xref: /linux/tools/testing/selftests/kvm/steal_time.c (revision e1914add2799225a87502051415fc5c32aeb02ae)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * steal/stolen time test
4  *
5  * Copyright (C) 2020, Red Hat, Inc.
6  */
7 #include <stdio.h>
8 #include <time.h>
9 #include <sched.h>
10 #include <pthread.h>
11 #include <linux/kernel.h>
12 #include <asm/kvm.h>
13 #ifdef __riscv
14 #include "sbi.h"
15 #else
16 #include <asm/kvm_para.h>
17 #endif
18 
19 #include "test_util.h"
20 #include "kvm_util.h"
21 #include "processor.h"
22 #include "ucall_common.h"
23 
24 #define NR_VCPUS		4
25 #define ST_GPA_BASE		(1 << 30)
26 
27 static void *st_gva[NR_VCPUS];
28 static u64 guest_stolen_time[NR_VCPUS];
29 
30 #if defined(__x86_64__)
31 
32 /* steal_time must have 64-byte alignment */
33 #define STEAL_TIME_SIZE		((sizeof(struct kvm_steal_time) + 63) & ~63)
34 
check_status(struct kvm_steal_time * st)35 static void check_status(struct kvm_steal_time *st)
36 {
37 	GUEST_ASSERT(!(READ_ONCE(st->version) & 1));
38 	GUEST_ASSERT_EQ(READ_ONCE(st->flags), 0);
39 	GUEST_ASSERT_EQ(READ_ONCE(st->preempted), 0);
40 }
41 
guest_code(int cpu)42 static void guest_code(int cpu)
43 {
44 	struct kvm_steal_time *st = st_gva[cpu];
45 	u32 version;
46 
47 	GUEST_ASSERT_EQ(rdmsr(MSR_KVM_STEAL_TIME), ((u64)st_gva[cpu] | KVM_MSR_ENABLED));
48 
49 	memset(st, 0, sizeof(*st));
50 	GUEST_SYNC(0);
51 
52 	check_status(st);
53 	WRITE_ONCE(guest_stolen_time[cpu], st->steal);
54 	version = READ_ONCE(st->version);
55 	check_status(st);
56 	GUEST_SYNC(1);
57 
58 	check_status(st);
59 	GUEST_ASSERT(version < READ_ONCE(st->version));
60 	WRITE_ONCE(guest_stolen_time[cpu], st->steal);
61 	check_status(st);
62 	GUEST_DONE();
63 }
64 
is_steal_time_supported(struct kvm_vcpu * vcpu)65 static bool is_steal_time_supported(struct kvm_vcpu *vcpu)
66 {
67 	return kvm_cpu_has(X86_FEATURE_KVM_STEAL_TIME);
68 }
69 
steal_time_init(struct kvm_vcpu * vcpu,u32 i)70 static void steal_time_init(struct kvm_vcpu *vcpu, u32 i)
71 {
72 	/* ST_GPA_BASE is identity mapped */
73 	st_gva[i] = (void *)(ST_GPA_BASE + i * STEAL_TIME_SIZE);
74 	sync_global_to_guest(vcpu->vm, st_gva[i]);
75 
76 	vcpu_set_msr(vcpu, MSR_KVM_STEAL_TIME, (ulong)st_gva[i] | KVM_MSR_ENABLED);
77 }
78 
steal_time_dump(struct kvm_vm * vm,u32 vcpu_idx)79 static void steal_time_dump(struct kvm_vm *vm, u32 vcpu_idx)
80 {
81 	struct kvm_steal_time *st = addr_gva2hva(vm, (ulong)st_gva[vcpu_idx]);
82 
83 	ksft_print_msg("VCPU%d:\n", vcpu_idx);
84 	ksft_print_msg("    steal:     %lld\n", st->steal);
85 	ksft_print_msg("    version:   %d\n", st->version);
86 	ksft_print_msg("    flags:     %d\n", st->flags);
87 	ksft_print_msg("    preempted: %d\n", st->preempted);
88 	ksft_print_msg("    u8_pad:    %d %d %d\n",
89 			st->u8_pad[0], st->u8_pad[1], st->u8_pad[2]);
90 	ksft_print_msg("    pad:       %d %d %d %d %d %d %d %d %d %d %d\n",
91 			st->pad[0], st->pad[1], st->pad[2], st->pad[3],
92 			st->pad[4], st->pad[5], st->pad[6], st->pad[7],
93 			st->pad[8], st->pad[9], st->pad[10]);
94 }
95 
