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/qmp/json-writer.h"
  18 #include "qemu-file.h"
  19 #include "qemu/bitops.h"
  20 #include "qemu/error-report.h"
  21 #include "trace.h"
  22
  23 static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
  24                                    void *opaque, JSONWriter *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         error_report("%s: incoming version_id %d is too old "
  94                      "for local minimum version_id  %d",
  95                      vmsd->name, version_id, vmsd->minimum_version_id);
  96         trace_vmstate_load_state_end(vmsd->name, "too old", -EINVAL);
  97         return -EINVAL;
  98     }
  99     if (vmsd->pre_load) {
 100         int ret = vmsd->pre_load(opaque);
 101         if (ret) {
 102             return ret;
 103         }
 104     }
 105     while (field->name) {
 106         trace_vmstate_load_state_field(vmsd->name, field->name);
 107         if ((field->field_exists &&
 108              field->field_exists(opaque, version_id)) ||
 109             (!field->field_exists &&
 110              field->version_id <= version_id)) {
 111             void *first_elem = opaque + field->offset;
 112             int i, n_elems = vmstate_n_elems(opaque, field);
 113             int size = vmstate_size(opaque, field);
 114
 115             vmstate_handle_alloc(first_elem, field, opaque);
 116             if (field->flags & VMS_POINTER) {
 117                 first_elem = *(void **)first_elem;
 118                 assert(first_elem || !n_elems || !size);
 119             }
 120             for (i = 0; i < n_elems; i++) {
 121                 void *curr_elem = first_elem + size * i;
 122
 123                 if (field->flags & VMS_ARRAY_OF_POINTER) {
 124                     curr_elem = *(void **)curr_elem;
 125                 }
 126                 if (!curr_elem && size) {
 127                     /* if null pointer check placeholder and do not follow */
 128                     assert(field->flags & VMS_ARRAY_OF_POINTER);
 129                     ret = vmstate_info_nullptr.get(f, curr_elem, size, NULL);
 130                 } else if (field->flags & VMS_STRUCT) {
 131                     ret = vmstate_load_state(f, field->vmsd, curr_elem,
 132                                              field->vmsd->version_id);
 133                 } else if (field->flags & VMS_VSTRUCT) {
 134                     ret = vmstate_load_state(f, field->vmsd, curr_elem,
 135                                              field->struct_version_id);
 136                 } else {
 137                     ret = field->info->get(f, curr_elem, size, field);
 138                 }
 139                 if (ret >= 0) {
 140                     ret = qemu_file_get_error(f);
 141                 }
 142                 if (ret < 0) {
 143                     qemu_file_set_error(f, ret);
 144                     error_report("Failed to load %s:%s", vmsd->name,
 145                                  field->name);
 146                     trace_vmstate_load_field_error(field->name, ret);
 147                     return ret;
 148                 }
 149             }
 150         } else if (field->flags & VMS_MUST_EXIST) {
 151             error_report("Input validation failed: %s/%s",
 152                          vmsd->name, field->name);
 153             return -1;
 154         }
 155         field++;
 156     }
 157     ret = vmstate_subsection_load(f, vmsd, opaque);
 158     if (ret != 0) {
 159         return ret;
 160     }
 161     if (vmsd->post_load) {
 162         ret = vmsd->post_load(opaque, version_id);
 163     }
 164     trace_vmstate_load_state_end(vmsd->name, "end", ret);
 165     return ret;
 166 }
 167
 168 static int vmfield_name_num(const VMStateField *start,
 169                             const VMStateField *search)
 170 {
 171     const VMStateField *field;
 172     int found = 0;
 173
 174     for (field = start; field->name; field++) {
 175         if (!strcmp(field->name, search->name)) {
 176             if (field == search) {
 177                 return found;
 178             }
 179             found++;
 180         }
 181     }
 182
 183     return -1;
 184 }
 185
 186 static bool vmfield_name_is_unique(const VMStateField *start,
 187                                    const VMStateField *search)
 188 {
 189     const VMStateField *field;
 190     int found = 0;
 191
 192     for (field = start; field->name; field++) {
 193         if (!strcmp(field->name, search->name)) {
 194             found++;
 195             /* name found more than once, so it's not unique */
 196             if (found > 1) {
 197                 return false;
 198             }
 199         }
 200     }
 201
 202     return true;
 203 }
 204
 205 static const char *vmfield_get_type_name(const VMStateField *field)
 206 {
 207     const char *type = "unknown";
 208
 209     if (field->flags & VMS_STRUCT) {
 210         type = "struct";
 211     } else if (field->flags & VMS_VSTRUCT) {
 212         type = "vstruct";
 213     } else if (field->info->name) {
 214         type = field->info->name;
 215     }
 216
 217     return type;
 218 }
 219
 220 static bool vmsd_can_compress(const VMStateField *field)
 221 {
 222     if (field->field_exists) {
 223         /* Dynamically existing fields mess up compression */
