summaryrefslogtreecommitdiff
path: root/tools/testing/selftests/kvm/demand_paging_test.c
blob: 09c116a82a8499d7b14dc60bdcb088dd6c6914c7 (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
// SPDX-License-Identifier: GPL-2.0
/*
 * KVM demand paging test
 * Adapted from dirty_log_test.c
 *
 * Copyright (C) 2018, Red Hat, Inc.
 * Copyright (C) 2019, Google, Inc.
 */

#define _GNU_SOURCE /* for pipe2 */

#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <poll.h>
#include <pthread.h>
#include <linux/userfaultfd.h>
#include <sys/syscall.h>

#include "kvm_util.h"
#include "test_util.h"
#include "memstress.h"
#include "guest_modes.h"
#include "userfaultfd_util.h"

#ifdef __NR_userfaultfd

static int nr_vcpus = 1;
static uint64_t guest_percpu_mem_size = DEFAULT_PER_VCPU_MEM_SIZE;

static size_t demand_paging_size;
static char *guest_data_prototype;

static void vcpu_worker(struct memstress_vcpu_args *vcpu_args)
{
	struct kvm_vcpu *vcpu = vcpu_args->vcpu;
	int vcpu_idx = vcpu_args->vcpu_idx;
	struct kvm_run *run = vcpu->run;
	struct timespec start;
	struct timespec ts_diff;
	int ret;

	clock_gettime(CLOCK_MONOTONIC, &start);

	/* Let the guest access its memory */
	ret = _vcpu_run(vcpu);
	TEST_ASSERT(ret == 0, "vcpu_run failed: %d\n", ret);
	if (get_ucall(vcpu, NULL) != UCALL_SYNC) {
		TEST_ASSERT(false,
			    "Invalid guest sync status: exit_reason=%s\n",
			    exit_reason_str(run->exit_reason));
	}

	ts_diff = timespec_elapsed(start);
	PER_VCPU_DEBUG("vCPU %d execution time: %ld.%.9lds\n", vcpu_idx,
		       ts_diff.tv_sec, ts_diff.tv_nsec);
}

static int handle_uffd_page_request(int uffd_mode, int uffd,
		struct uffd_msg *msg)
{
	pid_t tid = syscall(__NR_gettid);
	uint64_t addr = msg->arg.pagefault.address;
	struct timespec start;
	struct timespec ts_diff;
	int r;

	clock_gettime(CLOCK_MONOTONIC, &start);

	if (uffd_mode == UFFDIO_REGISTER_MODE_MISSING) {
		struct uffdio_copy copy;

		copy.src = (uint64_t)guest_data_prototype;
		copy.dst = addr;
		copy.len = demand_paging_size;
		copy.mode = 0;

		r = ioctl(uffd, UFFDIO_COPY, &copy);
		if (r == -1) {
			pr_info("Failed UFFDIO_COPY in 0x%lx from thread %d with errno: %d\n",
				addr, tid, errno);
			return r;
		}
	} else if (uffd_mode == UFFDIO_REGISTER_MODE_MINOR) {
		struct uffdio_continue cont = {0};

		cont.range.start = addr;
		cont.range.len = demand_paging_size;

		r = ioctl(uffd, UFFDIO_CONTINUE, &cont);
		if (r == -1) {
			pr_info("Failed UFFDIO_CONTINUE in 0x%lx from thread %d with errno: %d\n",
				addr, tid, errno);
			return r;
		}
	} else {
		TEST_FAIL("Invalid uffd mode %d", uffd_mode);
	}

	ts_diff = timespec_elapsed(start);

	PER_PAGE_DEBUG("UFFD page-in %d \t%ld ns\n", tid,
		       timespec_to_ns(ts_diff));
	PER_PAGE_DEBUG("Paged in %ld bytes at 0x%lx from thread %d\n",
		       demand_paging_size, addr, tid);

	return 0;
}

struct test_params {
	int uffd_mode;
	useconds_t uffd_delay;
	enum vm_mem_backing_src_type src_type;
	bool partition_vcpu_memory_access;
};

static void prefault_mem(void *alias, uint64_t len)
{
	size_t p;

	TEST_ASSERT(alias != NULL, "Alias required for minor faults");
	for (p = 0; p < (len / demand_paging_size); ++p) {
		memcpy(alias + (p * demand_paging_size),
		       guest_data_prototype, demand_paging_size);
	}
}

static void run_test(enum vm_guest_mode mode, void *arg)
{
	struct memstress_vcpu_args *vcpu_args;
	struct test_params *p = arg;
	struct uffd_desc **uffd_descs = NULL;
	struct timespec start;
	struct timespec ts_diff;
	struct kvm_vm *vm;
	int i;

	vm = memstress_create_vm(mode, nr_vcpus, guest_percpu_mem_size, 1,
				 p->src_type, p->partition_vcpu_memory_access);

	demand_paging_size = get_backing_src_pagesz(p->src_type);

	guest_data_prototype = malloc(demand_paging_size);
	TEST_ASSERT(guest_data_prototype,
		    "Failed to allocate buffer for guest data pattern");
	memset(guest_data_prototype, 0xAB, demand_paging_size);

	if (p->uffd_mode == UFFDIO_REGISTER_MODE_MINOR) {
		for (i = 0; i < nr_vcpus; i++) {
			vcpu_args = &memstress_args.vcpu_args[i];
			prefault_mem(addr_gpa2alias(vm, vcpu_args->gpa),
				     vcpu_args->pages * memstress_args.guest_page_size);
		}
	}

	if (p->uffd_mode) {
		uffd_descs = malloc(nr_vcpus * sizeof(struct uffd_desc *));
		TEST_ASSERT(uffd_descs, "Memory allocation failed");
		for (i = 0; i < nr_vcpus; i++) {
			void *vcpu_hva;

			vcpu_args = &memstress_args.vcpu_args[i];

