_SHIFT;
157 npages = (end - addr) >> PAGE_SHIFT;
158 hmm_pfns = &range->hmm_pfns[i];
159 required_fault =
160 hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, 0);
161 if (!walk->vma) {
162 if (required_fault)
163 return -EFAULT;
164 return hmm_pfns_fill(addr, end, range, HMM_PFN_ERROR);
165 }
166 if (required_fault)
167 return hmm_vma_fault(addr, end, required_fault, walk);
168 return hmm_pfns_fill(addr, end, range, 0);
169}
170
171static inline unsigned long hmm_pfn_flags_order(unsigned long order)
172{
173 return order << HMM_PFN_ORDER_SHIFT;
174}
175
176static inline unsigned long pmd_to_hmm_pfn_flags(struct hmm_range *range,
177 pmd_t pmd)
178{
179 if (pmd_protnone(pmd))
180 return 0;
181 return (pmd_write(pmd) ? (HMM_PFN_VALID | HMM_PFN_WRITE) :
182 HMM_PFN_VALID) |
183 hmm_pfn_flags_order(PMD_SHIFT - PAGE_SHIFT);
184}
185
186#ifdef CONFIG_TRANSPARENT_HUGEPAGE
187static int hmm_vma_handle_pmd(struct mm_walk *walk, unsigned long addr,
188 unsigned long end, unsigned long hmm_pfns[],
189 pmd_t pmd)
190{
191 struct hmm_vma_walk *hmm_vma_walk = walk->private;
192 struct hmm_range *range = hmm_vma_walk->range;
193 unsigned long pfn, npages, i;
194 unsigned int required_fault;
195 unsigned long cpu_flags;
196
197 npages = (end - addr) >> PAGE_SHIFT;
198 cpu_flags = pmd_to_hmm_pfn_flags(range, pmd);
199 required_fault =
200 hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, cpu_flags);
201 if (required_fault)
202 return hmm_vma_fault(addr, end, required_fault, walk);
203
204 pfn = pmd_pfn(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
205 for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++)
206 hmm_pfns[i] = pfn | cpu_flags;
207 return 0;
208}
209#else
210
211int hmm_vma_handle_pmd(struct mm_walk *walk, unsigned long addr,
212 unsigned long end, unsigned long hmm_pfns[], pmd_t pmd);
213#endif
214
215static inline bool hmm_is_device_private_entry(struct hmm_range *range,
216 swp_entry_t entry)
217{
218 return is_device_private_entry(entry) &&
219 pfn_swap_entry_to_page(entry)->pgmap->owner ==
220 range->dev_private_owner;
221}
222
223static inline unsigned long pte_to_hmm_pfn_flags(struct hmm_range *range,
224 pte_t pte)
225{
226 if (pte_none(pte) || !pte_present(pte) || pte_protnone(pte))
227 return 0;
228 return pte_write(pte) ? (HMM_PFN_VALID | HMM_PFN_WRITE) : HMM_PFN_VALID;
229}
230
231static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
232 unsigned long end, pmd_t *pmdp, pte_t *ptep,
233 unsigned long *hmm_pfn)
234{
235 struct hmm_vma_walk *hmm_vma_walk = walk->private;
236 struct hmm_range *range = hmm_vma_walk->range;
237 unsigned int required_fault;
238 unsigned long cpu_flags;
239 pte_t pte = *ptep;
240 uint64_t pfn_req_flags = *hmm_pfn;
241
242 if (pte_none(pte)) {
243 required_fault =
244 hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0);
245 if (required_fault)
246 goto fault;
247 *hmm_pfn = 0;
248 return 0;
249 }
250
251 if (!pte_present(pte)) {
252 swp_entry_t entry = pte_to_swp_entry(pte);
253
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256
257
258 if (hmm_is_device_private_entry(range, entry)) {
259 cpu_flags = HMM_PFN_VALID;
260 if (is_writable_device_private_entry(entry))
261 cpu_flags |= HMM_PFN_WRITE;
262 *hmm_pfn = swp_offset(entry) | cpu_flags;
263 return 0;
264 }
265
266 required_fault =
267 hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0);
268 if (!required_fault) {
269 *hmm_pfn = 0;
270 return 0;
271 }
272
273 if (!non_swap_entry(entry))
274 goto fault;
275
276 if (is_device_exclusive_entry(entry))
277 goto fault;
278
279 if (is_migration_entry(entry)) {
280 pte_unmap(ptep);
281 hmm_vma_walk->last = addr;
