src/basic/virt.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2011 Lennart Poettering
   6 ***/
   7
   8 #if defined(__i386__) || defined(__x86_64__)
   9 #include <cpuid.h>
  10 #endif
  11 #include <errno.h>
  12 #include <stdint.h>
  13 #include <stdlib.h>
  14 #include <string.h>
  15 #include <unistd.h>
  16
  17 #include "alloc-util.h"
  18 #include "dirent-util.h"
  19 #include "env-util.h"
  20 #include "fd-util.h"
  21 #include "fileio.h"
  22 #include "macro.h"
  23 #include "process-util.h"
  24 #include "stat-util.h"
  25 #include "string-table.h"
  26 #include "string-util.h"
  27 #include "virt.h"
  28
  29 static int detect_vm_cpuid(void) {
  30
  31         /* CPUID is an x86 specific interface. */
  32 #if defined(__i386__) || defined(__x86_64__)
  33
  34         static const struct {
  35                 const char *cpuid;
  36                 int id;
  37         } cpuid_vendor_table[] = {
  38                 { "XenVMMXenVMM", VIRTUALIZATION_XEN       },
  39                 { "KVMKVMKVM",    VIRTUALIZATION_KVM       },
  40                 { "TCGTCGTCGTCG", VIRTUALIZATION_QEMU      },
  41                 /* http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1009458 */
  42                 { "VMwareVMware", VIRTUALIZATION_VMWARE    },
  43                 /* https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs */
  44                 { "Microsoft Hv", VIRTUALIZATION_MICROSOFT },
  45                 /* https://wiki.freebsd.org/bhyve */
  46                 { "bhyve bhyve ", VIRTUALIZATION_BHYVE     },
  47                 { "QNXQVMBSQG",   VIRTUALIZATION_QNX       },
  48         };
  49
  50         uint32_t eax, ebx, ecx, edx;
  51         bool hypervisor;
  52
  53         /* http://lwn.net/Articles/301888/ */
  54
  55         /* First detect whether there is a hypervisor */
  56         if (__get_cpuid(1, &eax, &ebx, &ecx, &edx) == 0)
  57                 return VIRTUALIZATION_NONE;
  58
  59         hypervisor = !!(ecx & 0x80000000U);
  60
  61         if (hypervisor) {
  62                 union {
  63                         uint32_t sig32[3];
  64                         char text[13];
  65                 } sig = {};
  66                 unsigned j;
  67
  68                 /* There is a hypervisor, see what it is */
  69                 __cpuid(0x40000000U, eax, ebx, ecx, edx);
  70
  71                 sig.sig32[0] = ebx;
  72                 sig.sig32[1] = ecx;
  73                 sig.sig32[2] = edx;
  74
  75                 log_debug("Virtualization found, CPUID=%s", sig.text);
  76
  77                 for (j = 0; j < ELEMENTSOF(cpuid_vendor_table); j ++)
  78                         if (streq(sig.text, cpuid_vendor_table[j].cpuid))
  79                                 return cpuid_vendor_table[j].id;
  80
  81                 return VIRTUALIZATION_VM_OTHER;
  82         }
  83 #endif
  84         log_debug("No virtualization found in CPUID");
  85
  86         return VIRTUALIZATION_NONE;
  87 }
  88
  89 static int detect_vm_device_tree(void) {
  90 #if defined(__arm__) || defined(__aarch64__) || defined(__powerpc__) || defined(__powerpc64__)
  91         _cleanup_free_ char *hvtype = NULL;
  92         int r;
  93
  94         r = read_one_line_file("/proc/device-tree/hypervisor/compatible", &hvtype);
  95         if (r == -ENOENT) {
  96                 _cleanup_closedir_ DIR *dir = NULL;
  97                 struct dirent *dent;
  98
  99                 dir = opendir("/proc/device-tree");
 100                 if (!dir) {
 101                         if (errno == ENOENT) {
 102                                 log_debug_errno(errno, "/proc/device-tree: %m");
 103                                 return VIRTUALIZATION_NONE;
 104                         }
 105                         return -errno;
 106                 }
 107
 108                 FOREACH_DIRENT(dent, dir, return -errno)
 109                         if (strstr(dent->d_name, "fw-cfg")) {
 110                                 log_debug("Virtualization QEMU: \"fw-cfg\" present in /proc/device-tree/%s", dent->d_name);
 111                                 return VIRTUALIZATION_QEMU;
 112                         }
 113
