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 "qemu-common.h"
  15 #include "migration.h"
  16 #include "migration/vmstate.h"
  17 #include "savevm.h"
  18 #include "qemu-file.h"
  19 #include "qemu/bitops.h"
  20 #include "qemu/error-report.h"
  21 #include "trace.h"
  22 #include "qjson.h"
  23
  24 static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
  25                                    void *opaque, QJSON *vmdesc);
  26 static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
  27                                    void *opaque);
  28
  29 static int vmstate_n_elems(void *opaque, VMStateField *field)
  30 {
  31     int n_elems = 1;
  32
  33     if (field->flags & VMS_ARRAY) {
  34         n_elems = field->num;
  35     } else if (field->flags & VMS_VARRAY_INT32) {
  36         n_elems = *(int32_t *)(opaque+field->num_offset);
  37     } else if (field->flags & VMS_VARRAY_UINT32) {
  38         n_elems = *(uint32_t *)(opaque+field->num_offset);
  39     } else if (field->flags & VMS_VARRAY_UINT16) {
  40         n_elems = *(uint16_t *)(opaque+field->num_offset);
  41     } else if (field->flags & VMS_VARRAY_UINT8) {
  42         n_elems = *(uint8_t *)(opaque+field->num_offset);
  43     }
  44
  45     if (field->flags & VMS_MULTIPLY_ELEMENTS) {
  46         n_elems *= field->num;
  47     }
  48
  49     trace_vmstate_n_elems(field->name, n_elems);
  50     return n_elems;
  51 }
  52
  53 static int vmstate_size(void *opaque, VMStateField *field)
  54 {
  55     int size = field->size;
  56
  57     if (field->flags & VMS_VBUFFER) {
  58         size = *(int32_t *)(opaque+field->size_offset);
  59         if (field->flags & VMS_MULTIPLY) {
  60             size *= field->size;
  61         }
  62     }
  63
  64     return size;
  65 }
  66
  67 static void vmstate_handle_alloc(void *ptr, VMStateField *field, void *opaque)
  68 {
  69     if (field->flags & VMS_POINTER && field->flags & VMS_ALLOC) {
  70         gsize size = vmstate_size(opaque, field);
  71         size *= vmstate_n_elems(opaque, field);
  72         if (size) {
  73             *(void **)ptr = g_malloc(size);
  74         }
  75     }
  76 }
  77
  78 int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
  79                        void *opaque, int version_id)
  80 {
  81     VMStateField *field = vmsd->fields;
  82     int ret = 0;
  83
  84     trace_vmstate_load_state(vmsd->name, version_id);
  85     if (version_id > vmsd->version_id) {
  86         error_report("%s: incoming version_id %d is too new "
  87                      "for local version_id %d",
  88                      vmsd->name, version_id, vmsd->version_id);
  89         trace_vmstate_load_state_end(vmsd->name, "too new", -EINVAL);
  90         return -EINVAL;
  91     }
  92     if  (version_id < vmsd->minimum_version_id) {
  93         if (vmsd->load_state_old &&
  94             version_id >= vmsd->minimum_version_id_old) {
  95             ret = vmsd->load_state_old(f, opaque, version_id);
  96             trace_vmstate_load_state_end(vmsd->name, "old path", ret);
  97             return ret;
  98         }
  99         error_report("%s: incoming version_id %d is too old "
 100                      "for local minimum version_id  %d",
 101                      vmsd->name, version_id, vmsd->minimum_version_id);
 102         trace_vmstate_load_state_end(vmsd->name, "too old", -EINVAL);
 103         return -EINVAL;
 104     }
 105     if (vmsd->pre_load) {
 106         int ret = vmsd->pre_load(opaque);
 107         if (ret) {
 108             return ret;
 109         }
 110     }
 111     while (field->name) {
 112         trace_vmstate_load_state_field(vmsd->name, field->name);
 113         if ((field->field_exists &&
 114              field->field_exists(opaque, version_id)) ||
 115             (!field->field_exists &&
 116              field->version_id <= version_id)) {
 117             void *first_elem = opaque + field->offset;
 118             int i, n_elems = vmstate_n_elems(opaque, field);
 119             int size = vmstate_size(opaque, field);
 120
 121             vmstate_handle_alloc(first_elem, field, opaque);
 122             if (field->flags & VMS_POINTER) {
 123                 first_elem = *(void **)first_elem;
 124                 assert(first_elem || !n_elems || !size);
 125             }
 126             for (i = 0; i < n_elems; i++) {
 127                 void *curr_elem = first_elem + size * i;
 128
 129                 if (field->flags & VMS_ARRAY_OF_POINTER) {
 130                     curr_elem = *(void **)curr_elem;
 131                 }
 132                 if (!curr_elem && size) {
 133                     /* if null pointer check placeholder and do not follow */
