summaryrefslogtreecommitdiff
path: root/arch/s390/kvm/guestdbg.c
blob: 3765c4223bf944f7c96a4b44430ca739e14696b2 (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
// SPDX-License-Identifier: GPL-2.0
/*
 * kvm guest debug support
 *
 * Copyright IBM Corp. 2014
 *
 *    Author(s): David Hildenbrand <dahi@linux.vnet.ibm.com>
 */
#include <linux/kvm_host.h>
#include <linux/errno.h>
#include "kvm-s390.h"
#include "gaccess.h"

/*
 * Extends the address range given by *start and *stop to include the address
 * range starting with estart and the length len. Takes care of overflowing
 * intervals and tries to minimize the overall interval size.
 */
static void extend_address_range(u64 *start, u64 *stop, u64 estart, int len)
{
	u64 estop;

	if (len > 0)
		len--;
	else
		len = 0;

	estop = estart + len;

	/* 0-0 range represents "not set" */
	if ((*start == 0) && (*stop == 0)) {
		*start = estart;
		*stop = estop;
	} else if (*start <= *stop) {
		/* increase the existing range */
		if (estart < *start)
			*start = estart;
		if (estop > *stop)
			*stop = estop;
	} else {
		/* "overflowing" interval, whereby *stop > *start */
		if (estart <= *stop) {
			if (estop > *stop)
				*stop = estop;
		} else if (estop > *start) {
			if (estart < *start)
				*start = estart;
		}
		/* minimize the range */
		else if ((estop - *stop) < (*start - estart))
			*stop = estop;
		else
			*start = estart;
	}
}

#define MAX_INST_SIZE 6

static void enable_all_hw_bp(struct kvm_vcpu *vcpu)
{
	unsigned long start, len;
	u64 *cr9 = &vcpu->arch.sie_block->gcr[9];
	u64 *cr10 = &vcpu->arch.sie_block->gcr[10];
	u64 *cr11 = &vcpu->arch.sie_block->gcr[11];
	int i;

	if (vcpu->arch.guestdbg.nr_hw_bp <= 0 ||
	    vcpu->arch.guestdbg.hw_bp_info == NULL)
		return;

	/*
	 * If the guest is not interested in branching events, we can safely
	 * limit them to the PER address range.
	 */
	if (!(*cr9 & PER_EVENT_BRANCH))
		*cr9 |= PER_CONTROL_BRANCH_ADDRESS;
	*cr9 |= PER_EVENT_IFETCH | PER_EVENT_BRANCH;

	for (i = 0; i < vcpu->arch.guestdbg.nr_hw_bp; i++) {
		start = vcpu->arch.guestdbg.hw_bp_info[i].addr;
		len = vcpu->arch.guestdbg.hw_bp_info[i].len;

		/*
		 * The instruction in front of the desired bp has to
		 * report instruction-fetching events
		 */
		if (start < MAX_INST_SIZE) {
			len += start;
			start = 0;
		} else {
			start -= MAX_INST_SIZE;
			len += MAX_INST_SIZE;
		}

		extend_address_range(cr10, cr11, start, len);
	}
}

static void enable_all_hw_wp(struct kvm_vcpu *vcpu)
{
	unsigned long start, len;
	u64 *cr9 = &vcpu->arch.sie_block->gcr[9];
	u64 *cr10 = &vcpu->arch.sie_block->gcr[10];
	u64 *cr11 = &vcpu->arch.sie_block->gcr[11];
	int i;

	if (vcpu->arch.guestdbg.nr_hw_wp <= 0 ||
	    vcpu->arch.guestdbg.hw_wp_info == NULL)
		return;