 224         return false;
 225     }
 226
 227     if (field->flags & VMS_STRUCT) {
 228         const VMStateField *sfield = field->vmsd->fields;
 229         while (sfield->name) {
 230             if (!vmsd_can_compress(sfield)) {
 231                 /* Child elements can't compress, so can't we */
 232                 return false;
 233             }
 234             sfield++;
 235         }
 236
 237         if (field->vmsd->subsections) {
 238             /* Subsections may come and go, better don't compress */
 239             return false;
 240         }
 241     }
 242
 243     return true;
 244 }
 245
 246 static void vmsd_desc_field_start(const VMStateDescription *vmsd,
 247                                   JSONWriter *vmdesc,
 248                                   const VMStateField *field, int i, int max)
 249 {
 250     char *name, *old_name;
 251     bool is_array = max > 1;
 252     bool can_compress = vmsd_can_compress(field);
 253
 254     if (!vmdesc) {
 255         return;
 256     }
 257
 258     name = g_strdup(field->name);
 259
 260     /* Field name is not unique, need to make it unique */
 261     if (!vmfield_name_is_unique(vmsd->fields, field)) {
 262         int num = vmfield_name_num(vmsd->fields, field);
 263         old_name = name;
 264         name = g_strdup_printf("%s[%d]", name, num);
 265         g_free(old_name);
 266     }
 267
 268     json_writer_start_object(vmdesc, NULL);
 269     json_writer_str(vmdesc, "name", name);
 270     if (is_array) {
 271         if (can_compress) {
 272             json_writer_int64(vmdesc, "array_len", max);
 273         } else {
 274             json_writer_int64(vmdesc, "index", i);
 275         }
 276     }
 277     json_writer_str(vmdesc, "type", vmfield_get_type_name(field));
 278
 279     if (field->flags & VMS_STRUCT) {
 280         json_writer_start_object(vmdesc, "struct");
 281     }
 282
 283     g_free(name);
 284 }
 285
 286 static void vmsd_desc_field_end(const VMStateDescription *vmsd,
 287                                 JSONWriter *vmdesc,
 288                                 const VMStateField *field, size_t size, int i)
 289 {
 290     if (!vmdesc) {
 291         return;
 292     }
 293
 294     if (field->flags & VMS_STRUCT) {
 295         /* We printed a struct in between, close its child object */
 296         json_writer_end_object(vmdesc);
 297     }
 298
 299     json_writer_int64(vmdesc, "size", size);
 300     json_writer_end_object(vmdesc);
 301 }
 302
 303
 304 bool vmstate_save_needed(const VMStateDescription *vmsd, void *opaque)
 305 {
 306     if (vmsd->needed && !vmsd->needed(opaque)) {
 307         /* optional section not needed */
 308         return false;
 309     }
 310     return true;
 311 }
 312
 313
 314 int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
 315                        void *opaque, JSONWriter *vmdesc_id)
 316 {
 317     return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id);
 318 }
 319
 320 int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
 321                          void *opaque, JSONWriter *vmdesc, int version_id)
 322 {
 323     int ret = 0;
 324     const VMStateField *field = vmsd->fields;
 325
 326     trace_vmstate_save_state_top(vmsd->name);
 327
 328     if (vmsd->pre_save) {
 329         ret = vmsd->pre_save(opaque);
 330         trace_vmstate_save_state_pre_save_res(vmsd->name, ret);
 331         if (ret) {
 332             error_report("pre-save failed: %s", vmsd->name);
 333             return ret;
 334         }
 335     }
 336
 337     if (vmdesc) {
 338         json_writer_str(vmdesc, "vmsd_name", vmsd->name);
 339         json_writer_int64(vmdesc, "version", version_id);
 340         json_writer_start_array(vmdesc, "fields");
 341     }
 342
 343     while (field->name) {
 344         if ((field->field_exists &&
 345              field->field_exists(opaque, version_id)) ||
 346             (!field->field_exists &&
 347              field->version_id <= version_id)) {
 348             void *first_elem = opaque + field->offset;
 349             int i, n_elems = vmstate_n_elems(opaque, field);
 350             int size = vmstate_size(opaque, field);
 351             int64_t old_offset, written_bytes;
 352             JSONWriter *vmdesc_loop = vmdesc;
 353
 354             trace_vmstate_save_state_loop(vmsd->name, field->name, n_elems);
 355             if (field->flags & VMS_POINTER) {
 356                 first_elem = *(void **)first_elem;
 357                 assert(first_elem || !n_elems || !size);
 358             }
 359             for (i = 0; i < n_elems; i++) {
 360                 void *curr_elem = first_elem + size * i;
 361
 362                 vmsd_desc_field_start(vmsd, vmdesc_loop, field, i, n_elems);
 363                 old_offset = qemu_ftell_fast(f);
 364                 if (field->flags & VMS_ARRAY_OF_POINTER) {
 365                     assert(curr_elem);
 366                     curr_elem = *(void **)curr_elem;
 367                 }
 368                 if (!curr_elem && size) {
 369                     /* if null pointer write placeholder and do not follow */
 370                     assert(field->flags & VMS_ARRAY_OF_POINTER);
 371                     ret = vmstate_info_nullptr.put(f, curr_elem, size, NULL,
 372                                                    NULL);
