aboutsummaryrefslogtreecommitdiffstats
path: root/arch/s390/kvm/gaccess.c
blob: 8a1be901773055c407d2ca7327707fdc6a70ddc9 (plain) (blame)
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
/*
 * guest access functions
 *
 * Copyright IBM Corp. 2014
 *
 */

#include <linux/vmalloc.h>
#include <linux/err.h>
#include <asm/pgtable.h>
#include "kvm-s390.h"
#include "gaccess.h"

union asce {
	unsigned long val;
	struct {
		unsigned long origin : 52; /* Region- or Segment-Table Origin */
		unsigned long	 : 2;
		unsigned long g  : 1; /* Subspace Group Control */
		unsigned long p  : 1; /* Private Space Control */
		unsigned long s  : 1; /* Storage-Alteration-Event Control */
		unsigned long x  : 1; /* Space-Switch-Event Control */
		unsigned long r  : 1; /* Real-Space Control */
		unsigned long	 : 1;
		unsigned long dt : 2; /* Designation-Type Control */
		unsigned long tl : 2; /* Region- or Segment-Table Length */
	};
};

enum {
	ASCE_TYPE_SEGMENT = 0,
	ASCE_TYPE_REGION3 = 1,
	ASCE_TYPE_REGION2 = 2,
	ASCE_TYPE_REGION1 = 3
};

union region1_table_entry {
	unsigned long val;
	struct {
		unsigned long rto: 52;/* Region-Table Origin */
		unsigned long	 : 2;
		unsigned long p  : 1; /* DAT-Protection Bit */
		unsigned long	 : 1;
		unsigned long tf : 2; /* Region-Second-Table Offset */
		unsigned long i  : 1; /* Region-Invalid Bit */
		unsigned long	 : 1;
		unsigned long tt : 2; /* Table-Type Bits */
		unsigned long tl : 2; /* Region-Second-Table Length */
	};
};

union region2_table_entry {
	unsigned long val;
	struct {
		unsigned long rto: 52;/* Region-Table Origin */
		unsigned long	 : 2;
		unsigned long p  : 1; /* DAT-Protection Bit */
		unsigned long	 : 1;
		unsigned long tf : 2; /* Region-Third-Table Offset */
		unsigned long i  : 1; /* Region-Invalid Bit */
		unsigned long	 : 1;
		unsigned long tt : 2; /* Table-Type Bits */
		unsigned long tl : 2; /* Region-Third-Table Length */
	};
};

struct region3_table_entry_fc0 {
	unsigned long sto: 52;/* Segment-Table Origin */
	unsigned long	 : 1;
	unsigned long fc : 1; /* Format-Control */
	unsigned long p  : 1; /* DAT-Protection Bit */
	unsigned long	 : 1;
	unsigned long tf : 2; /* Segment-Table Offset */
	unsigned long i  : 1; /* Region-Invalid Bit */
	unsigned long cr : 1; /* Common-Region Bit */
	unsigned long tt : 2; /* Table-Type Bits */
	unsigned long tl : 2; /* Segment-Table Length */
};

struct region3_table_entry_fc1 {
	unsigned long rfaa : 33; /* Region-Frame Absolute Address */
	unsigned long	 : 14;
	unsigned long av : 1; /* ACCF-Validity Control */
	unsigned long acc: 4; /* Access-Control Bits */
	unsigned long f  : 1; /* Fetch-Protection Bit */
	unsigned long fc : 1; /* Format-Control */
	unsigned long p  : 1; /* DAT-Protection Bit */
	unsigned long co : 1; /* Change-Recording Override */
	unsigned long	 : 2;
	unsigned long i  : 1; /* Region-Invalid Bit */
	unsigned long cr : 1; /* Common-Region Bit */
	unsigned long tt : 2; /* Table-Type Bits */
	unsigned long	 : 2;
};

