1// SPDX-License-Identifier: GPL-2.0
2/*
3 * KVM demand paging test
4 * Adapted from dirty_log_test.c
5 *
6 * Copyright (C) 2018, Red Hat, Inc.
7 * Copyright (C) 2019, Google, Inc.
8 */
9
10#define _GNU_SOURCE /* for pipe2 */
11
12#include <inttypes.h>
13#include <stdio.h>
14#include <stdlib.h>
15#include <time.h>
16#include <poll.h>
17#include <pthread.h>
18#include <linux/userfaultfd.h>
19#include <sys/syscall.h>
20
21#include "kvm_util.h"
22#include "test_util.h"
23#include "memstress.h"
24#include "guest_modes.h"
25#include "userfaultfd_util.h"
26
27#ifdef __NR_userfaultfd
28
29static int nr_vcpus = 1;
30static uint64_t guest_percpu_mem_size = DEFAULT_PER_VCPU_MEM_SIZE;
31
32static size_t demand_paging_size;
33static char *guest_data_prototype;
34
35static void vcpu_worker(struct memstress_vcpu_args *vcpu_args)
36{
37 struct kvm_vcpu *vcpu = vcpu_args->vcpu;
38 int vcpu_idx = vcpu_args->vcpu_idx;
39 struct kvm_run *run = vcpu->run;
40 struct timespec start;
41 struct timespec ts_diff;
42 int ret;
43
44 clock_gettime(CLOCK_MONOTONIC, &start);
45
46 /* Let the guest access its memory */
47 ret = _vcpu_run(vcpu);
48 TEST_ASSERT(ret == 0, "vcpu_run failed: %d", ret);
49 if (get_ucall(vcpu, NULL) != UCALL_SYNC) {
50 TEST_ASSERT(false,
51 "Invalid guest sync status: exit_reason=%s",
52 exit_reason_str(run->exit_reason));
53 }
54
55 ts_diff = timespec_elapsed(start);
56 PER_VCPU_DEBUG("vCPU %d execution time: %ld.%.9lds\n", vcpu_idx,
57 ts_diff.tv_sec, ts_diff.tv_nsec);
58}
59
60static int handle_uffd_page_request(int uffd_mode, int uffd,
61 struct uffd_msg *msg)
62{
63 pid_t tid = syscall(__NR_gettid);
64 uint64_t addr = msg->arg.pagefault.address;
65 struct timespec start;
66 struct timespec ts_diff;
67 int r;
68
69 clock_gettime(CLOCK_MONOTONIC, &start);
70
71 if (uffd_mode == UFFDIO_REGISTER_MODE_MISSING) {
72 struct uffdio_copy copy;
73
74 copy.src = (uint64_t)guest_data_prototype;
75 copy.dst = addr;
76 copy.len = demand_paging_size;
77 copy.mode = 0;
78
79 r = ioctl(uffd, UFFDIO_COPY, &copy);
80 if (r == -1) {
81 pr_info("Failed UFFDIO_COPY in 0x%lx from thread %d with errno: %d\n",
82 addr, tid, errno);
83 return r;
84 }
85 } else if (uffd_mode == UFFDIO_REGISTER_MODE_MINOR) {
86 struct uffdio_continue cont = {0};
87
88 cont.range.start = addr;
89 cont.range.len = demand_paging_size;
90
91 r = ioctl(uffd, UFFDIO_CONTINUE, &cont);
92 if (r == -1) {
93 pr_info("Failed UFFDIO_CONTINUE in 0x%lx from thread %d with errno: %d\n",
94 addr, tid, errno);
95 return r;
96 }
97 } else {
98 TEST_FAIL("Invalid uffd mode %d", uffd_mode);
99 }
100
101 ts_diff = timespec_elapsed(start);
102
103 PER_PAGE_DEBUG("UFFD page-in %d \t%ld ns\n", tid,
104 timespec_to_ns(ts_diff));
105 PER_PAGE_DEBUG("Paged in %ld bytes at 0x%lx from thread %d\n",
106 demand_paging_size, addr, tid);
107
108 return 0;
109}
110
111struct test_params {
112 int uffd_mode;
113 useconds_t uffd_delay;
114 enum vm_mem_backing_src_type src_type;
