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 program_invocation_name */
  11
  12 #include <stdio.h>
  13 #include <stdlib.h>
  14 #include <sys/syscall.h>
  15 #include <unistd.h>
  16 #include <asm/unistd.h>
  17 #include <time.h>
  18 #include <poll.h>
  19 #include <pthread.h>
  20 #include <linux/bitmap.h>
  21 #include <linux/bitops.h>
  22 #include <linux/userfaultfd.h>
  23
  24 #include "test_util.h"
  25 #include "kvm_util.h"
  26 #include "processor.h"
  27
  28 #ifdef __NR_userfaultfd
  29
  30 /* The memory slot index demand page */
  31 #define TEST_MEM_SLOT_INDEX             1
  32
  33 /* Default guest test virtual memory offset */
  34 #define DEFAULT_GUEST_TEST_MEM          0xc0000000
  35
  36 #define DEFAULT_GUEST_TEST_MEM_SIZE (1 << 30) /* 1G */
  37
  38 #ifdef PRINT_PER_PAGE_UPDATES
  39 #define PER_PAGE_DEBUG(...) printf(__VA_ARGS__)
  40 #else
  41 #define PER_PAGE_DEBUG(...) _no_printf(__VA_ARGS__)
  42 #endif
  43
  44 #ifdef PRINT_PER_VCPU_UPDATES
  45 #define PER_VCPU_DEBUG(...) printf(__VA_ARGS__)
  46 #else
  47 #define PER_VCPU_DEBUG(...) _no_printf(__VA_ARGS__)
  48 #endif
  49
  50 #define MAX_VCPUS 512
  51
  52 /*
  53  * Guest/Host shared variables. Ensure addr_gva2hva() and/or
  54  * sync_global_to/from_guest() are used when accessing from
  55  * the host. READ/WRITE_ONCE() should also be used with anything
  56  * that may change.
  57  */
  58 static uint64_t host_page_size;
  59 static uint64_t guest_page_size;
  60
  61 static char *guest_data_prototype;
  62
  63 /*
  64  * Guest physical memory offset of the testing memory slot.
  65  * This will be set to the topmost valid physical address minus
  66  * the test memory size.
  67  */
  68 static uint64_t guest_test_phys_mem;
  69
  70 /*
  71  * Guest virtual memory offset of the testing memory slot.
  72  * Must not conflict with identity mapped test code.
  73  */
  74 static uint64_t guest_test_virt_mem = DEFAULT_GUEST_TEST_MEM;
  75
  76 struct vcpu_args {
  77         uint64_t gva;
  78         uint64_t pages;
  79
  80         /* Only used by the host userspace part of the vCPU thread */
  81         int vcpu_id;
  82         struct kvm_vm *vm;
  83 };
  84
  85 static struct vcpu_args vcpu_args[MAX_VCPUS];
  86
  87 /*
  88  * Continuously write to the first 8 bytes of each page in the demand paging
  89  * memory region.
  90  */
  91 static void guest_code(uint32_t vcpu_id)
  92 {
  93         uint64_t gva;
  94         uint64_t pages;
  95         int i;
  96
  97         /* Make sure vCPU args data structure is not corrupt. */
  98         GUEST_ASSERT(vcpu_args[vcpu_id].vcpu_id == vcpu_id);
  99
 100         gva = vcpu_args[vcpu_id].gva;
 101         pages = vcpu_args[vcpu_id].pages;
 102
 103         for (i = 0; i < pages; i++) {
 104                 uint64_t addr = gva + (i * guest_page_size);
 105
 106                 addr &= ~(host_page_size - 1);
 107                 *(uint64_t *)addr = 0x0123456789ABCDEF;
 108         }
 109
 110         GUEST_SYNC(1);
 111 }
 112
 113 static void *vcpu_worker(void *data)
 114 {
 115         int ret;
 116         struct vcpu_args *args = (struct vcpu_args *)data;
 117         struct kvm_vm *vm = args->vm;
 118         int vcpu_id = args->vcpu_id;
 119         struct kvm_run *run;
 120         struct timespec start, end, ts_diff;
 121
 122         vcpu_args_set(vm, vcpu_id, 1, vcpu_id);
 123         run = vcpu_state(vm, vcpu_id);
 124
 125         clock_gettime(CLOCK_MONOTONIC, &start);
 126
 127         /* Let the guest access its memory */
 128         ret = _vcpu_run(vm, vcpu_id);
 129         TEST_ASSERT(ret == 0, "vcpu_run failed: %d\n", ret);
 130         if (get_ucall(vm, vcpu_id, NULL) != UCALL_SYNC) {
 131                 TEST_ASSERT(false,
 132                             "Invalid guest sync status: exit_reason=%s\n",
 133                             exit_reason_str(run->exit_reason));
 134         }
 135
 136         clock_gettime(CLOCK_MONOTONIC, &end);
 137         ts_diff = timespec_sub(end, start);
 138         PER_VCPU_DEBUG("vCPU %d execution time: %ld.%.9lds\n", vcpu_id,
 139                        ts_diff.tv_sec, ts_diff.tv_nsec);
 140
 141         return NULL;
 142 }
 143
 144 #define PAGE_SHIFT_4K  12
 145 #define PTES_PER_4K_PT 512
 146
 147 static struct kvm_vm *create_vm(enum vm_guest_mode mode, int vcpus,
 148                                 uint64_t vcpu_memory_bytes)