 114                 log_debug("No virtualization found in /proc/device-tree/*");
 115                 return VIRTUALIZATION_NONE;
 116         } else if (r < 0)
 117                 return r;
 118
 119         log_debug("Virtualization %s found in /proc/device-tree/hypervisor/compatible", hvtype);
 120         if (streq(hvtype, "linux,kvm"))
 121                 return VIRTUALIZATION_KVM;
 122         else if (strstr(hvtype, "xen"))
 123                 return VIRTUALIZATION_XEN;
 124         else
 125                 return VIRTUALIZATION_VM_OTHER;
 126 #else
 127         log_debug("This platform does not support /proc/device-tree");
 128         return VIRTUALIZATION_NONE;
 129 #endif
 130 }
 131
 132 static int detect_vm_dmi(void) {
 133 #if defined(__i386__) || defined(__x86_64__) || defined(__arm__) || defined(__aarch64__)
 134
 135         static const char *const dmi_vendors[] = {
 136                 "/sys/class/dmi/id/product_name", /* Test this before sys_vendor to detect KVM over QEMU */
 137                 "/sys/class/dmi/id/sys_vendor",
 138                 "/sys/class/dmi/id/board_vendor",
 139                 "/sys/class/dmi/id/bios_vendor"
 140         };
 141
 142         static const struct {
 143                 const char *vendor;
 144                 int id;
 145         } dmi_vendor_table[] = {
 146                 { "KVM",           VIRTUALIZATION_KVM       },
 147                 { "QEMU",          VIRTUALIZATION_QEMU      },
 148                 /* http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1009458 */
 149                 { "VMware",        VIRTUALIZATION_VMWARE    },
 150                 { "VMW",           VIRTUALIZATION_VMWARE    },
 151                 { "innotek GmbH",  VIRTUALIZATION_ORACLE    },
 152                 { "Xen",           VIRTUALIZATION_XEN       },
 153                 { "Bochs",         VIRTUALIZATION_BOCHS     },
 154                 { "Parallels",     VIRTUALIZATION_PARALLELS },
 155                 /* https://wiki.freebsd.org/bhyve */
 156                 { "BHYVE",         VIRTUALIZATION_BHYVE     },
 157         };
 158         unsigned i;
 159         int r;
 160
 161         for (i = 0; i < ELEMENTSOF(dmi_vendors); i++) {
 162                 _cleanup_free_ char *s = NULL;
 163                 unsigned j;
 164
 165                 r = read_one_line_file(dmi_vendors[i], &s);
 166                 if (r < 0) {
 167                         if (r == -ENOENT)
 168                                 continue;
 169
 170                         return r;
 171                 }
 172
 173                 for (j = 0; j < ELEMENTSOF(dmi_vendor_table); j++)
 174                         if (startswith(s, dmi_vendor_table[j].vendor)) {
 175                                 log_debug("Virtualization %s found in DMI (%s)", s, dmi_vendors[i]);
 176                                 return dmi_vendor_table[j].id;
 177                         }
 178         }
 179 #endif
 180
 181         log_debug("No virtualization found in DMI");
 182
 183         return VIRTUALIZATION_NONE;
 184 }
 185
 186 static int detect_vm_xen(void) {
 187
 188         /* Check for Dom0 will be executed later in detect_vm_xen_dom0
 189            The presence of /proc/xen indicates some form of a Xen domain */
 190         if (access("/proc/xen", F_OK) < 0) {
 191                 log_debug("Virtualization XEN not found, /proc/xen does not exist");
 192                 return VIRTUALIZATION_NONE;
 193         }
 194
 195         log_debug("Virtualization XEN found (/proc/xen exists)");
 196         return VIRTUALIZATION_XEN;
 197 }
 198
 199 #define XENFEAT_dom0 11 /* xen/include/public/features.h */
 200 #define PATH_FEATURES "/sys/hypervisor/properties/features"
 201 /* Returns -errno, or 0 for domU, or 1 for dom0 */
 202 static int detect_vm_xen_dom0(void) {
 203         _cleanup_free_ char *domcap = NULL;
 204         char *cap, *i;
 205         int r;
 206
 207         r = read_one_line_file(PATH_FEATURES, &domcap);
 208         if (r < 0 && r != -ENOENT)
 209                 return r;
 210         if (r == 0) {
 211                 unsigned long features;
 212
 213                 /* Here, we need to use sscanf() instead of safe_atoul()