282 migration_entry_wait(walk->mm, pmdp, addr);
283 return -EBUSY;
284 }
285
286
287 pte_unmap(ptep);
288 return -EFAULT;
289 }
290
291 cpu_flags = pte_to_hmm_pfn_flags(range, pte);
292 required_fault =
293 hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, cpu_flags);
294 if (required_fault)
295 goto fault;
296
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301 if (pte_special(pte) && !is_zero_pfn(pte_pfn(pte))) {
302 if (hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0)) {
303 pte_unmap(ptep);
304 return -EFAULT;
305 }
306 *hmm_pfn = HMM_PFN_ERROR;
307 return 0;
308 }
309
310 *hmm_pfn = pte_pfn(pte) | cpu_flags;
311 return 0;
312
313fault:
314 pte_unmap(ptep);
315
316 return hmm_vma_fault(addr, end, required_fault, walk);
317}
318
319static int hmm_vma_walk_pmd(pmd_t *pmdp,
320 unsigned long start,
321 unsigned long end,
322 struct mm_walk *walk)
323{
324 struct hmm_vma_walk *hmm_vma_walk = walk->private;
325 struct hmm_range *range = hmm_vma_walk->range;
326 unsigned long *hmm_pfns =
327 &range->hmm_pfns[(start - range->start) >> PAGE_SHIFT];
328 unsigned long npages = (end - start) >> PAGE_SHIFT;
329 unsigned long addr = start;
330 pte_t *ptep;
331 pmd_t pmd;
332
333again:
334 pmd = READ_ONCE(*pmdp);
335 if (pmd_none(pmd))
336 return hmm_vma_walk_hole(start, end, -1, walk);
337
338 if (thp_migration_supported() && is_pmd_migration_entry(pmd)) {
339 if (hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, 0)) {
340 hmm_vma_walk->last = addr;
341 pmd_migration_entry_wait(walk->mm, pmdp);
342 return -EBUSY;
343 }
344 return hmm_pfns_fill(start, end, range, 0);
345 }
346
347 if (!pmd_present(pmd)) {
348 if (hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, 0))
349 return -EFAULT;
350 return hmm_pfns_fill(start, end, range, HMM_PFN_ERROR);
351 }
352
353 if (pmd_devmap(pmd) || pmd_trans_huge(pmd)) {
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363 pmd = pmd_read_atomic(pmdp);
364 barrier();
365 if (!pmd_devmap(pmd) && !pmd_trans_huge(pmd))
366 goto again;
367
368 return hmm_vma_handle_pmd(walk, addr, end, hmm_pfns, pmd);
369 }
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376
377 if (pmd_bad(pmd)) {
378 if (hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, 0))
379 return -EFAULT;
380 return hmm_pfns_fill(start, end, range, HMM_PFN_ERROR);
381 }
382
383 ptep = pte_offset_map(pmdp, addr);
384 for (; addr < end; addr += PAGE_SIZE, ptep++, hmm_pfns++) {
385 int r;
386
387 r = hmm_vma_handle_pte(walk, addr, end, pmdp, ptep, hmm_pfns);
388 if (r) {
389
390 return r;
391 }
392 }
393 pte_unmap(ptep - 1);
394 return 0;
395}
396
397#if defined(CONFIG_ARCH_HAS_PTE_DEVMAP) && \
398 defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
399static inline unsigned long pud_to_hmm_pfn_flags(struct hmm_range *range,
400 pud_t pud)
401{
402 if (!pud_present(pud))
403 return 0;
404 return (pud_write(pud) ? (HMM_PFN_VALID | HMM_PFN_WRITE) :
405 HMM_PFN_VALID) |
406 hmm_pfn_flags_order(PUD_SHIFT - PAGE_SHIFT);
407}
408
409static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end,
410 struct mm_walk *walk)
411{
412 struct hmm_vma_walk *hmm_vma_walk = walk->private;
413 struct hmm_range *range = hmm_vma_walk->range;
414 unsigned long addr = start;
415 pud_t pud;
416 int ret = 0;
417 spinlock_t *ptl = pud_trans_huge_lock(pudp, walk->vma);
418
419 if (!ptl)
420 return 0;
421
422
423 walk->action = ACTION_CONTINUE;
424
425 pud = READ_ONCE(*pudp);
426 if (pud_none(pud)) {
427 spin_unlock(ptl);
428 return hmm_vma_walk_hole(start, end, -1, walk);
429 }
430
431 if (pud_huge(pud) && pud_devmap(pud)) {
432 unsigned long i, npages, pfn;
433 unsigned int required_fault;
434 unsigned long *hmm_pfns;
