summaryrefslogtreecommitdiffstats
path: root/arch/s390/mm/pgtable.c
blob: 4a1f7366b17aeffacb6c766ab891227e2609f1b9 (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
/*
 *    Copyright IBM Corp. 2007, 2011
 *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
 */

#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/gfp.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/slab.h>
#include <linux/swapops.h>
#include <linux/sysctl.h>
#include <linux/ksm.h>
#include <linux/mman.h>

#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/page-states.h>

static inline pte_t ptep_flush_direct(struct mm_struct *mm,
				      unsigned long addr, pte_t *ptep)
{
	pte_t old;

	old = *ptep;
	if (unlikely(pte_val(old) & _PAGE_INVALID))
		return old;
	atomic_inc(&mm->context.flush_count);
	if (MACHINE_HAS_TLB_LC &&
	    cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id())))
		__ptep_ipte(addr, ptep, IPTE_LOCAL);
	else
		__ptep_ipte(addr, ptep, IPTE_GLOBAL);
	atomic_dec(&mm->context.flush_count);
	return old;
}

static inline pte_t ptep_flush_lazy(struct mm_struct *mm,
				    unsigned long addr, pte_t *ptep)
{
	pte_t old;

	old = *ptep;
	if (unlikely(pte_val(old) & _PAGE_INVALID))
		return old;
	atomic_inc(&mm->context.flush_count);
	if (cpumask_equal(&mm->context.cpu_attach_mask,
			  cpumask_of(smp_processor_id()))) {
		pte_val(*ptep) |= _PAGE_INVALID;
		mm->context.flush_mm = 1;
	} else
		__ptep_ipte(addr, ptep, IPTE_GLOBAL);
	atomic_dec(&mm->context.flush_count);
	return old;
}

static inline pgste_t pgste_get_lock(pte_t *ptep)
{
	unsigned long new = 0;
#ifdef CONFIG_PGSTE
	unsigned long old;

	asm(
		"	lg	%0,%2\n"
		"0:	lgr	%1,%0\n"
		"	nihh	%0,0xff7f\n"	/* clear PCL bit in old */
		"	oihh	%1,0x0080\n"	/* set PCL bit in new */
		"	csg	%0,%1,%2\n"
		"	jl	0b\n"
		: "=&d" (old), "=&d" (new), "=Q" (ptep[PTRS_PER_PTE])
		: "Q" (ptep[PTRS_PER_PTE]) : "cc", "memory");
#endif
	return __pgste(new);
}

static inline void pgste_set_unlock(pte_t *ptep, pgste_t pgste)
{
#ifdef CONFIG_PGSTE
	asm(
		"	nihh	%1,0xff7f\n"	/* clear PCL bit */
		"	stg	%1,%0\n"
		: "=Q" (ptep[PTRS_PER_PTE])
		: "d" (pgste_val(pgste)), "Q" (ptep[PTRS_PER_PTE])
		: "cc", "memory");
#endif
}

static inline pgste_t pgste_get(pte_t *ptep)
{
	unsigned long pgste = 0;
#ifdef CONFIG_PGSTE
	pgste = *(unsigned long *)(ptep + PTRS_PER_PTE);
#endif
	return __pgste(pgste);
}

static inline void pgste_set(pte_t *ptep, pgste_t pgste)
{
#ifdef CONFIG_PGSTE
	*(pgste_t *)(ptep + PTRS_PER_PTE) = pgste;
#endif
}

static inline pgste_t pgste_update_all(pte_t pte, pgste_t pgste,
				       struct mm_struct *mm)
{
#ifdef CONFIG_PGSTE
	unsigned long address, bits, skey;

	if (!mm_use_skey(mm) || pte_val(pte) & _PAGE_INVALID)
		return pgste;
	address = pte_val(pte) & PAGE_MASK;
	skey = (unsigned long) page_get_storage_key(address);
	bits = skey & (_PAGE_CHANGED | _PAGE_REFERENCED);
	/* Transfer page changed & referenced bit to guest bits in pgste */
	pgste_val(pgste) |= bits << 48;		/* GR bit & GC bit */
	/* Copy page access key and fetch protection bit to pgste */
	pgste_val(pgste) &= ~(PGSTE_ACC_BITS | PGSTE_FP_BIT);
	pgste_val(pgste) |= (skey & (_PAGE_ACC_BITS | _PAGE_FP_BIT)) << 56;
#endif
	return pgste;

