arch_timer.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * arch_timer.c - Tests the arch timer IRQ functionality
  4 *
  5 * The guest's main thread configures the timer interrupt and waits
  6 * for it to fire, with a timeout equal to the timer period.
  7 * It asserts that the timeout doesn't exceed the timer period plus
  8 * a user configurable error margin(default to 100us)
  9 *
 10 * On the other hand, upon receipt of an interrupt, the guest's interrupt
 11 * handler validates the interrupt by checking if the architectural state
 12 * is in compliance with the specifications.
 13 *
 14 * The test provides command-line options to configure the timer's
 15 * period (-p), number of vCPUs (-n), iterations per stage (-i) and timer
 16 * interrupt arrival error margin (-e). To stress-test the timer stack
 17 * even more, an option to migrate the vCPUs across pCPUs (-m), at a
 18 * particular rate, is also provided.
 19 *
 20 * Copyright (c) 2021, Google LLC.
 21 */
 22#include <stdlib.h>
 23#include <pthread.h>
 24#include <linux/sizes.h>
 25#include <linux/bitmap.h>
 26#include <sys/sysinfo.h>
 27
 28#include "timer_test.h"
 29#include "ucall_common.h"
 30
 31struct test_args test_args = {
 32	.nr_vcpus = NR_VCPUS_DEF,
 33	.nr_iter = NR_TEST_ITERS_DEF,
 34	.timer_period_ms = TIMER_TEST_PERIOD_MS_DEF,
 35	.migration_freq_ms = TIMER_TEST_MIGRATION_FREQ_MS,
 36	.timer_err_margin_us = TIMER_TEST_ERR_MARGIN_US,
 37	.reserved = 1,
 38};
 39
 40struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
 41struct test_vcpu_shared_data vcpu_shared_data[KVM_MAX_VCPUS];
 42
 43static pthread_t pt_vcpu_run[KVM_MAX_VCPUS];
 44static unsigned long *vcpu_done_map;
 45static pthread_mutex_t vcpu_done_map_lock;
 46
 47static void *test_vcpu_run(void *arg)
 48{
 49	unsigned int vcpu_idx = (unsigned long)arg;
 50	struct ucall uc;
 51	struct kvm_vcpu *vcpu = vcpus[vcpu_idx];
 52	struct kvm_vm *vm = vcpu->vm;
 53	struct test_vcpu_shared_data *shared_data = &vcpu_shared_data[vcpu_idx];
 54
 55	vcpu_run(vcpu);
 56
 57	/* Currently, any exit from guest is an indication of completion */
 58	pthread_mutex_lock(&vcpu_done_map_lock);
 59	__set_bit(vcpu_idx, vcpu_done_map);
 60	pthread_mutex_unlock(&vcpu_done_map_lock);
 61
 62	switch (get_ucall(vcpu, &uc)) {
 63	case UCALL_SYNC:
 64	case UCALL_DONE:
 65		break;
 66	case UCALL_ABORT:
 67		sync_global_from_guest(vm, *shared_data);
 68		fprintf(stderr, "Guest assert failed,  vcpu %u; stage; %u; iter: %u\n",
 69			vcpu_idx, shared_data->guest_stage, shared_data->nr_iter);
 70		REPORT_GUEST_ASSERT(uc);
 71		break;
 72	default:
 73		TEST_FAIL("Unexpected guest exit");
 74	}
 75
 76	pr_info("PASS(vCPU-%d).\n", vcpu_idx);
 77
 78	return NULL;
 79}
 80
 81static uint32_t test_get_pcpu(void)
 82{
 83	uint32_t pcpu;
 84	unsigned int nproc_conf;
 85	cpu_set_t online_cpuset;
 86
 87	nproc_conf = get_nprocs_conf();
 88	sched_getaffinity(0, sizeof(cpu_set_t), &online_cpuset);
 89
 90	/* Randomly find an available pCPU to place a vCPU on */
 91	do {
 92		pcpu = rand() % nproc_conf;
 93	} while (!CPU_ISSET(pcpu, &online_cpuset));
 94
 95	return pcpu;
 96}
 97
 98static int test_migrate_vcpu(unsigned int vcpu_idx)
 99{
100	int ret;
101	uint32_t new_pcpu = test_get_pcpu();
102
103	pr_debug("Migrating vCPU: %u to pCPU: %u\n", vcpu_idx, new_pcpu);
104
105	ret = __pin_task_to_cpu(pt_vcpu_run[vcpu_idx], new_pcpu);
106
107	/* Allow the error where the vCPU thread is already finished */
108	TEST_ASSERT(ret == 0 || ret == ESRCH,
109		    "Failed to migrate the vCPU:%u to pCPU: %u; ret: %d",
110		    vcpu_idx, new_pcpu, ret);
111
112	return ret;
113}
114
115static void *test_vcpu_migration(void *arg)
116{
117	unsigned int i, n_done;
118	bool vcpu_done;
119
120	do {
121		usleep(msecs_to_usecs(test_args.migration_freq_ms));
122