 149 {
 150         struct kvm_vm *vm;
 151         uint64_t pages = DEFAULT_GUEST_PHY_PAGES;
 152
 153         /* Account for a few pages per-vCPU for stacks */
 154         pages += DEFAULT_STACK_PGS * vcpus;
 155
 156         /*
 157          * Reserve twice the ammount of memory needed to map the test region and
 158          * the page table / stacks region, at 4k, for page tables. Do the
 159          * calculation with 4K page size: the smallest of all archs. (e.g., 64K
 160          * page size guest will need even less memory for page tables).
 161          */
 162         pages += (2 * pages) / PTES_PER_4K_PT;
 163         pages += ((2 * vcpus * vcpu_memory_bytes) >> PAGE_SHIFT_4K) /
 164                  PTES_PER_4K_PT;
 165         pages = vm_adjust_num_guest_pages(mode, pages);
 166
 167         pr_info("Testing guest mode: %s\n", vm_guest_mode_string(mode));
 168
 169         vm = _vm_create(mode, pages, O_RDWR);
 170         kvm_vm_elf_load(vm, program_invocation_name, 0, 0);
 171 #ifdef __x86_64__
 172         vm_create_irqchip(vm);
 173 #endif
 174         return vm;
 175 }
 176
 177 static int handle_uffd_page_request(int uffd, uint64_t addr)
 178 {
 179         pid_t tid;
 180         struct timespec start;
 181         struct timespec end;
 182         struct uffdio_copy copy;
 183         int r;
 184
 185         tid = syscall(__NR_gettid);
 186
 187         copy.src = (uint64_t)guest_data_prototype;
 188         copy.dst = addr;
 189         copy.len = host_page_size;
 190         copy.mode = 0;
 191
 192         clock_gettime(CLOCK_MONOTONIC, &start);
 193
 194         r = ioctl(uffd, UFFDIO_COPY, &copy);
 195         if (r == -1) {
 196                 pr_info("Failed Paged in 0x%lx from thread %d with errno: %d\n",
 197                         addr, tid, errno);
 198                 return r;
 199         }
 200
 201         clock_gettime(CLOCK_MONOTONIC, &end);
 202
 203         PER_PAGE_DEBUG("UFFDIO_COPY %d \t%ld ns\n", tid,
 204                        timespec_to_ns(timespec_sub(end, start)));
 205         PER_PAGE_DEBUG("Paged in %ld bytes at 0x%lx from thread %d\n",
 206                        host_page_size, addr, tid);
 207
 208         return 0;
 209 }
 210
 211 bool quit_uffd_thread;
 212
 213 struct uffd_handler_args {
 214         int uffd;
 215         int pipefd;
 216         useconds_t delay;
 217 };
 218
 219 static void *uffd_handler_thread_fn(void *arg)
 220 {
 221         struct uffd_handler_args *uffd_args = (struct uffd_handler_args *)arg;
 222         int uffd = uffd_args->uffd;
 223         int pipefd = uffd_args->pipefd;
 224         useconds_t delay = uffd_args->delay;
 225         int64_t pages = 0;
 226         struct timespec start, end, ts_diff;
 227
 228         clock_gettime(CLOCK_MONOTONIC, &start);
 229         while (!quit_uffd_thread) {
 230                 struct uffd_msg msg;
 231                 struct pollfd pollfd[2];
 232                 char tmp_chr;
 233                 int r;
 234                 uint64_t addr;
 235
 236                 pollfd[0].fd = uffd;
 237                 pollfd[0].events = POLLIN;
 238                 pollfd[1].fd = pipefd;
 239                 pollfd[1].events = POLLIN;
 240
 241                 r = poll(pollfd, 2, -1);
 242                 switch (r) {
 243                 case -1:
 244                         pr_info("poll err");
 245                         continue;
 246                 case 0:
 247                         continue;
 248                 case 1:
 249                         break;
 250                 default:
 251                         pr_info("Polling uffd returned %d", r);
 252                         return NULL;
 253                 }
 254
 255                 if (pollfd[0].revents & POLLERR) {
 256                         pr_info("uffd revents has POLLERR");
 257                         return NULL;
 258                 }
 259
 260                 if (pollfd[1].revents & POLLIN) {
 261                         r = read(pollfd[1].fd, &tmp_chr, 1);
 262                         TEST_ASSERT(r == 1,
 263                                     "Error reading pipefd in UFFD thread\n");
 264                         return NULL;
 265                 }
 266
 267                 if (!pollfd[0].revents & POLLIN)
 268                         continue;
 269
 270                 r = read(uffd, &msg, sizeof(msg));