}

static inline void pgste_set_key(pte_t *ptep, pgste_t pgste, pte_t entry,
				 struct mm_struct *mm)
{
#ifdef CONFIG_PGSTE
	unsigned long address;
	unsigned long nkey;

	if (!mm_use_skey(mm) || pte_val(entry) & _PAGE_INVALID)
		return;
	VM_BUG_ON(!(pte_val(*ptep) & _PAGE_INVALID));
	address = pte_val(entry) & PAGE_MASK;
	/*
	 * Set page access key and fetch protection bit from pgste.
	 * The guest C/R information is still in the PGSTE, set real
	 * key C/R to 0.
	 */
	nkey = (pgste_val(pgste) & (PGSTE_ACC_BITS | PGSTE_FP_BIT)) >> 56;
	nkey |= (pgste_val(pgste) & (PGSTE_GR_BIT | PGSTE_GC_BIT)) >> 48;
	page_set_storage_key(address, nkey, 0);
#endif
}

static inline pgste_t pgste_set_pte(pte_t *ptep, pgste_t pgste, pte_t entry)
{
#ifdef CONFIG_PGSTE
	if ((pte_val(entry) & _PAGE_PRESENT) &&
	    (pte_val(entry) & _PAGE_WRITE) &&
	    !(pte_val(entry) & _PAGE_INVALID)) {
		if (!MACHINE_HAS_ESOP) {
			/*
			 * Without enhanced suppression-on-protection force
			 * the dirty bit on for all writable ptes.
			 */
			pte_val(entry) |= _PAGE_DIRTY;
			pte_val(entry) &= ~_PAGE_PROTECT;
		}
		if (!(pte_val(entry) & _PAGE_PROTECT))
			/* This pte allows write access, set user-dirty */
			pgste_val(pgste) |= PGSTE_UC_BIT;
	}
#endif
	*ptep = entry;
	return pgste;
}

static inline pgste_t pgste_pte_notify(struct mm_struct *mm,
				       unsigned long addr,
				       pte_t *ptep, pgste_t pgste)
{
#ifdef CONFIG_PGSTE
	unsigned long bits;

	bits = pgste_val(pgste) & (PGSTE_IN_BIT | PGSTE_VSIE_BIT);
	if (bits) {
		pgste_val(pgste) ^= bits;
		ptep_notify(mm, addr, ptep, bits);
	}
#endif
	return pgste;
}

static inline pgste_t ptep_xchg_start(struct mm_struct *mm,
				      unsigned long addr, pte_t *ptep)
{
	pgste_t pgste = __pgste(0);

	if (mm_has_pgste(mm)) {
		pgste = pgste_get_lock(ptep);
		pgste = pgste_pte_notify(mm, addr, ptep, pgste);
	}
	return pgste;
}

static inline pte_t ptep_xchg_commit(struct mm_struct *mm,
				    unsigned long addr, pte_t *ptep,
				    pgste_t pgste, pte_t old, pte_t new)
{
	if (mm_has_pgste(mm)) {
		if (pte_val(old) & _PAGE_INVALID)
			pgste_set_key(ptep, pgste, new, mm);
		if (pte_val(new) & _PAGE_INVALID) {
			pgste = pgste_update_all(old, pgste, mm);
			if ((pgste_val(pgste) & _PGSTE_GPS_USAGE_MASK) ==
			    _PGSTE_GPS_USAGE_UNUSED)
				pte_val(old) |= _PAGE_UNUSED;
		}
		pgste = pgste_set_pte(ptep, pgste, new);
		pgste_set_unlock(ptep, pgste);
	} else {
		*ptep = new;
	}
	return old;
}

pte_t ptep_xchg_direct(struct mm_struct *mm, unsigned long addr,
		       pte_t *ptep, pte_t new)
{
	pgste_t pgste;
	pte_t old;

	preempt_disable();
	pgste = ptep_xchg_start(mm, addr, ptep);
	old = ptep_flush_direct(mm, addr, ptep);
	old = ptep_xchg_commit(mm, addr, ptep, pgste, old, new);
	preempt_enable();
	return old;
}
EXPORT_SYMBOL(ptep_xchg_direct);

pte_t ptep_xchg_lazy(struct mm_struct *mm, unsigned long addr,
		     pte_t *ptep, pte_t new)
{
	pgste_t pgste;
	pte_t old;

