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         qemu_file_set_error(f, ret);
 183         return ret;
 184     }
 185     if (vmsd->post_load) {
 186         ret = vmsd->post_load(opaque, version_id);
 187     }
 188     trace_vmstate_load_state_end(vmsd->name, "end", ret);
 189     return ret;
 190 }
 191
 192 static int vmfield_name_num(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             if (field == search) {
 201                 return found;
 202             }
 203             found++;
 204         }
 205     }
 206
 207     return -1;
 208 }
 209
 210 static bool vmfield_name_is_unique(const VMStateField *start,
 211                                    const VMStateField *search)
 212 {
 213     const VMStateField *field;
 214     int found = 0;
 215
 216     for (field = start; field->name; field++) {
 217         if (!strcmp(field->name, search->name)) {
 218             found++;
 219             /* name found more than once, so it's not unique */
 220             if (found > 1) {
 221                 return false;
 222             }
 223         }
 224     }
 225
 226     return true;
 227 }
 228
 229 static const char *vmfield_get_type_name(const VMStateField *field)
 230 {
 231     const char *type = "unknown";
 232
 233     if (field->flags & VMS_STRUCT) {
 234         type = "struct";
 235     } else if (field->flags & VMS_VSTRUCT) {
 236         type = "vstruct";
 237     } else if (field->info->name) {
 238         type = field->info->name;
 239     }
 240
 241     return type;
 242 }
 243
 244 static bool vmsd_can_compress(const VMStateField *field)
 245 {
 246     if (field->field_exists) {
 247         /* Dynamically existing fields mess up compression */
 248         return false;
 249     }
 250
 251     if (field->flags & VMS_STRUCT) {
 252         const VMStateField *sfield = field->vmsd->fields;
 253         while (sfield->name) {
 254             if (!vmsd_can_compress(sfield)) {
 255                 /* Child elements can't compress, so can't we */
 256                 return false;
 257             }
 258             sfield++;
 259         }
 260
 261         if (field->vmsd->subsections) {
 262             /* Subsections may come and go, better don't compress */
 263             return false;
 264         }
 265     }
 266
 267     return true;
 268 }
 269
 270 static void vmsd_desc_field_start(const VMStateDescription *vmsd,
 271                                   JSONWriter *vmdesc,
 272                                   const VMStateField *field, int i, int max)
 273 {
 274     char *name, *old_name;
 275     bool is_array = max > 1;
 276     bool can_compress = vmsd_can_compress(field);
 277
 278     if (!vmdesc) {
 279         return;
 280     }
 281
 282     name = g_strdup(field->name);
 283
 284     /* Field name is not unique, need to make it unique */
 285     if (!vmfield_name_is_unique(vmsd->fields, field)) {
 286         int num = vmfield_name_num(vmsd->fields, field);
 287         old_name = name;
 288         name = g_strdup_printf("%s[%d]", name, num);
 289         g_free(old_name);
 290     }
 291
 292     json_writer_start_object(vmdesc, NULL);
 293     json_writer_str(vmdesc, "name", name);
 294     if (is_array) {
 295         if (can_compress) {
 296             json_writer_int64(vmdesc, "array_len", max);
 297         } else {
 298             json_writer_int64(vmdesc, "index", i);
 299         }
 300     }
 301     json_writer_str(vmdesc, "type", vmfield_get_type_name(field));
 302
 303     if (field->flags & VMS_STRUCT) {
 304         json_writer_start_object(vmdesc, "struct");
 305     }
 306
 307     g_free(name);
 308 }
 309
 310 static void vmsd_desc_field_end(const VMStateDescription *vmsd,
 311                                 JSONWriter *vmdesc,
 312                                 const VMStateField *field, size_t size, int i)
 313 {
 314     if (!vmdesc) {
 315         return;
 316     }
 317
 318     if (field->flags & VMS_STRUCT) {
 319         /* We printed a struct in between, close its child object */
 320         json_writer_end_object(vmdesc);
 321     }
 322
 323     json_writer_int64(vmdesc, "size", size);
 324     json_writer_end_object(vmdesc);
 325 }
 326
 327
 328 bool vmstate_section_needed(const VMStateDescription *vmsd, void *opaque)
 329 {
 330     if (vmsd->needed && !vmsd->needed(opaque)) {
 331         /* optional section not needed */
 332         return false;
 333     }
 334     return true;
 335 }