check_steal_time_uapi(void)96 static void check_steal_time_uapi(void)
97 {
98 	struct kvm_vm *vm;
99 	struct kvm_vcpu *vcpu;
100 	int ret;
101 
102 	vm = vm_create_with_one_vcpu(&vcpu, NULL);
103 
104 	ret = _vcpu_set_msr(vcpu, MSR_KVM_STEAL_TIME,
105 			    (ulong)ST_GPA_BASE | KVM_STEAL_RESERVED_MASK);
106 	TEST_ASSERT(ret == 0, "Bad GPA didn't fail");
107 
108 	kvm_vm_free(vm);
109 }
110 
111 #elif defined(__aarch64__)
112 
113 /* PV_TIME_ST must have 64-byte alignment */
114 #define STEAL_TIME_SIZE		((sizeof(struct st_time) + 63) & ~63)
115 
116 #define SMCCC_ARCH_FEATURES	0x80000001
117 #define PV_TIME_FEATURES	0xc5000020
118 #define PV_TIME_ST		0xc5000021
119 
120 struct st_time {
121 	u32 rev;
122 	u32 attr;
123 	u64 st_time;
124 };
125 
smccc(u32 func,u64 arg)126 static s64 smccc(u32 func, u64 arg)
127 {
128 	struct arm_smccc_res res;
129 
130 	do_smccc(func, arg, 0, 0, 0, 0, 0, 0, &res);
131 	return res.a0;
132 }
133 
check_status(struct st_time * st)134 static void check_status(struct st_time *st)
135 {
136 	GUEST_ASSERT_EQ(READ_ONCE(st->rev), 0);
137 	GUEST_ASSERT_EQ(READ_ONCE(st->attr), 0);
138 }
139 
guest_code(int cpu)140 static void guest_code(int cpu)
141 {
142 	struct st_time *st;
143 	s64 status;
144 
145 	status = smccc(SMCCC_ARCH_FEATURES, PV_TIME_FEATURES);
146 	GUEST_ASSERT_EQ(status, 0);
147 	status = smccc(PV_TIME_FEATURES, PV_TIME_FEATURES);
148 	GUEST_ASSERT_EQ(status, 0);
149 	status = smccc(PV_TIME_FEATURES, PV_TIME_ST);
150 	GUEST_ASSERT_EQ(status, 0);
151 
152 	status = smccc(PV_TIME_ST, 0);
153 	GUEST_ASSERT_NE(status, -1);
154 	GUEST_ASSERT_EQ(status, (ulong)st_gva[cpu]);
155 
156 	st = (struct st_time *)status;
157 	GUEST_SYNC(0);
158 
159 	check_status(st);
160 	WRITE_ONCE(guest_stolen_time[cpu], st->st_time);
161 	GUEST_SYNC(1);
162 
163 	check_status(st);
164 	WRITE_ONCE(guest_stolen_time[cpu], st->st_time);
165 	GUEST_DONE();
166 }
167 
is_steal_time_supported(struct kvm_vcpu * vcpu)168 static bool is_steal_time_supported(struct kvm_vcpu *vcpu)
169 {
170 	struct kvm_device_attr dev = {
171 		.group = KVM_ARM_VCPU_PVTIME_CTRL,
172 		.attr = KVM_ARM_VCPU_PVTIME_IPA,
173 	};
174 
175 	return !__vcpu_ioctl(vcpu, KVM_HAS_DEVICE_ATTR, &dev);
176 }
177 
steal_time_init(struct kvm_vcpu * vcpu,u32 i)178 static void steal_time_init(struct kvm_vcpu *vcpu, u32 i)
179 {
180 	struct kvm_vm *vm = vcpu->vm;
181 	u64 st_ipa;
182 
183 	struct kvm_device_attr dev = {
184 		.group = KVM_ARM_VCPU_PVTIME_CTRL,
185 		.attr = KVM_ARM_VCPU_PVTIME_IPA,
186 		.addr = (u64)&st_ipa,
187 	};
188 
189 	/* ST_GPA_BASE is identity mapped */
190 	st_gva[i] = (void *)(ST_GPA_BASE + i * STEAL_TIME_SIZE);
191 	sync_global_to_guest(vm, st_gva[i]);
192 
193 	st_ipa = (ulong)st_gva[i];
194 	vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &dev);
195 }
196 
steal_time_dump(struct kvm_vm * vm,u32 vcpu_idx)197 static void steal_time_dump(struct kvm_vm *vm, u32 vcpu_idx)
198 {
199 	struct st_time *st = addr_gva2hva(vm, (ulong)st_gva[vcpu_idx]);
200 
201 	ksft_print_msg("VCPU%d:\n", vcpu_idx);
202 	ksft_print_msg("    rev:     %d\n", st->rev);