	preempt_disable();
	pgste = ptep_xchg_start(mm, addr, ptep);
	old = ptep_flush_lazy(mm, addr, ptep);
	old = ptep_xchg_commit(mm, addr, ptep, pgste, old, new);
	preempt_enable();
	return old;
}
EXPORT_SYMBOL(ptep_xchg_lazy);

pte_t ptep_modify_prot_start(struct mm_struct *mm, unsigned long addr,
			     pte_t *ptep)
{
	pgste_t pgste;
	pte_t old;

	preempt_disable();
	pgste = ptep_xchg_start(mm, addr, ptep);
	old = ptep_flush_lazy(mm, addr, ptep);
	if (mm_has_pgste(mm)) {
		pgste = pgste_update_all(old, pgste, mm);
		pgste_set(ptep, pgste);
	}
	return old;
}
EXPORT_SYMBOL(ptep_modify_prot_start);

void ptep_modify_prot_commit(struct mm_struct *mm, unsigned long addr,
			     pte_t *ptep, pte_t pte)
{
	pgste_t pgste;

	if (!MACHINE_HAS_NX)
		pte_val(pte) &= ~_PAGE_NOEXEC;
	if (mm_has_pgste(mm)) {
		pgste = pgste_get(ptep);
		pgste_set_key(ptep, pgste, pte, mm);
		pgste = pgste_set_pte(ptep, pgste, pte);
		pgste_set_unlock(ptep, pgste);
	} else {
		*ptep = pte;
	}
	preempt_enable();
}
EXPORT_SYMBOL(ptep_modify_prot_commit);

static inline pmd_t pmdp_flush_direct(struct mm_struct *mm,
				      unsigned long addr, pmd_t *pmdp)
{
	pmd_t old;

	old = *pmdp;
	if (pmd_val(old) & _SEGMENT_ENTRY_INVALID)
		return old;
	if (!MACHINE_HAS_IDTE) {
		__pmdp_csp(pmdp);
		return old;
	}
	atomic_inc(&mm->context.flush_count);
	if (MACHINE_HAS_TLB_LC &&
	    cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id())))
		__pmdp_idte(addr, pmdp, IDTE_LOCAL);
	else
		__pmdp_idte(addr, pmdp, IDTE_GLOBAL);
	atomic_dec(&mm->context.flush_count);
	return old;
}

static inline pmd_t pmdp_flush_lazy(struct mm_struct *mm,
				    unsigned long addr, pmd_t *pmdp)
{
	pmd_t old;

	old = *pmdp;
	if (pmd_val(old) & _SEGMENT_ENTRY_INVALID)
		return old;
	atomic_inc(&mm->context.flush_count);
	if (cpumask_equal(&mm->context.cpu_attach_mask,
			  cpumask_of(smp_processor_id()))) {
		pmd_val(*pmdp) |= _SEGMENT_ENTRY_INVALID;
		mm->context.flush_mm = 1;
	} else if (MACHINE_HAS_IDTE)
		__pmdp_idte(addr, pmdp, IDTE_GLOBAL);
	else
		__pmdp_csp(pmdp);
	atomic_dec(&mm->context.flush_count);
	return old;
}

pmd_t pmdp_xchg_direct(struct mm_struct *mm, unsigned long addr,
		       pmd_t *pmdp, pmd_t new)
{
	pmd_t old;

	preempt_disable();
	old = pmdp_flush_direct(mm, addr, pmdp);
	*pmdp = new;
	preempt_enable();
	return old;
}
EXPORT_SYMBOL(pmdp_xchg_direct);

pmd_t pmdp_xchg_lazy(struct mm_struct *mm, unsigned long addr,
		     pmd_t *pmdp, pmd_t new)
{
	pmd_t old;

	preempt_disable();
	old = pmdp_flush_lazy(mm, addr, pmdp);
	*pmdp = new;
	preempt_enable();
	return old;
}
EXPORT_SYMBOL(pmdp_xchg_lazy);

static inline pud_t pudp_flush_direct(struct mm_struct *mm,
				      unsigned long addr, pud_t *pudp)
{
	pud_t old;