 336
 337
 338 int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
 339                        void *opaque, JSONWriter *vmdesc_id)
 340 {
 341     return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, NULL);
 342 }
 343
 344 int vmstate_save_state_with_err(QEMUFile *f, const VMStateDescription *vmsd,
 345                        void *opaque, JSONWriter *vmdesc_id, Error **errp)
 346 {
 347     return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, errp);
 348 }
 349
 350 int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
 351                          void *opaque, JSONWriter *vmdesc, int version_id, Error **errp)
 352 {
 353     int ret = 0;
 354     const VMStateField *field = vmsd->fields;
 355
 356     trace_vmstate_save_state_top(vmsd->name);
 357
 358     if (vmsd->pre_save) {
 359         ret = vmsd->pre_save(opaque);
 360         trace_vmstate_save_state_pre_save_res(vmsd->name, ret);
 361         if (ret) {
 362             error_setg(errp, "pre-save failed: %s", vmsd->name);
 363             return ret;
 364         }
 365     }
 366
 367     if (vmdesc) {
 368         json_writer_str(vmdesc, "vmsd_name", vmsd->name);
 369         json_writer_int64(vmdesc, "version", version_id);
 370         json_writer_start_array(vmdesc, "fields");
 371     }
 372
 373     while (field->name) {
 374         if (vmstate_field_exists(vmsd, field, opaque, version_id)) {
 375             void *first_elem = opaque + field->offset;
 376             int i, n_elems = vmstate_n_elems(opaque, field);
 377             int size = vmstate_size(opaque, field);
 378             uint64_t old_offset, written_bytes;
 379             JSONWriter *vmdesc_loop = vmdesc;
 380
 381             trace_vmstate_save_state_loop(vmsd->name, field->name, n_elems);
 382             if (field->flags & VMS_POINTER) {
 383                 first_elem = *(void **)first_elem;
 384                 assert(first_elem || !n_elems || !size);
 385             }
 386             for (i = 0; i < n_elems; i++) {
 387                 void *curr_elem = first_elem + size * i;
 388
 389                 vmsd_desc_field_start(vmsd, vmdesc_loop, field, i, n_elems);
 390                 old_offset = qemu_file_transferred(f);
 391                 if (field->flags & VMS_ARRAY_OF_POINTER) {
 392                     assert(curr_elem);
 393                     curr_elem = *(void **)curr_elem;
 394                 }
 395                 if (!curr_elem && size) {
 396                     /* if null pointer write placeholder and do not follow */
 397                     assert(field->flags & VMS_ARRAY_OF_POINTER);
 398                     ret = vmstate_info_nullptr.put(f, curr_elem, size, NULL,
 399                                                    NULL);
 400                 } else if (field->flags & VMS_STRUCT) {
 401                     ret = vmstate_save_state(f, field->vmsd, curr_elem,
 402                                              vmdesc_loop);
 403                 } else if (field->flags & VMS_VSTRUCT) {
 404                     ret = vmstate_save_state_v(f, field->vmsd, curr_elem,
 405                                                vmdesc_loop,
 406                                                field->struct_version_id, errp);
 407                 } else {
 408                     ret = field->info->put(f, curr_elem, size, field,
 409                                      vmdesc_loop);
 410                 }
 411                 if (ret) {
 412                     error_setg(errp, "Save of field %s/%s failed",
 413                                 vmsd->name, field->name);
 414                     if (vmsd->post_save) {
 415                         vmsd->post_save(opaque);
 416                     }
 417                     return ret;
 418                 }
 419
 420                 written_bytes = qemu_file_transferred(f) - old_offset;
 421                 vmsd_desc_field_end(vmsd, vmdesc_loop, field, written_bytes, i);
 422
 423                 /* Compressed arrays only care about the first element */
 424                 if (vmdesc_loop && vmsd_can_compress(field)) {
 425                     vmdesc_loop = NULL;
 426                 }
 427             }
 428         } else {
 429             if (field->flags & VMS_MUST_EXIST) {
 430                 error_report("Output state validation failed: %s/%s",
 431                         vmsd->name, field->name);
 432                 assert(!(field->flags & VMS_MUST_EXIST));
 433             }
