summaryrefslogtreecommitdiffstats
path: root/drivers/iommu/iommufd/io_pagetable.c
blob: 3467cea795684c9f203f519ee7db7f88b59b4d47 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES.
 *
 * The io_pagetable is the top of datastructure that maps IOVA's to PFNs. The
 * PFNs can be placed into an iommu_domain, or returned to the caller as a page
 * list for access by an in-kernel user.
 *
 * The datastructure uses the iopt_pages to optimize the storage of the PFNs
 * between the domains and xarray.
 */
#include <linux/iommufd.h>
#include <linux/lockdep.h>
#include <linux/iommu.h>
#include <linux/sched/mm.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/errno.h>

#include "io_pagetable.h"
#include "double_span.h"

struct iopt_pages_list {
	struct iopt_pages *pages;
	struct iopt_area *area;
	struct list_head next;
	unsigned long start_byte;
	unsigned long length;
};

struct iopt_area *iopt_area_contig_init(struct iopt_area_contig_iter *iter,
					struct io_pagetable *iopt,
					unsigned long iova,
					unsigned long last_iova)
{
	lockdep_assert_held(&iopt->iova_rwsem);

	iter->cur_iova = iova;
	iter->last_iova = last_iova;
	iter->area = iopt_area_iter_first(iopt, iova, iova);
	if (!iter->area)
		return NULL;
	if (!iter->area->pages) {
		iter->area = NULL;
		return NULL;
	}
	return iter->area;
}

struct iopt_area *iopt_area_contig_next(struct iopt_area_contig_iter *iter)
{
	unsigned long last_iova;

	if (!iter->area)
		return NULL;
	last_iova = iopt_area_last_iova(iter->area);
	if (iter->last_iova <= last_iova)
		return NULL;

	iter->cur_iova = last_iova + 1;
	iter->area = iopt_area_iter_next(iter->area, iter->cur_iova,
					 iter->last_iova);
	if (!iter->area)
		return NULL;
	if (iter->cur_iova != iopt_area_iova(iter->area) ||
	    !iter->area->pages) {
		iter->area = NULL;
		return NULL;
	}
	return iter->area;
}

static bool __alloc_iova_check_hole(struct interval_tree_double_span_iter *span,
				    unsigned long length,
				    unsigned long iova_alignment,
				    unsigned long page_offset)
{
	if (span->is_used || span->last_hole - span->start_hole < length - 1)
		return false;

	span->start_hole = ALIGN(span->start_hole, iova_alignment) |
			   page_offset;
	if (span->start_hole > span->last_hole ||
	    span->last_hole - span->start_hole < length - 1)
		return false;
	return true;
}

static bool __alloc_iova_check_used(struct interval_tree_span_iter *span,
				    unsigned long length,
				    unsigned long iova_alignment,
				    unsigned long page_offset)
{
	if (span->is_hole || span->last_used - span->start_used < length - 1)
		return false;

	span->start_used = ALIGN(span->start_used, iova_alignment) |
			   page_offset;
	if (span->start_used > span->last_used ||
	    span->last_used - span->start_used < length - 1)
		return false;
	return true;
}

/*
 * Automatically find a block of IOVA that is not being used and not reserved.
 * Does not return a 0 IOVA even if it is valid.
 */
static int iopt_alloc_iova(struct io_pagetable *iopt, unsigned long *iova,
			   unsigned long uptr, unsigned long length)
{
	unsigned long page_offset = uptr % PAGE_SIZE;
	struct interval_tree_double_span_iter used_span;
	struct interval_tree_span_iter allowed_span;
	unsigned long iova_alignment;

	lockdep_assert_held(&iopt->iova_rwsem);

	/* Protect roundup_pow-of_two() from overflow */
	if (length == 0 || length >= ULONG_MAX / 2)
		return -EOVERFLOW;

	/*
	 * Keep alignment present in the uptr when building the IOVA, this
	 * increases the chance we can map a THP.
	 */
	if (!uptr)
		iova_alignment = roundup_pow_of_two(length);
	else
		iova_alignment = min_t(unsigned long,
				       roundup_pow_of_two(length),
				       1UL << __ffs64(uptr));

	if (iova_alignment < iopt->iova_alignment)
		return -EINVAL;

	interval_tree_for_each_span(&allowed_span, &iopt->allowed_itree,
				    PAGE_SIZE, ULONG_MAX - PAGE_SIZE) {
		if (RB_EMPTY_ROOT(&iopt->allowed_itree.rb_root)) {
			allowed_span.start_used = PAGE_SIZE;
			allowed_span.last_used = ULONG_MAX - PAGE_SIZE;
			allowed_span.is_hole = false;
		}

		if (!__alloc_iova_check_used(&allowed_span, length,
					     iova_alignment, page_offset))
			continue;

		interval_tree_for_each_double_span(
			&used_span, &iopt->reserved_itree, &iopt->area_itree,
			allowed_span.start_used, allowed_span.last_used) {
			if (!__alloc_iova_check_hole(&used_span, length,
						     iova_alignment,
						     page_offset))
				continue;