union region3_table_entry {
	unsigned long val;
	struct region3_table_entry_fc0 fc0;
	struct region3_table_entry_fc1 fc1;
	struct {
		unsigned long	 : 53;
		unsigned long fc : 1; /* Format-Control */
		unsigned long	 : 4;
		unsigned long i  : 1; /* Region-Invalid Bit */
		unsigned long cr : 1; /* Common-Region Bit */
		unsigned long tt : 2; /* Table-Type Bits */
		unsigned long	 : 2;
	};
};

struct segment_entry_fc0 {
	unsigned long pto: 53;/* Page-Table Origin */
	unsigned long fc : 1; /* Format-Control */
	unsigned long p  : 1; /* DAT-Protection Bit */
	unsigned long	 : 3;
	unsigned long i  : 1; /* Segment-Invalid Bit */
	unsigned long cs : 1; /* Common-Segment Bit */
	unsigned long tt : 2; /* Table-Type Bits */
	unsigned long	 : 2;
};

struct segment_entry_fc1 {
	unsigned long sfaa : 44; /* Segment-Frame Absolute Address */
	unsigned long	 : 3;
	unsigned long av : 1; /* ACCF-Validity Control */
	unsigned long acc: 4; /* Access-Control Bits */
	unsigned long f  : 1; /* Fetch-Protection Bit */
	unsigned long fc : 1; /* Format-Control */
	unsigned long p  : 1; /* DAT-Protection Bit */
	unsigned long co : 1; /* Change-Recording Override */
	unsigned long	 : 2;
	unsigned long i  : 1; /* Segment-Invalid Bit */
	unsigned long cs : 1; /* Common-Segment Bit */
	unsigned long tt : 2; /* Table-Type Bits */
	unsigned long	 : 2;
};

union segment_table_entry {
	unsigned long val;
	struct segment_entry_fc0 fc0;
	struct segment_entry_fc1 fc1;
	struct {
		unsigned long	 : 53;
		unsigned long fc : 1; /* Format-Control */
		unsigned long	 : 4;
		unsigned long i  : 1; /* Segment-Invalid Bit */
		unsigned long cs : 1; /* Common-Segment Bit */
		unsigned long tt : 2; /* Table-Type Bits */
		unsigned long	 : 2;
	};
};

enum {
	TABLE_TYPE_SEGMENT = 0,
	TABLE_TYPE_REGION3 = 1,
	TABLE_TYPE_REGION2 = 2,
	TABLE_TYPE_REGION1 = 3
};

union page_table_entry {
	unsigned long val;
	struct {
		unsigned long pfra : 52; /* Page-Frame Real Address */
		unsigned long z  : 1; /* Zero Bit */
		unsigned long i  : 1; /* Page-Invalid Bit */
		unsigned long p  : 1; /* DAT-Protection Bit */
		unsigned long co : 1; /* Change-Recording Override */
		unsigned long	 : 8;
	};
};

/*
 * vaddress union in order to easily decode a virtual address into its
 * region first index, region second index etc. parts.
 */
union vaddress {
	unsigned long addr;
	struct {
		unsigned long rfx : 11;
		unsigned long rsx : 11;
		unsigned long rtx : 11;
		unsigned long sx  : 11;
		unsigned long px  : 8;
		unsigned long bx  : 12;
	};
	struct {
		unsigned long rfx01 : 2;
		unsigned long	    : 9;
		unsigned long rsx01 : 2;
		unsigned long	    : 9;
		unsigned long rtx01 : 2;
		unsigned long	    : 9;
		unsigned long sx01  : 2;
		unsigned long	    : 29;
	};
};