 434         }
 435         field++;
 436     }
 437     assert(field->flags == VMS_END);
 438
 439     if (vmdesc) {
 440         json_writer_end_array(vmdesc);
 441     }
 442
 443     ret = vmstate_subsection_save(f, vmsd, opaque, vmdesc);
 444
 445     if (vmsd->post_save) {
 446         int ps_ret = vmsd->post_save(opaque);
 447         if (!ret) {
 448             ret = ps_ret;
 449         }
 450     }
 451     return ret;
 452 }
 453
 454 static const VMStateDescription *
 455 vmstate_get_subsection(const VMStateDescription **sub, char *idstr)
 456 {
 457     while (sub && *sub) {
 458         if (strcmp(idstr, (*sub)->name) == 0) {
 459             return *sub;
 460         }
 461         sub++;
 462     }
 463     return NULL;
 464 }
 465
 466 static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
 467                                    void *opaque)
 468 {
 469     trace_vmstate_subsection_load(vmsd->name);
 470
 471     while (qemu_peek_byte(f, 0) == QEMU_VM_SUBSECTION) {
 472         char idstr[256], *idstr_ret;
 473         int ret;
 474         uint8_t version_id, len, size;
 475         const VMStateDescription *sub_vmsd;
 476
 477         len = qemu_peek_byte(f, 1);
 478         if (len < strlen(vmsd->name) + 1) {
 479             /* subsection name has be be "section_name/a" */
 480             trace_vmstate_subsection_load_bad(vmsd->name, "(short)", "");
 481             return 0;
 482         }
 483         size = qemu_peek_buffer(f, (uint8_t **)&idstr_ret, len, 2);
 484         if (size != len) {
 485             trace_vmstate_subsection_load_bad(vmsd->name, "(peek fail)", "");
 486             return 0;
 487         }
 488         memcpy(idstr, idstr_ret, size);
 489         idstr[size] = 0;
 490
 491         if (strncmp(vmsd->name, idstr, strlen(vmsd->name)) != 0) {
 492             trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(prefix)");
 493             /* it doesn't have a valid subsection name */
 494             return 0;
 495         }
 496         sub_vmsd = vmstate_get_subsection(vmsd->subsections, idstr);
 497         if (sub_vmsd == NULL) {
 498             trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(lookup)");
 499             return -ENOENT;
 500         }
 501         qemu_file_skip(f, 1); /* subsection */
 502         qemu_file_skip(f, 1); /* len */
 503         qemu_file_skip(f, len); /* idstr */
 504         version_id = qemu_get_be32(f);
 505
 506         ret = vmstate_load_state(f, sub_vmsd, opaque, version_id);
 507         if (ret) {
 508             trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(child)");
 509             return ret;
 510         }
 511     }
 512
 513     trace_vmstate_subsection_load_good(vmsd->name);
 514     return 0;
 515 }
 516
 517 static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
 518                                    void *opaque, JSONWriter *vmdesc)
 519 {
 520     const VMStateDescription **sub = vmsd->subsections;
 521     bool vmdesc_has_subsections = false;
 522     int ret = 0;
 523
 524     trace_vmstate_subsection_save_top(vmsd->name);
 525     while (sub && *sub) {
 526         if (vmstate_section_needed(*sub, opaque)) {
 527             const VMStateDescription *vmsdsub = *sub;
 528             uint8_t len;
 529
 530             trace_vmstate_subsection_save_loop(vmsd->name, vmsdsub->name);
 531             if (vmdesc) {
 532                 /* Only create subsection array when we have any */
 533                 if (!vmdesc_has_subsections) {
 534                     json_writer_start_array(vmdesc, "subsections");
 535                     vmdesc_has_subsections = true;
 536                 }
 537
 538                 json_writer_start_object(vmdesc, NULL);
 539             }
 540
 541             qemu_put_byte(f, QEMU_VM_SUBSECTION);
 542             len = strlen(vmsdsub->name);
 543             qemu_put_byte(f, len);
 544             qemu_put_buffer(f, (uint8_t *)vmsdsub->name, len);
 545             qemu_put_be32(f, vmsdsub->version_id);
 546             ret = vmstate_save_state(f, vmsdsub, opaque, vmdesc);
 547             if (ret) {
 548                 return ret;
 549             }
 550
 551             if (vmdesc) {
 552                 json_writer_end_object(vmdesc);
 553             }
 554         }
 555         sub++;
 556     }
 557
 558     if (vmdesc_has_subsections) {
 559         json_writer_end_array(vmdesc);
 560     }
 561
 562     return ret;
 563 }