 134                     assert(field->flags & VMS_ARRAY_OF_POINTER);
 135                     ret = vmstate_info_nullptr.get(f, curr_elem, size, NULL);
 136                 } else if (field->flags & VMS_STRUCT) {
 137                     ret = vmstate_load_state(f, field->vmsd, curr_elem,
 138                                              field->vmsd->version_id);
 139                 } else if (field->flags & VMS_VSTRUCT) {
 140                     ret = vmstate_load_state(f, field->vmsd, curr_elem,
 141                                              field->struct_version_id);
 142                 } else {
 143                     ret = field->info->get(f, curr_elem, size, field);
 144                 }
 145                 if (ret >= 0) {
 146                     ret = qemu_file_get_error(f);
 147                 }
 148                 if (ret < 0) {
 149                     qemu_file_set_error(f, ret);
 150                     error_report("Failed to load %s:%s", vmsd->name,
 151                                  field->name);
 152                     trace_vmstate_load_field_error(field->name, ret);
 153                     return ret;
 154                 }
 155             }
 156         } else if (field->flags & VMS_MUST_EXIST) {
 157             error_report("Input validation failed: %s/%s",
 158                          vmsd->name, field->name);
 159             return -1;
 160         }
 161         field++;
 162     }
 163     ret = vmstate_subsection_load(f, vmsd, opaque);
 164     if (ret != 0) {
 165         return ret;
 166     }
 167     if (vmsd->post_load) {
 168         ret = vmsd->post_load(opaque, version_id);
 169     }
 170     trace_vmstate_load_state_end(vmsd->name, "end", ret);
 171     return ret;
 172 }
 173
 174 static int vmfield_name_num(VMStateField *start, VMStateField *search)
 175 {
 176     VMStateField *field;
 177     int found = 0;
 178
 179     for (field = start; field->name; field++) {
 180         if (!strcmp(field->name, search->name)) {
 181             if (field == search) {
 182                 return found;
 183             }
 184             found++;
 185         }
 186     }
 187
 188     return -1;
 189 }
 190
 191 static bool vmfield_name_is_unique(VMStateField *start, VMStateField *search)
 192 {
 193     VMStateField *field;
 194     int found = 0;
 195
 196     for (field = start; field->name; field++) {
 197         if (!strcmp(field->name, search->name)) {
 198             found++;
 199             /* name found more than once, so it's not unique */
 200             if (found > 1) {
 201                 return false;
 202             }
 203         }
 204     }
 205
 206     return true;
 207 }
 208
 209 static const char *vmfield_get_type_name(VMStateField *field)
 210 {
 211     const char *type = "unknown";
 212
 213     if (field->flags & VMS_STRUCT) {
 214         type = "struct";
 215     } else if (field->flags & VMS_VSTRUCT) {
 216         type = "vstruct";
 217     } else if (field->info->name) {
 218         type = field->info->name;
 219     }
 220
 221     return type;
 222 }
 223
 224 static bool vmsd_can_compress(VMStateField *field)
 225 {
 226     if (field->field_exists) {
 227         /* Dynamically existing fields mess up compression */
 228         return false;
 229     }
 230
 231     if (field->flags & VMS_STRUCT) {
 232         VMStateField *sfield = field->vmsd->fields;
 233         while (sfield->name) {
 234             if (!vmsd_can_compress(sfield)) {
 235                 /* Child elements can't compress, so can't we */
 236                 return false;
 237             }
 238             sfield++;
 239         }
 240
 241         if (field->vmsd->subsections) {
 242             /* Subsections may come and go, better don't compress */
 243             return false;
 244         }
 245     }
 246
 247     return true;
 248 }
 249
 250 static void vmsd_desc_field_start(const VMStateDescription *vmsd, QJSON *vmdesc,
 251                                   VMStateField *field, int i, int max)
 252 {
 253     char *name, *old_name;
 254     bool is_array = max > 1;
 255     bool can_compress = vmsd_can_compress(field);
 256
 257     if (!vmdesc) {
 258         return;
 259     }
 260
 261     name = g_strdup(field->name);
 262
 263     /* Field name is not unique, need to make it unique */
 264     if (!vmfield_name_is_unique(vmsd->fields, field)) {
 265         int num = vmfield_name_num(vmsd->fields, field);
 266         old_name = name;
 267         name = g_strdup_printf("%s[%d]", name, num);
 268         g_free(old_name);
 269     }
 270
 271     json_start_object(vmdesc, NULL);
 272     json_prop_str(vmdesc, "name", name);
 273     if (is_array) {
 274         if (can_compress) {