 214                  * as the string lacks the leading "0x". */
 215                 r = sscanf(domcap, "%lx", &features);
 216                 if (r == 1) {
 217                         r = !!(features & (1U << XENFEAT_dom0));
 218                         log_debug("Virtualization XEN, found %s with value %08lx, "
 219                                   "XENFEAT_dom0 (indicating the 'hardware domain') is%s set.",
 220                                   PATH_FEATURES, features, r ? "" : " not");
 221                         return r;
 222                 }
 223                 log_debug("Virtualization XEN, found %s, unhandled content '%s'",
 224                           PATH_FEATURES, domcap);
 225         }
 226
 227         r = read_one_line_file("/proc/xen/capabilities", &domcap);
 228         if (r == -ENOENT) {
 229                 log_debug("Virtualization XEN because /proc/xen/capabilities does not exist");
 230                 return 0;
 231         }
 232         if (r < 0)
 233                 return r;
 234
 235         i = domcap;
 236         while ((cap = strsep(&i, ",")))
 237                 if (streq(cap, "control_d"))
 238                         break;
 239         if (!cap) {
 240                 log_debug("Virtualization XEN DomU found (/proc/xen/capabilites)");
 241                 return 0;
 242         }
 243
 244         log_debug("Virtualization XEN Dom0 ignored (/proc/xen/capabilities)");
 245         return 1;
 246 }
 247
 248 static int detect_vm_hypervisor(void) {
 249         _cleanup_free_ char *hvtype = NULL;
 250         int r;
 251
 252         r = read_one_line_file("/sys/hypervisor/type", &hvtype);
 253         if (r == -ENOENT)
 254                 return VIRTUALIZATION_NONE;
 255         if (r < 0)
 256                 return r;
 257
 258         log_debug("Virtualization %s found in /sys/hypervisor/type", hvtype);
 259
 260         if (streq(hvtype, "xen"))
 261                 return VIRTUALIZATION_XEN;
 262         else
 263                 return VIRTUALIZATION_VM_OTHER;
 264 }
 265
 266 static int detect_vm_uml(void) {
 267         _cleanup_free_ char *cpuinfo_contents = NULL;
 268         int r;
 269
 270         /* Detect User-Mode Linux by reading /proc/cpuinfo */
 271         r = read_full_file("/proc/cpuinfo", &cpuinfo_contents, NULL);
 272         if (r == -ENOENT) {
 273                 log_debug("/proc/cpuinfo not found, assuming no UML virtualization.");
 274                 return VIRTUALIZATION_NONE;
 275         }
 276         if (r < 0)
 277                 return r;
 278
 279         if (strstr(cpuinfo_contents, "\nvendor_id\t: User Mode Linux\n")) {
 280                 log_debug("UML virtualization found in /proc/cpuinfo");
 281                 return VIRTUALIZATION_UML;
 282         }
 283
 284         log_debug("UML virtualization not found in /proc/cpuinfo.");
 285         return VIRTUALIZATION_NONE;
 286 }
 287
 288 static int detect_vm_zvm(void) {
 289
 290 #if defined(__s390__)
 291         _cleanup_free_ char *t = NULL;
 292         int r;
 293
 294         r = get_proc_field("/proc/sysinfo", "VM00 Control Program", WHITESPACE, &t);
 295         if (r == -ENOENT)
 296                 return VIRTUALIZATION_NONE;
 297         if (r < 0)
 298                 return r;
 299
 300         log_debug("Virtualization %s found in /proc/sysinfo", t);
 301         if (streq(t, "z/VM"))
 302                 return VIRTUALIZATION_ZVM;
 303         else
 304                 return VIRTUALIZATION_KVM;
 305 #else
 306         log_debug("This platform does not support /proc/sysinfo");
 307         return VIRTUALIZATION_NONE;
 308 #endif
 309 }
 310
 311 /* Returns a short identifier for the various VM implementations */
 312 int detect_vm(void) {
 313         static thread_local int cached_found = _VIRTUALIZATION_INVALID;
 314         bool other = false;
 315         int r, dmi;
 316
 317         if (cached_found >= 0)
 318                 return cached_found;
 319
 320         /* We have to use the correct order here:
 321          *
 322          * → First, try to detect Oracle Virtualbox, even if it uses KVM, as well as Xen even if it cloaks as Microsoft
 323          *   Hyper-V.