	old = *pudp;
	if (pud_val(old) & _REGION_ENTRY_INVALID)
		return old;
	if (!MACHINE_HAS_IDTE) {
		/*
		 * Invalid bit position is the same for pmd and pud, so we can
		 * re-use _pmd_csp() here
		 */
		__pmdp_csp((pmd_t *) pudp);
		return old;
	}
	atomic_inc(&mm->context.flush_count);
	if (MACHINE_HAS_TLB_LC &&
	    cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id())))
		__pudp_idte(addr, pudp, IDTE_LOCAL);
	else
		__pudp_idte(addr, pudp, IDTE_GLOBAL);
	atomic_dec(&mm->context.flush_count);
	return old;
}

pud_t pudp_xchg_direct(struct mm_struct *mm, unsigned long addr,
		       pud_t *pudp, pud_t new)
{
	pud_t old;

	preempt_disable();
	old = pudp_flush_direct(mm, addr, pudp);
	*pudp = new;
	preempt_enable();
	return old;
}
EXPORT_SYMBOL(pudp_xchg_direct);

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
				pgtable_t pgtable)
{
	struct list_head *lh = (struct list_head *) pgtable;

	assert_spin_locked(pmd_lockptr(mm, pmdp));

	/* FIFO */
	if (!pmd_huge_pte(mm, pmdp))
		INIT_LIST_HEAD(lh);
	else
		list_add(lh, (struct list_head *) pmd_huge_pte(mm, pmdp));
	pmd_huge_pte(mm, pmdp) = pgtable;
}

pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
{
	struct list_head *lh;
	pgtable_t pgtable;
	pte_t *ptep;

	assert_spin_locked(pmd_lockptr(mm, pmdp));

	/* FIFO */
	pgtable = pmd_huge_pte(mm, pmdp);
	lh = (struct list_head *) pgtable;
	if (list_empty(lh))
		pmd_huge_pte(mm, pmdp) = NULL;
	else {
		pmd_huge_pte(mm, pmdp) = (pgtable_t) lh->next;
		list_del(lh);
	}
	ptep = (pte_t *) pgtable;
	pte_val(*ptep) = _PAGE_INVALID;
	ptep++;
	pte_val(*ptep) = _PAGE_INVALID;
	return pgtable;
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

#ifdef CONFIG_PGSTE
void ptep_set_pte_at(struct mm_struct *mm, unsigned long addr,
		     pte_t *ptep, pte_t entry)
{
	pgste_t pgste;

	/* the mm_has_pgste() check is done in set_pte_at() */
	preempt_disable();
	pgste = pgste_get_lock(ptep);
	pgste_val(pgste) &= ~_PGSTE_GPS_ZERO;
	pgste_set_key(ptep, pgste, entry, mm);
	pgste = pgste_set_pte(ptep, pgste, entry);
	pgste_set_unlock(ptep, pgste);
	preempt_enable();
}

void ptep_set_notify(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
	pgste_t pgste;

	preempt_disable();
	pgste = pgste_get_lock(ptep);
	pgste_val(pgste) |= PGSTE_IN_BIT;
	pgste_set_unlock(ptep, pgste);
	preempt_enable();
}

/**
 * ptep_force_prot - change access rights of a locked pte
 * @mm: pointer to the process mm_struct
 * @addr: virtual address in the guest address space
 * @ptep: pointer to the page table entry
 * @prot: indicates guest access rights: PROT_NONE, PROT_READ or PROT_WRITE
 * @bit: pgste bit to set (e.g. for notification)
 *
 * Returns 0 if the access rights were changed and -EAGAIN if the current
 * and requested access rights are incompatible.
 */
int ptep_force_prot(struct mm_struct *mm, unsigned long addr,
		    pte_t *ptep, int prot, unsigned long bit)
{
	pte_t entry;
	pgste_t pgste;
	int pte_i, pte_p;

	pgste = pgste_get_lock(ptep);
	entry = *ptep;
	/* Check pte entry after all locks have been acquired */
	pte_i = pte_val(entry) & _PAGE_INVALID;
	pte_p = pte_val(entry) & _PAGE_PROTECT;
	if ((pte_i && (prot != PROT_NONE)) ||
	    (pte_p && (prot & PROT_WRITE))) {
		pgste_set_unlock(ptep, pgste);
		return -EAGAIN;
	}
	/* Change access rights and set pgste bit */
	if (prot == PROT_NONE && !pte_i) {
		ptep_flush_direct(mm, addr, ptep);
		pgste = pgste_update_all(entry, pgste, mm);
		pte_val(entry) |= _PAGE_INVALID;
	}
	if (prot == PROT_READ && !pte_p) {
		ptep_flush_direct(mm, addr, ptep);
		pte_val(entry) &= ~_PAGE_INVALID;
		pte_val(entry) |= _PAGE_PROTECT;
	}
	pgste_val(pgste) |= bit;
	pgste = pgste_set_pte(ptep, pgste, entry);
	pgste_set_unlock(ptep, pgste);
	return 0;
}

