migration/vmstate.c

   1 /*
   2  * VMState interpreter
   3  *
   4  * Copyright (c) 2009-2017 Red Hat Inc
   5  *
   6  * Authors:
   7  *  Juan Quintela <quintela@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  */
  12
  13 #include "qemu/osdep.h"
  14 #include "migration.h"
  15 #include "migration/vmstate.h"
  16 #include "savevm.h"
  17 #include "qapi/error.h"
  18 #include "qapi/qmp/json-writer.h"
  19 #include "qemu-file.h"
  20 #include "qemu/bitops.h"
  21 #include "qemu/error-report.h"
  22 #include "trace.h"
  23
  24 static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
  25                                    void *opaque, JSONWriter *vmdesc);
  26 static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
  27                                    void *opaque);
  28
  29 /* Whether this field should exist for either save or load the VM? */
  30 static bool
  31 vmstate_field_exists(const VMStateDescription *vmsd, const VMStateField *field,
  32                      void *opaque, int version_id)
  33 {
  34     bool result;
  35
  36     if (field->field_exists) {
  37         /* If there's the function checker, that's the solo truth */
  38         result = field->field_exists(opaque, version_id);
  39         trace_vmstate_field_exists(vmsd->name, field->name, field->version_id,
  40                                    version_id, result);
  41     } else {
  42         /*
  43          * Otherwise, we only save/load if field version is same or older.
  44          * For example, when loading from an old binary with old version,
  45          * we ignore new fields with newer version_ids.
  46          */
  47         result = field->version_id <= version_id;
  48     }
  49
  50     return result;
  51 }
  52
  53 static int vmstate_n_elems(void *opaque, const VMStateField *field)
  54 {
  55     int n_elems = 1;
  56
  57     if (field->flags & VMS_ARRAY) {
  58         n_elems = field->num;
  59     } else if (field->flags & VMS_VARRAY_INT32) {
  60         n_elems = *(int32_t *)(opaque + field->num_offset);
  61     } else if (field->flags & VMS_VARRAY_UINT32) {
  62         n_elems = *(uint32_t *)(opaque + field->num_offset);
  63     } else if (field->flags & VMS_VARRAY_UINT16) {
  64         n_elems = *(uint16_t *)(opaque + field->num_offset);
  65     } else if (field->flags & VMS_VARRAY_UINT8) {
  66         n_elems = *(uint8_t *)(opaque + field->num_offset);
  67     }
  68
  69     if (field->flags & VMS_MULTIPLY_ELEMENTS) {
  70         n_elems *= field->num;
  71     }
  72
  73     trace_vmstate_n_elems(field->name, n_elems);
  74     return n_elems;
  75 }
  76
  77 static int vmstate_size(void *opaque, const VMStateField *field)
  78 {
  79     int size = field->size;
  80
  81     if (field->flags & VMS_VBUFFER) {
  82         size = *(int32_t *)(opaque + field->size_offset);
  83         if (field->flags & VMS_MULTIPLY) {
  84             size *= field->size;
  85         }
  86     }
  87
  88     return size;
  89 }
  90
  91 static void vmstate_handle_alloc(void *ptr, const VMStateField *field,
  92                                  void *opaque)
  93 {
  94     if (field->flags & VMS_POINTER && field->flags & VMS_ALLOC) {
  95         gsize size = vmstate_size(opaque, field);
  96         size *= vmstate_n_elems(opaque, field);
  97         if (size) {
  98             *(void **)ptr = g_malloc(size);
  99         }
 100     }
 101 }
 102
 103 int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
 104                        void *opaque, int version_id)
 105 {
 106     const VMStateField *field = vmsd->fields;
 107     int ret = 0;
 108
 109     trace_vmstate_load_state(vmsd->name, version_id);
 110     if (version_id > vmsd->version_id) {
 111         error_report("%s: incoming version_id %d is too new "
 112                      "for local version_id %d",
 113                      vmsd->name, version_id, vmsd->version_id);
 114         trace_vmstate_load_state_end(vmsd->name, "too new", -EINVAL);
 115         return -EINVAL;
 116     }
 117     if  (version_id < vmsd->minimum_version_id) {
 118         error_report("%s: incoming version_id %d is too old "