/*
 * raddress union which will contain the result (real or absolute address)
 * after a page table walk. The rfaa, sfaa and pfra members are used to
 * simply assign them the value of a region, segment or page table entry.
 */
union raddress {
	unsigned long addr;
	unsigned long rfaa : 33; /* Region-Frame Absolute Address */
	unsigned long sfaa : 44; /* Segment-Frame Absolute Address */
	unsigned long pfra : 52; /* Page-Frame Real Address */
};


int ipte_lock_held(struct kvm_vcpu *vcpu)
{
	union ipte_control *ic = &vcpu->kvm->arch.sca->ipte_control;

	if (vcpu->arch.sie_block->eca & 1)
		return ic->kh != 0;
	return vcpu->kvm->arch.ipte_lock_count != 0;
}

static void ipte_lock_simple(struct kvm_vcpu *vcpu)
{
	union ipte_control old, new, *ic;

	mutex_lock(&vcpu->kvm->arch.ipte_mutex);
	vcpu->kvm->arch.ipte_lock_count++;
	if (vcpu->kvm->arch.ipte_lock_count > 1)
		goto out;
	ic = &vcpu->kvm->arch.sca->ipte_control;
	do {
		old = READ_ONCE(*ic);
		while (old.k) {
			cond_resched();
			old = READ_ONCE(*ic);
		}
		new = old;
		new.k = 1;
	} while (cmpxchg(&ic->val, old.val, new.val) != old.val);
out:
	mutex_unlock(&vcpu->kvm->arch.ipte_mutex);
}

static void ipte_unlock_simple(struct kvm_vcpu *vcpu)
{
	union ipte_control old, new, *ic;

	mutex_lock(&vcpu->kvm->arch.ipte_mutex);
	vcpu->kvm->arch.ipte_lock_count--;
	if (vcpu->kvm->arch.ipte_lock_count)
		goto out;
	ic = &vcpu->kvm->arch.sca->ipte_control;
	do {
		old = READ_ONCE(*ic);
		new = old;
		new.k = 0;
	} while (cmpxchg(&ic->val, old.val, new.val) != old.val);
	wake_up(&vcpu->kvm->arch.ipte_wq);
out:
	mutex_unlock(&vcpu->kvm->arch.ipte_mutex);
}

static void ipte_lock_siif(struct kvm_vcpu *vcpu)
{
	union ipte_control old, new, *ic;

	ic = &vcpu->kvm->arch.sca->ipte_control;
	do {
		old = READ_ONCE(*ic);
		while (old.kg) {
			cond_resched();
			old = READ_ONCE(*ic);
		}
		new = old;
		new.k = 1;
		new.kh++;
	} while (cmpxchg(&ic->val, old.val, new.val) != old.val);
}

static void ipte_unlock_siif(struct kvm_vcpu *vcpu)
{
	union ipte_control old, new, *ic;

	ic = &vcpu->kvm->arch.sca->ipte_control;
	do {
		old = READ_ONCE(*ic);
		new = old;
		new.kh--;
		if (!new.kh)
			new.k = 0;
	} while (cmpxchg(&ic->val, old.val, new.val) != old.val);
	if (!new.kh)
		wake_up(&vcpu->kvm->arch.ipte_wq);
}

void ipte_lock(struct kvm_vcpu *vcpu)
{
	if (vcpu->arch.sie_block->eca & 1)
		ipte_lock_siif(vcpu);
	else
		ipte_lock_simple(vcpu);
}

void ipte_unlock(struct kvm_vcpu *vcpu)
{
	if (vcpu->arch.sie_block->eca & 1)
		ipte_unlock_siif(vcpu);
	else
		ipte_unlock_simple(vcpu);
}

static unsigned long get_vcpu_asce(struct kvm_vcpu *vcpu)
{
	switch (psw_bits(vcpu->arch.sie_block->gpsw).as) {
	case PSW_AS_PRIMARY:
		return vcpu->arch.sie_block->gcr[1];
	case PSW_AS_SECONDARY:
		return vcpu->arch.sie_block->gcr[7];
	case PSW_AS_HOME:
		return vcpu->arch.sie_block->gcr[13];
	}
	return 0;
}

static int deref_table(struct kvm *kvm, unsigned long gpa, unsigned long *val)
{
	return kvm_read_guest(kvm, gpa, val, sizeof(*val));
}

