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 "qemu-file.h"
  18 #include "qemu/bitops.h"
  19 #include "qemu/error-report.h"
  20 #include "trace.h"
  21 #include "qjson.h"
  22
  23 static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
  24                                    void *opaque, QJSON *vmdesc);
  25 static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
  26                                    void *opaque);
  27
  28 static int vmstate_n_elems(void *opaque, const VMStateField *field)
  29 {
  30     int n_elems = 1;
  31
  32     if (field->flags & VMS_ARRAY) {
  33         n_elems = field->num;
  34     } else if (field->flags & VMS_VARRAY_INT32) {
  35         n_elems = *(int32_t *)(opaque + field->num_offset);
  36     } else if (field->flags & VMS_VARRAY_UINT32) {
  37         n_elems = *(uint32_t *)(opaque + field->num_offset);
  38     } else if (field->flags & VMS_VARRAY_UINT16) {
  39         n_elems = *(uint16_t *)(opaque + field->num_offset);
  40     } else if (field->flags & VMS_VARRAY_UINT8) {
  41         n_elems = *(uint8_t *)(opaque + field->num_offset);
  42     }
  43
  44     if (field->flags & VMS_MULTIPLY_ELEMENTS) {
  45         n_elems *= field->num;
  46     }
  47
  48     trace_vmstate_n_elems(field->name, n_elems);
  49     return n_elems;
  50 }
  51
  52 static int vmstate_size(void *opaque, const VMStateField *field)
  53 {
  54     int size = field->size;
  55
  56     if (field->flags & VMS_VBUFFER) {
  57         size = *(int32_t *)(opaque + field->size_offset);
  58         if (field->flags & VMS_MULTIPLY) {
  59             size *= field->size;
  60         }
  61     }
  62
  63     return size;
  64 }
  65
  66 static void vmstate_handle_alloc(void *ptr, const VMStateField *field,
  67                                  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     const 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(const VMStateField *start,
 175                             const VMStateField *search)
 176 {
 177     const VMStateField *field;
 178     int found = 0;
 179
 180     for (field = start; field->name; field++) {
 181         if (!strcmp(field->name, search->name)) {
 182             if (field == search) {
 183                 return found;
 184             }
 185             found++;
 186         }
 187     }
 188
 189     return -1;
 190 }
 191
 192 static bool vmfield_name_is_unique(const VMStateField *start,
 193                                    const VMStateField *search)
 194 {
 195     const VMStateField *field;
 196     int found = 0;
 197
 198     for (field = start; field->name; field++) {
 199         if (!strcmp(field->name, search->name)) {
 200             found++;
 201             /* name found more than once, so it's not unique */
 202             if (found > 1) {
 203                 return false;
 204             }
 205         }
 206     }
 207
 208     return true;
 209 }
 210
 211 static const char *vmfield_get_type_name(const VMStateField *field)
 212 {
 213     const char *type = "unknown";
 214
 215     if (field->flags & VMS_STRUCT) {
 216         type = "struct";
 217     } else if (field->flags & VMS_VSTRUCT) {
 218         type = "vstruct";
 219     } else if (field->info->name) {
 220         type = field->info->name;
 221     }
 222
 223     return type;
 224 }
 225
 226 static bool vmsd_can_compress(const VMStateField *field)
 227 {
 228     if (field->field_exists) {
 229         /* Dynamically existing fields mess up compression */
 230         return false;
 231     }
 232
 233     if (field->flags & VMS_STRUCT) {
 234         const VMStateField *sfield = field->vmsd->fields;
 235         while (sfield->name) {
 236             if (!vmsd_can_compress(sfield)) {
 237                 /* Child elements can't compress, so can't we */
 238                 return false;
 239             }
 240             sfield++;
 241         }
 242
 243         if (field->vmsd->subsections) {
 244             /* Subsections may come and go, better don't compress */
 245             return false;
 246         }
 247     }
 248
 249     return true;
 250 }
 251
 252 static void vmsd_desc_field_start(const VMStateDescription *vmsd, QJSON *vmdesc,
 253                                   const VMStateField *field, int i, int max)
 254 {
 255     char *name, *old_name;
 256     bool is_array = max > 1;
 257     bool can_compress = vmsd_can_compress(field);
 258
 259     if (!vmdesc) {
 260         return;
 261     }
 262
 263     name = g_strdup(field->name);
 264
 265     /* Field name is not unique, need to make it unique */
 266     if (!vmfield_name_is_unique(vmsd->fields, field)) {
 267         int num = vmfield_name_num(vmsd->fields, field);
 268         old_name = name;
 269         name = g_strdup_printf("%s[%d]", name, num);
 270         g_free(old_name);
 271     }
 272
 273     json_start_object(vmdesc, NULL);
 274     json_prop_str(vmdesc, "name", name);