123		for (n_done = 0, i = 0; i < test_args.nr_vcpus; i++) {
124			pthread_mutex_lock(&vcpu_done_map_lock);
125			vcpu_done = test_bit(i, vcpu_done_map);
126			pthread_mutex_unlock(&vcpu_done_map_lock);
127
128			if (vcpu_done) {
129				n_done++;
130				continue;
131			}
132
133			test_migrate_vcpu(i);
134		}
135	} while (test_args.nr_vcpus != n_done);
136
137	return NULL;
138}
139
140static void test_run(struct kvm_vm *vm)
141{
142	pthread_t pt_vcpu_migration;
143	unsigned int i;
144	int ret;
145
146	pthread_mutex_init(&vcpu_done_map_lock, NULL);
147	vcpu_done_map = bitmap_zalloc(test_args.nr_vcpus);
148	TEST_ASSERT(vcpu_done_map, "Failed to allocate vcpu done bitmap");
149
150	for (i = 0; i < (unsigned long)test_args.nr_vcpus; i++) {
151		ret = pthread_create(&pt_vcpu_run[i], NULL, test_vcpu_run,
152				     (void *)(unsigned long)i);
153		TEST_ASSERT(!ret, "Failed to create vCPU-%d pthread", i);
154	}
155
156	/* Spawn a thread to control the vCPU migrations */
157	if (test_args.migration_freq_ms) {
158		srand(time(NULL));
159
160		ret = pthread_create(&pt_vcpu_migration, NULL,
161					test_vcpu_migration, NULL);
162		TEST_ASSERT(!ret, "Failed to create the migration pthread");
163	}
164
165
166	for (i = 0; i < test_args.nr_vcpus; i++)
167		pthread_join(pt_vcpu_run[i], NULL);
168
169	if (test_args.migration_freq_ms)
170		pthread_join(pt_vcpu_migration, NULL);
171
172	bitmap_free(vcpu_done_map);
173}
174
175static void test_print_help(char *name)
176{
177	pr_info("Usage: %s [-h] [-n nr_vcpus] [-i iterations] [-p timer_period_ms]\n"
178		"\t\t    [-m migration_freq_ms] [-o counter_offset]\n"
179		"\t\t    [-e timer_err_margin_us]\n", name);
180	pr_info("\t-n: Number of vCPUs to configure (default: %u; max: %u)\n",
181		NR_VCPUS_DEF, KVM_MAX_VCPUS);
182	pr_info("\t-i: Number of iterations per stage (default: %u)\n",
183		NR_TEST_ITERS_DEF);
184	pr_info("\t-p: Periodicity (in ms) of the guest timer (default: %u)\n",
185		TIMER_TEST_PERIOD_MS_DEF);
186	pr_info("\t-m: Frequency (in ms) of vCPUs to migrate to different pCPU. 0 to turn off (default: %u)\n",
187		TIMER_TEST_MIGRATION_FREQ_MS);
188	pr_info("\t-o: Counter offset (in counter cycles, default: 0) [aarch64-only]\n");
189	pr_info("\t-e: Interrupt arrival error margin (in us) of the guest timer (default: %u)\n",
190		TIMER_TEST_ERR_MARGIN_US);
191	pr_info("\t-h: print this help screen\n");
192}
193
194static bool parse_args(int argc, char *argv[])
195{
196	int opt;
197
198	while ((opt = getopt(argc, argv, "hn:i:p:m:o:e:")) != -1) {
199		switch (opt) {
200		case 'n':
201			test_args.nr_vcpus = atoi_positive("Number of vCPUs", optarg);
202			if (test_args.nr_vcpus > KVM_MAX_VCPUS) {
203				pr_info("Max allowed vCPUs: %u\n",
204					KVM_MAX_VCPUS);
205				goto err;
206			}
207			break;
208		case 'i':
209			test_args.nr_iter = atoi_positive("Number of iterations", optarg);
210			break;
211		case 'p':
212			test_args.timer_period_ms = atoi_positive("Periodicity", optarg);
213			break;
214		case 'm':
215			test_args.migration_freq_ms = atoi_non_negative("Frequency", optarg);
216			break;
217		case 'e':
218			test_args.timer_err_margin_us = atoi_non_negative("Error Margin", optarg);
219			break;
220		case 'o':
221			test_args.counter_offset = strtol(optarg, NULL, 0);
222			test_args.reserved = 0;
223			break;
224		case 'h':
225		default:
226			goto err;
227		}
228	}
229
230	return true;
231
232err:
233	test_print_help(argv[0]);
234	return false;
235}
236
237int main(int argc, char *argv[])
238{
239	struct kvm_vm *vm;
240
241	if (!parse_args(argc, argv))
242		exit(KSFT_SKIP);
243
244	__TEST_REQUIRE(!test_args.migration_freq_ms || get_nprocs() >= 2,
245		       "At least two physical CPUs needed for vCPU migration");
246
247	vm = test_vm_create();
248	test_run(vm);
249	test_vm_cleanup(vm);
250
251	return 0;
252}