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 "qobject/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 Error **errp); 27 static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd, 28 void *opaque); 29 30 /* Whether this field should exist for either save or load the VM? */ 31 static bool 32 vmstate_field_exists(const VMStateDescription *vmsd, const VMStateField *field, 33 void *opaque, int version_id) 34 { 35 bool result; 36 37 if (field->field_exists) { 38 /* If there's the function checker, that's the solo truth */ 39 result = field->field_exists(opaque, version_id); 40 trace_vmstate_field_exists(vmsd->name, field->name, field->version_id, 41 version_id, result); 42 } else { 43 /* 44 * Otherwise, we only save/load if field version is same or older. 45 * For example, when loading from an old binary with old version, 46 * we ignore new fields with newer version_ids. 47 */ 48 result = field->version_id <= version_id; 49 } 50 51 return result; 52 } 53 54 /* 55 * Create a fake nullptr field when there's a NULL pointer detected in the 56 * array of a VMS_ARRAY_OF_POINTER VMSD field. It's needed because we 57 * can't dereference the NULL pointer. 58 */ 59 static const VMStateField * 60 vmsd_create_fake_nullptr_field(const VMStateField *field) 61 { 62 VMStateField *fake = g_new0(VMStateField, 1); 63 64 /* It can only happen on an array of pointers! */ 65 assert(field->flags & VMS_ARRAY_OF_POINTER); 66 67 /* Some of fake's properties should match the original's */ 68 fake->name = field->name; 69 fake->version_id = field->version_id; 70 71 /* Do not need "field_exists" check as it always exists (which is null) */ 72 fake->field_exists = NULL; 73 74 /* See vmstate_info_nullptr - use 1 byte to represent nullptr */ 75 fake->size = 1; 76 fake->info = &vmstate_info_nullptr; 77 fake->flags = VMS_SINGLE; 78 79 /* All the rest fields shouldn't matter.. */ 80 81 return (const VMStateField *)fake; 82 } 83 84 static int vmstate_n_elems(void *opaque, const VMStateField *field) 85 { 86 int n_elems = 1; 87 88 if (field->flags & VMS_ARRAY) { 89 n_elems = field->num; 90 } else if (field->flags & VMS_VARRAY_INT32) { 91 n_elems = *(int32_t *)(opaque + field->num_offset); 92 } else if (field->flags & VMS_VARRAY_UINT32) { 93 n_elems = *(uint32_t *)(opaque + field->num_offset); 94 } else if (field->flags & VMS_VARRAY_UINT16) { 95 n_elems = *(uint16_t *)(opaque + field->num_offset); 96 } else if (field->flags & VMS_VARRAY_UINT8) { 97 n_elems = *(uint8_t *)(opaque + field->num_offset); 98 } 99 100 if (field->flags & VMS_MULTIPLY_ELEMENTS) { 101 n_elems *= field->num; 102 } 103 104 trace_vmstate_n_elems(field->name, n_elems); 105 return n_elems; 106 } 107 108 static int vmstate_size(void *opaque, const VMStateField *field) 109 { 110 int size = field->size; 111 112 if (field->flags & VMS_VBUFFER) { 113 size = *(int32_t *)(opaque + field->size_offset); 114 if (field->flags & VMS_MULTIPLY) { 115 size *= field->size; 116 } 117 } 118 119 return size; 120 } 121 122 static void vmstate_handle_alloc(void *ptr, const VMStateField *field, 123 void *opaque) 124 { 125 if (field->flags & VMS_POINTER && field->flags & VMS_ALLOC) { 126 gsize size = vmstate_size(opaque, field); 127 size *= vmstate_n_elems(opaque, field); 128 if (size) { 129 *(void **)ptr = g_malloc(size); 130 } 131 } 132 } 133 134 int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd, 135 void *opaque, int version_id) 136 { 137 const VMStateField *field = vmsd->fields; 138 int ret = 0; 139 140 trace_vmstate_load_state(vmsd->name, version_id); 141 if (version_id > vmsd->version_id) { 142 error_report("%s: incoming version_id %d is too new " 143 "for local version_id %d", 144 vmsd->name, version_id, vmsd->version_id); 145 trace_vmstate_load_state_end(vmsd->name, "too new", -EINVAL); 146 return -EINVAL; 147 } 148 if (version_id < vmsd->minimum_version_id) { 149 error_report("%s: incoming version_id %d is too old " 150 "for local minimum version_id %d", 151 vmsd->name, version_id, vmsd->minimum_version_id); 152 trace_vmstate_load_state_end(vmsd->name, "too old", -EINVAL); 153 return -EINVAL; 154 } 155 if (vmsd->pre_load) { 156 ret = vmsd->pre_load(opaque); 157 if (ret) { 158 return ret; 159 } 160 } 161 while (field->name) { 162 bool exists = vmstate_field_exists(vmsd, field, opaque, version_id); 163 trace_vmstate_load_state_field(vmsd->name, field->name, exists); 164 if (exists) { 165 void *first_elem = opaque + field->offset; 166 int i, n_elems = vmstate_n_elems(opaque, field); 167 int size = vmstate_size(opaque, field); 168 169 vmstate_handle_alloc(first_elem, field, opaque); 170 if (field->flags & VMS_POINTER) { 171 first_elem = *(void **)first_elem; 172 assert(first_elem || !n_elems || !size); 173 } 174 for (i = 0; i < n_elems; i++) { 175 void *curr_elem = first_elem + size * i; 176 const VMStateField *inner_field; 177 178 if (field->flags & VMS_ARRAY_OF_POINTER) { 179 curr_elem = *(void **)curr_elem; 180 } 181 182 if (!curr_elem && size) { 183 /* 184 * If null pointer found (which should only happen in 185 * an array of pointers), use null placeholder and do 186 * not follow. 187 */ 188 inner_field = vmsd_create_fake_nullptr_field(field); 189 } else { 190 inner_field = field; 191 } 192 193 if (inner_field->flags & VMS_STRUCT) { 194 ret = vmstate_load_state(f, inner_field->vmsd, curr_elem, 195 inner_field->vmsd->version_id); 196 } else if (inner_field->flags & VMS_VSTRUCT) { 197 ret = vmstate_load_state(f, inner_field->vmsd, curr_elem, 198 inner_field->struct_version_id); 199 } else { 200 ret = inner_field->info->get(f, curr_elem, size, 201 inner_field); 202 } 203 204 /* If we used a fake temp field.. free it now */ 205 if (inner_field != field) { 206 g_clear_pointer((gpointer *)&inner_field, g_free); 207 } 208 209 if (ret >= 0) { 210 ret = qemu_file_get_error(f); 211 } 212 if (ret < 0) { 213 qemu_file_set_error(f, ret); 214 error_report("Failed to load %s:%s", vmsd->name, 215 field->name); 216 trace_vmstate_load_field_error(field->name, ret); 217 return ret; 218 } 219 } 220 } else if (field->flags & VMS_MUST_EXIST) { 221 error_report("Input validation failed: %s/%s", 222 vmsd->name, field->name); 223 return -1; 224 } 225 field++; 226 } 227 assert(field->flags == VMS_END); 228 ret = vmstate_subsection_load(f, vmsd, opaque); 229 if (ret != 0) { 230 qemu_file_set_error(f, ret); 231 return ret; 232 } 233 if (vmsd->post_load) { 234 ret = vmsd->post_load(opaque, version_id); 235 } 236 trace_vmstate_load_state_end(vmsd->name, "end", ret); 237 return ret; 238 } 239 240 static int vmfield_name_num(const VMStateField *start, 241 const VMStateField *search) 242 { 243 const VMStateField *field; 244 int found = 0; 245 246 for (field = start; field->name; field++) { 247 if (!strcmp(field->name, search->name)) { 248 if (field == search) { 249 return found; 250 } 251 found++; 252 } 253 } 254 255 return -1; 256 } 257 258 static bool vmfield_name_is_unique(const VMStateField *start, 259 const VMStateField *search) 260 { 261 const VMStateField *field; 262 int found = 0; 263 264 for (field = start; field->name; field++) { 265 if (!strcmp(field->name, search->name)) { 266 found++; 267 /* name found