 324          *
 325          * → Second, try to detect from CPUID, this will report KVM for whatever software is used even if info in DMI is
 326          *   overwritten.
 327          *
 328          * → Third, try to detect from DMI. */
 329
 330         dmi = detect_vm_dmi();
 331         if (IN_SET(dmi, VIRTUALIZATION_ORACLE, VIRTUALIZATION_XEN)) {
 332                 r = dmi;
 333                 goto finish;
 334         }
 335
 336         r = detect_vm_cpuid();
 337         if (r < 0)
 338                 return r;
 339         if (r == VIRTUALIZATION_VM_OTHER)
 340                 other = true;
 341         else if (r != VIRTUALIZATION_NONE)
 342                 goto finish;
 343
 344         /* Now, let's get back to DMI */
 345         if (dmi < 0)
 346                 return dmi;
 347         if (dmi == VIRTUALIZATION_VM_OTHER)
 348                 other = true;
 349         else if (dmi != VIRTUALIZATION_NONE) {
 350                 r = dmi;
 351                 goto finish;
 352         }
 353
 354         /* x86 xen will most likely be detected by cpuid. If not (most likely
 355          * because we're not an x86 guest), then we should try the /proc/xen
 356          * directory next. If that's not found, then we check for the high-level
 357          * hypervisor sysfs file.
 358          */
 359
 360         r = detect_vm_xen();
 361         if (r < 0)
 362                 return r;
 363         if (r == VIRTUALIZATION_VM_OTHER)
 364                 other = true;
 365         else if (r != VIRTUALIZATION_NONE)
 366                 goto finish;
 367
 368         r = detect_vm_hypervisor();
 369         if (r < 0)
 370                 return r;
 371         if (r == VIRTUALIZATION_VM_OTHER)
 372                 other = true;
 373         else if (r != VIRTUALIZATION_NONE)
 374                 goto finish;
 375
 376         r = detect_vm_device_tree();
 377         if (r < 0)
 378                 return r;
 379         if (r == VIRTUALIZATION_VM_OTHER)
 380                 other = true;
 381         else if (r != VIRTUALIZATION_NONE)
 382                 goto finish;
 383
 384         r = detect_vm_uml();
 385         if (r < 0)
 386                 return r;
 387         if (r == VIRTUALIZATION_VM_OTHER)
 388                 other = true;
 389         else if (r != VIRTUALIZATION_NONE)
 390                 goto finish;
 391
 392         r = detect_vm_zvm();
 393         if (r < 0)
 394                 return r;
 395
 396 finish:
 397         /* x86 xen Dom0 is detected as XEN in hypervisor and maybe others.