 271                 if (r == -1) {
 272                         if (errno == EAGAIN)
 273                                 continue;
 274                         pr_info("Read of uffd gor errno %d", errno);
 275                         return NULL;
 276                 }
 277
 278                 if (r != sizeof(msg)) {
 279                         pr_info("Read on uffd returned unexpected size: %d bytes", r);
 280                         return NULL;
 281                 }
 282
 283                 if (!(msg.event & UFFD_EVENT_PAGEFAULT))
 284                         continue;
 285
 286                 if (delay)
 287                         usleep(delay);
 288                 addr =  msg.arg.pagefault.address;
 289                 r = handle_uffd_page_request(uffd, addr);
 290                 if (r < 0)
 291                         return NULL;
 292                 pages++;
 293         }
 294
 295         clock_gettime(CLOCK_MONOTONIC, &end);
 296         ts_diff = timespec_sub(end, start);
 297         PER_VCPU_DEBUG("userfaulted %ld pages over %ld.%.9lds. (%f/sec)\n",
 298                        pages, ts_diff.tv_sec, ts_diff.tv_nsec,
 299                        pages / ((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / 100000000.0));
 300
 301         return NULL;
 302 }
 303
 304 static int setup_demand_paging(struct kvm_vm *vm,
 305                                pthread_t *uffd_handler_thread, int pipefd,
 306                                useconds_t uffd_delay,
 307                                struct uffd_handler_args *uffd_args,
 308                                void *hva, uint64_t len)
 309 {
 310         int uffd;
 311         struct uffdio_api uffdio_api;
 312         struct uffdio_register uffdio_register;
 313
 314         uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
 315         if (uffd == -1) {
 316                 pr_info("uffd creation failed\n");
 317                 return -1;
 318         }
 319
 320         uffdio_api.api = UFFD_API;
 321         uffdio_api.features = 0;
 322         if (ioctl(uffd, UFFDIO_API, &uffdio_api) == -1) {
 323                 pr_info("ioctl uffdio_api failed\n");
 324                 return -1;
 325         }
 326
 327         uffdio_register.range.start = (uint64_t)hva;
 328         uffdio_register.range.len = len;
 329         uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
 330         if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) == -1) {
 331                 pr_info("ioctl uffdio_register failed\n");
 332                 return -1;
 333         }
 334
 335         if ((uffdio_register.ioctls & UFFD_API_RANGE_IOCTLS) !=
 336                         UFFD_API_RANGE_IOCTLS) {
 337                 pr_info("unexpected userfaultfd ioctl set\n");
 338                 return -1;
 339         }
 340
 341         uffd_args->uffd = uffd;
 342         uffd_args->pipefd = pipefd;
 343         uffd_args->delay = uffd_delay;
 344         pthread_create(uffd_handler_thread, NULL, uffd_handler_thread_fn,
 345                        uffd_args);
 346
 347         PER_VCPU_DEBUG("Created uffd thread for HVA range [%p, %p)\n",
 348                        hva, hva + len);
 349
 350         return 0;
 351 }
 352
 353 static void run_test(enum vm_guest_mode mode, bool use_uffd,
 354                      useconds_t uffd_delay, int vcpus,
 355                      uint64_t vcpu_memory_bytes)
 356 {
 357         pthread_t *vcpu_threads;
 358         pthread_t *uffd_handler_threads = NULL;
 359         struct uffd_handler_args *uffd_args = NULL;
 360         struct timespec start, end, ts_diff;
 361         int *pipefds = NULL;
 362         struct kvm_vm *vm;
 363         uint64_t guest_num_pages;
 364         int vcpu_id;
 365         int r;
 366
 367         vm = create_vm(mode, vcpus, vcpu_memory_bytes);
 368
 369         guest_page_size = vm_get_page_size(vm);
 370
 371         TEST_ASSERT(vcpu_memory_bytes % guest_page_size == 0,
 372                     "Guest memory size is not guest page size aligned.");
 373
 374         guest_num_pages = (vcpus * vcpu_memory_bytes) / guest_page_size;
 375         guest_num_pages = vm_adjust_num_guest_pages(mode, guest_num_pages);
 376
 377         /*
 378          * If there should be more memory in the guest test region than there
 379          * can be pages in the guest, it will definitely cause problems.