115 bool partition_vcpu_memory_access;
116};
117
118static void prefault_mem(void *alias, uint64_t len)
119{
120 size_t p;
121
122 TEST_ASSERT(alias != NULL, "Alias required for minor faults");
123 for (p = 0; p < (len / demand_paging_size); ++p) {
124 memcpy(alias + (p * demand_paging_size),
125 guest_data_prototype, demand_paging_size);
126 }
127}
128
129static void run_test(enum vm_guest_mode mode, void *arg)
130{
131 struct memstress_vcpu_args *vcpu_args;
132 struct test_params *p = arg;
133 struct uffd_desc **uffd_descs = NULL;
134 struct timespec start;
135 struct timespec ts_diff;
136 struct kvm_vm *vm;
137 int i;
138
139 vm = memstress_create_vm(mode, nr_vcpus, guest_percpu_mem_size, 1,
140 p->src_type, p->partition_vcpu_memory_access);
141
142 demand_paging_size = get_backing_src_pagesz(p->src_type);
143
144 guest_data_prototype = malloc(demand_paging_size);
145 TEST_ASSERT(guest_data_prototype,
146 "Failed to allocate buffer for guest data pattern");
147 memset(guest_data_prototype, 0xAB, demand_paging_size);
148
149 if (p->uffd_mode == UFFDIO_REGISTER_MODE_MINOR) {
150 for (i = 0; i < nr_vcpus; i++) {
151 vcpu_args = &memstress_args.vcpu_args[i];
152 prefault_mem(addr_gpa2alias(vm, vcpu_args->gpa),
153 vcpu_args->pages * memstress_args.guest_page_size);
154 }
155 }
156
157 if (p->uffd_mode) {
158 uffd_descs = malloc(nr_vcpus * sizeof(struct uffd_desc *));
159 TEST_ASSERT(uffd_descs, "Memory allocation failed");
160 for (i = 0; i < nr_vcpus; i++) {
161 void *vcpu_hva;
162
163 vcpu_args = &memstress_args.vcpu_args[i];
164
165 /* Cache the host addresses of the region */
166 vcpu_hva = addr_gpa2hva(vm, vcpu_args->gpa);
167 /*
168 * Set up user fault fd to handle demand paging
169 * requests.
170 */
171 uffd_descs[i] = uffd_setup_demand_paging(
172 p->uffd_mode, p->uffd_delay, vcpu_hva,
173 vcpu_args->pages * memstress_args.guest_page_size,
174 &handle_uffd_page_request);
175 }
176 }
177
178 pr_info("Finished creating vCPUs and starting uffd threads\n");
179
180 clock_gettime(CLOCK_MONOTONIC, &start);
181 memstress_start_vcpu_threads(nr_vcpus, vcpu_worker);
182 pr_info("Started all vCPUs\n");
183
184 memstress_join_vcpu_threads(nr_vcpus);
185 ts_diff = timespec_elapsed(start);
186 pr_info("All vCPU threads joined\n");
187
188 if (p->uffd_mode) {
189 /* Tell the user fault fd handler threads to quit */
190 for (i = 0; i < nr_vcpus; i++)
191 uffd_stop_demand_paging(uffd_descs[i]);
192 }
193
194 pr_info("Total guest execution time: %ld.%.9lds\n",
195 ts_diff.tv_sec, ts_diff.tv_nsec);
196 pr_info("Overall demand paging rate: %f pgs/sec\n",
197 memstress_args.vcpu_args[0].pages * nr_vcpus /
198 ((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / NSEC_PER_SEC));
199
200 memstress_destroy_vm(vm);
201
202 free(guest_data_prototype);
203 if (p->uffd_mode)
204 free(uffd_descs);
205}
206
207static void help(char *name)
208{
209 puts("");
210 printf("usage: %s [-h] [-m vm_mode] [-u uffd_mode] [-d uffd_delay_usec]\n"