int ptep_shadow_pte(struct mm_struct *mm, unsigned long saddr,
		    pte_t *sptep, pte_t *tptep, pte_t pte)
{
	pgste_t spgste, tpgste;
	pte_t spte, tpte;
	int rc = -EAGAIN;

	if (!(pte_val(*tptep) & _PAGE_INVALID))
		return 0;	/* already shadowed */
	spgste = pgste_get_lock(sptep);
	spte = *sptep;
	if (!(pte_val(spte) & _PAGE_INVALID) &&
	    !((pte_val(spte) & _PAGE_PROTECT) &&
	      !(pte_val(pte) & _PAGE_PROTECT))) {
		pgste_val(spgste) |= PGSTE_VSIE_BIT;
		tpgste = pgste_get_lock(tptep);
		pte_val(tpte) = (pte_val(spte) & PAGE_MASK) |
				(pte_val(pte) & _PAGE_PROTECT);
		/* don't touch the storage key - it belongs to parent pgste */
		tpgste = pgste_set_pte(tptep, tpgste, tpte);
		pgste_set_unlock(tptep, tpgste);
		rc = 1;
	}
	pgste_set_unlock(sptep, spgste);
	return rc;
}

void ptep_unshadow_pte(struct mm_struct *mm, unsigned long saddr, pte_t *ptep)
{
	pgste_t pgste;

	pgste = pgste_get_lock(ptep);
	/* notifier is called by the caller */
	ptep_flush_direct(mm, saddr, ptep);
	/* don't touch the storage key - it belongs to parent pgste */
	pgste = pgste_set_pte(ptep, pgste, __pte(_PAGE_INVALID));
	pgste_set_unlock(ptep, pgste);
}

static void ptep_zap_swap_entry(struct mm_struct *mm, swp_entry_t entry)
{
	if (!non_swap_entry(entry))
		dec_mm_counter(mm, MM_SWAPENTS);
	else if (is_migration_entry(entry)) {
		struct page *page = migration_entry_to_page(entry);

		dec_mm_counter(mm, mm_counter(page));
	}
	free_swap_and_cache(entry);
}

void ptep_zap_unused(struct mm_struct *mm, unsigned long addr,
		     pte_t *ptep, int reset)
{
	unsigned long pgstev;
	pgste_t pgste;
	pte_t pte;

	/* Zap unused and logically-zero pages */
	preempt_disable();
	pgste = pgste_get_lock(ptep);
	pgstev = pgste_val(pgste);
	pte = *ptep;
	if (!reset && pte_swap(pte) &&
	    ((pgstev & _PGSTE_GPS_USAGE_MASK) == _PGSTE_GPS_USAGE_UNUSED ||
	     (pgstev & _PGSTE_GPS_ZERO))) {
		ptep_zap_swap_entry(mm, pte_to_swp_entry(pte));
		pte_clear(mm, addr, ptep);
	}
	if (reset)
		pgste_val(pgste) &= ~_PGSTE_GPS_USAGE_MASK;
	pgste_set_unlock(ptep, pgste);
	preempt_enable();
}

void ptep_zap_key(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
	unsigned long ptev;
	pgste_t pgste;

	/* Clear storage key ACC and F, but set R/C */
	preempt_disable();
	pgste = pgste_get_lock(ptep);
	pgste_val(pgste) &= ~(PGSTE_ACC_BITS | PGSTE_FP_BIT);
	pgste_val(pgste) |= PGSTE_GR_BIT | PGSTE_GC_BIT;
	ptev = pte_val(*ptep);
	if (!(ptev & _PAGE_INVALID) && (ptev & _PAGE_WRITE))
		page_set_storage_key(ptev & PAGE_MASK, PAGE_DEFAULT_KEY, 1);
	pgste_set_unlock(ptep, pgste);
	preempt_enable();
}