	/* if host uses storage alternation for special address
	 * spaces, enable all events and give all to the guest */
	if (*cr9 & PER_EVENT_STORE && *cr9 & PER_CONTROL_ALTERATION) {
		*cr9 &= ~PER_CONTROL_ALTERATION;
		*cr10 = 0;
		*cr11 = -1UL;
	} else {
		*cr9 &= ~PER_CONTROL_ALTERATION;
		*cr9 |= PER_EVENT_STORE;

		for (i = 0; i < vcpu->arch.guestdbg.nr_hw_wp; i++) {
			start = vcpu->arch.guestdbg.hw_wp_info[i].addr;
			len = vcpu->arch.guestdbg.hw_wp_info[i].len;

			extend_address_range(cr10, cr11, start, len);
		}
	}
}

void kvm_s390_backup_guest_per_regs(struct kvm_vcpu *vcpu)
{
	vcpu->arch.guestdbg.cr0 = vcpu->arch.sie_block->gcr[0];
	vcpu->arch.guestdbg.cr9 = vcpu->arch.sie_block->gcr[9];
	vcpu->arch.guestdbg.cr10 = vcpu->arch.sie_block->gcr[10];
	vcpu->arch.guestdbg.cr11 = vcpu->arch.sie_block->gcr[11];
}

void kvm_s390_restore_guest_per_regs(struct kvm_vcpu *vcpu)
{
	vcpu->arch.sie_block->gcr[0] = vcpu->arch.guestdbg.cr0;
	vcpu->arch.sie_block->gcr[9] = vcpu->arch.guestdbg.cr9;
	vcpu->arch.sie_block->gcr[10] = vcpu->arch.guestdbg.cr10;
	vcpu->arch.sie_block->gcr[11] = vcpu->arch.guestdbg.cr11;
}

void kvm_s390_patch_guest_per_regs(struct kvm_vcpu *vcpu)
{
	/*
	 * TODO: if guest psw has per enabled, otherwise 0s!
	 * This reduces the amount of reported events.
	 * Need to intercept all psw changes!
	 */

	if (guestdbg_sstep_enabled(vcpu)) {
		/* disable timer (clock-comparator) interrupts */
		vcpu->arch.sie_block->gcr[0] &= ~CR0_CLOCK_COMPARATOR_SUBMASK;
		vcpu->arch.sie_block->gcr[9] |= PER_EVENT_IFETCH;
		vcpu->arch.sie_block->gcr[10] = 0;
		vcpu->arch.sie_block->gcr[11] = -1UL;
	}

	if (guestdbg_hw_bp_enabled(vcpu)) {
		enable_all_hw_bp(vcpu);
		enable_all_hw_wp(vcpu);
	}

	/* TODO: Instruction-fetching-nullification not allowed for now */
	if (vcpu->arch.sie_block->gcr[9] & PER_EVENT_NULLIFICATION)
		vcpu->arch.sie_block->gcr[9] &= ~PER_EVENT_NULLIFICATION;
}

#define MAX_WP_SIZE 100

static int __import_wp_info(struct kvm_vcpu *vcpu,
			    struct kvm_hw_breakpoint *bp_data,
			    struct kvm_hw_wp_info_arch *wp_info)
{
	int ret = 0;
	wp_info->len = bp_data->len;
	wp_info->addr = bp_data->addr;
	wp_info->phys_addr = bp_data->phys_addr;
	wp_info->old_data = NULL;

	if (wp_info->len < 0 || wp_info->len > MAX_WP_SIZE)
		return -EINVAL;

	wp_info->old_data = kmalloc(bp_data->len, GFP_KERNEL_ACCOUNT);
	if (!wp_info->old_data)
		return -ENOMEM;
	/* try to backup the original value */
	ret = read_guest_abs(vcpu, wp_info->phys_addr, wp_info->old_data,
			     wp_info->len);
	if (ret) {
		kfree(wp_info->old_data);
		wp_info->old_data = NULL;
	}

	return ret;
}

#define MAX_BP_COUNT 50

int kvm_s390_import_bp_data(struct kvm_vcpu *vcpu,
			    struct kvm_guest_debug *dbg)
{
	int ret = 0, nr_wp = 0, nr_bp = 0, i;
	struct kvm_hw_breakpoint *bp_data = NULL;
	struct kvm_hw_wp_info_arch *wp_info = NULL;
	struct kvm_hw_bp_info_arch *bp_info = NULL;