			*iova = used_span.start_hole;
			return 0;
		}
	}
	return -ENOSPC;
}

static int iopt_check_iova(struct io_pagetable *iopt, unsigned long iova,
			   unsigned long length)
{
	unsigned long last;

	lockdep_assert_held(&iopt->iova_rwsem);

	if ((iova & (iopt->iova_alignment - 1)))
		return -EINVAL;

	if (check_add_overflow(iova, length - 1, &last))
		return -EOVERFLOW;

	/* No reserved IOVA intersects the range */
	if (iopt_reserved_iter_first(iopt, iova, last))
		return -EINVAL;

	/* Check that there is not already a mapping in the range */
	if (iopt_area_iter_first(iopt, iova, last))
		return -EEXIST;
	return 0;
}

/*
 * The area takes a slice of the pages from start_bytes to start_byte + length
 */
static int iopt_insert_area(struct io_pagetable *iopt, struct iopt_area *area,
			    struct iopt_pages *pages, unsigned long iova,
			    unsigned long start_byte, unsigned long length,
			    int iommu_prot)
{
	lockdep_assert_held_write(&iopt->iova_rwsem);

	if ((iommu_prot & IOMMU_WRITE) && !pages->writable)
		return -EPERM;

	area->iommu_prot = iommu_prot;
	area->page_offset = start_byte % PAGE_SIZE;
	if (area->page_offset & (iopt->iova_alignment - 1))
		return -EINVAL;

	area->node.start = iova;
	if (check_add_overflow(iova, length - 1, &area->node.last))
		return -EOVERFLOW;

	area->pages_node.start = start_byte / PAGE_SIZE;
	if (check_add_overflow(start_byte, length - 1, &area->pages_node.last))
		return -EOVERFLOW;
	area->pages_node.last = area->pages_node.last / PAGE_SIZE;
	if (WARN_ON(area->pages_node.last >= pages->npages))
		return -EOVERFLOW;

	/*
	 * The area is inserted with a NULL pages indicating it is not fully
	 * initialized yet.
	 */
	area->iopt = iopt;
	interval_tree_insert(&area->node, &iopt->area_itree);
	return 0;
}

static int iopt_alloc_area_pages(struct io_pagetable *iopt,
				 struct list_head *pages_list,
				 unsigned long length, unsigned long *dst_iova,
				 int iommu_prot, unsigned int flags)
{
	struct iopt_pages_list *elm;
	unsigned long iova;
	int rc = 0;

	list_for_each_entry(elm, pages_list, next) {
		elm->area = kzalloc(sizeof(*elm->area), GFP_KERNEL_ACCOUNT);
		if (!elm->area)
			return -ENOMEM;
	}

	down_write(&iopt->iova_rwsem);
	if ((length & (iopt->iova_alignment - 1)) || !length) {
		rc = -EINVAL;
		goto out_unlock;
	}

	if (flags & IOPT_ALLOC_IOVA) {
		/* Use the first entry to guess the ideal IOVA alignment */
		elm = list_first_entry(pages_list, struct iopt_pages_list,
				       next);
		rc = iopt_alloc_iova(
			iopt, dst_iova,
			(uintptr_t)elm->pages->uptr + elm->start_byte, length);
		if (rc)
			goto out_unlock;
		if (IS_ENABLED(CONFIG_IOMMUFD_TEST) &&
		    WARN_ON(iopt_check_iova(iopt, *dst_iova, length))) {
			rc = -EINVAL;
			goto out_unlock;
		}
	} else {
		rc = iopt_check_iova(iopt, *dst_iova, length);
		if (rc)
			goto out_unlock;
	}

	/*
	 * Areas are created with a NULL pages so that the IOVA space is
	 * reserved and we can unlock the iova_rwsem.
	 */
	iova = *dst_iova;
	list_for_each_entry(elm, pages_list, next) {
		rc = iopt_insert_area(iopt, elm->area, elm->pages, iova,
				      elm->start_byte, elm->length, iommu_prot);
		if (rc)
			goto out_unlock;
		iova += elm->length;
	}

out_unlock:
	up_write(&iopt->iova_rwsem);
	return rc;
}

static void iopt_abort_area(struct iopt_area *area)
{
	if (IS_ENABLED(CONFIG_IOMMUFD_TEST))
		WARN_ON(area->pages);
	if (area->iopt) {
		down_write(&area->iopt->iova_rwsem);
		interval_tree_remove(&area->node, &area->iopt->area_itree);
		up_write(&area->iopt->iova_rwsem);
	}
	kfree(area);
}

void iopt_free_pages_list(struct list_head *pages_list)
{
	struct iopt_pages_list *elm;

	while ((elm = list_first_entry_or_null(pages_list,
					       struct iopt_pages_list, next))) {
		if (elm->area)
			iopt_abort_area(elm->area);
		if (elm->pages)
			iopt_put_pages(elm->pages);
		list_del(&elm->next);
		kfree(elm);
	}
}

static int iopt_fill_domains_pages(struct list_head *pages_list)
{
	struct iopt_pages_list *undo_elm;
	struct iopt_pages_list *elm;
	int rc;