 119                      "for local minimum version_id  %d",
 120                      vmsd->name, version_id, vmsd->minimum_version_id);
 121         trace_vmstate_load_state_end(vmsd->name, "too old", -EINVAL);
 122         return -EINVAL;
 123     }
 124     if (vmsd->pre_load) {
 125         ret = vmsd->pre_load(opaque);
 126         if (ret) {
 127             return ret;
 128         }
 129     }
 130     while (field->name) {
 131         trace_vmstate_load_state_field(vmsd->name, field->name);
 132         if (vmstate_field_exists(vmsd, field, opaque, version_id)) {
 133             void *first_elem = opaque + field->offset;
 134             int i, n_elems = vmstate_n_elems(opaque, field);
 135             int size = vmstate_size(opaque, field);
 136
 137             vmstate_handle_alloc(first_elem, field, opaque);
 138             if (field->flags & VMS_POINTER) {
 139                 first_elem = *(void **)first_elem;
 140                 assert(first_elem || !n_elems || !size);
 141             }
 142             for (i = 0; i < n_elems; i++) {
 143                 void *curr_elem = first_elem + size * i;
 144
 145                 if (field->flags & VMS_ARRAY_OF_POINTER) {
 146                     curr_elem = *(void **)curr_elem;
 147                 }
 148                 if (!curr_elem && size) {
 149                     /* if null pointer check placeholder and do not follow */
 150                     assert(field->flags & VMS_ARRAY_OF_POINTER);
 151                     ret = vmstate_info_nullptr.get(f, curr_elem, size, NULL);
 152                 } else if (field->flags & VMS_STRUCT) {
 153                     ret = vmstate_load_state(f, field->vmsd, curr_elem,
 154                                              field->vmsd->version_id);
 155                 } else if (field->flags & VMS_VSTRUCT) {
 156                     ret = vmstate_load_state(f, field->vmsd, curr_elem,
 157                                              field->struct_version_id);
 158                 } else {
 159                     ret = field->info->get(f, curr_elem, size, field);
 160                 }
 161                 if (ret >= 0) {
 162                     ret = qemu_file_get_error(f);
 163                 }
 164                 if (ret < 0) {
 165                     qemu_file_set_error(f, ret);
 166                     error_report("Failed to load %s:%s", vmsd->name,
 167                                  field->name);
 168                     trace_vmstate_load_field_error(field->name, ret);
 169                     return ret;
 170                 }
 171             }
 172         } else if (field->flags & VMS_MUST_EXIST) {
 173             error_report("Input validation failed: %s/%s",
 174                          vmsd->name, field->name);
 175             return -1;
 176         }
 177         field++;
 178     }
 179     assert(field->flags == VMS_END);
 180     ret = vmstate_subsection_load(f, vmsd, opaque);
 181     if (ret != 0) {
 182         return ret;
 183     }
 184     if (vmsd->post_load) {
 185         ret = vmsd->post_load(opaque, version_id);
 186     }
 187     trace_vmstate_load_state_end(vmsd->name, "end", ret);
 188     return ret;
 189 }
 190
 191 static int vmfield_name_num(const VMStateField *start,
 192                             const VMStateField *search)
 193 {
 194     const VMStateField *field;
 195     int found = 0;
 196
 197     for (field = start; field->name; field++) {
 198         if (!strcmp(field->name, search->name)) {
 199             if (field == search) {
 200                 return found;
 201             }
 202             found++;
 203         }
 204     }
 205
 206     return -1;
 207 }
 208
 209 static bool vmfield_name_is_unique(const VMStateField *start,
 210                                    const VMStateField *search)
 211 {
 212     const VMStateField *field;
 213     int found = 0;
 214
 215     for (field = start; field->name; field++) {
 216         if (!strcmp(field->name, search->name)) {
 217             found++;
 218             /* name found more than once, so it's not unique */