 380          */
 381         TEST_ASSERT(guest_num_pages < vm_get_max_gfn(vm),
 382                     "Requested more guest memory than address space allows.\n"
 383                     "    guest pages: %lx max gfn: %x vcpus: %d wss: %lx]\n",
 384                     guest_num_pages, vm_get_max_gfn(vm), vcpus,
 385                     vcpu_memory_bytes);
 386
 387         host_page_size = getpagesize();
 388         TEST_ASSERT(vcpu_memory_bytes % host_page_size == 0,
 389                     "Guest memory size is not host page size aligned.");
 390
 391         guest_test_phys_mem = (vm_get_max_gfn(vm) - guest_num_pages) *
 392                               guest_page_size;
 393         guest_test_phys_mem &= ~(host_page_size - 1);
 394
 395 #ifdef __s390x__
 396         /* Align to 1M (segment size) */
 397         guest_test_phys_mem &= ~((1 << 20) - 1);
 398 #endif
 399
 400         pr_info("guest physical test memory offset: 0x%lx\n", guest_test_phys_mem);
 401
 402         /* Add an extra memory slot for testing demand paging */
 403         vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
 404                                     guest_test_phys_mem,
 405                                     TEST_MEM_SLOT_INDEX,
 406                                     guest_num_pages, 0);
 407
 408         /* Do mapping for the demand paging memory slot */
 409         virt_map(vm, guest_test_virt_mem, guest_test_phys_mem, guest_num_pages, 0);
 410
 411         ucall_init(vm, NULL);
 412
 413         guest_data_prototype = malloc(host_page_size);
 414         TEST_ASSERT(guest_data_prototype,
 415                     "Failed to allocate buffer for guest data pattern");
 416         memset(guest_data_prototype, 0xAB, host_page_size);
 417
 418         vcpu_threads = malloc(vcpus * sizeof(*vcpu_threads));
 419         TEST_ASSERT(vcpu_threads, "Memory allocation failed");
 420
 421         if (use_uffd) {
 422                 uffd_handler_threads =
 423                         malloc(vcpus * sizeof(*uffd_handler_threads));
 424                 TEST_ASSERT(uffd_handler_threads, "Memory allocation failed");
 425
 426                 uffd_args = malloc(vcpus * sizeof(*uffd_args));
 427                 TEST_ASSERT(uffd_args, "Memory allocation failed");
 428
 429                 pipefds = malloc(sizeof(int) * vcpus * 2);
 430                 TEST_ASSERT(pipefds, "Unable to allocate memory for pipefd");
 431         }
 432
 433         for (vcpu_id = 0; vcpu_id < vcpus; vcpu_id++) {
 434                 vm_paddr_t vcpu_gpa;
 435                 void *vcpu_hva;
 436
 437                 vm_vcpu_add_default(vm, vcpu_id, guest_code);
 438
 439                 vcpu_gpa = guest_test_phys_mem + (vcpu_id * vcpu_memory_bytes);
 440                 PER_VCPU_DEBUG("Added VCPU %d with test mem gpa [%lx, %lx)\n",
 441                                vcpu_id, vcpu_gpa, vcpu_gpa + vcpu_memory_bytes);
 442
 443                 /* Cache the HVA pointer of the region */
 444                 vcpu_hva = addr_gpa2hva(vm, vcpu_gpa);
 445
 446                 if (use_uffd) {
 447                         /*
 448                          * Set up user fault fd to handle demand paging
 449                          * requests.