	list_for_each_entry(elm, pages_list, next) {
		rc = iopt_area_fill_domains(elm->area, elm->pages);
		if (rc)
			goto err_undo;
	}
	return 0;

err_undo:
	list_for_each_entry(undo_elm, pages_list, next) {
		if (undo_elm == elm)
			break;
		iopt_area_unfill_domains(undo_elm->area, undo_elm->pages);
	}
	return rc;
}

int iopt_map_pages(struct io_pagetable *iopt, struct list_head *pages_list,
		   unsigned long length, unsigned long *dst_iova,
		   int iommu_prot, unsigned int flags)
{
	struct iopt_pages_list *elm;
	int rc;

	rc = iopt_alloc_area_pages(iopt, pages_list, length, dst_iova,
				   iommu_prot, flags);
	if (rc)
		return rc;

	down_read(&iopt->domains_rwsem);
	rc = iopt_fill_domains_pages(pages_list);
	if (rc)
		goto out_unlock_domains;

	down_write(&iopt->iova_rwsem);
	list_for_each_entry(elm, pages_list, next) {
		/*
		 * area->pages must be set inside the domains_rwsem to ensure
		 * any newly added domains will get filled. Moves the reference
		 * in from the list.
		 */
		elm->area->pages = elm->pages;
		elm->pages = NULL;
		elm->area = NULL;
	}
	up_write(&iopt->iova_rwsem);
out_unlock_domains:
	up_read(&iopt->domains_rwsem);
	return rc;
}

/**
 * iopt_map_user_pages() - Map a user VA to an iova in the io page table
 * @ictx: iommufd_ctx the iopt is part of
 * @iopt: io_pagetable to act on
 * @iova: If IOPT_ALLOC_IOVA is set this is unused on input and contains
 *        the chosen iova on output. Otherwise is the iova to map to on input
 * @uptr: User VA to map
 * @length: Number of bytes to map
 * @iommu_prot: Combination of IOMMU_READ/WRITE/etc bits for the mapping
 * @flags: IOPT_ALLOC_IOVA or zero
 *
 * iova, uptr, and length must be aligned to iova_alignment. For domain backed
 * page tables this will pin the pages and load them into the domain at iova.
 * For non-domain page tables this will only setup a lazy reference and the
 * caller must use iopt_access_pages() to touch them.
 *
 * iopt_unmap_iova() must be called to undo this before the io_pagetable can be
 * destroyed.
 */
int iopt_map_user_pages(struct iommufd_ctx *ictx, struct io_pagetable *iopt,
			unsigned long *iova, void __user *uptr,
			unsigned long length, int iommu_prot,
			unsigned int flags)
{
	struct iopt_pages_list elm = {};
	LIST_HEAD(pages_list);
	int rc;

	elm.pages = iopt_alloc_pages(uptr, length, iommu_prot & IOMMU_WRITE);
	if (IS_ERR(elm.pages))
		return PTR_ERR(elm.pages);
	if (ictx->account_mode == IOPT_PAGES_ACCOUNT_MM &&
	    elm.pages->account_mode == IOPT_PAGES_ACCOUNT_USER)
		elm.pages->account_mode = IOPT_PAGES_ACCOUNT_MM;
	elm.start_byte = uptr - elm.pages->uptr;
	elm.length = length;
	list_add(&elm.next, &pages_list);

	rc = iopt_map_pages(iopt, &pages_list, length, iova, iommu_prot, flags);
	if (rc) {
		if (elm.area)
			iopt_abort_area(elm.area);
		if (elm.pages)
			iopt_put_pages(elm.pages);
		return rc;
	}
	return 0;
}

int iopt_get_pages(struct io_pagetable *iopt, unsigned long iova,
		   unsigned long length, struct list_head *pages_list)
{
	struct iopt_area_contig_iter iter;
	unsigned long last_iova;
	struct iopt_area *area;
	int rc;

	if (!length)
		return -EINVAL;
	if (check_add_overflow(iova, length - 1, &last_iova))
		return -EOVERFLOW;

	down_read(&iopt->iova_rwsem);
	iopt_for_each_contig_area(&iter, area, iopt, iova, last_iova) {
		struct iopt_pages_list *elm;
		unsigned long last = min(last_iova, iopt_area_last_iova(area));

		elm = kzalloc(sizeof(*elm), GFP_KERNEL_ACCOUNT);
		if (!elm) {
			rc = -ENOMEM;
			goto err_free;
		}
		elm->start_byte = iopt_area_start_byte(area, iter.cur_iova);
		elm->pages = area->pages;
		elm->length = (last - iter.cur_iova) + 1;
		kref_get(&elm->pages->kref);
		list_add_tail(&elm->next, pages_list);
	}
	if (!iopt_area_contig_done(&iter)) {
		rc = -ENOENT;
		goto err_free;
	}
	up_read(&iopt->iova_rwsem);
	return 0;
err_free:
	up_read(&iopt->iova_rwsem);
	iopt_free_pages_list(pages_list);
	return rc;
}

static int iopt_unmap_iova_range(struct io_pagetable *iopt, unsigned long start,
				 unsigned long last, unsigned long *unmapped)
{
	struct iopt_area *area;
	unsigned long unmapped_bytes = 0;
	int rc = -ENOENT;