 219             if (found > 1) {
 220                 return false;
 221             }
 222         }
 223     }
 224
 225     return true;
 226 }
 227
 228 static const char *vmfield_get_type_name(const VMStateField *field)
 229 {
 230     const char *type = "unknown";
 231
 232     if (field->flags & VMS_STRUCT) {
 233         type = "struct";
 234     } else if (field->flags & VMS_VSTRUCT) {
 235         type = "vstruct";
 236     } else if (field->info->name) {
 237         type = field->info->name;
 238     }
 239
 240     return type;
 241 }
 242
 243 static bool vmsd_can_compress(const VMStateField *field)
 244 {
 245     if (field->field_exists) {
 246         /* Dynamically existing fields mess up compression */
 247         return false;
 248     }
 249
 250     if (field->flags & VMS_STRUCT) {
 251         const VMStateField *sfield = field->vmsd->fields;
 252         while (sfield->name) {
 253             if (!vmsd_can_compress(sfield)) {
 254                 /* Child elements can't compress, so can't we */
 255                 return false;
 256             }
 257             sfield++;
 258         }
 259
 260         if (field->vmsd->subsections) {
 261             /* Subsections may come and go, better don't compress */
 262             return false;
 263         }
 264     }
 265
 266     return true;
 267 }
 268
 269 static void vmsd_desc_field_start(const VMStateDescription *vmsd,
 270                                   JSONWriter *vmdesc,
 271                                   const VMStateField *field, int i, int max)
 272 {
 273     char *name, *old_name;
 274     bool is_array = max > 1;
 275     bool can_compress = vmsd_can_compress(field);
 276
 277     if (!vmdesc) {
 278         return;
 279     }
 280
 281     name = g_strdup(field->name);
 282
 283     /* Field name is not unique, need to make it unique */
 284     if (!vmfield_name_is_unique(vmsd->fields, field)) {
 285         int num = vmfield_name_num(vmsd->fields, field);
 286         old_name = name;
 287         name = g_strdup_printf("%s[%d]", name, num);
 288         g_free(old_name);
 289     }
 290
 291     json_writer_start_object(vmdesc, NULL);
 292     json_writer_str(vmdesc, "name", name);
 293     if (is_array) {
 294         if (can_compress) {
 295             json_writer_int64(vmdesc, "array_len", max);
 296         } else {
 297             json_writer_int64(vmdesc, "index", i);
 298         }
 299     }
 300     json_writer_str(vmdesc, "type", vmfield_get_type_name(field));
 301
 302     if (field->flags & VMS_STRUCT) {
 303         json_writer_start_object(vmdesc, "struct");
 304     }
 305
 306     g_free(name);
 307 }
 308
 309 static void vmsd_desc_field_end(const VMStateDescription *vmsd,
 310                                 JSONWriter *vmdesc,
 311                                 const VMStateField *field, size_t size, int i)
 312 {
 313     if (!vmdesc) {
 314         return;
 315     }
 316
 317     if (field->flags & VMS_STRUCT) {
 318         /* We printed a struct in between, close its child object */
 319         json_writer_end_object(vmdesc);
 320     }
 321
 322     json_writer_int64(vmdesc, "size", size);
 323     json_writer_end_object(vmdesc);
 324 }
 325
 326
 327 bool vmstate_save_needed(const VMStateDescription *vmsd, void *opaque)
 328 {
 329     if (vmsd->needed && !vmsd->needed(opaque)) {
 330         /* optional section not needed */
 331         return false;
 332     }
 333     return true;
 334 }
 335
 336
 337 int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
 338                        void *opaque, JSONWriter *vmdesc_id)
 339 {
 340     return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, NULL);
 341 }
 342
 343 int vmstate_save_state_with_err(QEMUFile *f, const VMStateDescription *vmsd,
 344                        void *opaque, JSONWriter *vmdesc_id, Error **errp)
 345 {
 346     return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, errp);
 347 }
 348
 349 int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
 350                          void *opaque, JSONWriter *vmdesc, int version_id, Error **errp)
 351 {
 352     int ret = 0;