 275             json_prop_int(vmdesc, "array_len", max);
 276         } else {
 277             json_prop_int(vmdesc, "index", i);
 278         }
 279     }
 280     json_prop_str(vmdesc, "type", vmfield_get_type_name(field));
 281
 282     if (field->flags & VMS_STRUCT) {
 283         json_start_object(vmdesc, "struct");
 284     }
 285
 286     g_free(name);
 287 }
 288
 289 static void vmsd_desc_field_end(const VMStateDescription *vmsd, QJSON *vmdesc,
 290                                 VMStateField *field, size_t size, int i)
 291 {
 292     if (!vmdesc) {
 293         return;
 294     }
 295
 296     if (field->flags & VMS_STRUCT) {
 297         /* We printed a struct in between, close its child object */
 298         json_end_object(vmdesc);
 299     }
 300
 301     json_prop_int(vmdesc, "size", size);
 302     json_end_object(vmdesc);
 303 }
 304
 305
 306 bool vmstate_save_needed(const VMStateDescription *vmsd, void *opaque)
 307 {
 308     if (vmsd->needed && !vmsd->needed(opaque)) {
 309         /* optional section not needed */
 310         return false;
 311     }
 312     return true;
 313 }
 314
 315
 316 int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
 317                        void *opaque, QJSON *vmdesc_id)
 318 {
 319     return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id);
 320 }
 321
 322 int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
 323                          void *opaque, QJSON *vmdesc, int version_id)
 324 {
 325     int ret = 0;
 326     VMStateField *field = vmsd->fields;
 327
 328     trace_vmstate_save_state_top(vmsd->name);
 329
 330     if (vmsd->pre_save) {
 331         ret = vmsd->pre_save(opaque);
 332         trace_vmstate_save_state_pre_save_res(vmsd->name, ret);
 333         if (ret) {
 334             error_report("pre-save failed: %s", vmsd->name);
 335             return ret;
 336         }
 337     }
 338
 339     if (vmdesc) {
 340         json_prop_str(vmdesc, "vmsd_name", vmsd->name);
 341         json_prop_int(vmdesc, "version", version_id);
 342         json_start_array(vmdesc, "fields");
 343     }
 344
 345     while (field->name) {
 346         if ((field->field_exists &&
 347              field->field_exists(opaque, version_id)) ||
 348             (!field->field_exists &&
 349              field->version_id <= version_id)) {
 350             void *first_elem = opaque + field->offset;
 351             int i, n_elems = vmstate_n_elems(opaque, field);
 352             int size = vmstate_size(opaque, field);
 353             int64_t old_offset, written_bytes;
 354             QJSON *vmdesc_loop = vmdesc;
 355
 356             trace_vmstate_save_state_loop(vmsd->name, field->name, n_elems);
 357             if (field->flags & VMS_POINTER) {
 358                 first_elem = *(void **)first_elem;
 359                 assert(first_elem || !n_elems || !size);
 360             }
 361             for (i = 0; i < n_elems; i++) {
 362                 void *curr_elem = first_elem + size * i;
 363                 ret = 0;
 364
 365                 vmsd_desc_field_start(vmsd, vmdesc_loop, field, i, n_elems);
 366                 old_offset = qemu_ftell_fast(f);
 367                 if (field->flags & VMS_ARRAY_OF_POINTER) {
 368                     assert(curr_elem);
 369                     curr_elem = *(void **)curr_elem;
 370                 }
 371                 if (!curr_elem && size) {
 372                     /* if null pointer write placeholder and do not follow */
 373                     assert(field->flags & VMS_ARRAY_OF_POINTER);
 374                     ret = vmstate_info_nullptr.put(f, curr_elem, size, NULL,
 375                                                    NULL);
 376                 } else if (field->flags & VMS_STRUCT) {
 377                     ret = vmstate_save_state(f, field->vmsd, curr_elem,
 378                                              vmdesc_loop);
 379                 } else if (field->flags & VMS_VSTRUCT) {
 380                     ret = vmstate_save_state_v(f, field->vmsd, curr_elem,
 381                                                vmdesc_loop,
 382                                                field->struct_version_id);
 383                 } else {
 384                     ret = field->info->put(f, curr_elem, size, field,
 385                                      vmdesc_loop);
 386                 }
 387                 if (ret) {
 388                     error_report("Save of field %s/%s failed",
 389                                  vmsd->name, field->name);
 390                     return ret;
 391                 }
 392
 393                 written_bytes = qemu_ftell_fast(f) - old_offset;
 394                 vmsd_desc_field_end(vmsd, vmdesc_loop, field, written_bytes, i);
