tools/testing/selftests/kvm/demand_paging_test.c

   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
  29 static int nr_vcpus = 1;
  30 static uint64_t guest_percpu_mem_size = DEFAULT_PER_VCPU_MEM_SIZE;
  31
  32 static size_t demand_paging_size;
  33 static char *guest_data_prototype;
  34
  35 static 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\n", ret);
  49         if (get_ucall(vcpu, NULL) != UCALL_SYNC) {
  50                 TEST_ASSERT(false,
  51                             "Invalid guest sync status: exit_reason=%s\n",
  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
  60 static 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
 111 struct 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
 118 static 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
 129 static void run_test(enum vm_guest_mode mode, void *arg)
 130 {
 131         struct test_params *p = arg;
 132         struct uffd_desc **uffd_descs = NULL;
 133         struct timespec start;
 134         struct timespec ts_diff;
 135         struct kvm_vm *vm;
 136         int i;
 137
 138         vm = memstress_create_vm(mode, nr_vcpus, guest_percpu_mem_size, 1,
 139                                  p->src_type, p->partition_vcpu_memory_access);
 140
 141         demand_paging_size = get_backing_src_pagesz(p->src_type);
 142
 143         guest_data_prototype = malloc(demand_paging_size);
 144         TEST_ASSERT(guest_data_prototype,
 145                     "Failed to allocate buffer for guest data pattern");
 146         memset(guest_data_prototype, 0xAB, demand_paging_size);
 147
 148         if (p->uffd_mode) {
 149                 uffd_descs = malloc(nr_vcpus * sizeof(struct uffd_desc *));
 150                 TEST_ASSERT(uffd_descs, "Memory allocation failed");
 151
 152                 for (i = 0; i < nr_vcpus; i++) {
 153                         struct memstress_vcpu_args *vcpu_args;
 154                         void *vcpu_hva;
 155                         void *vcpu_alias;
 156
 157                         vcpu_args = &memstress_args.vcpu_args[i];
 158
 159                         /* Cache the host addresses of the region */
 160                         vcpu_hva = addr_gpa2hva(vm, vcpu_args->gpa);
 161                         vcpu_alias = addr_gpa2alias(vm, vcpu_args->gpa);
 162
 163                         prefault_mem(vcpu_alias,
 164                                 vcpu_args->pages * memstress_args.guest_page_size);
 165
 166                         /*
 167                          * Set up user fault fd to handle demand paging
 168                          * requests.
 169                          */
 170                         uffd_descs[i] = uffd_setup_demand_paging(
 171                                 p->uffd_mode, p->uffd_delay, vcpu_hva,
 172                                 vcpu_args->pages * memstress_args.guest_page_size,
 173                                 &handle_uffd_page_request);
 174                 }
 175         }
 176
 177         pr_info("Finished creating vCPUs and starting uffd threads\n");
 178
 179         clock_gettime(CLOCK_MONOTONIC, &start);
 180         memstress_start_vcpu_threads(nr_vcpus, vcpu_worker);
 181         pr_info("Started all vCPUs\n");
 182
 183         memstress_join_vcpu_threads(nr_vcpus);
 184         ts_diff = timespec_elapsed(start);
 185         pr_info("All vCPU threads joined\n");
 186
 187         if (p->uffd_mode) {
 188                 /* Tell the user fault fd handler threads to quit */
 189                 for (i = 0; i < nr_vcpus; i++)
 190                         uffd_stop_demand_paging(uffd_descs[i]);
 191         }
 192
 193         pr_info("Total guest execution time: %ld.%.9lds\n",
 194                 ts_diff.tv_sec, ts_diff.tv_nsec);
 195         pr_info("Overall demand paging rate: %f pgs/sec\n",
 196                 memstress_args.vcpu_args[0].pages * nr_vcpus /
 197                 ((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / NSEC_PER_SEC));
 198
 199         memstress_destroy_vm(vm);
 200