	if (dbg->arch.nr_hw_bp <= 0 || !dbg->arch.hw_bp)
		return 0;
	else if (dbg->arch.nr_hw_bp > MAX_BP_COUNT)
		return -EINVAL;

	bp_data = memdup_user(dbg->arch.hw_bp,
			      sizeof(*bp_data) * dbg->arch.nr_hw_bp);
	if (IS_ERR(bp_data))
		return PTR_ERR(bp_data);

	for (i = 0; i < dbg->arch.nr_hw_bp; i++) {
		switch (bp_data[i].type) {
		case KVM_HW_WP_WRITE:
			nr_wp++;
			break;
		case KVM_HW_BP:
			nr_bp++;
			break;
		default:
			break;
		}
	}

	if (nr_wp > 0) {
		wp_info = kmalloc_array(nr_wp,
					sizeof(*wp_info),
					GFP_KERNEL_ACCOUNT);
		if (!wp_info) {
			ret = -ENOMEM;
			goto error;
		}
	}
	if (nr_bp > 0) {
		bp_info = kmalloc_array(nr_bp,
					sizeof(*bp_info),
					GFP_KERNEL_ACCOUNT);
		if (!bp_info) {
			ret = -ENOMEM;
			goto error;
		}
	}

	for (nr_wp = 0, nr_bp = 0, i = 0; i < dbg->arch.nr_hw_bp; i++) {
		switch (bp_data[i].type) {
		case KVM_HW_WP_WRITE:
			ret = __import_wp_info(vcpu, &bp_data[i],
					       &wp_info[nr_wp]);
			if (ret)
				goto error;
			nr_wp++;
			break;
		case KVM_HW_BP:
			bp_info[nr_bp].len = bp_data[i].len;
			bp_info[nr_bp].addr = bp_data[i].addr;
			nr_bp++;
			break;
		}
	}

	vcpu->arch.guestdbg.nr_hw_bp = nr_bp;
	vcpu->arch.guestdbg.hw_bp_info = bp_info;
	vcpu->arch.guestdbg.nr_hw_wp = nr_wp;
	vcpu->arch.guestdbg.hw_wp_info = wp_info;
	return 0;
error:
	kfree(bp_data);
	kfree(wp_info);
	kfree(bp_info);
	return ret;
}

void kvm_s390_clear_bp_data(struct kvm_vcpu *vcpu)
{
	int i;
	struct kvm_hw_wp_info_arch *hw_wp_info = NULL;

	for (i = 0; i < vcpu->arch.guestdbg.nr_hw_wp; i++) {
		hw_wp_info = &vcpu->arch.guestdbg.hw_wp_info[i];
		kfree(hw_wp_info->old_data);
		hw_wp_info->old_data = NULL;
	}
	kfree(vcpu->arch.guestdbg.hw_wp_info);
	vcpu->arch.guestdbg.hw_wp_info = NULL;

	kfree(vcpu->arch.guestdbg.hw_bp_info);
	vcpu->arch.guestdbg.hw_bp_info = NULL;

	vcpu->arch.guestdbg.nr_hw_wp = 0;
	vcpu->arch.guestdbg.nr_hw_bp = 0;
}

static inline int in_addr_range(u64 addr, u64 a, u64 b)
{
	if (a <= b)
		return (addr >= a) && (addr <= b);
	else
		/* "overflowing" interval */
		return (addr >= a) || (addr <= b);
}

#define end_of_range(bp_info) (bp_info->addr + bp_info->len - 1)

static struct kvm_hw_bp_info_arch *find_hw_bp(struct kvm_vcpu *vcpu,
					      unsigned long addr)
{
	struct kvm_hw_bp_info_arch *bp_info = vcpu->arch.guestdbg.hw_bp_info;
	int i;

	if (vcpu->arch.guestdbg.nr_hw_bp == 0)
		return NULL;

	for (i = 0; i < vcpu->arch.guestdbg.nr_hw_bp; i++) {
		/* addr is directly the start or in the range of a bp */
		if (addr == bp_info->addr)
			goto found;
		if (bp_info->len > 0 &&
		    in_addr_range(addr, bp_info->addr, end_of_range(bp_info)))
			goto found;