more than once, so it's not unique */ 268 if (found > 1) { 269 return false; 270 } 271 } 272 } 273 274 return true; 275 } 276 277 static const char *vmfield_get_type_name(const VMStateField *field) 278 { 279 const char *type = "unknown"; 280 281 if (field->flags & VMS_STRUCT) { 282 type = "struct"; 283 } else if (field->flags & VMS_VSTRUCT) { 284 type = "vstruct"; 285 } else if (field->info->name) { 286 type = field->info->name; 287 } 288 289 return type; 290 } 291 292 static bool vmsd_can_compress(const VMStateField *field) 293 { 294 if (field->field_exists) { 295 /* Dynamically existing fields mess up compression */ 296 return false; 297 } 298 299 if (field->flags & VMS_STRUCT) { 300 const VMStateField *sfield = field->vmsd->fields; 301 while (sfield->name) { 302 if (!vmsd_can_compress(sfield)) { 303 /* Child elements can't compress, so can't we */ 304 return false; 305 } 306 sfield++; 307 } 308 309 if (field->vmsd->subsections) { 310 /* Subsections may come and go, better don't compress */ 311 return false; 312 } 313 } 314 315 return true; 316 } 317 318 static void vmsd_desc_field_start(const VMStateDescription *vmsd, 319 JSONWriter *vmdesc, 320 const VMStateField *field, int i, int max) 321 { 322 char *name, *old_name; 323 bool is_array = max > 1; 324 bool can_compress = vmsd_can_compress(field); 325 326 if (!vmdesc) { 327 return; 328 } 329 330 name = g_strdup(field->name); 331 332 /* Field name is not unique, need to make it unique */ 333 if (!vmfield_name_is_unique(vmsd->fields, field)) { 334 int num = vmfield_name_num(vmsd->fields, field); 335 old_name = name; 336 name = g_strdup_printf("%s[%d]", name, num); 337 g_free(old_name); 338 } 339 340 json_writer_start_object(vmdesc, NULL); 341 json_writer_str(vmdesc, "name", name); 342 if (is_array) { 343 if (can_compress) { 344 json_writer_int64(vmdesc, "array_len", max); 345 } else { 346 json_writer_int64(vmdesc, "index", i); 347 } 348 } 349 json_writer_str(vmdesc, "type", vmfield_get_type_name(field)); 350 351 if (field->flags & VMS_STRUCT) { 352 json_writer_start_object(vmdesc, "struct"); 353 } 354 355 g_free(name); 356 } 357 358 static void vmsd_desc_field_end(const VMStateDescription *vmsd, 359 JSONWriter *vmdesc, 360 const VMStateField *field, size_t size) 361 { 362 if (!vmdesc) { 363 return; 364 } 365 366 if (field->flags & VMS_STRUCT) { 367 /* We printed a struct in between, close its child object */ 368 json_writer_end_object(vmdesc); 369 } 370 371 json_writer_int64(vmdesc, "size", size); 372 json_writer_end_object(vmdesc); 373 } 374 375 376 bool vmstate_section_needed(const VMStateDescription *vmsd, void *opaque) 377 { 378 if (vmsd->needed && !vmsd->needed(opaque)) { 379 /* optional section not needed */ 380 return false; 381 } 382 return true; 383 } 384 385 386 int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd, 387 void *opaque, JSONWriter *vmdesc_id) 388 { 389 return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, NULL); 390 } 391 392 int vmstate_save_state_with_err(QEMUFile *f, const VMStateDescription *vmsd, 393 void *opaque, JSONWriter *vmdesc_id, Error **errp) 394 { 395 return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, errp); 396 } 397 398 int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd, 399 void *opaque, JSONWriter *vmdesc, int version_id, Error **errp) 400 { 401 int ret = 0; 402 const VMStateField *field = vmsd->fields; 403 404 trace_vmstate_save_state_top(vmsd->name); 405 406 if (vmsd->pre_save) { 407 ret = vmsd->pre_save(opaque); 408 trace_vmstate_save_state_pre_save_res(vmsd->name, ret); 409 if (ret) { 410 