 201         free(guest_data_prototype);
 202         if (p->uffd_mode)
 203                 free(uffd_descs);
 204 }
 205
 206 static void help(char *name)
 207 {
 208         puts("");
 209         printf("usage: %s [-h] [-m vm_mode] [-u uffd_mode] [-d uffd_delay_usec]\n"
 210                "          [-b memory] [-s type] [-v vcpus] [-o]\n", name);
 211         guest_modes_help();
 212         printf(" -u: use userfaultfd to handle vCPU page faults. Mode is a\n"
 213                "     UFFD registration mode: 'MISSING' or 'MINOR'.\n");
 214         printf(" -d: add a delay in usec to the User Fault\n"
 215                "     FD handler to simulate demand paging\n"
 216                "     overheads. Ignored without -u.\n");
 217         printf(" -b: specify the size of the memory region which should be\n"
 218                "     demand paged by each vCPU. e.g. 10M or 3G.\n"
 219                "     Default: 1G\n");
 220         backing_src_help("-s");
 221         printf(" -v: specify the number of vCPUs to run.\n");
 222         printf(" -o: Overlap guest memory accesses instead of partitioning\n"
 223                "     them into a separate region of memory for each vCPU.\n");
 224         puts("");
 225         exit(0);
 226 }
 227
 228 int main(int argc, char *argv[])
 229 {
 230         int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
 231         struct test_params p = {
 232                 .src_type = DEFAULT_VM_MEM_SRC,
 233                 .partition_vcpu_memory_access = true,
 234         };
 235         int opt;
 236
 237         guest_modes_append_default();
 238
 239         while ((opt = getopt(argc, argv, "hm:u:d:b:s:v:o")) != -1) {
 240                 switch (opt) {
 241                 case 'm':
 242                         guest_modes_cmdline(optarg);
 243                         break;
 244                 case 'u':
 245                         if (!strcmp("MISSING", optarg))
 246                                 p.uffd_mode = UFFDIO_REGISTER_MODE_MISSING;
 247                         else if (!strcmp("MINOR", optarg))
 248                                 p.uffd_mode = UFFDIO_REGISTER_MODE_MINOR;
 249                         TEST_ASSERT(p.uffd_mode, "UFFD mode must be 'MISSING' or 'MINOR'.");
 250                         break;
 251                 case 'd':
 252                         p.uffd_delay = strtoul(optarg, NULL, 0);
 253                         TEST_ASSERT(p.uffd_delay >= 0, "A negative UFFD delay is not supported.");
 254                         break;
 255                 case 'b':
 256                         guest_percpu_mem_size = parse_size(optarg);
 257                         break;
 258                 case 's':
 259                         p.src_type = parse_backing_src_type(optarg);
 260                         break;
 261                 case 'v':
 262                         nr_vcpus = atoi_positive("Number of vCPUs", optarg);
 263                         TEST_ASSERT(nr_vcpus <= max_vcpus,
 264                                     "Invalid number of vcpus, must be between 1 and %d", max_vcpus);
 265                         break;
 266                 case 'o':
 267                         p.partition_vcpu_memory_access = false;
 268                         break;
 269                 case 'h':
 270                 default:
 271                         help(argv[0]);
 272                         break;
 273                 }
 274         }
 275
 276         if (p.uffd_mode == UFFDIO_REGISTER_MODE_MINOR &&
 277             !backing_src_is_shared(p.src_type)) {
 278                 TEST_FAIL("userfaultfd MINOR mode requires shared memory; pick a different -s");
 279         }
 280
 281         for_each_guest_mode(run_test, &p);
 282
 283         return 0;
 284 }
 285
 286 #else /* __NR_userfaultfd */
 287
 288 #warning "missing __NR_userfaultfd definition"
 289
 290 int main(void)
 291 {
 292         print_skip("__NR_userfaultfd must be present for userfaultfd test");
 293         return KSFT_SKIP;
 294 }
 295
 296 #endif /* __NR_userfaultfd */