/*
 * Test and reset if a guest page is dirty
 */
bool test_and_clear_guest_dirty(struct mm_struct *mm, unsigned long addr)
{
	spinlock_t *ptl;
	pgd_t *pgd;
	p4d_t *p4d;
	pud_t *pud;
	pmd_t *pmd;
	pgste_t pgste;
	pte_t *ptep;
	pte_t pte;
	bool dirty;

	pgd = pgd_offset(mm, addr);
	p4d = p4d_alloc(mm, pgd, addr);
	if (!p4d)
		return false;
	pud = pud_alloc(mm, p4d, addr);
	if (!pud)
		return false;
	pmd = pmd_alloc(mm, pud, addr);
	if (!pmd)
		return false;
	/* We can't run guests backed by huge pages, but userspace can
	 * still set them up and then try to migrate them without any
	 * migration support.
	 */
	if (pmd_large(*pmd))
		return true;

	ptep = pte_alloc_map_lock(mm, pmd, addr, &ptl);
	if (unlikely(!ptep))
		return false;

	pgste = pgste_get_lock(ptep);
	dirty = !!(pgste_val(pgste) & PGSTE_UC_BIT);
	pgste_val(pgste) &= ~PGSTE_UC_BIT;
	pte = *ptep;
	if (dirty && (pte_val(pte) & _PAGE_PRESENT)) {
		pgste = pgste_pte_notify(mm, addr, ptep, pgste);
		__ptep_ipte(addr, ptep, IPTE_GLOBAL);
		if (MACHINE_HAS_ESOP || !(pte_val(pte) & _PAGE_WRITE))
			pte_val(pte) |= _PAGE_PROTECT;
		else
			pte_val(pte) |= _PAGE_INVALID;
		*ptep = pte;
	}
	pgste_set_unlock(ptep, pgste);

	spin_unlock(ptl);
	return dirty;
}
EXPORT_SYMBOL_GPL(test_and_clear_guest_dirty);

int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
			  unsigned char key, bool nq)
{
	unsigned long keyul;
	spinlock_t *ptl;
	pgste_t old, new;
	pte_t *ptep;

	ptep = get_locked_pte(mm, addr, &ptl);
	if (unlikely(!ptep))
		return -EFAULT;

	new = old = pgste_get_lock(ptep);
	pgste_val(new) &= ~(PGSTE_GR_BIT | PGSTE_GC_BIT |
			    PGSTE_ACC_BITS | PGSTE_FP_BIT);
	keyul = (unsigned long) key;
	pgste_val(new) |= (keyul & (_PAGE_CHANGED | _PAGE_REFERENCED)) << 48;
	pgste_val(new) |= (keyul & (_PAGE_ACC_BITS | _PAGE_FP_BIT)) << 56;
	if (!(pte_val(*ptep) & _PAGE_INVALID)) {
		unsigned long address, bits, skey;

		address = pte_val(*ptep) & PAGE_MASK;
		skey = (unsigned long) page_get_storage_key(address);
		bits = skey & (_PAGE_CHANGED | _PAGE_REFERENCED);
		skey = key & (_PAGE_ACC_BITS | _PAGE_FP_BIT);
		/* Set storage key ACC and FP */
		page_set_storage_key(address, skey, !nq);
		/* Merge host changed & referenced into pgste  */
		pgste_val(new) |= bits << 52;
	}
	/* changing the guest storage key is considered a change of the page */
	if ((pgste_val(new) ^ pgste_val(old)) &
	    (PGSTE_ACC_BITS | PGSTE_FP_BIT | PGSTE_GR_BIT | PGSTE_GC_BIT))
		pgste_val(new) |= PGSTE_UC_BIT;

	pgste_set_unlock(ptep, new);
	pte_unmap_unlock(ptep, ptl);
	return 0;
}
EXPORT_SYMBOL(set_guest_storage_key);

/**
 * Conditionally set a guest storage key (handling csske).
 * oldkey will be updated when either mr or mc is set and a pointer is given.
 *
 * Returns 0 if a guests storage key update wasn't necessary, 1 if the guest
 * storage key was updated and -EFAULT on access errors.
 */
int cond_set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
			       unsigned char key, unsigned char *oldkey,
			       bool nq, bool mr, bool mc)
{
	unsigned char tmp, mask = _PAGE_ACC_BITS | _PAGE_FP_BIT;
	int rc;