	/*
	 * The domains_rwsem must be held in read mode any time any area->pages
	 * is NULL. This prevents domain attach/detatch from running
	 * concurrently with cleaning up the area.
	 */
again:
	down_read(&iopt->domains_rwsem);
	down_write(&iopt->iova_rwsem);
	while ((area = iopt_area_iter_first(iopt, start, last))) {
		unsigned long area_last = iopt_area_last_iova(area);
		unsigned long area_first = iopt_area_iova(area);
		struct iopt_pages *pages;

		/* Userspace should not race map/unmap's of the same area */
		if (!area->pages) {
			rc = -EBUSY;
			goto out_unlock_iova;
		}

		if (area_first < start || area_last > last) {
			rc = -ENOENT;
			goto out_unlock_iova;
		}

		/*
		 * num_accesses writers must hold the iova_rwsem too, so we can
		 * safely read it under the write side of the iovam_rwsem
		 * without the pages->mutex.
		 */
		if (area->num_accesses) {
			start = area_first;
			area->prevent_access = true;
			up_write(&iopt->iova_rwsem);
			up_read(&iopt->domains_rwsem);
			iommufd_access_notify_unmap(iopt, area_first,
						    iopt_area_length(area));
			if (WARN_ON(READ_ONCE(area->num_accesses)))
				return -EDEADLOCK;
			goto again;
		}

		pages = area->pages;
		area->pages = NULL;
		up_write(&iopt->iova_rwsem);

		iopt_area_unfill_domains(area, pages);
		iopt_abort_area(area);
		iopt_put_pages(pages);

		unmapped_bytes += area_last - area_first + 1;

		down_write(&iopt->iova_rwsem);
	}
	if (unmapped_bytes)
		rc = 0;

out_unlock_iova:
	up_write(&iopt->iova_rwsem);
	up_read(&iopt->domains_rwsem);
	if (unmapped)
		*unmapped = unmapped_bytes;
	return rc;
}

/**
 * iopt_unmap_iova() - Remove a range of iova
 * @iopt: io_pagetable to act on
 * @iova: Starting iova to unmap
 * @length: Number of bytes to unmap
 * @unmapped: Return number of bytes unmapped
 *
 * The requested range must be a superset of existing ranges.
 * Splitting/truncating IOVA mappings is not allowed.
 */
int iopt_unmap_iova(struct io_pagetable *iopt, unsigned long iova,
		    unsigned long length, unsigned long *unmapped)
{
	unsigned long iova_last;

	if (!length)
		return -EINVAL;

	if (check_add_overflow(iova, length - 1, &iova_last))
		return -EOVERFLOW;

	return iopt_unmap_iova_range(iopt, iova, iova_last, unmapped);
}

int iopt_unmap_all(struct io_pagetable *iopt, unsigned long *unmapped)
{
	int rc;

	rc = iopt_unmap_iova_range(iopt, 0, ULONG_MAX, unmapped);
	/* If the IOVAs are empty then unmap all succeeds */
	if (rc == -ENOENT)
		return 0;
	return rc;
}

/* The caller must always free all the nodes in the allowed_iova rb_root. */
int iopt_set_allow_iova(struct io_pagetable *iopt,
			struct rb_root_cached *allowed_iova)
{
	struct iopt_allowed *allowed;

	down_write(&iopt->iova_rwsem);
	swap(*allowed_iova, iopt->allowed_itree);

	for (allowed = iopt_allowed_iter_first(iopt, 0, ULONG_MAX); allowed;
	     allowed = iopt_allowed_iter_next(allowed, 0, ULONG_MAX)) {
		if (iopt_reserved_iter_first(iopt, allowed->node.start,
					     allowed->node.last)) {
			swap(*allowed_iova, iopt->allowed_itree);
			up_write(&iopt->iova_rwsem);
			return -EADDRINUSE;
		}
	}
	up_write(&iopt->iova_rwsem);
	return 0;
}

int iopt_reserve_iova(struct io_pagetable *iopt, unsigned long start,
		      unsigned long last, void *owner)
{
	struct iopt_reserved *reserved;

	lockdep_assert_held_write(&iopt->iova_rwsem);

	if (iopt_area_iter_first(iopt, start, last) ||
	    iopt_allowed_iter_first(iopt, start, last))
		return -EADDRINUSE;

	reserved = kzalloc(sizeof(*reserved), GFP_KERNEL_ACCOUNT);
	if (!reserved)
		return -ENOMEM;
	reserved->node.start = start;
	reserved->node.last = last;
	reserved->owner = owner;
	interval_tree_insert(&reserved->node, &iopt->reserved_itree);
	return 0;
}

static void __iopt_remove_reserved_iova(struct io_pagetable *iopt, void *owner)
{
	struct iopt_reserved *reserved, *next;

	lockdep_assert_held_write(&iopt->iova_rwsem);

