xref: /qemu/migration/vmstate.c (revision b21e2380) 
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 }
536