/**
 * guest_translate - translate a guest virtual into a guest absolute address
 * @vcpu: virtual cpu
 * @gva: guest virtual address
 * @gpa: points to where guest physical (absolute) address should be stored
 * @write: indicates if access is a write access
 *
 * Translate a guest virtual address into a guest absolute address by means
 * of dynamic address translation as specified by the architecuture.
 * If the resulting absolute address is not available in the configuration
 * an addressing exception is indicated and @gpa will not be changed.
 *
 * Returns: - zero on success; @gpa contains the resulting absolute address
 *	    - a negative value if guest access failed due to e.g. broken
 *	      guest mapping
 *	    - a positve value if an access exception happened. In this case
 *	      the returned value is the program interruption code as defined
 *	      by the architecture
 */
static unsigned long guest_translate(struct kvm_vcpu *vcpu, unsigned long gva,
				     unsigned long *gpa, int write)
{
	union vaddress vaddr = {.addr = gva};
	union raddress raddr = {.addr = gva};
	union page_table_entry pte;
	int dat_protection = 0;
	union ctlreg0 ctlreg0;
	unsigned long ptr;
	int edat1, edat2;
	union asce asce;

	ctlreg0.val = vcpu->arch.sie_block->gcr[0];
	edat1 = ctlreg0.edat && test_vfacility(8);
	edat2 = edat1 && test_vfacility(78);
	asce.val = get_vcpu_asce(vcpu);
	if (asce.r)
		goto real_address;
	ptr = asce.origin * 4096;
	switch (asce.dt) {
	case ASCE_TYPE_REGION1:
		if (vaddr.rfx01 > asce.tl)
			return PGM_REGION_FIRST_TRANS;
		ptr += vaddr.rfx * 8;
		break;
	case ASCE_TYPE_REGION2:
		if (vaddr.rfx)
			return PGM_ASCE_TYPE;
		if (vaddr.rsx01 > asce.tl)
			return PGM_REGION_SECOND_TRANS;
		ptr += vaddr.rsx * 8;
		break;
	case ASCE_TYPE_REGION3:
		if (vaddr.rfx || vaddr.rsx)
			return PGM_ASCE_TYPE;
		if (vaddr.rtx01 > asce.tl)
			return PGM_REGION_THIRD_TRANS;
		ptr += vaddr.rtx * 8;
		break;
	case ASCE_TYPE_SEGMENT:
		if (vaddr.rfx || vaddr.rsx || vaddr.rtx)
			return PGM_ASCE_TYPE;
		if (vaddr.sx01 > asce.tl)
			return PGM_SEGMENT_TRANSLATION;
		ptr += vaddr.sx * 8;
		break;
	}
	switch (asce.dt) {
	case ASCE_TYPE_REGION1:	{
		union region1_table_entry rfte;

		if (kvm_is_error_gpa(vcpu->kvm, ptr))
			return PGM_ADDRESSING;
		if (deref_table(vcpu->kvm, ptr, &rfte.val))
			return -EFAULT;
		if (rfte.i)
			return PGM_REGION_FIRST_TRANS;
		if (rfte.tt != TABLE_TYPE_REGION1)
			return PGM_TRANSLATION_SPEC;
		if (vaddr.rsx01 < rfte.tf || vaddr.rsx01 > rfte.tl)
			return PGM_REGION_SECOND_TRANS;
		if (edat1)
			dat_protection |= rfte.p;
		ptr = rfte.rto * 4096 + vaddr.rsx * 8;
	}
		/* fallthrough */
	case ASCE_TYPE_REGION2: {
		union region2_table_entry rste;