	for (reserved = iopt_reserved_iter_first(iopt, 0, ULONG_MAX); reserved;
	     reserved = next) {
		next = iopt_reserved_iter_next(reserved, 0, ULONG_MAX);

		if (reserved->owner == owner) {
			interval_tree_remove(&reserved->node,
					     &iopt->reserved_itree);
			kfree(reserved);
		}
	}
}

void iopt_remove_reserved_iova(struct io_pagetable *iopt, void *owner)
{
	down_write(&iopt->iova_rwsem);
	__iopt_remove_reserved_iova(iopt, owner);
	up_write(&iopt->iova_rwsem);
}

void iopt_init_table(struct io_pagetable *iopt)
{
	init_rwsem(&iopt->iova_rwsem);
	init_rwsem(&iopt->domains_rwsem);
	iopt->area_itree = RB_ROOT_CACHED;
	iopt->allowed_itree = RB_ROOT_CACHED;
	iopt->reserved_itree = RB_ROOT_CACHED;
	xa_init_flags(&iopt->domains, XA_FLAGS_ACCOUNT);
	xa_init_flags(&iopt->access_list, XA_FLAGS_ALLOC);

	/*
	 * iopt's start as SW tables that can use the entire size_t IOVA space
	 * due to the use of size_t in the APIs. They have no alignment
	 * restriction.
	 */
	iopt->iova_alignment = 1;
}

void iopt_destroy_table(struct io_pagetable *iopt)
{
	struct interval_tree_node *node;

	if (IS_ENABLED(CONFIG_IOMMUFD_TEST))
		iopt_remove_reserved_iova(iopt, NULL);

	while ((node = interval_tree_iter_first(&iopt->allowed_itree, 0,
						ULONG_MAX))) {
		interval_tree_remove(node, &iopt->allowed_itree);
		kfree(container_of(node, struct iopt_allowed, node));
	}

	WARN_ON(!RB_EMPTY_ROOT(&iopt->reserved_itree.rb_root));
	WARN_ON(!xa_empty(&iopt->domains));
	WARN_ON(!xa_empty(&iopt->access_list));
	WARN_ON(!RB_EMPTY_ROOT(&iopt->area_itree.rb_root));
}

/**
 * iopt_unfill_domain() - Unfill a domain with PFNs
 * @iopt: io_pagetable to act on
 * @domain: domain to unfill
 *
 * This is used when removing a domain from the iopt. Every area in the iopt
 * will be unmapped from the domain. The domain must already be removed from the
 * domains xarray.
 */
static void iopt_unfill_domain(struct io_pagetable *iopt,
			       struct iommu_domain *domain)
{
	struct iopt_area *area;

	lockdep_assert_held(&iopt->iova_rwsem);
	lockdep_assert_held_write(&iopt->domains_rwsem);

	/*
	 * Some other domain is holding all the pfns still, rapidly unmap this
	 * domain.
	 */
	if (iopt->next_domain_id != 0) {
		/* Pick an arbitrary remaining domain to act as storage */
		struct iommu_domain *storage_domain =
			xa_load(&iopt->domains, 0);

		for (area = iopt_area_iter_first(iopt, 0, ULONG_MAX); area;
		     area = iopt_area_iter_next(area, 0, ULONG_MAX)) {
			struct iopt_pages *pages = area->pages;

			if (!pages)
				continue;

			mutex_lock(&pages->mutex);
			if (IS_ENABLED(CONFIG_IOMMUFD_TEST))
				WARN_ON(!area->storage_domain);
			if (area->storage_domain == domain)
				area->storage_domain = storage_domain;
			mutex_unlock(&pages->mutex);

			iopt_area_unmap_domain(area, domain);
		}
		return;
	}

	for (area = iopt_area_iter_first(iopt, 0, ULONG_MAX); area;
	     area = iopt_area_iter_next(area, 0, ULONG_MAX)) {
		struct iopt_pages *pages = area->pages;

		if (!pages)
			continue;

		mutex_lock(&pages->mutex);
		interval_tree_remove(&area->pages_node, &pages->domains_itree);
		WARN_ON(area->storage_domain != domain);
		area->storage_domain = NULL;
		iopt_area_unfill_domain(area, pages, domain);
		mutex_unlock(&pages->mutex);
	}
}

/**
 * iopt_fill_domain() - Fill a domain with PFNs
 * @iopt: io_pagetable to act on
 * @domain: domain to fill
 *
 * Fill the domain with PFNs from every area in the iopt. On failure the domain
 * is left unchanged.
 */
static int iopt_fill_domain(struct io_pagetable *iopt,
			    struct iommu_domain *domain)
{
	struct iopt_area *end_area;
	struct iopt_area *area;
	int rc;

	lockdep_assert_held(&iopt->iova_rwsem);
	lockdep_assert_held_write(&iopt->domains_rwsem);

	for (area = iopt_area_iter_first(iopt, 0, ULONG_MAX); area;
	     area = iopt_area_iter_next(area, 0, ULONG_MAX)) {
		struct iopt_pages *pages = area->pages;

		if (!pages)
			continue;