203 	ksft_print_msg("    attr:    %d\n", st->attr);
204 	ksft_print_msg("    st_time: %ld\n", st->st_time);
205 }
206 
check_steal_time_uapi(void)207 static void check_steal_time_uapi(void)
208 {
209 	struct kvm_vm *vm;
210 	struct kvm_vcpu *vcpu;
211 	u64 st_ipa;
212 	int ret;
213 
214 	vm = vm_create_with_one_vcpu(&vcpu, NULL);
215 
216 	struct kvm_device_attr dev = {
217 		.group = KVM_ARM_VCPU_PVTIME_CTRL,
218 		.attr = KVM_ARM_VCPU_PVTIME_IPA,
219 		.addr = (u64)&st_ipa,
220 	};
221 
222 	vcpu_ioctl(vcpu, KVM_HAS_DEVICE_ATTR, &dev);
223 	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, ST_GPA_BASE, 1, 1, 0);
224 	virt_map(vm, ST_GPA_BASE, ST_GPA_BASE, 1);
225 
226 	st_ipa = (ulong)ST_GPA_BASE | 1;
227 	ret = __vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &dev);
228 	TEST_ASSERT(ret == -1 && errno == EINVAL, "Bad IPA didn't report EINVAL");
229 
230 	st_ipa = (ulong)ST_GPA_BASE;
231 	vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &dev);
232 
233 	ret = __vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &dev);
234 	TEST_ASSERT(ret == -1 && errno == EEXIST, "Set IPA twice without EEXIST");
235 
236 	kvm_vm_free(vm);
237 }
238 
239 #elif defined(__riscv)
240 
241 /* SBI STA shmem must have 64-byte alignment */
242 #define STEAL_TIME_SIZE		((sizeof(struct sta_struct) + 63) & ~63)
243 
244 static gpa_t st_gpa[NR_VCPUS];
245 
246 struct sta_struct {
247 	u32 sequence;
248 	u32 flags;
249 	u64 steal;
250 	u8 preempted;
251 	u8 pad[47];
252 } __packed;
253 
sta_set_shmem(gpa_t gpa,unsigned long flags)254 static void sta_set_shmem(gpa_t gpa, unsigned long flags)
255 {
256 	unsigned long lo = (unsigned long)gpa;
257 #if __riscv_xlen == 32
258 	unsigned long hi = (unsigned long)(gpa >> 32);
259 #else
260 	unsigned long hi = gpa == -1 ? -1 : 0;
261 #endif
262 	struct sbiret ret = sbi_ecall(SBI_EXT_STA, 0, lo, hi, flags, 0, 0, 0);
263 
264 	GUEST_ASSERT(ret.value == 0 && ret.error == 0);
265 }
266 
check_status(struct sta_struct * st)267 static void check_status(struct sta_struct *st)
268 {
269 	GUEST_ASSERT(!(READ_ONCE(st->sequence) & 1));
270 	GUEST_ASSERT(READ_ONCE(st->flags) == 0);
271 	GUEST_ASSERT(READ_ONCE(st->preempted) == 0);
272 }
273 
guest_code(int cpu)274 static void guest_code(int cpu)
275 {
276 	struct sta_struct *st = st_gva[cpu];
277 	u32 sequence;
278 	long out_val = 0;
279 	bool probe;
280 
281 	probe = guest_sbi_probe_extension(SBI_EXT_STA, &out_val);
282 	GUEST_ASSERT(probe && out_val == 1);
283 
284 	sta_set_shmem(st_gpa[cpu], 0);
285 	GUEST_SYNC(0);
286 
287 	check_status(st);
288 	WRITE_ONCE(guest_stolen_time[cpu], st->steal);
289 	sequence = READ_ONCE(st->sequence);
290 	check_status(st);
291 	GUEST_SYNC(1);
292 
293 	check_status(st);
294 	GUEST_ASSERT(sequence < READ_ONCE(st->sequence));
295 	WRITE_ONCE(guest_stolen_time[cpu], st->steal);
296 	check_status(st);
297 	GUEST_DONE();
298 }
299 
is_steal_time_supported(struct kvm_vcpu * vcpu)300 static bool is_steal_time_supported(struct kvm_vcpu *vcpu)
301 {
302 	u64 id = RISCV_SBI_EXT_REG(KVM_RISCV_SBI_EXT_STA);