 373                 } else if (field->flags & VMS_STRUCT) {
 374                     ret = vmstate_save_state(f, field->vmsd, curr_elem,
 375                                              vmdesc_loop);
 376                 } else if (field->flags & VMS_VSTRUCT) {
 377                     ret = vmstate_save_state_v(f, field->vmsd, curr_elem,
 378                                                vmdesc_loop,
 379                                                field->struct_version_id);
 380                 } else {
 381                     ret = field->info->put(f, curr_elem, size, field,
 382                                      vmdesc_loop);
 383                 }
 384                 if (ret) {
 385                     error_report("Save of field %s/%s failed",
 386                                  vmsd->name, field->name);
 387                     if (vmsd->post_save) {
 388                         vmsd->post_save(opaque);
 389                     }
 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_writer_end_array(vmdesc);
 413     }
 414
 415     ret = vmstate_subsection_save(f, vmsd, opaque, vmdesc);
 416
 417     if (vmsd->post_save) {
 418         int ps_ret = vmsd->post_save(opaque);
 419         if (!ret) {
 420             ret = ps_ret;
 421         }
 422     }
 423     return ret;
 424 }
 425
 426 static const VMStateDescription *
 427 vmstate_get_subsection(const VMStateDescription **sub, char *idstr)
 428 {
 429     while (sub && *sub) {
 430         if (strcmp(idstr, (*sub)->name) == 0) {
 431             return *sub;
 432         }
 433         sub++;
 434     }
 435     return NULL;
 436 }
 437
 438 static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
 439                                    void *opaque)
 440 {
 441     trace_vmstate_subsection_load(vmsd->name);
 442
 443     while (qemu_peek_byte(f, 0) == QEMU_VM_SUBSECTION) {
 444         char idstr[256], *idstr_ret;
 445         int ret;
 446         uint8_t version_id, len, size;
 447         const VMStateDescription *sub_vmsd;
 448
 449         len = qemu_peek_byte(f, 1);
 450         if (len < strlen(vmsd->name) + 1) {
 451             /* subsection name has be be "section_name/a" */
 452             trace_vmstate_subsection_load_bad(vmsd->name, "(short)", "");
 453             return 0;
 454         }
 455         size = qemu_peek_buffer(f, (uint8_t **)&idstr_ret, len, 2);
 456         if (size != len) {
 457             trace_vmstate_subsection_load_bad(vmsd->name, "(peek fail)", "");
 458             return 0;
 459         }
 460         memcpy(idstr, idstr_ret, size);
 461         idstr[size] = 0;
 462
 463         if (strncmp(vmsd->name, idstr, strlen(vmsd->name)) != 0) {
 464             trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(prefix)");
 465             /* it doesn't have a valid subsection name */
 466             return 0;
 467         }
 468         sub_vmsd = vmstate_get_subsection(vmsd->subsections, idstr);
 469         if (sub_vmsd == NULL) {
 470             trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(lookup)");
 471             return -ENOENT;
 472         }
 473         qemu_file_skip(f, 1); /* subsection */
 474         qemu_file_skip(f, 1); /* len */
 475         qemu_file_skip(f, len); /* idstr */
 476         version_id = qemu_get_be32(f);
 477
 478         ret = vmstate_load_state(f, sub_vmsd, opaque, version_id);
 479         if (ret) {
 480             trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(child)");
 481             return ret;
 482         }
 483     }
 484
 485     trace_vmstate_subsection_load_good(vmsd->name);
 486     return 0;
 487 }
 488
 489 static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
 490                                    void *opaque, JSONWriter *vmdesc)
 491 {
 492     const VMStateDescription **sub = vmsd->subsections;
 493     bool vmdesc_has_subsections = false;
 494     int ret = 0;
 495
 496     trace_vmstate_subsection_save_top(vmsd->name);
 497     while (sub && *sub) {
 498         if (vmstate_save_needed(*sub, opaque)) {
 499             const VMStateDescription *vmsdsub = *sub;
 500             uint8_t len;
 501
 502             trace_vmstate_subsection_save_loop(vmsd->name, vmsdsub->name);
 503             if (vmdesc) {
 504                 /* Only create subsection array when we have any */
 505                 if (!vmdesc_has_subsections) {
 506                     json_writer_start_array(vmdesc, "subsections");
 507                     vmdesc_has_subsections = true;
 508                 }
 509
 510                 json_writer_start_object(vmdesc, NULL);
 511             }
 512
 513             qemu_put_byte(f, QEMU_VM_SUBSECTION);
 514             len = strlen(vmsdsub->name);
 515             qemu_put_byte(f, len);
 516             qemu_put_buffer(f, (uint8_t *)vmsdsub->name, len);
 517             qemu_put_be32(f, vmsdsub->version_id);
 518             ret = vmstate_save_state(f, vmsdsub, opaque, vmdesc);
 519             if (ret) {
 520                 return ret;
 521             }
 522
 523             if (vmdesc) {
 524                 json_writer_end_object(vmdesc);
 525             }
 526         }
 527         sub++;
 528     }
 529
 530     if (vmdesc_has_subsections) {
 531         json_writer_end_array(vmdesc);
 532     }
 533
 534     return ret;
 535 }