		mutex_lock(&pages->mutex);
		rc = iopt_area_fill_domain(area, domain);
		if (rc) {
			mutex_unlock(&pages->mutex);
			goto out_unfill;
		}
		if (!area->storage_domain) {
			WARN_ON(iopt->next_domain_id != 0);
			area->storage_domain = domain;
			interval_tree_insert(&area->pages_node,
					     &pages->domains_itree);
		}
		mutex_unlock(&pages->mutex);
	}
	return 0;

out_unfill:
	end_area = area;
	for (area = iopt_area_iter_first(iopt, 0, ULONG_MAX); area;
	     area = iopt_area_iter_next(area, 0, ULONG_MAX)) {
		struct iopt_pages *pages = area->pages;

		if (area == end_area)
			break;
		if (!pages)
			continue;
		mutex_lock(&pages->mutex);
		if (iopt->next_domain_id == 0) {
			interval_tree_remove(&area->pages_node,
					     &pages->domains_itree);
			area->storage_domain = NULL;
		}
		iopt_area_unfill_domain(area, pages, domain);
		mutex_unlock(&pages->mutex);
	}
	return rc;
}

/* All existing area's conform to an increased page size */
static int iopt_check_iova_alignment(struct io_pagetable *iopt,
				     unsigned long new_iova_alignment)
{
	unsigned long align_mask = new_iova_alignment - 1;
	struct iopt_area *area;

	lockdep_assert_held(&iopt->iova_rwsem);
	lockdep_assert_held(&iopt->domains_rwsem);

	for (area = iopt_area_iter_first(iopt, 0, ULONG_MAX); area;
	     area = iopt_area_iter_next(area, 0, ULONG_MAX))
		if ((iopt_area_iova(area) & align_mask) ||
		    (iopt_area_length(area) & align_mask) ||
		    (area->page_offset & align_mask))
			return -EADDRINUSE;

	if (IS_ENABLED(CONFIG_IOMMUFD_TEST)) {
		struct iommufd_access *access;
		unsigned long index;

		xa_for_each(&iopt->access_list, index, access)
			if (WARN_ON(access->iova_alignment >
				    new_iova_alignment))
				return -EADDRINUSE;
	}
	return 0;
}

int iopt_table_add_domain(struct io_pagetable *iopt,
			  struct iommu_domain *domain)
{
	const struct iommu_domain_geometry *geometry = &domain->geometry;
	struct iommu_domain *iter_domain;
	unsigned int new_iova_alignment;
	unsigned long index;
	int rc;

	down_write(&iopt->domains_rwsem);
	down_write(&iopt->iova_rwsem);

	xa_for_each(&iopt->domains, index, iter_domain) {
		if (WARN_ON(iter_domain == domain)) {
			rc = -EEXIST;
			goto out_unlock;
		}
	}

	/*
	 * The io page size drives the iova_alignment. Internally the iopt_pages
	 * works in PAGE_SIZE units and we adjust when mapping sub-PAGE_SIZE
	 * objects into the iommu_domain.
	 *
	 * A iommu_domain must always be able to accept PAGE_SIZE to be
	 * compatible as we can't guarantee higher contiguity.
	 */
	new_iova_alignment = max_t(unsigned long,
				   1UL << __ffs(domain->pgsize_bitmap),
				   iopt->iova_alignment);
	if (new_iova_alignment > PAGE_SIZE) {
		rc = -EINVAL;
		goto out_unlock;
	}
	if (new_iova_alignment != iopt->iova_alignment) {
		rc = iopt_check_iova_alignment(iopt, new_iova_alignment);
		if (rc)
			goto out_unlock;
	}

	/* No area exists that is outside the allowed domain aperture */
	if (geometry->aperture_start != 0) {
		rc = iopt_reserve_iova(iopt, 0, geometry->aperture_start - 1,
				       domain);
		if (rc)
			goto out_reserved;
	}
	if (geometry->aperture_end != ULONG_MAX) {
		rc = iopt_reserve_iova(iopt, geometry->aperture_end + 1,
				       ULONG_MAX, domain);
		if (rc)
			goto out_reserved;
	}

	rc = xa_reserve(&iopt->domains, iopt->next_domain_id, GFP_KERNEL);
	if (rc)
		goto out_reserved;

	rc = iopt_fill_domain(iopt, domain);
	if (rc)
		goto out_release;

	iopt->iova_alignment = new_iova_alignment;
	xa_store(&iopt->domains, iopt->next_domain_id, domain, GFP_KERNEL);
	iopt->next_domain_id++;
	up_write(&iopt->iova_rwsem);
	up_write(&iopt->domains_rwsem);
	return 0;
out_release:
	xa_release(&iopt->domains, iopt->next_domain_id);
out_reserved:
	__iopt_remove_reserved_iova(iopt, domain);
out_unlock:
	up_write(&iopt->iova_rwsem);
	up_write(&iopt->domains_rwsem);
	return rc;
}

static int iopt_calculate_iova_alignment(struct io_pagetable *iopt)
{
	unsigned long new_iova_alignment;
	struct iommufd_access *access;
	struct iommu_domain *domain;
	unsigned long index;

	lockdep_assert_held_write(&iopt->iova_rwsem);
	lockdep_assert_held(&iopt->domains_rwsem);