 398          * In order to detect the Dom0 as not virtualization we need to
 399          * double-check it */
 400         if (r == VIRTUALIZATION_XEN) {
 401                 int dom0;
 402
 403                 dom0 = detect_vm_xen_dom0();
 404                 if (dom0 < 0)
 405                         return dom0;
 406                 if (dom0 > 0)
 407                         r = VIRTUALIZATION_NONE;
 408         } else if (r == VIRTUALIZATION_NONE && other)
 409                 r = VIRTUALIZATION_VM_OTHER;
 410
 411         cached_found = r;
 412         log_debug("Found VM virtualization %s", virtualization_to_string(r));
 413         return r;
 414 }
 415
 416 int detect_container(void) {
 417
 418         static const struct {
 419                 const char *value;
 420                 int id;
 421         } value_table[] = {
 422                 { "lxc",            VIRTUALIZATION_LXC            },
 423                 { "lxc-libvirt",    VIRTUALIZATION_LXC_LIBVIRT    },
 424                 { "systemd-nspawn", VIRTUALIZATION_SYSTEMD_NSPAWN },
 425                 { "docker",         VIRTUALIZATION_DOCKER         },
 426                 { "rkt",            VIRTUALIZATION_RKT            },
 427         };
 428
 429         static thread_local int cached_found = _VIRTUALIZATION_INVALID;
 430         _cleanup_free_ char *m = NULL;
 431         const char *e = NULL;
 432         unsigned j;
 433         int r;
 434
 435         if (cached_found >= 0)
 436                 return cached_found;
 437
 438         /* /proc/vz exists in container and outside of the container, /proc/bc only outside of the container. */
 439         if (access("/proc/vz", F_OK) >= 0 &&
 440             access("/proc/bc", F_OK) < 0) {
 441                 r = VIRTUALIZATION_OPENVZ;
 442                 goto finish;
 443         }
 444
 445         if (getpid_cached() == 1) {
 446                 /* If we are PID 1 we can just check our own environment variable, and that's authoritative. */
 447
 448                 e = getenv("container");
 449                 if (isempty(e)) {
 450                         r = VIRTUALIZATION_NONE;
 451                         goto finish;
 452                 }
 453
 454                 goto translate_name;
 455         }
 456
 457         /* Otherwise, PID 1 might have dropped this information into a file in /run. This is better than accessing
 458          * /proc/1/environ, since we don't need CAP_SYS_PTRACE for that. */
 459         r = read_one_line_file("/run/systemd/container", &m);
 460         if (r >= 0) {
 461                 e = m;
 462                 goto translate_name;
 463         }
 464         if (r != -ENOENT)
 465                 return log_debug_errno(r, "Failed to read /run/systemd/container: %m");
 466
 467         /* Fallback for cases where PID 1 was not systemd (for example, cases where init=/bin/sh is used. */
 468         r = getenv_for_pid(1, "container", &m);
 469         if (r > 0) {
 470                 e = m;
 471                 goto translate_name;
 472         }
 473         if (r < 0) /* This only works if we have CAP_SYS_PTRACE, hence let's better ignore failures here */
 474                 log_debug_errno(r, "Failed to read $container of PID 1, ignoring: %m");
 475
 476         /* Interestingly /proc/1/sched actually shows the host's PID for what we see as PID 1. Hence, if the PID shown
 477          * there is not 1, we know we are in a PID namespace. and hence a container. */
 478         r = read_one_line_file("/proc/1/sched", &m);
 479         if (r >= 0) {
 480                 const char *t;
 481
 482                 t = strrchr(m, '(');
 483                 if (!t)
 484                         return -EIO;
 485
 486                 if (!startswith(t, "(1,")) {
 487                         r = VIRTUALIZATION_CONTAINER_OTHER;
 488                         goto finish;
 489                 }
 490         } else if (r != -ENOENT)
 491                 return r;
 492
 493         /* If that didn't work, give up, assume no container manager. */
 494         r = VIRTUALIZATION_NONE;
 495         goto finish;
 496
 497 translate_name:
 498         for (j = 0; j < ELEMENTSOF(value_table); j++)
 499                 if (streq(e, value_table[j].value)) {
 500                         r = value_table[j].id;
 501                         goto finish;
 502                 }
 503
 504         r = VIRTUALIZATION_CONTAINER_OTHER;
 505
 506 finish:
 507         log_debug("Found container virtualization %s.", virtualization_to_string(r));
 508         cached_found = r;