303 	unsigned long enabled = vcpu_get_reg(vcpu, id);
304 
305 	TEST_ASSERT(enabled == 0 || enabled == 1, "Expected boolean result");
306 
307 	return enabled;
308 }
309 
steal_time_init(struct kvm_vcpu * vcpu,u32 i)310 static void steal_time_init(struct kvm_vcpu *vcpu, u32 i)
311 {
312 	/* ST_GPA_BASE is identity mapped */
313 	st_gva[i] = (void *)(ST_GPA_BASE + i * STEAL_TIME_SIZE);
314 	st_gpa[i] = addr_gva2gpa(vcpu->vm, (gva_t)st_gva[i]);
315 	sync_global_to_guest(vcpu->vm, st_gva[i]);
316 	sync_global_to_guest(vcpu->vm, st_gpa[i]);
317 }
318 
steal_time_dump(struct kvm_vm * vm,u32 vcpu_idx)319 static void steal_time_dump(struct kvm_vm *vm, u32 vcpu_idx)
320 {
321 	struct sta_struct *st = addr_gva2hva(vm, (ulong)st_gva[vcpu_idx]);
322 	int i;
323 
324 	pr_info("VCPU%d:\n", vcpu_idx);
325 	pr_info("    sequence:  %d\n", st->sequence);
326 	pr_info("    flags:     %d\n", st->flags);
327 	pr_info("    steal:     %"PRIu64"\n", st->steal);
328 	pr_info("    preempted: %d\n", st->preempted);
329 	pr_info("    pad:      ");
330 	for (i = 0; i < 47; ++i)
331 		pr_info("%d", st->pad[i]);
332 	pr_info("\n");
333 }
334 
check_steal_time_uapi(void)335 static void check_steal_time_uapi(void)
336 {
337 	struct kvm_vm *vm;
338 	struct kvm_vcpu *vcpu;
339 	struct kvm_one_reg reg;
340 	u64 shmem;
341 	int ret;
342 
343 	vm = vm_create_with_one_vcpu(&vcpu, NULL);
344 
345 	reg.id = KVM_REG_RISCV |
346 			 KVM_REG_SIZE_ULONG |
347 			 KVM_REG_RISCV_SBI_STATE |
348 			 KVM_REG_RISCV_SBI_STA |
349 			 KVM_REG_RISCV_SBI_STA_REG(shmem_lo);
350 	reg.addr = (u64)&shmem;
351 
352 	shmem = ST_GPA_BASE + 1;
353 	ret = __vcpu_ioctl(vcpu, KVM_SET_ONE_REG, &reg);
354 	TEST_ASSERT(ret == -1 && errno == EINVAL,
355 		    "misaligned STA shmem returns -EINVAL");
356 
357 	shmem = ST_GPA_BASE;
358 	ret = __vcpu_ioctl(vcpu, KVM_SET_ONE_REG, &reg);
359 	TEST_ASSERT(ret == 0,
360 		    "aligned STA shmem succeeds");
361 
362 	shmem = INVALID_GPA;
363 	ret = __vcpu_ioctl(vcpu, KVM_SET_ONE_REG, &reg);
364 	TEST_ASSERT(ret == 0,
365 		    "all-ones for STA shmem succeeds");
366 
367 	kvm_vm_free(vm);
368 }
369 
370 #elif defined(__loongarch__)
371 
372 /* steal_time must have 64-byte alignment */
373 #define STEAL_TIME_SIZE		((sizeof(struct kvm_steal_time) + 63) & ~63)
374 #define KVM_STEAL_PHYS_VALID	BIT_ULL(0)
375 
376 struct kvm_steal_time {
377 	__u64 steal;
378 	__u32 version;
379 	__u32 flags;
380 	__u8  preempted;
381 	__u8  pad[47];
382 };
383 
check_status(struct kvm_steal_time * st)384 static void check_status(struct kvm_steal_time *st)
385 {
386 	GUEST_ASSERT(!(READ_ONCE(st->version) & 1));
387 	GUEST_ASSERT_EQ(READ_ONCE(st->flags), 0);
388 	GUEST_ASSERT_EQ(READ_ONCE(st->preempted), 0);
389 }
390 
guest_code(int cpu)391 static void guest_code(int cpu)
392 {
393 	u32 version;
394 	struct kvm_steal_time *st = st_gva[cpu];
395 
396 	memset(st, 0, sizeof(*st));
397 	GUEST_SYNC(0);
398 
399 	check_status(st);
400 	WRITE_ONCE(guest_stolen_time[cpu], st->steal);
401 	version = READ_ONCE(st->version);
402 	check_status(st);