 275     if (is_array) {
 276         if (can_compress) {
 277             json_prop_int(vmdesc, "array_len", max);
 278         } else {
 279             json_prop_int(vmdesc, "index", i);
 280         }
 281     }
 282     json_prop_str(vmdesc, "type", vmfield_get_type_name(field));
 283
 284     if (field->flags & VMS_STRUCT) {
 285         json_start_object(vmdesc, "struct");
 286     }
 287
 288     g_free(name);
 289 }
 290
 291 static void vmsd_desc_field_end(const VMStateDescription *vmsd, QJSON *vmdesc,
 292                                 const VMStateField *field, size_t size, int i)
 293 {
 294     if (!vmdesc) {
 295         return;
 296     }
 297
 298     if (field->flags & VMS_STRUCT) {
 299         /* We printed a struct in between, close its child object */
 300         json_end_object(vmdesc);
 301     }
 302
 303     json_prop_int(vmdesc, "size", size);
 304     json_end_object(vmdesc);
 305 }
 306
 307
 308 bool vmstate_save_needed(const VMStateDescription *vmsd, void *opaque)
 309 {
 310     if (vmsd->needed && !vmsd->needed(opaque)) {
 311         /* optional section not needed */
 312         return false;
 313     }
 314     return true;
 315 }
 316
 317
 318 int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
 319                        void *opaque, QJSON *vmdesc_id)
 320 {
 321     return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id);
 322 }
 323
 324 int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
 325                          void *opaque, QJSON *vmdesc, int version_id)
 326 {
 327     int ret = 0;
 328     const VMStateField *field = vmsd->fields;
 329
 330     trace_vmstate_save_state_top(vmsd->name);
 331
 332     if (vmsd->pre_save) {
 333         ret = vmsd->pre_save(opaque);
 334         trace_vmstate_save_state_pre_save_res(vmsd->name, ret);
 335         if (ret) {
 336             error_report("pre-save failed: %s", vmsd->name);
 337             return ret;
 338         }
 339     }
 340
 341     if (vmdesc) {
 342         json_prop_str(vmdesc, "vmsd_name", vmsd->name);
 343         json_prop_int(vmdesc, "version", version_id);
 344         json_start_array(vmdesc, "fields");
 345     }
 346
 347     while (field->name) {
 348         if ((field->field_exists &&
 349              field->field_exists(opaque, version_id)) ||
 350             (!field->field_exists &&
 351              field->version_id <= version_id)) {
 352             void *first_elem = opaque + field->offset;
 353             int i, n_elems = vmstate_n_elems(opaque, field);
 354             int size = vmstate_size(opaque, field);
 355             int64_t old_offset, written_bytes;
 356             QJSON *vmdesc_loop = vmdesc;
 357
 358             trace_vmstate_save_state_loop(vmsd->name, field->name, n_elems);
 359             if (field->flags & VMS_POINTER) {
 360                 first_elem = *(void **)first_elem;
 361                 assert(first_elem || !n_elems || !size);
 362             }
 363             for (i = 0; i < n_elems; i++) {
 364                 void *curr_elem = first_elem + size * i;
 365
 366                 vmsd_desc_field_start(vmsd, vmdesc_loop, field, i, n_elems);
 367                 old_offset = qemu_ftell_fast(f);
 368                 if (field->flags & VMS_ARRAY_OF_POINTER) {
 369                     assert(curr_elem);
 370                     curr_elem = *(void **)curr_elem;
 371                 }
 372                 if (!curr_elem && size) {
 373                     /* if null pointer write placeholder and do not follow */
 374                     assert(field->flags & VMS_ARRAY_OF_POINTER);
 375                     ret = vmstate_info_nullptr.put(f, curr_elem, size, NULL,
 376                                                    NULL);
 377                 } else if (field->flags & VMS_STRUCT) {
 378                     ret = vmstate_save_state(f, field->vmsd, curr_elem,
 379                                              vmdesc_loop);
 380                 } else if (field->flags & VMS_VSTRUCT) {
 381                     ret = vmstate_save_state_v(f, field->vmsd, curr_elem,
 382                                                vmdesc_loop,
 383                                                field->struct_version_id);
 384                 } else {
 385                     ret = field->info->put(f, curr_elem, size, field,
 386                                      vmdesc_loop);
 387                 }
 388                 if (ret) {
 389                     error_report("Save of field %s/%s failed",
 390                                  vmsd->name, field->name);
 391                     if (vmsd->post_save) {
 392                         vmsd->post_save(opaque);
 393                     }
 394                     return ret;
 395                 }
 396
 397                 written_bytes = qemu_ftell_fast(f) - old_offset;
 398                 vmsd_desc_field_end(vmsd, vmdesc_loop, field, written_bytes, i);