		if (kvm_is_error_gpa(vcpu->kvm, ptr))
			return PGM_ADDRESSING;
		if (deref_table(vcpu->kvm, ptr, &rste.val))
			return -EFAULT;
		if (rste.i)
			return PGM_REGION_SECOND_TRANS;
		if (rste.tt != TABLE_TYPE_REGION2)
			return PGM_TRANSLATION_SPEC;
		if (vaddr.rtx01 < rste.tf || vaddr.rtx01 > rste.tl)
			return PGM_REGION_THIRD_TRANS;
		if (edat1)
			dat_protection |= rste.p;
		ptr = rste.rto * 4096 + vaddr.rtx * 8;
	}
		/* fallthrough */
	case ASCE_TYPE_REGION3: {
		union region3_table_entry rtte;

		if (kvm_is_error_gpa(vcpu->kvm, ptr))
			return PGM_ADDRESSING;
		if (deref_table(vcpu->kvm, ptr, &rtte.val))
			return -EFAULT;
		if (rtte.i)
			return PGM_REGION_THIRD_TRANS;
		if (rtte.tt != TABLE_TYPE_REGION3)
			return PGM_TRANSLATION_SPEC;
		if (rtte.cr && asce.p && edat2)
			return PGM_TRANSLATION_SPEC;
		if (rtte.fc && edat2) {
			dat_protection |= rtte.fc1.p;
			raddr.rfaa = rtte.fc1.rfaa;
			goto absolute_address;
		}
		if (vaddr.sx01 < rtte.fc0.tf)
			return PGM_SEGMENT_TRANSLATION;
		if (vaddr.sx01 > rtte.fc0.tl)
			return PGM_SEGMENT_TRANSLATION;
		if (edat1)
			dat_protection |= rtte.fc0.p;
		ptr = rtte.fc0.sto * 4096 + vaddr.sx * 8;
	}
		/* fallthrough */
	case ASCE_TYPE_SEGMENT: {
		union segment_table_entry ste;

		if (kvm_is_error_gpa(vcpu->kvm, ptr))
			return PGM_ADDRESSING;
		if (deref_table(vcpu->kvm, ptr, &ste.val))
			return -EFAULT;
		if (ste.i)
			return PGM_SEGMENT_TRANSLATION;
		if (ste.tt != TABLE_TYPE_SEGMENT)
			return PGM_TRANSLATION_SPEC;
		if (ste.cs && asce.p)
			return PGM_TRANSLATION_SPEC;
		if (ste.fc && edat1) {
			dat_protection |= ste.fc1.p;
			raddr.sfaa = ste.fc1.sfaa;
			goto absolute_address;
		}
		dat_protection |= ste.fc0.p;
		ptr = ste.fc0.pto * 2048 + vaddr.px * 8;
	}
	}
	if (kvm_is_error_gpa(vcpu->kvm, ptr))
		return PGM_ADDRESSING;
	if (deref_table(vcpu->kvm, ptr, &pte.val))
		return -EFAULT;
	if (pte.i)
		return PGM_PAGE_TRANSLATION;
	if (pte.z)
		return PGM_TRANSLATION_SPEC;
	if (pte.co && !edat1)
		return PGM_TRANSLATION_SPEC;
	dat_protection |= pte.p;
	raddr.pfra = pte.pfra;
real_address:
	raddr.addr = kvm_s390_real_to_abs(vcpu, raddr.addr);
absolute_address:
	if (write && dat_protection)
		return PGM_PROTECTION;
	if (kvm_is_error_gpa(vcpu->kvm, raddr.addr))
		return PGM_ADDRESSING;
	*gpa = raddr.addr;
	return 0;
}

static inline int is_low_address(unsigned long ga)
{
	/* Check for address ranges 0..511 and 4096..4607 */
	return (ga & ~0x11fful) == 0;
}

static int low_address_protection_enabled(struct kvm_vcpu *vcpu)
{
	union ctlreg0 ctlreg0 = {.val = vcpu->arch.sie_block->gcr[0]};
	psw_t *psw = &vcpu->arch.sie_block->gpsw;
	union asce asce;

	if (!ctlreg0.lap)
		return 0;
	asce.val = get_vcpu_asce(vcpu);
	if (psw_bits(*psw).t && asce.p)
		return 0;
	return 1;
}