435 unsigned long cpu_flags;
436
437 if (!pud_present(pud)) {
438 spin_unlock(ptl);
439 return hmm_vma_walk_hole(start, end, -1, walk);
440 }
441
442 i = (addr - range->start) >> PAGE_SHIFT;
443 npages = (end - addr) >> PAGE_SHIFT;
444 hmm_pfns = &range->hmm_pfns[i];
445
446 cpu_flags = pud_to_hmm_pfn_flags(range, pud);
447 required_fault = hmm_range_need_fault(hmm_vma_walk, hmm_pfns,
448 npages, cpu_flags);
449 if (required_fault) {
450 spin_unlock(ptl);
451 return hmm_vma_fault(addr, end, required_fault, walk);
452 }
453
454 pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
455 for (i = 0; i < npages; ++i, ++pfn)
456 hmm_pfns[i] = pfn | cpu_flags;
457 goto out_unlock;
458 }
459
460
461 walk->action = ACTION_SUBTREE;
462
463out_unlock:
464 spin_unlock(ptl);
465 return ret;
466}
467#else
468#define hmm_vma_walk_pud NULL
469#endif
470
471#ifdef CONFIG_HUGETLB_PAGE
472static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask,
473 unsigned long start, unsigned long end,
474 struct mm_walk *walk)
475{
476 unsigned long addr = start, i, pfn;
477 struct hmm_vma_walk *hmm_vma_walk = walk->private;
478 struct hmm_range *range = hmm_vma_walk->range;
479 struct vm_area_struct *vma = walk->vma;
480 unsigned int required_fault;
481 unsigned long pfn_req_flags;
482 unsigned long cpu_flags;
483 spinlock_t *ptl;
484 pte_t entry;
485
486 ptl = huge_pte_lock(hstate_vma(vma), walk->mm, pte);
487 entry = huge_ptep_get(pte);
488
489 i = (start - range->start) >> PAGE_SHIFT;
490 pfn_req_flags = range->hmm_pfns[i];
491 cpu_flags = pte_to_hmm_pfn_flags(range, entry) |
492 hmm_pfn_flags_order(huge_page_order(hstate_vma(vma)));
493 required_fault =
494 hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, cpu_flags);
495 if (required_fault) {
496 spin_unlock(ptl);
497 return hmm_vma_fault(addr, end, required_fault, walk);
498 }
499
500 pfn = pte_pfn(entry) + ((start & ~hmask) >> PAGE_SHIFT);
501 for (; addr < end; addr += PAGE_SIZE, i++, pfn++)
502 range->hmm_pfns[i] = pfn | cpu_flags;
503
504 spin_unlock(ptl);
505 return 0;
506}
507#else
508#define hmm_vma_walk_hugetlb_entry NULL
509#endif
510
511static int hmm_vma_walk_test(unsigned long start, unsigned long end,
512 struct mm_walk *walk)
513{
514 struct hmm_vma_walk *hmm_vma_walk = walk->private;
515 struct hmm_range *range = hmm_vma_walk->range;
516 struct vm_area_struct *vma = walk->vma;
517
518 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP | VM_MIXEDMAP)) &&
519 vma->vm_flags & VM_READ)
520 return 0;
521
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533 if (hmm_range_need_fault(hmm_vma_walk,
534 range->hmm_pfns +
535 ((start - range->start) >> PAGE_SHIFT),
536 (end - start) >> PAGE_SHIFT, 0))
537 return -EFAULT;
538
539 hmm_pfns_fill(start, end, range, HMM_PFN_ERROR);
540
541
542 return 1;
543}
544
545static const struct mm_walk_ops hmm_walk_ops = {
546 .pud_entry = hmm_vma_walk_pud,
547 .pmd_entry = hmm_vma_walk_pmd,
548 .pte_hole = hmm_vma_walk_hole,
549 .hugetlb_entry = hmm_vma_walk_hugetlb_entry,
550 .test_walk = hmm_vma_walk_test,
551};
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571
572int hmm_range_fault(struct hmm_range *range)
573{
574 struct hmm_vma_walk hmm_vma_walk = {
575 .range = range,
576 .last = range->start,
577 };
578 struct mm_struct *mm = range->notifier->mm;
579 int ret;
580
581 mmap_assert_locked(mm);
582
583 do {
584
585 if (mmu_interval_check_retry(range->notifier,
586 range->notifier_seq))
587 return -EBUSY;
588 ret = walk_page_range(mm, hmm_vma_walk.last, range->end,
589 &hmm_walk_ops, &hmm_vma_walk);
590
591
592
593
594
595
596 } while (ret == -EBUSY);
597 return ret;
598}
599EXPORT_SYMBOL(hmm_range_fault);
600