xref: /openbmc/qemu/block/qcow2.h (revision 15faf946)
1 /*
2  * Block driver for the QCOW version 2 format
3  *
4  * Copyright (c) 2004-2006 Fabrice Bellard
5  *
6  * Permission is hereby granted, free of charge, to any person obtaining a copy
7  * of this software and associated documentation files (the "Software"), to deal
8  * in the Software without restriction, including without limitation the rights
9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10  * copies of the Software, and to permit persons to whom the Software is
11  * furnished to do so, subject to the following conditions:
12  *
13  * The above copyright notice and this permission notice shall be included in
14  * all copies or substantial portions of the Software.
15  *
16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22  * THE SOFTWARE.
23  */
24 
25 #ifndef BLOCK_QCOW2_H
26 #define BLOCK_QCOW2_H
27 
28 #include "aes.h"
29 #include "qemu-coroutine.h"
30 
31 //#define DEBUG_ALLOC
32 //#define DEBUG_ALLOC2
33 //#define DEBUG_EXT
34 
35 #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
36 
37 #define QCOW_CRYPT_NONE 0
38 #define QCOW_CRYPT_AES  1
39 
40 #define QCOW_MAX_CRYPT_CLUSTERS 32
41 
42 /* indicate that the refcount of the referenced cluster is exactly one. */
43 #define QCOW_OFLAG_COPIED     (1LL << 63)
44 /* indicate that the cluster is compressed (they never have the copied flag) */
45 #define QCOW_OFLAG_COMPRESSED (1LL << 62)
46 /* The cluster reads as all zeros */
47 #define QCOW_OFLAG_ZERO (1LL << 0)
48 
49 #define REFCOUNT_SHIFT 1 /* refcount size is 2 bytes */
50 
51 #define MIN_CLUSTER_BITS 9
52 #define MAX_CLUSTER_BITS 21
53 
54 #define L2_CACHE_SIZE 16
55 
56 /* Must be at least 4 to cover all cases of refcount table growth */
57 #define REFCOUNT_CACHE_SIZE 4
58 
59 #define DEFAULT_CLUSTER_SIZE 65536
60 
61 typedef struct QCowHeader {
62     uint32_t magic;
63     uint32_t version;
64     uint64_t backing_file_offset;
65     uint32_t backing_file_size;
66     uint32_t cluster_bits;
67     uint64_t size; /* in bytes */
68     uint32_t crypt_method;
69     uint32_t l1_size; /* XXX: save number of clusters instead ? */
70     uint64_t l1_table_offset;
71     uint64_t refcount_table_offset;
72     uint32_t refcount_table_clusters;
73     uint32_t nb_snapshots;
74     uint64_t snapshots_offset;
75 
76     /* The following fields are only valid for version >= 3 */
77     uint64_t incompatible_features;
78     uint64_t compatible_features;
79     uint64_t autoclear_features;
80 
81     uint32_t refcount_order;
82     uint32_t header_length;
83 } QCowHeader;
84 
85 typedef struct QCowSnapshot {
86     uint64_t l1_table_offset;
87     uint32_t l1_size;
88     char *id_str;
89     char *name;
90     uint64_t disk_size;
91     uint64_t vm_state_size;
92     uint32_t date_sec;
93     uint32_t date_nsec;
94     uint64_t vm_clock_nsec;
95 } QCowSnapshot;
96 
97 struct Qcow2Cache;
98 typedef struct Qcow2Cache Qcow2Cache;
99 
100 typedef struct Qcow2UnknownHeaderExtension {
101     uint32_t magic;
102     uint32_t len;
103     QLIST_ENTRY(Qcow2UnknownHeaderExtension) next;
104     uint8_t data[];
105 } Qcow2UnknownHeaderExtension;
106 
107 enum {
108     QCOW2_FEAT_TYPE_INCOMPATIBLE    = 0,
109     QCOW2_FEAT_TYPE_COMPATIBLE      = 1,
110     QCOW2_FEAT_TYPE_AUTOCLEAR       = 2,
111 };
112 
113 /* Incompatible feature bits */
114 enum {
115     QCOW2_INCOMPAT_DIRTY_BITNR   = 0,
116     QCOW2_INCOMPAT_DIRTY         = 1 << QCOW2_INCOMPAT_DIRTY_BITNR,
117 
118     QCOW2_INCOMPAT_MASK          = QCOW2_INCOMPAT_DIRTY,
119 };
120 
121 /* Compatible feature bits */
122 enum {
123     QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR = 0,
124     QCOW2_COMPAT_LAZY_REFCOUNTS       = 1 << QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR,