struct trans_exc_code_bits {
	unsigned long addr : 52; /* Translation-exception Address */
	unsigned long fsi  : 2;  /* Access Exception Fetch/Store Indication */
	unsigned long	   : 7;
	unsigned long b61  : 1;
	unsigned long as   : 2;  /* ASCE Identifier */
};

enum {
	FSI_UNKNOWN = 0, /* Unknown wether fetch or store */
	FSI_STORE   = 1, /* Exception was due to store operation */
	FSI_FETCH   = 2  /* Exception was due to fetch operation */
};

static int guest_page_range(struct kvm_vcpu *vcpu, unsigned long ga,
			    unsigned long *pages, unsigned long nr_pages,
			    int write)
{
	struct kvm_s390_pgm_info *pgm = &vcpu->arch.pgm;
	psw_t *psw = &vcpu->arch.sie_block->gpsw;
	struct trans_exc_code_bits *tec_bits;
	int lap_enabled, rc;

	memset(pgm, 0, sizeof(*pgm));
	tec_bits = (struct trans_exc_code_bits *)&pgm->trans_exc_code;
	tec_bits->fsi = write ? FSI_STORE : FSI_FETCH;
	tec_bits->as = psw_bits(*psw).as;
	lap_enabled = low_address_protection_enabled(vcpu);
	while (nr_pages) {
		ga = kvm_s390_logical_to_effective(vcpu, ga);
		tec_bits->addr = ga >> PAGE_SHIFT;
		if (write && lap_enabled && is_low_address(ga)) {
			pgm->code = PGM_PROTECTION;
			return pgm->code;
		}
		ga &= PAGE_MASK;
		if (psw_bits(*psw).t) {
			rc = guest_translate(vcpu, ga, pages, write);
			if (rc < 0)
				return rc;
			if (rc == PGM_PROTECTION)
				tec_bits->b61 = 1;
			if (rc)
				pgm->code = rc;
		} else {
			*pages = kvm_s390_real_to_abs(vcpu, ga);
			if (kvm_is_error_gpa(vcpu->kvm, *pages))
				pgm->code = PGM_ADDRESSING;
		}
		if (pgm->code)
			return pgm->code;
		ga += PAGE_SIZE;
		pages++;
		nr_pages--;
	}
	return 0;
}

int access_guest(struct kvm_vcpu *vcpu, unsigned long ga, void *data,
		 unsigned long len, int write)
{
	psw_t *psw = &vcpu->arch.sie_block->gpsw;
	unsigned long _len, nr_pages, gpa, idx;
	unsigned long pages_array[2];
	unsigned long *pages;
	int need_ipte_lock;
	union asce asce;
	int rc;

	if (!len)
		return 0;
	/* Access register mode is not supported yet. */
	if (psw_bits(*psw).t && psw_bits(*psw).as == PSW_AS_ACCREG)
		return -EOPNOTSUPP;
	nr_pages = (((ga & ~PAGE_MASK) + len - 1) >> PAGE_SHIFT) + 1;
	pages = pages_array;
	if (nr_pages > ARRAY_SIZE(pages_array))
		pages = vmalloc(nr_pages * sizeof(unsigned long));
	if (!pages)
		return -ENOMEM;
	asce.val = get_vcpu_asce(vcpu);
	need_ipte_lock = psw_bits(*psw).t && !asce.r;
	if (need_ipte_lock)
		ipte_lock(vcpu);
	rc = guest_page_range(vcpu, ga, pages, nr_pages, write);
	for (idx = 0; idx < nr_pages && !rc; idx++) {
		gpa = *(pages + idx) + (ga & ~PAGE_MASK);
		_len = min(PAGE_SIZE - (gpa & ~PAGE_MASK), len);
		if (write)
			rc = kvm_write_guest(vcpu->kvm, gpa, data, _len);
		else
			rc = kvm_read_guest(vcpu->kvm, gpa, data, _len);
		len -= _len;
		ga += _len;
		data += _len;
	}
	if (need_ipte_lock)
		ipte_unlock(vcpu);
	if (nr_pages > ARRAY_SIZE(pages_array))
		vfree(pages);
	return rc;
}