	/* we can drop the pgste lock between getting and setting the key */
	if (mr | mc) {
		rc = get_guest_storage_key(current->mm, addr, &tmp);
		if (rc)
			return rc;
		if (oldkey)
			*oldkey = tmp;
		if (!mr)
			mask |= _PAGE_REFERENCED;
		if (!mc)
			mask |= _PAGE_CHANGED;
		if (!((tmp ^ key) & mask))
			return 0;
	}
	rc = set_guest_storage_key(current->mm, addr, key, nq);
	return rc < 0 ? rc : 1;
}
EXPORT_SYMBOL(cond_set_guest_storage_key);

/**
 * Reset a guest reference bit (rrbe), returning the reference and changed bit.
 *
 * Returns < 0 in case of error, otherwise the cc to be reported to the guest.
 */
int reset_guest_reference_bit(struct mm_struct *mm, unsigned long addr)
{
	spinlock_t *ptl;
	pgste_t old, new;
	pte_t *ptep;
	int cc = 0;

	ptep = get_locked_pte(mm, addr, &ptl);
	if (unlikely(!ptep))
		return -EFAULT;

	new = old = pgste_get_lock(ptep);
	/* Reset guest reference bit only */
	pgste_val(new) &= ~PGSTE_GR_BIT;

	if (!(pte_val(*ptep) & _PAGE_INVALID)) {
		cc = page_reset_referenced(pte_val(*ptep) & PAGE_MASK);
		/* Merge real referenced bit into host-set */
		pgste_val(new) |= ((unsigned long) cc << 53) & PGSTE_HR_BIT;
	}
	/* Reflect guest's logical view, not physical */
	cc |= (pgste_val(old) & (PGSTE_GR_BIT | PGSTE_GC_BIT)) >> 49;
	/* Changing the guest storage key is considered a change of the page */
	if ((pgste_val(new) ^ pgste_val(old)) & PGSTE_GR_BIT)
		pgste_val(new) |= PGSTE_UC_BIT;

	pgste_set_unlock(ptep, new);
	pte_unmap_unlock(ptep, ptl);
	return cc;
}
EXPORT_SYMBOL(reset_guest_reference_bit);

int get_guest_storage_key(struct mm_struct *mm, unsigned long addr,
			  unsigned char *key)
{
	spinlock_t *ptl;
	pgste_t pgste;
	pte_t *ptep;

	ptep = get_locked_pte(mm, addr, &ptl);
	if (unlikely(!ptep))
		return -EFAULT;

	pgste = pgste_get_lock(ptep);
	*key = (pgste_val(pgste) & (PGSTE_ACC_BITS | PGSTE_FP_BIT)) >> 56;
	if (!(pte_val(*ptep) & _PAGE_INVALID))
		*key = page_get_storage_key(pte_val(*ptep) & PAGE_MASK);
	/* Reflect guest's logical view, not physical */
	*key |= (pgste_val(pgste) & (PGSTE_GR_BIT | PGSTE_GC_BIT)) >> 48;
	pgste_set_unlock(ptep, pgste);
	pte_unmap_unlock(ptep, ptl);
	return 0;
}
EXPORT_SYMBOL(get_guest_storage_key);

/**
 * pgste_perform_essa - perform ESSA actions on the PGSTE.
 * @mm: the memory context. It must have PGSTEs, no check is performed here!
 * @hva: the host virtual address of the page whose PGSTE is to be processed
 * @orc: the specific action to perform, see the ESSA_SET_* macros.
 * @oldpte: the PTE will be saved there if the pointer is not NULL.
 * @oldpgste: the old PGSTE will be saved there if the pointer is not NULL.
 *
 * Return: 1 if the page is to be added to the CBRL, otherwise 0,
 *	   or < 0 in case of error. -EINVAL is returned for invalid values
 *	   of orc, -EFAULT for invalid addresses.
 */
int pgste_perform_essa(struct mm_struct *mm, unsigned long hva, int orc,
			unsigned long *oldpte, unsigned long *oldpgste)
{
	unsigned long pgstev;
	spinlock_t *ptl;
	pgste_t pgste;
	pte_t *ptep;
	int res = 0;