	/* See batch_iommu_map_small() */
	if (iopt->disable_large_pages)
		new_iova_alignment = PAGE_SIZE;
	else
		new_iova_alignment = 1;

	xa_for_each(&iopt->domains, index, domain)
		new_iova_alignment = max_t(unsigned long,
					   1UL << __ffs(domain->pgsize_bitmap),
					   new_iova_alignment);
	xa_for_each(&iopt->access_list, index, access)
		new_iova_alignment = max_t(unsigned long,
					   access->iova_alignment,
					   new_iova_alignment);

	if (new_iova_alignment > iopt->iova_alignment) {
		int rc;

		rc = iopt_check_iova_alignment(iopt, new_iova_alignment);
		if (rc)
			return rc;
	}
	iopt->iova_alignment = new_iova_alignment;
	return 0;
}

void iopt_table_remove_domain(struct io_pagetable *iopt,
			      struct iommu_domain *domain)
{
	struct iommu_domain *iter_domain = NULL;
	unsigned long index;

	down_write(&iopt->domains_rwsem);
	down_write(&iopt->iova_rwsem);

	xa_for_each(&iopt->domains, index, iter_domain)
		if (iter_domain == domain)
			break;
	if (WARN_ON(iter_domain != domain) || index >= iopt->next_domain_id)
		goto out_unlock;

	/*
	 * Compress the xarray to keep it linear by swapping the entry to erase
	 * with the tail entry and shrinking the tail.
	 */
	iopt->next_domain_id--;
	iter_domain = xa_erase(&iopt->domains, iopt->next_domain_id);
	if (index != iopt->next_domain_id)
		xa_store(&iopt->domains, index, iter_domain, GFP_KERNEL);

	iopt_unfill_domain(iopt, domain);
	__iopt_remove_reserved_iova(iopt, domain);

	WARN_ON(iopt_calculate_iova_alignment(iopt));
out_unlock:
	up_write(&iopt->iova_rwsem);
	up_write(&iopt->domains_rwsem);
}

/**
 * iopt_area_split - Split an area into two parts at iova
 * @area: The area to split
 * @iova: Becomes the last of a new area
 *
 * This splits an area into two. It is part of the VFIO compatibility to allow
 * poking a hole in the mapping. The two areas continue to point at the same
 * iopt_pages, just with different starting bytes.
 */
static int iopt_area_split(struct iopt_area *area, unsigned long iova)
{
	unsigned long alignment = area->iopt->iova_alignment;
	unsigned long last_iova = iopt_area_last_iova(area);
	unsigned long start_iova = iopt_area_iova(area);
	unsigned long new_start = iova + 1;
	struct io_pagetable *iopt = area->iopt;
	struct iopt_pages *pages = area->pages;
	struct iopt_area *lhs;
	struct iopt_area *rhs;
	int rc;

	lockdep_assert_held_write(&iopt->iova_rwsem);

	if (iova == start_iova || iova == last_iova)
		return 0;

	if (!pages || area->prevent_access)
		return -EBUSY;

	if (new_start & (alignment - 1) ||
	    iopt_area_start_byte(area, new_start) & (alignment - 1))
		return -EINVAL;

	lhs = kzalloc(sizeof(*area), GFP_KERNEL_ACCOUNT);
	if (!lhs)
		return -ENOMEM;

	rhs = kzalloc(sizeof(*area), GFP_KERNEL_ACCOUNT);
	if (!rhs) {
		rc = -ENOMEM;
		goto err_free_lhs;
	}

	mutex_lock(&pages->mutex);
	/*
	 * Splitting is not permitted if an access exists, we don't track enough
	 * information to split existing accesses.
	 */
	if (area->num_accesses) {
		rc = -EINVAL;
		goto err_unlock;
	}

	/*
	 * Splitting is not permitted if a domain could have been mapped with
	 * huge pages.
	 */
	if (area->storage_domain && !iopt->disable_large_pages) {
		rc = -EINVAL;
		goto err_unlock;
	}

	interval_tree_remove(&area->node, &iopt->area_itree);
	rc = iopt_insert_area(iopt, lhs, area->pages, start_iova,
			      iopt_area_start_byte(area, start_iova),
			      (new_start - 1) - start_iova + 1,
			      area->iommu_prot);
	if (WARN_ON(rc))
		goto err_insert;

	rc = iopt_insert_area(iopt, rhs, area->pages, new_start,
			      iopt_area_start_byte(area, new_start),
			      last_iova - new_start + 1, area->iommu_prot);
	if (WARN_ON(rc))
		goto err_remove_lhs;

	lhs->storage_domain = area->storage_domain;
	lhs->pages = area->pages;
	rhs->storage_domain = area->storage_domain;
	rhs->pages = area->pages;
	kref_get(&rhs->pages->kref);
	kfree(area);
	mutex_unlock(&pages->mutex);