211 " [-b memory] [-s type] [-v vcpus] [-c cpu_list] [-o]\n", name);
212 guest_modes_help();
213 printf(" -u: use userfaultfd to handle vCPU page faults. Mode is a\n"
214 " UFFD registration mode: 'MISSING' or 'MINOR'.\n");
215 kvm_print_vcpu_pinning_help();
216 printf(" -d: add a delay in usec to the User Fault\n"
217 " FD handler to simulate demand paging\n"
218 " overheads. Ignored without -u.\n");
219 printf(" -b: specify the size of the memory region which should be\n"
220 " demand paged by each vCPU. e.g. 10M or 3G.\n"
221 " Default: 1G\n");
222 backing_src_help("-s");
223 printf(" -v: specify the number of vCPUs to run.\n");
224 printf(" -o: Overlap guest memory accesses instead of partitioning\n"
225 " them into a separate region of memory for each vCPU.\n");
226 puts("");
227 exit(0);
228}
229
230int main(int argc, char *argv[])
231{
232 int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
233 const char *cpulist = NULL;
234 struct test_params p = {
235 .src_type = DEFAULT_VM_MEM_SRC,
236 .partition_vcpu_memory_access = true,
237 };
238 int opt;
239
240 guest_modes_append_default();
241
242 while ((opt = getopt(argc, argv, "hm:u:d:b:s:v:c:o")) != -1) {
243 switch (opt) {
244 case 'm':
245 guest_modes_cmdline(optarg);
246 break;
247 case 'u':
248 if (!strcmp("MISSING", optarg))
249 p.uffd_mode = UFFDIO_REGISTER_MODE_MISSING;
250 else if (!strcmp("MINOR", optarg))
251 p.uffd_mode = UFFDIO_REGISTER_MODE_MINOR;
252 TEST_ASSERT(p.uffd_mode, "UFFD mode must be 'MISSING' or 'MINOR'.");
253 break;
254 case 'd':
255 p.uffd_delay = strtoul(optarg, NULL, 0);
256 TEST_ASSERT(p.uffd_delay >= 0, "A negative UFFD delay is not supported.");
257 break;
258 case 'b':
259 guest_percpu_mem_size = parse_size(optarg);
260 break;
261 case 's':
262 p.src_type = parse_backing_src_type(optarg);
263 break;
264 case 'v':
265 nr_vcpus = atoi_positive("Number of vCPUs", optarg);
266 TEST_ASSERT(nr_vcpus <= max_vcpus,
267 "Invalid number of vcpus, must be between 1 and %d", max_vcpus);
268 break;
269 case 'c':
270 cpulist = optarg;
271 break;
272 case 'o':
273 p.partition_vcpu_memory_access = false;
274 break;
275 case 'h':
276 default:
277 help(argv[0]);
278 break;
279 }
280 }
281
282 if (p.uffd_mode == UFFDIO_REGISTER_MODE_MINOR &&
283 !backing_src_is_shared(p.src_type)) {
284 TEST_FAIL("userfaultfd MINOR mode requires shared memory; pick a different -s");
285 }
286
287 if (cpulist) {
288 kvm_parse_vcpu_pinning(cpulist, memstress_args.vcpu_to_pcpu,
289 nr_vcpus);
290 memstress_args.pin_vcpus = true;
291 }
292
293 for_each_guest_mode(run_test, &p);
294
295 return 0;
296}
297
298#else /* __NR_userfaultfd */
299
300#warning "missing __NR_userfaultfd definition"
301
302int main(void)
303{
304 print_skip("__NR_userfaultfd must be present for userfaultfd test");
305 return KSFT_SKIP;
306}
307
308#endif /* __NR_userfaultfd */
309

source code of linux/tools/testing/selftests/kvm/demand_paging_test.c