 509         return r;
 510 }
 511
 512 int detect_virtualization(void) {
 513         int r;
 514
 515         r = detect_container();
 516         if (r == 0)
 517                 r = detect_vm();
 518
 519         return r;
 520 }
 521
 522 static int userns_has_mapping(const char *name) {
 523         _cleanup_fclose_ FILE *f = NULL;
 524         _cleanup_free_ char *buf = NULL;
 525         size_t n_allocated = 0;
 526         ssize_t n;
 527         uint32_t a, b, c;
 528         int r;
 529
 530         f = fopen(name, "re");
 531         if (!f) {
 532                 log_debug_errno(errno, "Failed to open %s: %m", name);
 533                 return errno == ENOENT ? false : -errno;
 534         }
 535
 536         n = getline(&buf, &n_allocated, f);
 537         if (n < 0) {
 538                 if (feof(f)) {
 539                         log_debug("%s is empty, we're in an uninitialized user namespace", name);
 540                         return true;
 541                 }
 542
 543                 return log_debug_errno(errno, "Failed to read %s: %m", name);
 544         }
 545
 546         r = sscanf(buf, "%"PRIu32" %"PRIu32" %"PRIu32, &a, &b, &c);
 547         if (r < 3)
 548                 return log_debug_errno(errno, "Failed to parse %s: %m", name);
 549
 550         if (a == 0 && b == 0 && c == UINT32_MAX) {
 551                 /* The kernel calls mappings_overlap() and does not allow overlaps */
 552                 log_debug("%s has a full 1:1 mapping", name);
 553                 return false;
 554         }
 555
 556         /* Anything else implies that we are in a user namespace */
 557         log_debug("Mapping found in %s, we're in a user namespace", name);
 558         return true;
 559 }
 560
 561 int running_in_userns(void) {
 562         _cleanup_free_ char *line = NULL;
 563         int r;
 564
 565         r = userns_has_mapping("/proc/self/uid_map");
 566         if (r != 0)
 567                 return r;
 568
 569         r = userns_has_mapping("/proc/self/gid_map");
 570         if (r != 0)
 571                 return r;
 572
 573         /* "setgroups" file was added in kernel v3.18-rc6-15-g9cc46516dd. It is also
 574          * possible to compile a kernel without CONFIG_USER_NS, in which case "setgroups"
 575          * also does not exist. We cannot distinguish those two cases, so assume that
 576          * we're running on a stripped-down recent kernel, rather than on an old one,
 577          * and if the file is not found, return false.
 578          */
 579         r = read_one_line_file("/proc/self/setgroups", &line);
 580         if (r < 0) {
 581                 log_debug_errno(r, "/proc/self/setgroups: %m");
 582                 return r == -ENOENT ? false : r;
 583         }
 584
 585         truncate_nl(line);
 586         r = streq(line, "deny");
 587         /* See user_namespaces(7) for a description of this "setgroups" contents. */
 588         log_debug("/proc/self/setgroups contains \"%s\", %s user namespace", line, r ? "in" : "not in");
 589         return r;
 590 }
 591
 592 int running_in_chroot(void) {
 593         int r;
 594
 595         if (getenv_bool("SYSTEMD_IGNORE_CHROOT") > 0)
 596                 return 0;
 597
 598         r = files_same("/proc/1/root", "/", 0);
 599         if (r < 0)
 600                 return r;
 601
 602         return r == 0;
 603 }
 604
 605 static const char *const virtualization_table[_VIRTUALIZATION_MAX] = {
 606         [VIRTUALIZATION_NONE] = "none",
 607         [VIRTUALIZATION_KVM] = "kvm",
 608         [VIRTUALIZATION_QEMU] = "qemu",
 609         [VIRTUALIZATION_BOCHS] = "bochs",
 610         [VIRTUALIZATION_XEN] = "xen",
 611         [VIRTUALIZATION_UML] = "uml",
 612         [VIRTUALIZATION_VMWARE] = "vmware",
 613         [VIRTUALIZATION_ORACLE] = "oracle",
 614         [VIRTUALIZATION_MICROSOFT] = "microsoft",
 615         [VIRTUALIZATION_ZVM] = "zvm",
 616         [VIRTUALIZATION_PARALLELS] = "parallels",
 617         [VIRTUALIZATION_BHYVE] = "bhyve",
 618         [VIRTUALIZATION_QNX] = "qnx",
 619         [VIRTUALIZATION_VM_OTHER] = "vm-other",
 620
 621         [VIRTUALIZATION_SYSTEMD_NSPAWN] = "systemd-nspawn",
 622         [VIRTUALIZATION_LXC_LIBVIRT] = "lxc-libvirt",
 623         [VIRTUALIZATION_LXC] = "lxc",
 624         [VIRTUALIZATION_OPENVZ] = "openvz",
 625         [VIRTUALIZATION_DOCKER] = "docker",
 626         [VIRTUALIZATION_RKT] = "rkt",
 627         [VIRTUALIZATION_CONTAINER_OTHER] = "container-other",
 628 };
 629
 630 DEFINE_STRING_TABLE_LOOKUP(virtualization, int);