int access_guest_real(struct kvm_vcpu *vcpu, unsigned long gra,
		      void *data, unsigned long len, int write)
{
	unsigned long _len, gpa;
	int rc = 0;

	while (len && !rc) {
		gpa = kvm_s390_real_to_abs(vcpu, gra);
		_len = min(PAGE_SIZE - (gpa & ~PAGE_MASK), len);
		if (write)
			rc = write_guest_abs(vcpu, gpa, data, _len);
		else
			rc = read_guest_abs(vcpu, gpa, data, _len);
		len -= _len;
		gra += _len;
		data += _len;
	}
	return rc;
}

/**
 * guest_translate_address - translate guest logical into guest absolute address
 *
 * Parameter semantics are the same as the ones from guest_translate.
 * The memory contents at the guest address are not changed.
 *
 * Note: The IPTE lock is not taken during this function, so the caller
 * has to take care of this.
 */
int guest_translate_address(struct kvm_vcpu *vcpu, unsigned long gva,
			    unsigned long *gpa, int write)
{
	struct kvm_s390_pgm_info *pgm = &vcpu->arch.pgm;
	psw_t *psw = &vcpu->arch.sie_block->gpsw;
	struct trans_exc_code_bits *tec;
	union asce asce;
	int rc;

	/* Access register mode is not supported yet. */
	if (psw_bits(*psw).t && psw_bits(*psw).as == PSW_AS_ACCREG)
		return -EOPNOTSUPP;

	gva = kvm_s390_logical_to_effective(vcpu, gva);
	memset(pgm, 0, sizeof(*pgm));
	tec = (struct trans_exc_code_bits *)&pgm->trans_exc_code;
	tec->as = psw_bits(*psw).as;
	tec->fsi = write ? FSI_STORE : FSI_FETCH;
	tec->addr = gva >> PAGE_SHIFT;
	if (is_low_address(gva) && low_address_protection_enabled(vcpu)) {
		if (write) {
			rc = pgm->code = PGM_PROTECTION;
			return rc;
		}
	}

	asce.val = get_vcpu_asce(vcpu);
	if (psw_bits(*psw).t && !asce.r) {	/* Use DAT? */
		rc = guest_translate(vcpu, gva, gpa, write);
		if (rc > 0) {
			if (rc == PGM_PROTECTION)
				tec->b61 = 1;
			pgm->code = rc;
		}
	} else {
		rc = 0;
		*gpa = kvm_s390_real_to_abs(vcpu, gva);
		if (kvm_is_error_gpa(vcpu->kvm, *gpa))
			rc = pgm->code = PGM_ADDRESSING;
	}

	return rc;
}

/**
 * kvm_s390_check_low_addr_protection - check for low-address protection
 * @ga: Guest address
 *
 * Checks whether an address is subject to low-address protection and set
 * up vcpu->arch.pgm accordingly if necessary.
 *
 * Return: 0 if no protection exception, or PGM_PROTECTION if protected.
 */
int kvm_s390_check_low_addr_protection(struct kvm_vcpu *vcpu, unsigned long ga)
{
	struct kvm_s390_pgm_info *pgm = &vcpu->arch.pgm;
	psw_t *psw = &vcpu->arch.sie_block->gpsw;
	struct trans_exc_code_bits *tec_bits;

	if (!is_low_address(ga) || !low_address_protection_enabled(vcpu))
		return 0;

	memset(pgm, 0, sizeof(*pgm));
	tec_bits = (struct trans_exc_code_bits *)&pgm->trans_exc_code;
	tec_bits->fsi = FSI_STORE;
	tec_bits->as = psw_bits(*psw).as;
	tec_bits->addr = ga >> PAGE_SHIFT;
	pgm->code = PGM_PROTECTION;

	return pgm->code;
}