403 	GUEST_SYNC(1);
404 
405 	check_status(st);
406 	GUEST_ASSERT(version < READ_ONCE(st->version));
407 	WRITE_ONCE(guest_stolen_time[cpu], st->steal);
408 	check_status(st);
409 	GUEST_DONE();
410 }
411 
is_steal_time_supported(struct kvm_vcpu * vcpu)412 static bool is_steal_time_supported(struct kvm_vcpu *vcpu)
413 {
414 	int err;
415 	u64 val;
416 	struct kvm_device_attr attr = {
417 		.group = KVM_LOONGARCH_VCPU_CPUCFG,
418 		.attr = CPUCFG_KVM_FEATURE,
419 		.addr = (u64)&val,
420 	};
421 
422 	err = __vcpu_ioctl(vcpu, KVM_HAS_DEVICE_ATTR, &attr);
423 	if (err)
424 		return false;
425 
426 	err = __vcpu_ioctl(vcpu, KVM_GET_DEVICE_ATTR, &attr);
427 	if (err)
428 		return false;
429 
430 	return val & BIT(KVM_FEATURE_STEAL_TIME);
431 }
432 
steal_time_init(struct kvm_vcpu * vcpu,u32 i)433 static void steal_time_init(struct kvm_vcpu *vcpu, u32 i)
434 {
435 	int err;
436 	u64 st_gpa;
437 	struct kvm_vm *vm = vcpu->vm;
438 	struct kvm_device_attr attr = {
439 		.group = KVM_LOONGARCH_VCPU_PVTIME_CTRL,
440 		.attr = KVM_LOONGARCH_VCPU_PVTIME_GPA,
441 		.addr = (u64)&st_gpa,
442 	};
443 
444 	/* ST_GPA_BASE is identity mapped */
445 	st_gva[i] = (void *)(ST_GPA_BASE + i * STEAL_TIME_SIZE);
446 	sync_global_to_guest(vm, st_gva[i]);
447 
448 	err = __vcpu_ioctl(vcpu, KVM_HAS_DEVICE_ATTR, &attr);
449 	TEST_ASSERT(err == 0, "No PV stealtime Feature");
450 
451 	st_gpa = (unsigned long)st_gva[i] | KVM_STEAL_PHYS_VALID;
452 	err = __vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &attr);
453 	TEST_ASSERT(err == 0, "Fail to set PV stealtime GPA");
454 }
455 
steal_time_dump(struct kvm_vm * vm,u32 vcpu_idx)456 static void steal_time_dump(struct kvm_vm *vm, u32 vcpu_idx)
457 {
458 	struct kvm_steal_time *st = addr_gva2hva(vm, (ulong)st_gva[vcpu_idx]);
459 
460 	ksft_print_msg("VCPU%d:\n", vcpu_idx);
461 	ksft_print_msg("    steal:     %lld\n", st->steal);
462 	ksft_print_msg("    flags:     %d\n", st->flags);
463 	ksft_print_msg("    version:   %d\n", st->version);
464 	ksft_print_msg("    preempted: %d\n", st->preempted);
465 }
466 
check_steal_time_uapi(void)467 static void check_steal_time_uapi(void)
468 {
469 
470 }
471 #endif
472 
do_steal_time(void * arg)473 static void *do_steal_time(void *arg)
474 {
475 	struct timespec ts, stop;
476 
477 	clock_gettime(CLOCK_MONOTONIC, &ts);
478 	stop = timespec_add_ns(ts, MIN_RUN_DELAY_NS);
479 
480 	while (1) {
481 		clock_gettime(CLOCK_MONOTONIC, &ts);
482 		if (timespec_to_ns(timespec_sub(ts, stop)) >= 0)
483 			break;
484 	}
485 
486 	return NULL;
487 }
488 
run_vcpu(struct kvm_vcpu * vcpu)489 static void run_vcpu(struct kvm_vcpu *vcpu)
490 {
491 	struct ucall uc;
492 
493 	vcpu_run(vcpu);
494 
495 	switch (get_ucall(vcpu, &uc)) {
496 	case UCALL_SYNC:
497 	case UCALL_DONE:
498 		break;
499 	case UCALL_ABORT:
500 		REPORT_GUEST_ASSERT(uc);
501 	default:
502 		TEST_ASSERT(false, "Unexpected exit: %s",
503 			    exit_reason_str(vcpu->run->exit_reason));
504 	}
505 }
506 
main(int ac,char ** av)507 int main(int ac, char **av)
508 {
509 	struct kvm_vcpu *vcpus[NR_VCPUS];