 353     const VMStateField *field = vmsd->fields;
 354
 355     trace_vmstate_save_state_top(vmsd->name);
 356
 357     if (vmsd->pre_save) {
 358         ret = vmsd->pre_save(opaque);
 359         trace_vmstate_save_state_pre_save_res(vmsd->name, ret);
 360         if (ret) {
 361             error_setg(errp, "pre-save failed: %s", vmsd->name);
 362             return ret;
 363         }
 364     }
 365
 366     if (vmdesc) {
 367         json_writer_str(vmdesc, "vmsd_name", vmsd->name);
 368         json_writer_int64(vmdesc, "version", version_id);
 369         json_writer_start_array(vmdesc, "fields");
 370     }
 371
 372     while (field->name) {
 373         if (vmstate_field_exists(vmsd, field, opaque, version_id)) {
 374             void *first_elem = opaque + field->offset;
 375             int i, n_elems = vmstate_n_elems(opaque, field);
 376             int size = vmstate_size(opaque, field);
 377             uint64_t old_offset, written_bytes;
 378             JSONWriter *vmdesc_loop = vmdesc;
 379
 380             trace_vmstate_save_state_loop(vmsd->name, field->name, n_elems);
 381             if (field->flags & VMS_POINTER) {
 382                 first_elem = *(void **)first_elem;
 383                 assert(first_elem || !n_elems || !size);
 384             }
 385             for (i = 0; i < n_elems; i++) {
 386                 void *curr_elem = first_elem + size * i;
 387
 388                 vmsd_desc_field_start(vmsd, vmdesc_loop, field, i, n_elems);
 389                 old_offset = qemu_file_transferred_noflush(f);
 390                 if (field->flags & VMS_ARRAY_OF_POINTER) {
 391                     assert(curr_elem);
 392                     curr_elem = *(void **)curr_elem;
 393                 }
 394                 if (!curr_elem && size) {
 395                     /* if null pointer write placeholder and do not follow */
 396                     assert(field->flags & VMS_ARRAY_OF_POINTER);
 397                     ret = vmstate_info_nullptr.put(f, curr_elem, size, NULL,
 398                                                    NULL);
 399                 } else if (field->flags & VMS_STRUCT) {
 400                     ret = vmstate_save_state(f, field->vmsd, curr_elem,
 401                                              vmdesc_loop);
 402                 } else if (field->flags & VMS_VSTRUCT) {
 403                     ret = vmstate_save_state_v(f, field->vmsd, curr_elem,
 404                                                vmdesc_loop,
 405                                                field->struct_version_id, errp);
 406                 } else {
 407                     ret = field->info->put(f, curr_elem, size, field,
 408                                      vmdesc_loop);
 409                 }
 410                 if (ret) {
 411                     error_setg(errp, "Save of field %s/%s failed",
 412                                 vmsd->name, field->name);
 413                     if (vmsd->post_save) {
 414                         vmsd->post_save(opaque);
 415                     }
 416                     return ret;
 417                 }
 418
 419                 written_bytes = qemu_file_transferred_noflush(f) - old_offset;
 420                 vmsd_desc_field_end(vmsd, vmdesc_loop, field, written_bytes, i);
 421
 422                 /* Compressed arrays only care about the first element */
 423                 if (vmdesc_loop && vmsd_can_compress(field)) {
 424                     vmdesc_loop = NULL;
 425                 }
 426             }
 427         } else {
 428             if (field->flags & VMS_MUST_EXIST) {
 429                 error_report("Output state validation failed: %s/%s",
 430                         vmsd->name, field->name);
 431                 assert(!(field->flags & VMS_MUST_EXIST));
 432             }
 433         }
 434         field++;
 435     }
 436     assert(field->flags == VMS_END);
 437
 438     if (vmdesc) {
 439         json_writer_end_array(vmdesc);
 440     }
 441
 442     ret = vmstate_subsection_save(f, vmsd, opaque, vmdesc);
 443
 444     if (vmsd->post_save) {
 445         int ps_ret = vmsd->post_save(opaque);