 450                          */
 451                         r = pipe2(&pipefds[vcpu_id * 2],
 452                                   O_CLOEXEC | O_NONBLOCK);
 453                         TEST_ASSERT(!r, "Failed to set up pipefd");
 454
 455                         r = setup_demand_paging(vm,
 456                                                 &uffd_handler_threads[vcpu_id],
 457                                                 pipefds[vcpu_id * 2],
 458                                                 uffd_delay, &uffd_args[vcpu_id],
 459                                                 vcpu_hva, vcpu_memory_bytes);
 460                         if (r < 0)
 461                                 exit(-r);
 462                 }
 463
 464 #ifdef __x86_64__
 465                 vcpu_set_cpuid(vm, vcpu_id, kvm_get_supported_cpuid());
 466 #endif
 467
 468                 vcpu_args[vcpu_id].vm = vm;
 469                 vcpu_args[vcpu_id].vcpu_id = vcpu_id;
 470                 vcpu_args[vcpu_id].gva = guest_test_virt_mem +
 471                                          (vcpu_id * vcpu_memory_bytes);
 472                 vcpu_args[vcpu_id].pages = vcpu_memory_bytes / guest_page_size;
 473         }
 474
 475         /* Export the shared variables to the guest */
 476         sync_global_to_guest(vm, host_page_size);
 477         sync_global_to_guest(vm, guest_page_size);
 478         sync_global_to_guest(vm, vcpu_args);
 479
 480         pr_info("Finished creating vCPUs and starting uffd threads\n");
 481
 482         clock_gettime(CLOCK_MONOTONIC, &start);
 483
 484         for (vcpu_id = 0; vcpu_id < vcpus; vcpu_id++) {
 485                 pthread_create(&vcpu_threads[vcpu_id], NULL, vcpu_worker,
 486                                &vcpu_args[vcpu_id]);
 487         }
 488
 489         pr_info("Started all vCPUs\n");
 490
 491         /* Wait for the vcpu threads to quit */
 492         for (vcpu_id = 0; vcpu_id < vcpus; vcpu_id++) {
 493                 pthread_join(vcpu_threads[vcpu_id], NULL);
 494                 PER_VCPU_DEBUG("Joined thread for vCPU %d\n", vcpu_id);
 495         }
 496
 497         pr_info("All vCPU threads joined\n");
 498
 499         clock_gettime(CLOCK_MONOTONIC, &end);
 500
 501         if (use_uffd) {
 502                 char c;
 503
 504                 /* Tell the user fault fd handler threads to quit */
 505                 for (vcpu_id = 0; vcpu_id < vcpus; vcpu_id++) {
 506                         r = write(pipefds[vcpu_id * 2 + 1], &c, 1);
 507                         TEST_ASSERT(r == 1, "Unable to write to pipefd");
 508
 509                         pthread_join(uffd_handler_threads[vcpu_id], NULL);
 510                 }
 511         }
 512
 513         ts_diff = timespec_sub(end, start);
 514         pr_info("Total guest execution time: %ld.%.9lds\n",
 515                 ts_diff.tv_sec, ts_diff.tv_nsec);
 516         pr_info("Overall demand paging rate: %f pgs/sec\n",
 517                 guest_num_pages / ((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / 100000000.0));
 518
 519         ucall_uninit(vm);
 520         kvm_vm_free(vm);
 521
 522         free(guest_data_prototype);
 523         free(vcpu_threads);
 524         if (use_uffd) {
 525                 free(uffd_handler_threads);
 526                 free(uffd_args);
 527                 free(pipefds);
 528         }
 529 }
 530
 531 struct guest_mode {
 532         bool supported;
 533         bool enabled;
 534 };
 535 static struct guest_mode guest_modes[NUM_VM_MODES];
 536
 537 #define guest_mode_init(mode, supported, enabled) ({ \
 538         guest_modes[mode] = (struct guest_mode){ supported, enabled }; \
 539 })
 540
 541 static void help(char *name)
 542 {
 543         int i;
 544
 545         puts("");
 546         printf("usage: %s [-h] [-m mode] [-u] [-d uffd_delay_usec]\n"
 547                "          [-b memory] [-v vcpus]\n", name);
 548         printf(" -m: specify the guest mode ID to test\n"
 549                "     (default: test all supported modes)\n"
 550                "     This option may be used multiple times.\n"
 551                "     Guest mode IDs:\n");
 552         for (i = 0; i < NUM_VM_MODES; ++i) {
 553                 printf("         %d:    %s%s\n", i, vm_guest_mode_string(i),
 554                        guest_modes[i].supported ? " (supported)" : "");
 555         }