 395
 396                 /* Compressed arrays only care about the first element */
 397                 if (vmdesc_loop && vmsd_can_compress(field)) {
 398                     vmdesc_loop = NULL;
 399                 }
 400             }
 401         } else {
 402             if (field->flags & VMS_MUST_EXIST) {
 403                 error_report("Output state validation failed: %s/%s",
 404                         vmsd->name, field->name);
 405                 assert(!(field->flags & VMS_MUST_EXIST));
 406             }
 407         }
 408         field++;
 409     }
 410
 411     if (vmdesc) {
 412         json_end_array(vmdesc);
 413     }
 414
 415     return vmstate_subsection_save(f, vmsd, opaque, vmdesc);
 416 }
 417
 418 static const VMStateDescription *
 419 vmstate_get_subsection(const VMStateDescription **sub, char *idstr)
 420 {
 421     while (sub && *sub && (*sub)->needed) {
 422         if (strcmp(idstr, (*sub)->name) == 0) {
 423             return *sub;
 424         }
 425         sub++;
 426     }
 427     return NULL;
 428 }
 429
 430 static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
 431                                    void *opaque)
 432 {
 433     trace_vmstate_subsection_load(vmsd->name);
 434
 435     while (qemu_peek_byte(f, 0) == QEMU_VM_SUBSECTION) {
 436         char idstr[256], *idstr_ret;
 437         int ret;
 438         uint8_t version_id, len, size;
 439         const VMStateDescription *sub_vmsd;
 440
 441         len = qemu_peek_byte(f, 1);
 442         if (len < strlen(vmsd->name) + 1) {
 443             /* subsection name has be be "section_name/a" */
 444             trace_vmstate_subsection_load_bad(vmsd->name, "(short)", "");
 445             return 0;
 446         }
 447         size = qemu_peek_buffer(f, (uint8_t **)&idstr_ret, len, 2);
 448         if (size != len) {
 449             trace_vmstate_subsection_load_bad(vmsd->name, "(peek fail)", "");
 450             return 0;
 451         }
 452         memcpy(idstr, idstr_ret, size);
 453         idstr[size] = 0;
 454
 455         if (strncmp(vmsd->name, idstr, strlen(vmsd->name)) != 0) {
 456             trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(prefix)");
 457             /* it doesn't have a valid subsection name */
 458             return 0;
 459         }
 460         sub_vmsd = vmstate_get_subsection(vmsd->subsections, idstr);
 461         if (sub_vmsd == NULL) {
 462             trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(lookup)");
 463             return -ENOENT;
 464         }
 465         qemu_file_skip(f, 1); /* subsection */
 466         qemu_file_skip(f, 1); /* len */
 467         qemu_file_skip(f, len); /* idstr */
 468         version_id = qemu_get_be32(f);
 469
 470         ret = vmstate_load_state(f, sub_vmsd, opaque, version_id);
 471         if (ret) {
 472             trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(child)");
 473             return ret;
 474         }
 475     }
 476
 477     trace_vmstate_subsection_load_good(vmsd->name);
 478     return 0;
 479 }
 480
 481 static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
 482                                    void *opaque, QJSON *vmdesc)
 483 {
 484     const VMStateDescription **sub = vmsd->subsections;
 485     bool subsection_found = false;
 486     int ret = 0;
 487
 488     trace_vmstate_subsection_save_top(vmsd->name);
 489     while (sub && *sub && (*sub)->needed) {
 490         if ((*sub)->needed(opaque)) {
 491             const VMStateDescription *vmsdsub = *sub;
 492             uint8_t len;
 493
 494             trace_vmstate_subsection_save_loop(vmsd->name, vmsdsub->name);
 495             if (vmdesc) {
 496                 /* Only create subsection array when we have any */
 497                 if (!subsection_found) {
 498                     json_start_array(vmdesc, "subsections");
 499                     subsection_found = true;
 500                 }
 501
 502                 json_start_object(vmdesc, NULL);
 503             }
 504
 505             qemu_put_byte(f, QEMU_VM_SUBSECTION);
 506             len = strlen(vmsdsub->name);
 507             qemu_put_byte(f, len);
 508             qemu_put_buffer(f, (uint8_t *)vmsdsub->name, len);
 509             qemu_put_be32(f, vmsdsub->version_id);
 510             ret = vmstate_save_state(f, vmsdsub, opaque, vmdesc);
 511             if (ret) {
 512                 return ret;
 513             }
 514
 515             if (vmdesc) {
 516                 json_end_object(vmdesc);
 517             }
 518         }
 519         sub++;
 520     }
 521
 522     if (vmdesc && subsection_found) {
 523         json_end_array(vmdesc);
 524     }
 525
 526     return ret;
 527 }