 399
 400                 /* Compressed arrays only care about the first element */
 401                 if (vmdesc_loop && vmsd_can_compress(field)) {
 402                     vmdesc_loop = NULL;
 403                 }
 404             }
 405         } else {
 406             if (field->flags & VMS_MUST_EXIST) {
 407                 error_report("Output state validation failed: %s/%s",
 408                         vmsd->name, field->name);
 409                 assert(!(field->flags & VMS_MUST_EXIST));
 410             }
 411         }
 412         field++;
 413     }
 414
 415     if (vmdesc) {
 416         json_end_array(vmdesc);
 417     }
 418
 419     ret = vmstate_subsection_save(f, vmsd, opaque, vmdesc);
 420
 421     if (vmsd->post_save) {
 422         int ps_ret = vmsd->post_save(opaque);
 423         if (!ret) {
 424             ret = ps_ret;
 425         }
 426     }
 427     return ret;
 428 }
 429
 430 static const VMStateDescription *
 431 vmstate_get_subsection(const VMStateDescription **sub, char *idstr)
 432 {
 433     while (sub && *sub) {
 434         if (strcmp(idstr, (*sub)->name) == 0) {
 435             return *sub;
 436         }
 437         sub++;
 438     }
 439     return NULL;
 440 }
 441
 442 static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
 443                                    void *opaque)
 444 {
 445     trace_vmstate_subsection_load(vmsd->name);
 446
 447     while (qemu_peek_byte(f, 0) == QEMU_VM_SUBSECTION) {
 448         char idstr[256], *idstr_ret;
 449         int ret;
 450         uint8_t version_id, len, size;
 451         const VMStateDescription *sub_vmsd;
 452
 453         len = qemu_peek_byte(f, 1);
 454         if (len < strlen(vmsd->name) + 1) {
 455             /* subsection name has be be "section_name/a" */
 456             trace_vmstate_subsection_load_bad(vmsd->name, "(short)", "");
 457             return 0;
 458         }
 459         size = qemu_peek_buffer(f, (uint8_t **)&idstr_ret, len, 2);
 460         if (size != len) {
 461             trace_vmstate_subsection_load_bad(vmsd->name, "(peek fail)", "");
 462             return 0;
 463         }
 464         memcpy(idstr, idstr_ret, size);
 465         idstr[size] = 0;
 466
 467         if (strncmp(vmsd->name, idstr, strlen(vmsd->name)) != 0) {
 468             trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(prefix)");
 469             /* it doesn't have a valid subsection name */
 470             return 0;
 471         }
 472         sub_vmsd = vmstate_get_subsection(vmsd->subsections, idstr);
 473         if (sub_vmsd == NULL) {
 474             trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(lookup)");
 475             return -ENOENT;
 476         }
 477         qemu_file_skip(f, 1); /* subsection */
 478         qemu_file_skip(f, 1); /* len */
 479         qemu_file_skip(f, len); /* idstr */
 480         version_id = qemu_get_be32(f);
 481
 482         ret = vmstate_load_state(f, sub_vmsd, opaque, version_id);
 483         if (ret) {
 484             trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(child)");
 485             return ret;
 486         }
 487     }
 488
 489     trace_vmstate_subsection_load_good(vmsd->name);
 490     return 0;
 491 }
 492
 493 static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
 494                                    void *opaque, QJSON *vmdesc)
 495 {
 496     const VMStateDescription **sub = vmsd->subsections;
 497     bool vmdesc_has_subsections = false;
 498     int ret = 0;
 499
 500     trace_vmstate_subsection_save_top(vmsd->name);
 501     while (sub && *sub) {
 502         if (vmstate_save_needed(*sub, opaque)) {
 503             const VMStateDescription *vmsdsub = *sub;
 504             uint8_t len;
 505
 506             trace_vmstate_subsection_save_loop(vmsd->name, vmsdsub->name);
 507             if (vmdesc) {
 508                 /* Only create subsection array when we have any */
 509                 if (!vmdesc_has_subsections) {
 510                     json_start_array(vmdesc, "subsections");
 511                     vmdesc_has_subsections = true;
 512                 }
 513
 514                 json_start_object(vmdesc, NULL);
 515             }
 516
 517             qemu_put_byte(f, QEMU_VM_SUBSECTION);
 518             len = strlen(vmsdsub->name);
 519             qemu_put_byte(f, len);
 520             qemu_put_buffer(f, (uint8_t *)vmsdsub->name, len);
 521             qemu_put_be32(f, vmsdsub->version_id);
 522             ret = vmstate_save_state(f, vmsdsub, opaque, vmdesc);
 523             if (ret) {
 524                 return ret;
 525             }
 526
 527             if (vmdesc) {
 528                 json_end_object(vmdesc);
 529             }
 530         }
 531         sub++;
 532     }
 533
 534     if (vmdesc_has_subsections) {
 535         json_end_array(vmdesc);
 536     }
 537
 538     return ret;
 539 }