	/*
	 * No change to domains or accesses because the pages hasn't been
	 * changed
	 */
	return 0;

err_remove_lhs:
	interval_tree_remove(&lhs->node, &iopt->area_itree);
err_insert:
	interval_tree_insert(&area->node, &iopt->area_itree);
err_unlock:
	mutex_unlock(&pages->mutex);
	kfree(rhs);
err_free_lhs:
	kfree(lhs);
	return rc;
}

int iopt_cut_iova(struct io_pagetable *iopt, unsigned long *iovas,
		  size_t num_iovas)
{
	int rc = 0;
	int i;

	down_write(&iopt->iova_rwsem);
	for (i = 0; i < num_iovas; i++) {
		struct iopt_area *area;

		area = iopt_area_iter_first(iopt, iovas[i], iovas[i]);
		if (!area)
			continue;
		rc = iopt_area_split(area, iovas[i]);
		if (rc)
			break;
	}
	up_write(&iopt->iova_rwsem);
	return rc;
}

void iopt_enable_large_pages(struct io_pagetable *iopt)
{
	int rc;

	down_write(&iopt->domains_rwsem);
	down_write(&iopt->iova_rwsem);
	WRITE_ONCE(iopt->disable_large_pages, false);
	rc = iopt_calculate_iova_alignment(iopt);
	WARN_ON(rc);
	up_write(&iopt->iova_rwsem);
	up_write(&iopt->domains_rwsem);
}

int iopt_disable_large_pages(struct io_pagetable *iopt)
{
	int rc = 0;

	down_write(&iopt->domains_rwsem);
	down_write(&iopt->iova_rwsem);
	if (iopt->disable_large_pages)
		goto out_unlock;

	/* Won't do it if domains already have pages mapped in them */
	if (!xa_empty(&iopt->domains) &&
	    !RB_EMPTY_ROOT(&iopt->area_itree.rb_root)) {
		rc = -EINVAL;
		goto out_unlock;
	}

	WRITE_ONCE(iopt->disable_large_pages, true);
	rc = iopt_calculate_iova_alignment(iopt);
	if (rc)
		WRITE_ONCE(iopt->disable_large_pages, false);
out_unlock:
	up_write(&iopt->iova_rwsem);
	up_write(&iopt->domains_rwsem);
	return rc;
}

int iopt_add_access(struct io_pagetable *iopt, struct iommufd_access *access)
{
	int rc;

	down_write(&iopt->domains_rwsem);
	down_write(&iopt->iova_rwsem);
	rc = xa_alloc(&iopt->access_list, &access->iopt_access_list_id, access,
		      xa_limit_16b, GFP_KERNEL_ACCOUNT);
	if (rc)
		goto out_unlock;

	rc = iopt_calculate_iova_alignment(iopt);
	if (rc) {
		xa_erase(&iopt->access_list, access->iopt_access_list_id);
		goto out_unlock;
	}

out_unlock:
	up_write(&iopt->iova_rwsem);
	up_write(&iopt->domains_rwsem);
	return rc;
}

void iopt_remove_access(struct io_pagetable *iopt,
			struct iommufd_access *access)
{
	down_write(&iopt->domains_rwsem);
	down_write(&iopt->iova_rwsem);
	WARN_ON(xa_erase(&iopt->access_list, access->iopt_access_list_id) !=
		access);
	WARN_ON(iopt_calculate_iova_alignment(iopt));
	up_write(&iopt->iova_rwsem);
	up_write(&iopt->domains_rwsem);
}

/* Narrow the valid_iova_itree to include reserved ranges from a group. */
int iopt_table_enforce_group_resv_regions(struct io_pagetable *iopt,
					  struct device *device,
					  struct iommu_group *group,
					  phys_addr_t *sw_msi_start)
{
	struct iommu_resv_region *resv;
	struct iommu_resv_region *tmp;
	LIST_HEAD(group_resv_regions);
	int rc;

	down_write(&iopt->iova_rwsem);
	rc = iommu_get_group_resv_regions(group, &group_resv_regions);
	if (rc)
		goto out_unlock;

	list_for_each_entry(resv, &group_resv_regions, list) {
		if (resv->type == IOMMU_RESV_DIRECT_RELAXABLE)
			continue;

		/*
		 * The presence of any 'real' MSI regions should take precedence
		 * over the software-managed one if the IOMMU driver happens to
		 * advertise both types.
		 */
		if (sw_msi_start && resv->type == IOMMU_RESV_MSI) {
			*sw_msi_start = 0;
			sw_msi_start = NULL;
		}
		if (sw_msi_start && resv->type == IOMMU_RESV_SW_MSI)
			*sw_msi_start = resv->start;

		rc = iopt_reserve_iova(iopt, resv->start,
				       resv->length - 1 + resv->start, device);
		if (rc)
			goto out_reserved;
	}
	rc = 0;
	goto out_free_resv;

out_reserved:
	__iopt_remove_reserved_iova(iopt, device);
out_free_resv:
	list_for_each_entry_safe(resv, tmp, &group_resv_regions, list)
		kfree(resv);
out_unlock:
	up_write(&iopt->iova_rwsem);
	return rc;
}