 446         if (!ret) {
 447             ret = ps_ret;
 448         }
 449     }
 450     return ret;
 451 }
 452
 453 static const VMStateDescription *
 454 vmstate_get_subsection(const VMStateDescription **sub, char *idstr)
 455 {
 456     while (sub && *sub) {
 457         if (strcmp(idstr, (*sub)->name) == 0) {
 458             return *sub;
 459         }
 460         sub++;
 461     }
 462     return NULL;
 463 }
 464
 465 static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
 466                                    void *opaque)
 467 {
 468     trace_vmstate_subsection_load(vmsd->name);
 469
 470     while (qemu_peek_byte(f, 0) == QEMU_VM_SUBSECTION) {
 471         char idstr[256], *idstr_ret;
 472         int ret;
 473         uint8_t version_id, len, size;
 474         const VMStateDescription *sub_vmsd;
 475
 476         len = qemu_peek_byte(f, 1);
 477         if (len < strlen(vmsd->name) + 1) {
 478             /* subsection name has be be "section_name/a" */
 479             trace_vmstate_subsection_load_bad(vmsd->name, "(short)", "");
 480             return 0;
 481         }
 482         size = qemu_peek_buffer(f, (uint8_t **)&idstr_ret, len, 2);
 483         if (size != len) {
 484             trace_vmstate_subsection_load_bad(vmsd->name, "(peek fail)", "");
 485             return 0;
 486         }
 487         memcpy(idstr, idstr_ret, size);
 488         idstr[size] = 0;
 489
 490         if (strncmp(vmsd->name, idstr, strlen(vmsd->name)) != 0) {
 491             trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(prefix)");
 492             /* it doesn't have a valid subsection name */
 493             return 0;
 494         }
 495         sub_vmsd = vmstate_get_subsection(vmsd->subsections, idstr);
 496         if (sub_vmsd == NULL) {
 497             trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(lookup)");
 498             return -ENOENT;
 499         }
 500         qemu_file_skip(f, 1); /* subsection */
 501         qemu_file_skip(f, 1); /* len */
 502         qemu_file_skip(f, len); /* idstr */
 503         version_id = qemu_get_be32(f);
 504
 505         ret = vmstate_load_state(f, sub_vmsd, opaque, version_id);
 506         if (ret) {
 507             trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(child)");
 508             return ret;
 509         }
 510     }
 511
 512     trace_vmstate_subsection_load_good(vmsd->name);
 513     return 0;
 514 }
 515
 516 static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
 517                                    void *opaque, JSONWriter *vmdesc)
 518 {
 519     const VMStateDescription **sub = vmsd->subsections;
 520     bool vmdesc_has_subsections = false;
 521     int ret = 0;
 522
 523     trace_vmstate_subsection_save_top(vmsd->name);
 524     while (sub && *sub) {
 525         if (vmstate_save_needed(*sub, opaque)) {
 526             const VMStateDescription *vmsdsub = *sub;
 527             uint8_t len;
 528
 529             trace_vmstate_subsection_save_loop(vmsd->name, vmsdsub->name);
 530             if (vmdesc) {
 531                 /* Only create subsection array when we have any */
 532                 if (!vmdesc_has_subsections) {
 533                     json_writer_start_array(vmdesc, "subsections");
 534                     vmdesc_has_subsections = true;
 535                 }
 536
 537                 json_writer_start_object(vmdesc, NULL);
 538             }
 539
 540             qemu_put_byte(f, QEMU_VM_SUBSECTION);
 541             len = strlen(vmsdsub->name);
 542             qemu_put_byte(f, len);
 543             qemu_put_buffer(f, (uint8_t *)vmsdsub->name, len);
 544             qemu_put_be32(f, vmsdsub->version_id);
 545             ret = vmstate_save_state(f, vmsdsub, opaque, vmdesc);
 546             if (ret) {
 547                 return ret;
 548             }
 549
 550             if (vmdesc) {
 551                 json_writer_end_object(vmdesc);
 552             }
 553         }
 554         sub++;
 555     }
 556
 557     if (vmdesc_has_subsections) {
 558         json_writer_end_array(vmdesc);
 559     }
 560
 561     return ret;
 562 }