error_setg(errp, "pre-save failed: %s", vmsd->name); 411 return ret; 412 } 413 } 414 415 if (vmdesc) { 416 json_writer_str(vmdesc, "vmsd_name", vmsd->name); 417 json_writer_int64(vmdesc, "version", version_id); 418 json_writer_start_array(vmdesc, "fields"); 419 } 420 421 while (field->name) { 422 if (vmstate_field_exists(vmsd, field, opaque, version_id)) { 423 void *first_elem = opaque + field->offset; 424 int i, n_elems = vmstate_n_elems(opaque, field); 425 int size = vmstate_size(opaque, field); 426 uint64_t old_offset, written_bytes; 427 JSONWriter *vmdesc_loop = vmdesc; 428 bool is_prev_null = false; 429 430 trace_vmstate_save_state_loop(vmsd->name, field->name, n_elems); 431 if (field->flags & VMS_POINTER) { 432 first_elem = *(void **)first_elem; 433 assert(first_elem || !n_elems || !size); 434 } 435 436 for (i = 0; i < n_elems; i++) { 437 void *curr_elem = first_elem + size * i; 438 const VMStateField *inner_field; 439 bool is_null; 440 int max_elems = n_elems - i; 441 442 old_offset = qemu_file_transferred(f); 443 if (field->flags & VMS_ARRAY_OF_POINTER) { 444 assert(curr_elem); 445 curr_elem = *(void **)curr_elem; 446 } 447 448 if (!curr_elem && size) { 449 /* 450 * If null pointer found (which should only happen in 451 * an array of pointers), use null placeholder and do 452 * not follow. 453 */ 454 inner_field = vmsd_create_fake_nullptr_field(field); 455 is_null = true; 456 } else { 457 inner_field = field; 458 is_null = false; 459 } 460 461 /* 462 * This logic only matters when dumping VM Desc. 463 * 464 * Due to the fake nullptr handling above, if there's mixed 465 * null/non-null data, it doesn't make sense to emit a 466 * compressed array representation spanning the entire array 467 * because the field types will be different (e.g. struct 468 * vs. nullptr). Search ahead for the next null/non-null element 469 * and start a new compressed array if found. 470 */ 471 if (vmdesc && (field->flags & VMS_ARRAY_OF_POINTER) && 472 is_null != is_prev_null) { 473 474 is_prev_null = is_null; 475 vmdesc_loop = vmdesc; 476 477 for (int j = i + 1; j < n_elems; j++) { 478 void *elem = *(void **)(first_elem + size * j); 479 bool elem_is_null = !elem && size; 480 481 if (is_null != elem_is_null) { 482 max_elems = j - i; 483 break; 484 } 485 } 486 } 487 488 vmsd_desc_field_start(vmsd, vmdesc_loop, inner_field, 489 i, max_elems); 490 491 if (inner_field->flags & VMS_STRUCT) { 492 ret = vmstate_save_state(f, inner_field->vmsd, 493 curr_elem, vmdesc_loop); 494 } else if (inner_field->flags & VMS_VSTRUCT) { 495 ret = vmstate_save_state_v(f, inner_field->vmsd, 496 curr_elem, vmdesc_loop, 497 inner_field->struct_version_id, 498 errp); 499 } else { 500 ret = inner_field->info->put(f, curr_elem, size, 501 inner_field, vmdesc_loop); 502 } 503 504 written_bytes = qemu_file_transferred(f) - old_offset; 505 vmsd_desc_field_end(vmsd, vmdesc_loop, inner_field, 506 written_bytes); 507 508 /* If we used a fake temp field.. free it now */ 509 if (is_null) { 510 g_clear_pointer((gpointer *)&inner_field, g_free); 511 } 512 513 if (ret) { 514 error_setg(errp, "Save of field %s/%s failed", 515 vmsd->name, field->name); 516 if (vmsd->post_save) { 517 vmsd->post_save(opaque); 518 } 519 return ret; 520 } 521 522 /* Compressed arrays only care about the first element */ 523 if (vmdesc_loop && vmsd_can_compress(field)) { 524 vmdesc_loop = NULL; 525 } 526 } 527 } else { 528 if (field->flags & VMS_MUST_EXIST) { 529 error_report("Output state validation failed: %s/%s", 530 vmsd->name, field->name); 531 assert(!