	WARN_ON_ONCE(orc > ESSA_MAX);
	if (unlikely(orc > ESSA_MAX))
		return -EINVAL;
	ptep = get_locked_pte(mm, hva, &ptl);
	if (unlikely(!ptep))
		return -EFAULT;
	pgste = pgste_get_lock(ptep);
	pgstev = pgste_val(pgste);
	if (oldpte)
		*oldpte = pte_val(*ptep);
	if (oldpgste)
		*oldpgste = pgstev;

	switch (orc) {
	case ESSA_GET_STATE:
		break;
	case ESSA_SET_STABLE:
		pgstev &= ~_PGSTE_GPS_USAGE_MASK;
		pgstev |= _PGSTE_GPS_USAGE_STABLE;
		break;
	case ESSA_SET_UNUSED:
		pgstev &= ~_PGSTE_GPS_USAGE_MASK;
		pgstev |= _PGSTE_GPS_USAGE_UNUSED;
		if (pte_val(*ptep) & _PAGE_INVALID)
			res = 1;
		break;
	case ESSA_SET_VOLATILE:
		pgstev &= ~_PGSTE_GPS_USAGE_MASK;
		pgstev |= _PGSTE_GPS_USAGE_VOLATILE;
		if (pte_val(*ptep) & _PAGE_INVALID)
			res = 1;
		break;
	case ESSA_SET_POT_VOLATILE:
		pgstev &= ~_PGSTE_GPS_USAGE_MASK;
		if (!(pte_val(*ptep) & _PAGE_INVALID)) {
			pgstev |= _PGSTE_GPS_USAGE_POT_VOLATILE;
			break;
		}
		if (pgstev & _PGSTE_GPS_ZERO) {
			pgstev |= _PGSTE_GPS_USAGE_VOLATILE;
			break;
		}
		if (!(pgstev & PGSTE_GC_BIT)) {
			pgstev |= _PGSTE_GPS_USAGE_VOLATILE;
			res = 1;
			break;
		}
		break;
	case ESSA_SET_STABLE_RESIDENT:
		pgstev &= ~_PGSTE_GPS_USAGE_MASK;
		pgstev |= _PGSTE_GPS_USAGE_STABLE;
		/*
		 * Since the resident state can go away any time after this
		 * call, we will not make this page resident. We can revisit
		 * this decision if a guest will ever start using this.
		 */
		break;
	case ESSA_SET_STABLE_IF_RESIDENT:
		if (!(pte_val(*ptep) & _PAGE_INVALID)) {
			pgstev &= ~_PGSTE_GPS_USAGE_MASK;
			pgstev |= _PGSTE_GPS_USAGE_STABLE;
		}
		break;
	default:
		/* we should never get here! */
		break;
	}
	/* If we are discarding a page, set it to logical zero */
	if (res)
		pgstev |= _PGSTE_GPS_ZERO;

	pgste_val(pgste) = pgstev;
	pgste_set_unlock(ptep, pgste);
	pte_unmap_unlock(ptep, ptl);
	return res;
}
EXPORT_SYMBOL(pgste_perform_essa);

/**
 * set_pgste_bits - set specific PGSTE bits.
 * @mm: the memory context. It must have PGSTEs, no check is performed here!
 * @hva: the host virtual address of the page whose PGSTE is to be processed
 * @bits: a bitmask representing the bits that will be touched
 * @value: the values of the bits to be written. Only the bits in the mask
 *	   will be written.
 *
 * Return: 0 on success, < 0 in case of error.
 */
int set_pgste_bits(struct mm_struct *mm, unsigned long hva,
			unsigned long bits, unsigned long value)
{
	spinlock_t *ptl;
	pgste_t new;
	pte_t *ptep;

	ptep = get_locked_pte(mm, hva, &ptl);
	if (unlikely(!ptep))
		return -EFAULT;
	new = pgste_get_lock(ptep);

	pgste_val(new) &= ~bits;
	pgste_val(new) |= value & bits;

	pgste_set_unlock(ptep, new);
	pte_unmap_unlock(ptep, ptl);
	return 0;
}
EXPORT_SYMBOL(set_pgste_bits);

/**
 * get_pgste - get the current PGSTE for the given address.
 * @mm: the memory context. It must have PGSTEs, no check is performed here!
 * @hva: the host virtual address of the page whose PGSTE is to be processed
 * @pgstep: will be written with the current PGSTE for the given address.
 *
 * Return: 0 on success, < 0 in case of error.
 */
int get_pgste(struct mm_struct *mm, unsigned long hva, unsigned long *pgstep)
{
	spinlock_t *ptl;
	pte_t *ptep;

	ptep = get_locked_pte(mm, hva, &ptl);
	if (unlikely(!ptep))
		return -EFAULT;
	*pgstep = pgste_val(pgste_get(ptep));
	pte_unmap_unlock(ptep, ptl);
	return 0;
}
EXPORT_SYMBOL(get_pgste);
#endif