		bp_info++;
	}

	return NULL;
found:
	return bp_info;
}

static struct kvm_hw_wp_info_arch *any_wp_changed(struct kvm_vcpu *vcpu)
{
	int i;
	struct kvm_hw_wp_info_arch *wp_info = NULL;
	void *temp = NULL;

	if (vcpu->arch.guestdbg.nr_hw_wp == 0)
		return NULL;

	for (i = 0; i < vcpu->arch.guestdbg.nr_hw_wp; i++) {
		wp_info = &vcpu->arch.guestdbg.hw_wp_info[i];
		if (!wp_info || !wp_info->old_data || wp_info->len <= 0)
			continue;

		temp = kmalloc(wp_info->len, GFP_KERNEL_ACCOUNT);
		if (!temp)
			continue;

		/* refetch the wp data and compare it to the old value */
		if (!read_guest_abs(vcpu, wp_info->phys_addr, temp,
				    wp_info->len)) {
			if (memcmp(temp, wp_info->old_data, wp_info->len)) {
				kfree(temp);
				return wp_info;
			}
		}
		kfree(temp);
		temp = NULL;
	}

	return NULL;
}

void kvm_s390_prepare_debug_exit(struct kvm_vcpu *vcpu)
{
	vcpu->run->exit_reason = KVM_EXIT_DEBUG;
	vcpu->guest_debug &= ~KVM_GUESTDBG_EXIT_PENDING;
}

#define PER_CODE_MASK		(PER_EVENT_MASK >> 24)
#define PER_CODE_BRANCH		(PER_EVENT_BRANCH >> 24)
#define PER_CODE_IFETCH		(PER_EVENT_IFETCH >> 24)
#define PER_CODE_STORE		(PER_EVENT_STORE >> 24)
#define PER_CODE_STORE_REAL	(PER_EVENT_STORE_REAL >> 24)

#define per_bp_event(code) \
			(code & (PER_CODE_IFETCH | PER_CODE_BRANCH))
#define per_write_wp_event(code) \
			(code & (PER_CODE_STORE | PER_CODE_STORE_REAL))

static int debug_exit_required(struct kvm_vcpu *vcpu, u8 perc,
			       unsigned long peraddr)
{
	struct kvm_debug_exit_arch *debug_exit = &vcpu->run->debug.arch;
	struct kvm_hw_wp_info_arch *wp_info = NULL;
	struct kvm_hw_bp_info_arch *bp_info = NULL;
	unsigned long addr = vcpu->arch.sie_block->gpsw.addr;

	if (guestdbg_hw_bp_enabled(vcpu)) {
		if (per_write_wp_event(perc) &&
		    vcpu->arch.guestdbg.nr_hw_wp > 0) {
			wp_info = any_wp_changed(vcpu);
			if (wp_info) {
				debug_exit->addr = wp_info->addr;
				debug_exit->type = KVM_HW_WP_WRITE;
				goto exit_required;
			}
		}
		if (per_bp_event(perc) &&
			 vcpu->arch.guestdbg.nr_hw_bp > 0) {
			bp_info = find_hw_bp(vcpu, addr);
			/* remove duplicate events if PC==PER address */
			if (bp_info && (addr != peraddr)) {
				debug_exit->addr = addr;
				debug_exit->type = KVM_HW_BP;
				vcpu->arch.guestdbg.last_bp = addr;
				goto exit_required;
			}
			/* breakpoint missed */
			bp_info = find_hw_bp(vcpu, peraddr);
			if (bp_info && vcpu->arch.guestdbg.last_bp != peraddr) {
				debug_exit->addr = peraddr;
				debug_exit->type = KVM_HW_BP;
				goto exit_required;
			}
		}
	}
	if (guestdbg_sstep_enabled(vcpu) && per_bp_event(perc)) {
		debug_exit->addr = addr;
		debug_exit->type = KVM_SINGLESTEP;
		goto exit_required;
	}