(field->flags & VMS_MUST_EXIST)); 532 } 533 } 534 field++; 535 } 536 assert(field->flags == VMS_END); 537 538 if (vmdesc) { 539 json_writer_end_array(vmdesc); 540 } 541 542 ret = vmstate_subsection_save(f, vmsd, opaque, vmdesc, errp); 543 544 if (vmsd->post_save) { 545 int ps_ret = vmsd->post_save(opaque); 546 if (!ret && ps_ret) { 547 ret = ps_ret; 548 error_setg(errp, "post-save failed: %s", vmsd->name); 549 } 550 } 551 return ret; 552 } 553 554 static const VMStateDescription * 555 vmstate_get_subsection(const VMStateDescription * const *sub, 556 const char *idstr) 557 { 558 if (sub) { 559 for (const VMStateDescription *s = *sub; s ; s = *++sub) { 560 if (strcmp(idstr, s->name) == 0) { 561 return s; 562 } 563 } 564 } 565 return NULL; 566 } 567 568 static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd, 569 void *opaque) 570 { 571 trace_vmstate_subsection_load(vmsd->name); 572 573 while (qemu_peek_byte(f, 0) == QEMU_VM_SUBSECTION) { 574 char idstr[256], *idstr_ret; 575 int ret; 576 uint8_t version_id, len, size; 577 const VMStateDescription *sub_vmsd; 578 579 len = qemu_peek_byte(f, 1); 580 if (len < strlen(vmsd->name) + 1) { 581 /* subsection name has to be "section_name/a" */ 582 trace_vmstate_subsection_load_bad(vmsd->name, "(short)", ""); 583 return 0; 584 } 585 size = qemu_peek_buffer(f, (uint8_t **)&idstr_ret, len, 2); 586 if (size != len) { 587 trace_vmstate_subsection_load_bad(vmsd->name, "(peek fail)", ""); 588 return 0; 589 } 590 memcpy(idstr, idstr_ret, size); 591 idstr[size] = 0; 592 593 if (strncmp(vmsd->name, idstr, strlen(vmsd->name)) != 0) { 594 trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(prefix)"); 595 /* it doesn't have a valid subsection name */ 596 return 0; 597 } 598 sub_vmsd = vmstate_get_subsection(vmsd->subsections, idstr); 599 if (sub_vmsd == NULL) { 600 trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(lookup)"); 601 return -ENOENT; 602 } 603 qemu_file_skip(f, 1); /* subsection */ 604 qemu_file_skip(f, 1); /* len */ 605 qemu_file_skip(f, len); /* idstr */ 606 version_id = qemu_get_be32(f); 607 608 ret = vmstate_load_state(f, sub_vmsd, opaque, version_id); 609 if (ret) { 610 trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(child)"); 611 return ret; 612 } 613 } 614 615 trace_vmstate_subsection_load_good(vmsd->name); 616 return 0; 617 } 618 619 static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd, 620 void *opaque, JSONWriter *vmdesc, 621 Error **errp) 622 { 623 const VMStateDescription * const *sub = vmsd->subsections; 624 bool vmdesc_has_subsections = false; 625 int ret = 0; 626 627 trace_vmstate_subsection_save_top(vmsd->name); 628 while (sub && *sub) { 629 if (vmstate_section_needed(*sub, opaque)) { 630 const VMStateDescription *vmsdsub = *sub; 631 uint8_t len; 632 633 trace_vmstate_subsection_save_loop(vmsd->name, vmsdsub->name); 634 if (vmdesc) { 635 /* Only create subsection array when we have any */ 636 if (!vmdesc_has_subsections) { 637 json_writer_start_array(vmdesc, "subsections"); 638 vmdesc_has_subsections = true; 639 } 640 641 json_writer_start_object(vmdesc, NULL); 642 } 643 644 qemu_put_byte(f, QEMU_VM_SUBSECTION); 645 len = strlen(vmsdsub->name); 646 qemu_put_byte(f, len); 647 qemu_put_buffer(f, (uint8_t *)vmsdsub->name, len); 648 qemu_put_be32(f, vmsdsub->version_id); 649 ret = vmstate_save_state_with_err(f, vmsdsub, opaque, vmdesc, errp); 650 if (ret) { 651 return ret; 652 } 653 654 if (vmdesc) { 655 json_writer_end_object(vmdesc); 656 } 657 } 658 sub++; 659 } 660 661 if (vmdesc_has_subsections) { 662 json_writer_end_array(vmdesc); 663 } 664 665 return ret; 666 } 667