 556         printf(" -u: use User Fault FD to handle vCPU page\n"
 557                "     faults.\n");
 558         printf(" -d: add a delay in usec to the User Fault\n"
 559                "     FD handler to simulate demand paging\n"
 560                "     overheads. Ignored without -u.\n");
 561         printf(" -b: specify the size of the memory region which should be\n"
 562                "     demand paged by each vCPU. e.g. 10M or 3G.\n"
 563                "     Default: 1G\n");
 564         printf(" -v: specify the number of vCPUs to run.\n");
 565         puts("");
 566         exit(0);
 567 }
 568
 569 int main(int argc, char *argv[])
 570 {
 571         bool mode_selected = false;
 572         uint64_t vcpu_memory_bytes = DEFAULT_GUEST_TEST_MEM_SIZE;
 573         int vcpus = 1;
 574         unsigned int mode;
 575         int opt, i;
 576         bool use_uffd = false;
 577         useconds_t uffd_delay = 0;
 578
 579 #ifdef __x86_64__
 580         guest_mode_init(VM_MODE_PXXV48_4K, true, true);
 581 #endif
 582 #ifdef __aarch64__
 583         guest_mode_init(VM_MODE_P40V48_4K, true, true);
 584         guest_mode_init(VM_MODE_P40V48_64K, true, true);
 585         {
 586                 unsigned int limit = kvm_check_cap(KVM_CAP_ARM_VM_IPA_SIZE);
 587
 588                 if (limit >= 52)
 589                         guest_mode_init(VM_MODE_P52V48_64K, true, true);
 590                 if (limit >= 48) {
 591                         guest_mode_init(VM_MODE_P48V48_4K, true, true);
 592                         guest_mode_init(VM_MODE_P48V48_64K, true, true);
 593                 }
 594         }
 595 #endif
 596 #ifdef __s390x__
 597         guest_mode_init(VM_MODE_P40V48_4K, true, true);
 598 #endif
 599
 600         while ((opt = getopt(argc, argv, "hm:ud:b:v:")) != -1) {
 601                 switch (opt) {
 602                 case 'm':
 603                         if (!mode_selected) {
 604                                 for (i = 0; i < NUM_VM_MODES; ++i)
 605                                         guest_modes[i].enabled = false;
 606                                 mode_selected = true;
 607                         }
 608                         mode = strtoul(optarg, NULL, 10);
 609                         TEST_ASSERT(mode < NUM_VM_MODES,
 610                                     "Guest mode ID %d too big", mode);
 611                         guest_modes[mode].enabled = true;
 612                         break;
 613                 case 'u':
 614                         use_uffd = true;
 615                         break;
 616                 case 'd':
 617                         uffd_delay = strtoul(optarg, NULL, 0);
 618                         TEST_ASSERT(uffd_delay >= 0,
 619                                     "A negative UFFD delay is not supported.");
 620                         break;
 621                 case 'b':
 622                         vcpu_memory_bytes = parse_size(optarg);
 623                         break;
 624                 case 'v':
 625                         vcpus = atoi(optarg);
 626                         TEST_ASSERT(vcpus > 0,
 627                                     "Must have a positive number of vCPUs");
 628                         TEST_ASSERT(vcpus <= MAX_VCPUS,
 629                                     "This test does not currently support\n"
 630                                     "more than %d vCPUs.", MAX_VCPUS);
 631                         break;
 632                 case 'h':
 633                 default:
 634                         help(argv[0]);
 635                         break;
 636                 }
 637         }
 638
 639         for (i = 0; i < NUM_VM_MODES; ++i) {
 640                 if (!guest_modes[i].enabled)
 641                         continue;
 642                 TEST_ASSERT(guest_modes[i].supported,
 643                             "Guest mode ID %d (%s) not supported.",
 644                             i, vm_guest_mode_string(i));
 645                 run_test(i, use_uffd, uffd_delay, vcpus, vcpu_memory_bytes);
 646         }
 647
 648         return 0;
 649 }
 650
 651 #else /* __NR_userfaultfd */
 652
 653 #warning "missing __NR_userfaultfd definition"
 654
 655 int main(void)
 656 {
 657         print_skip("__NR_userfaultfd must be present for userfaultfd test");
 658         return KSFT_SKIP;
 659 }
 660
 661 #endif /* __NR_userfaultfd */