	return 0;
exit_required:
	return 1;
}

static int per_fetched_addr(struct kvm_vcpu *vcpu, unsigned long *addr)
{
	u8 exec_ilen = 0;
	u16 opcode[3];
	int rc;

	if (vcpu->arch.sie_block->icptcode == ICPT_PROGI) {
		/* PER address references the fetched or the execute instr */
		*addr = vcpu->arch.sie_block->peraddr;
		/*
		 * Manually detect if we have an EXECUTE instruction. As
		 * instructions are always 2 byte aligned we can read the
		 * first two bytes unconditionally
		 */
		rc = read_guest_instr(vcpu, *addr, &opcode, 2);
		if (rc)
			return rc;
		if (opcode[0] >> 8 == 0x44)
			exec_ilen = 4;
		if ((opcode[0] & 0xff0f) == 0xc600)
			exec_ilen = 6;
	} else {
		/* instr was suppressed, calculate the responsible instr */
		*addr = __rewind_psw(vcpu->arch.sie_block->gpsw,
				     kvm_s390_get_ilen(vcpu));
		if (vcpu->arch.sie_block->icptstatus & 0x01) {
			exec_ilen = (vcpu->arch.sie_block->icptstatus & 0x60) >> 4;
			if (!exec_ilen)
				exec_ilen = 4;
		}
	}

	if (exec_ilen) {
		/* read the complete EXECUTE instr to detect the fetched addr */
		rc = read_guest_instr(vcpu, *addr, &opcode, exec_ilen);
		if (rc)
			return rc;
		if (exec_ilen == 6) {
			/* EXECUTE RELATIVE LONG - RIL-b format */
			s32 rl = *((s32 *) (opcode + 1));

			/* rl is a _signed_ 32 bit value specifying halfwords */
			*addr += (u64)(s64) rl * 2;
		} else {
			/* EXECUTE - RX-a format */
			u32 base = (opcode[1] & 0xf000) >> 12;
			u32 disp = opcode[1] & 0x0fff;
			u32 index = opcode[0] & 0x000f;

			*addr = base ? vcpu->run->s.regs.gprs[base] : 0;
			*addr += index ? vcpu->run->s.regs.gprs[index] : 0;
			*addr += disp;
		}
		*addr = kvm_s390_logical_to_effective(vcpu, *addr);
	}
	return 0;
}

#define guest_per_enabled(vcpu) \
			     (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PER)

int kvm_s390_handle_per_ifetch_icpt(struct kvm_vcpu *vcpu)
{
	const u64 cr10 = vcpu->arch.sie_block->gcr[10];
	const u64 cr11 = vcpu->arch.sie_block->gcr[11];
	const u8 ilen = kvm_s390_get_ilen(vcpu);
	struct kvm_s390_pgm_info pgm_info = {
		.code = PGM_PER,
		.per_code = PER_CODE_IFETCH,
		.per_address = __rewind_psw(vcpu->arch.sie_block->gpsw, ilen),
	};
	unsigned long fetched_addr;
	int rc;

	/*
	 * The PSW points to the next instruction, therefore the intercepted
	 * instruction generated a PER i-fetch event. PER address therefore
	 * points at the previous PSW address (could be an EXECUTE function).
	 */
	if (!guestdbg_enabled(vcpu))
		return kvm_s390_inject_prog_irq(vcpu, &pgm_info);

	if (debug_exit_required(vcpu, pgm_info.per_code, pgm_info.per_address))
		vcpu->guest_debug |= KVM_GUESTDBG_EXIT_PENDING;

	if (!guest_per_enabled(vcpu) ||
	    !(vcpu->arch.sie_block->gcr[9] & PER_EVENT_IFETCH))
		return 0;

	rc = per_fetched_addr(vcpu, &fetched_addr);
	if (rc < 0)
		return rc;
	if (rc)
		/* instruction-fetching exceptions */
		return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);

	if (in_addr_range(fetched_addr, cr10, cr11))
		return kvm_s390_inject_prog_irq(vcpu, &pgm_info);
	return 0;
}