510 	struct kvm_vm *vm;
511 	pthread_attr_t attr;
512 	pthread_t thread;
513 	cpu_set_t cpuset;
514 	unsigned int gpages;
515 	long stolen_time;
516 	long run_delay;
517 	bool verbose;
518 	int i;
519 
520 	verbose = ac > 1 && (!strncmp(av[1], "-v", 3) || !strncmp(av[1], "--verbose", 10));
521 
522 	/* Set CPU affinity so we can force preemption of the VCPU */
523 	CPU_ZERO(&cpuset);
524 	CPU_SET(0, &cpuset);
525 	pthread_attr_init(&attr);
526 	pthread_attr_setaffinity_np(&attr, sizeof(cpu_set_t), &cpuset);
527 	pthread_setaffinity_np(pthread_self(), sizeof(cpu_set_t), &cpuset);
528 
529 	/* Create a VM and an identity mapped memslot for the steal time structure */
530 	vm = vm_create_with_vcpus(NR_VCPUS, guest_code, vcpus);
531 	gpages = vm_calc_num_guest_pages(VM_MODE_DEFAULT, STEAL_TIME_SIZE * NR_VCPUS);
532 	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, ST_GPA_BASE, 1, gpages, 0);
533 	virt_map(vm, ST_GPA_BASE, ST_GPA_BASE, gpages);
534 
535 	ksft_print_header();
536 	TEST_REQUIRE(is_steal_time_supported(vcpus[0]));
537 	ksft_set_plan(NR_VCPUS);
538 
539 	check_steal_time_uapi();
540 
541 	/* Run test on each VCPU */
542 	for (i = 0; i < NR_VCPUS; ++i) {
543 		steal_time_init(vcpus[i], i);
544 
545 		vcpu_args_set(vcpus[i], 1, i);
546 
547 		/* First VCPU run initializes steal-time */
548 		run_vcpu(vcpus[i]);
549 
550 		/* Second VCPU run, expect guest stolen time to be <= run_delay */
551 		run_vcpu(vcpus[i]);
552 		sync_global_from_guest(vm, guest_stolen_time[i]);
553 		stolen_time = guest_stolen_time[i];
554 		run_delay = get_run_delay();
555 		TEST_ASSERT(stolen_time <= run_delay,
556 			    "Expected stolen time <= %ld, got %ld",
557 			    run_delay, stolen_time);
558 
559 		/* Steal time from the VCPU. The steal time thread has the same CPU affinity as the VCPUs. */
560 		run_delay = get_run_delay();
561 		pthread_create(&thread, &attr, do_steal_time, NULL);
562 		do
563 			sched_yield();
564 		while (get_run_delay() - run_delay < MIN_RUN_DELAY_NS);
565 		pthread_join(thread, NULL);
566 		run_delay = get_run_delay() - run_delay;
567 		TEST_ASSERT(run_delay >= MIN_RUN_DELAY_NS,
568 			    "Expected run_delay >= %ld, got %ld",
569 			    MIN_RUN_DELAY_NS, run_delay);
570 
571 		/* Run VCPU again to confirm stolen time is consistent with run_delay */
572 		run_vcpu(vcpus[i]);
573 		sync_global_from_guest(vm, guest_stolen_time[i]);
574 		stolen_time = guest_stolen_time[i] - stolen_time;
575 		TEST_ASSERT(stolen_time >= run_delay,
576 			    "Expected stolen time >= %ld, got %ld",
577 			    run_delay, stolen_time);
578 
579 		if (verbose) {
580 			ksft_print_msg("VCPU%d: total-stolen-time=%ld test-stolen-time=%ld%s\n",
581 				       i, guest_stolen_time[i], stolen_time,
582 				       stolen_time == run_delay ?
583 				       " (BONUS: guest test-stolen-time even exactly matches test-run_delay)" : "");
584 			steal_time_dump(vm, i);
585 		}
586 		ksft_test_result_pass("vcpu%d\n", i);
587 	}
588 
589 	/* Print results and exit() accordingly */
590 	ksft_finished();
591 }
592