			/* Cache the host addresses of the region */
			vcpu_hva = addr_gpa2hva(vm, vcpu_args->gpa);
			/*
			 * Set up user fault fd to handle demand paging
			 * requests.
			 */
			uffd_descs[i] = uffd_setup_demand_paging(
				p->uffd_mode, p->uffd_delay, vcpu_hva,
				vcpu_args->pages * memstress_args.guest_page_size,
				&handle_uffd_page_request);
		}
	}

	pr_info("Finished creating vCPUs and starting uffd threads\n");

	clock_gettime(CLOCK_MONOTONIC, &start);
	memstress_start_vcpu_threads(nr_vcpus, vcpu_worker);
	pr_info("Started all vCPUs\n");

	memstress_join_vcpu_threads(nr_vcpus);
	ts_diff = timespec_elapsed(start);
	pr_info("All vCPU threads joined\n");

	if (p->uffd_mode) {
		/* Tell the user fault fd handler threads to quit */
		for (i = 0; i < nr_vcpus; i++)
			uffd_stop_demand_paging(uffd_descs[i]);
	}

	pr_info("Total guest execution time: %ld.%.9lds\n",
		ts_diff.tv_sec, ts_diff.tv_nsec);
	pr_info("Overall demand paging rate: %f pgs/sec\n",
		memstress_args.vcpu_args[0].pages * nr_vcpus /
		((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / NSEC_PER_SEC));

	memstress_destroy_vm(vm);

	free(guest_data_prototype);
	if (p->uffd_mode)
		free(uffd_descs);
}

static void help(char *name)
{
	puts("");
	printf("usage: %s [-h] [-m vm_mode] [-u uffd_mode] [-d uffd_delay_usec]\n"
	       "          [-b memory] [-s type] [-v vcpus] [-c cpu_list] [-o]\n", name);
	guest_modes_help();
	printf(" -u: use userfaultfd to handle vCPU page faults. Mode is a\n"
	       "     UFFD registration mode: 'MISSING' or 'MINOR'.\n");
	kvm_print_vcpu_pinning_help();
	printf(" -d: add a delay in usec to the User Fault\n"
	       "     FD handler to simulate demand paging\n"
	       "     overheads. Ignored without -u.\n");
	printf(" -b: specify the size of the memory region which should be\n"
	       "     demand paged by each vCPU. e.g. 10M or 3G.\n"
	       "     Default: 1G\n");
	backing_src_help("-s");
	printf(" -v: specify the number of vCPUs to run.\n");
	printf(" -o: Overlap guest memory accesses instead of partitioning\n"
	       "     them into a separate region of memory for each vCPU.\n");
	puts("");
	exit(0);
}

int main(int argc, char *argv[])
{
	int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
	const char *cpulist = NULL;
	struct test_params p = {
		.src_type = DEFAULT_VM_MEM_SRC,
		.partition_vcpu_memory_access = true,
	};
	int opt;

	guest_modes_append_default();

	while ((opt = getopt(argc, argv, "hm:u:d:b:s:v:c:o")) != -1) {
		switch (opt) {
		case 'm':
			guest_modes_cmdline(optarg);
			break;
		case 'u':
			if (!strcmp("MISSING", optarg))
				p.uffd_mode = UFFDIO_REGISTER_MODE_MISSING;
			else if (!strcmp("MINOR", optarg))
				p.uffd_mode = UFFDIO_REGISTER_MODE_MINOR;
			TEST_ASSERT(p.uffd_mode, "UFFD mode must be 'MISSING' or 'MINOR'.");
			break;
		case 'd':
			p.uffd_delay = strtoul(optarg, NULL, 0);
			TEST_ASSERT(p.uffd_delay >= 0, "A negative UFFD delay is not supported.");
			break;
		case 'b':
			guest_percpu_mem_size = parse_size(optarg);
			break;
		case 's':
			p.src_type = parse_backing_src_type(optarg);
			break;
		case 'v':
			nr_vcpus = atoi_positive("Number of vCPUs", optarg);
			TEST_ASSERT(nr_vcpus <= max_vcpus,
				    "Invalid number of vcpus, must be between 1 and %d", max_vcpus);
			break;
		case 'c':
			cpulist = optarg;
			break;
		case 'o':
			p.partition_vcpu_memory_access = false;
			break;
		case 'h':
		default:
			help(argv[0]);
			break;
		}
	}

	if (p.uffd_mode == UFFDIO_REGISTER_MODE_MINOR &&
	    !backing_src_is_shared(p.src_type)) {
		TEST_FAIL("userfaultfd MINOR mode requires shared memory; pick a different -s");
	}

	if (cpulist) {
		kvm_parse_vcpu_pinning(cpulist, memstress_args.vcpu_to_pcpu,
				       nr_vcpus);
		memstress_args.pin_vcpus = true;
	}

	for_each_guest_mode(run_test, &p);

	return 0;
}

#else /* __NR_userfaultfd */

#warning "missing __NR_userfaultfd definition"

int main(void)
{
	print_skip("__NR_userfaultfd must be present for userfaultfd test");
	return KSFT_SKIP;
}

#endif /* __NR_userfaultfd */