static int filter_guest_per_event(struct kvm_vcpu *vcpu)
{
	const u8 perc = vcpu->arch.sie_block->perc;
	u64 addr = vcpu->arch.sie_block->gpsw.addr;
	u64 cr9 = vcpu->arch.sie_block->gcr[9];
	u64 cr10 = vcpu->arch.sie_block->gcr[10];
	u64 cr11 = vcpu->arch.sie_block->gcr[11];
	/* filter all events, demanded by the guest */
	u8 guest_perc = perc & (cr9 >> 24) & PER_CODE_MASK;
	unsigned long fetched_addr;
	int rc;

	if (!guest_per_enabled(vcpu))
		guest_perc = 0;

	/* filter "successful-branching" events */
	if (guest_perc & PER_CODE_BRANCH &&
	    cr9 & PER_CONTROL_BRANCH_ADDRESS &&
	    !in_addr_range(addr, cr10, cr11))
		guest_perc &= ~PER_CODE_BRANCH;

	/* filter "instruction-fetching" events */
	if (guest_perc & PER_CODE_IFETCH) {
		rc = per_fetched_addr(vcpu, &fetched_addr);
		if (rc < 0)
			return rc;
		/*
		 * Don't inject an irq on exceptions. This would make handling
		 * on icpt code 8 very complex (as PSW was already rewound).
		 */
		if (rc || !in_addr_range(fetched_addr, cr10, cr11))
			guest_perc &= ~PER_CODE_IFETCH;
	}

	/* All other PER events will be given to the guest */
	/* TODO: Check altered address/address space */

	vcpu->arch.sie_block->perc = guest_perc;

	if (!guest_perc)
		vcpu->arch.sie_block->iprcc &= ~PGM_PER;
	return 0;
}

#define pssec(vcpu) (vcpu->arch.sie_block->gcr[1] & _ASCE_SPACE_SWITCH)
#define hssec(vcpu) (vcpu->arch.sie_block->gcr[13] & _ASCE_SPACE_SWITCH)
#define old_ssec(vcpu) ((vcpu->arch.sie_block->tecmc >> 31) & 0x1)
#define old_as_is_home(vcpu) !(vcpu->arch.sie_block->tecmc & 0xffff)

int kvm_s390_handle_per_event(struct kvm_vcpu *vcpu)
{
	int rc, new_as;

	if (debug_exit_required(vcpu, vcpu->arch.sie_block->perc,
				vcpu->arch.sie_block->peraddr))
		vcpu->guest_debug |= KVM_GUESTDBG_EXIT_PENDING;

	rc = filter_guest_per_event(vcpu);
	if (rc)
		return rc;

	/*
	 * Only RP, SAC, SACF, PT, PTI, PR, PC instructions can trigger
	 * a space-switch event. PER events enforce space-switch events
	 * for these instructions. So if no PER event for the guest is left,
	 * we might have to filter the space-switch element out, too.
	 */
	if (vcpu->arch.sie_block->iprcc == PGM_SPACE_SWITCH) {
		vcpu->arch.sie_block->iprcc = 0;
		new_as = psw_bits(vcpu->arch.sie_block->gpsw).as;

		/*
		 * If the AS changed from / to home, we had RP, SAC or SACF
		 * instruction. Check primary and home space-switch-event
		 * controls. (theoretically home -> home produced no event)
		 */
		if (((new_as == PSW_BITS_AS_HOME) ^ old_as_is_home(vcpu)) &&
		    (pssec(vcpu) || hssec(vcpu)))
			vcpu->arch.sie_block->iprcc = PGM_SPACE_SWITCH;

		/*
		 * PT, PTI, PR, PC instruction operate on primary AS only. Check
		 * if the primary-space-switch-event control was or got set.
		 */
		if (new_as == PSW_BITS_AS_PRIMARY && !old_as_is_home(vcpu) &&
		    (pssec(vcpu) || old_ssec(vcpu)))
			vcpu->arch.sie_block->iprcc = PGM_SPACE_SWITCH;
	}
	return 0;
}