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