1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * KVM userfaultfd util
4 * Adapted from demand_paging_test.c
5 *
6 * Copyright (C) 2018, Red Hat, Inc.
7 * Copyright (C) 2019-2022 Google LLC
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 "userfaultfd_util.h"
25
26 #ifdef __NR_userfaultfd
27
uffd_handler_thread_fn(void * arg)28 static void *uffd_handler_thread_fn(void *arg)
29 {
30 struct uffd_desc *uffd_desc = (struct uffd_desc *)arg;
31 int uffd = uffd_desc->uffd;
32 int pipefd = uffd_desc->pipefds[0];
33 useconds_t delay = uffd_desc->delay;
34 int64_t pages = 0;
35 struct timespec start;
36 struct timespec ts_diff;
37
38 clock_gettime(CLOCK_MONOTONIC, &start);
39 while (1) {
40 struct uffd_msg msg;
41 struct pollfd pollfd[2];
42 char tmp_chr;
43 int r;
44
45 pollfd[0].fd = uffd;
46 pollfd[0].events = POLLIN;
47 pollfd[1].fd = pipefd;
48 pollfd[1].events = POLLIN;
49
50 r = poll(pollfd, 2, -1);
51 switch (r) {
52 case -1:
53 pr_info("poll err");
54 continue;
55 case 0:
56 continue;
57 case 1:
58 break;
59 default:
60 pr_info("Polling uffd returned %d", r);
61 return NULL;
62 }
63
64 if (pollfd[0].revents & POLLERR) {
65 pr_info("uffd revents has POLLERR");
66 return NULL;
67 }
68
69 if (pollfd[1].revents & POLLIN) {
70 r = read(pollfd[1].fd, &tmp_chr, 1);
71 TEST_ASSERT(r == 1,
72 "Error reading pipefd in UFFD thread\n");
73 break;
74 }
75
76 if (!(pollfd[0].revents & POLLIN))
77 continue;
78
79 r = read(uffd, &msg, sizeof(msg));
80 if (r == -1) {
81 if (errno == EAGAIN)
82 continue;
83 pr_info("Read of uffd got errno %d\n", errno);
84 return NULL;
85 }
86
87 if (r != sizeof(msg)) {
88 pr_info("Read on uffd returned unexpected size: %d bytes", r);
89 return NULL;
90 }
91
92 if (!(msg.event & UFFD_EVENT_PAGEFAULT))
93 continue;
94
95 if (delay)
96 usleep(delay);
97 r = uffd_desc->handler(uffd_desc->uffd_mode, uffd, &msg);
98 if (r < 0)
99 return NULL;
100 pages++;
101 }
102
103 ts_diff = timespec_elapsed(start);
104 PER_VCPU_DEBUG("userfaulted %ld pages over %ld.%.9lds. (%f/sec)\n",
105 pages, ts_diff.tv_sec, ts_diff.tv_nsec,
106 pages / ((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / NSEC_PER_SEC));
107
108 return NULL;
109 }
110
uffd_setup_demand_paging(int uffd_mode,useconds_t delay,void * hva,uint64_t len,uffd_handler_t handler)111 struct uffd_desc *uffd_setup_demand_paging(int uffd_mode, useconds_t delay,
112 void *hva, uint64_t len,
113 uffd_handler_t handler)
114 {
115 struct uffd_desc *uffd_desc;
116 bool is_minor = (uffd_mode == UFFDIO_REGISTER_MODE_MINOR);
117 int uffd;
118 struct uffdio_api uffdio_api;
119 struct uffdio_register uffdio_register;
120 uint64_t expected_ioctls = ((uint64_t) 1) << _UFFDIO_COPY;
121 int ret;
122
123 PER_PAGE_DEBUG("Userfaultfd %s mode, faults resolved with %s\n",
124 is_minor ? "MINOR" : "MISSING",
125 is_minor ? "UFFDIO_CONINUE" : "UFFDIO_COPY");
126
127 uffd_desc = malloc(sizeof(struct uffd_desc));
128 TEST_ASSERT(uffd_desc, "malloc failed");
129
130 /* In order to get minor faults, prefault via the alias. */
131 if (is_minor)
132 expected_ioctls = ((uint64_t) 1) << _UFFDIO_CONTINUE;
133
134 uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
135 TEST_ASSERT(uffd >= 0, "uffd creation failed, errno: %d", errno);
136
137 uffdio_api.api = UFFD_API;
138 uffdio_api.features = 0;
139 TEST_ASSERT(ioctl(uffd, UFFDIO_API, &uffdio_api) != -1,
140 "ioctl UFFDIO_API failed: %" PRIu64,
141 (uint64_t)uffdio_api.api);
142
143 uffdio_register.range.start = (uint64_t)hva;
144 uffdio_register.range.len = len;
145 uffdio_register.mode = uffd_mode;
146 TEST_ASSERT(ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) != -1,
147 "ioctl UFFDIO_REGISTER failed");
148 TEST_ASSERT((uffdio_register.ioctls & expected_ioctls) ==
149 expected_ioctls, "missing userfaultfd ioctls");
150
151 ret = pipe2(uffd_desc->pipefds, O_CLOEXEC | O_NONBLOCK);
152 TEST_ASSERT(!ret, "Failed to set up pipefd");
153
154 uffd_desc->uffd_mode = uffd_mode;
155 uffd_desc->uffd = uffd;
156 uffd_desc->delay = delay;
157 uffd_desc->handler = handler;
158 pthread_create(&uffd_desc->thread, NULL, uffd_handler_thread_fn,
159 uffd_desc);
160
161 PER_VCPU_DEBUG("Created uffd thread for HVA range [%p, %p)\n",
162 hva, hva + len);
163
164 return uffd_desc;
165 }
166
uffd_stop_demand_paging(struct uffd_desc * uffd)167 void uffd_stop_demand_paging(struct uffd_desc *uffd)
168 {
169 char c = 0;
170 int ret;
171
172 ret = write(uffd->pipefds[1], &c, 1);
173 TEST_ASSERT(ret == 1, "Unable to write to pipefd");
174
175 ret = pthread_join(uffd->thread, NULL);
176 TEST_ASSERT(ret == 0, "Pthread_join failed.");
177
178 close(uffd->uffd);
179
180 close(uffd->pipefds[1]);
181 close(uffd->pipefds[0]);
182
183 free(uffd);
184 }
185
186 #endif /* __NR_userfaultfd */
187