125 
126     QCOW2_COMPAT_FEAT_MASK            = QCOW2_COMPAT_LAZY_REFCOUNTS,
127 };
128 
129 typedef struct Qcow2Feature {
130     uint8_t type;
131     uint8_t bit;
132     char    name[46];
133 } QEMU_PACKED Qcow2Feature;
134 
135 typedef struct BDRVQcowState {
136     int cluster_bits;
137     int cluster_size;
138     int cluster_sectors;
139     int l2_bits;
140     int l2_size;
141     int l1_size;
142     int l1_vm_state_index;
143     int csize_shift;
144     int csize_mask;
145     uint64_t cluster_offset_mask;
146     uint64_t l1_table_offset;
147     uint64_t *l1_table;
148 
149     Qcow2Cache* l2_table_cache;
150     Qcow2Cache* refcount_block_cache;
151 
152     uint8_t *cluster_cache;
153     uint8_t *cluster_data;
154     uint64_t cluster_cache_offset;
155     QLIST_HEAD(QCowClusterAlloc, QCowL2Meta) cluster_allocs;
156 
157     uint64_t *refcount_table;
158     uint64_t refcount_table_offset;
159     uint32_t refcount_table_size;
160     int64_t free_cluster_index;
161     int64_t free_byte_offset;
162 
163     CoMutex lock;
164 
165     uint32_t crypt_method; /* current crypt method, 0 if no key yet */
166     uint32_t crypt_method_header;
167     AES_KEY aes_encrypt_key;
168     AES_KEY aes_decrypt_key;
169     uint64_t snapshots_offset;
170     int snapshots_size;
171     int nb_snapshots;
172     QCowSnapshot *snapshots;
173 
174     int flags;
175     int qcow_version;
176 
177     uint64_t incompatible_features;
178     uint64_t compatible_features;
179     uint64_t autoclear_features;
180 
181     size_t unknown_header_fields_size;
182     void* unknown_header_fields;
183     QLIST_HEAD(, Qcow2UnknownHeaderExtension) unknown_header_ext;
184 } BDRVQcowState;
185 
186 /* XXX: use std qcow open function ? */
187 typedef struct QCowCreateState {
188     int cluster_size;
189     int cluster_bits;
190     uint16_t *refcount_block;
191     uint64_t *refcount_table;
192     int64_t l1_table_offset;
193     int64_t refcount_table_offset;
194     int64_t refcount_block_offset;
195 } QCowCreateState;
196 
197 struct QCowAIOCB;
198 
199 typedef struct Qcow2COWRegion {
200     /**
201      * Offset of the COW region in bytes from the start of the first cluster
202      * touched by the request.
203      */
204     uint64_t    offset;
205 
206     /** Number of sectors to copy */
207     int         nb_sectors;
208 } Qcow2COWRegion;
209 
210 /**
211  * Describes an in-flight (part of a) write request that writes to clusters
212  * that are not referenced in their L2 table yet.
213  */
214 typedef struct QCowL2Meta
215 {
216     /** Guest offset of the first newly allocated cluster */
217     uint64_t offset;
218 
219     /** Host offset of the first newly allocated cluster */
220     uint64_t alloc_offset;
221 
222     /**
223      * Number of sectors from the start of the first allocated cluster to
224      * the end of the (possibly shortened) request
225      */
226     int nb_available;
227 
228     /** Number of newly allocated clusters */
229     int nb_clusters;
230 
231     /**
232      * Requests that overlap with this allocation and wait to be restarted
233      * when the allocating request has completed.
234      */
235     CoQueue dependent_requests;
236 
237     /**
238      * The COW Region between the start of the first allocated cluster and the
239      * area the guest actually writes to.
240      */
241     Qcow2COWRegion cow_start;
242 
243     /**
244      * The COW Region between the area the guest actually writes to and the
245      * end of the last allocated cluster.
246      */
247     Qcow2COWRegion cow_end;
248 
249     QLIST_ENTRY(QCowL2Meta) next_in_flight;
250 } QCowL2Meta;
251 
252 enum {
253     QCOW2_CLUSTER_UNALLOCATED,
254     QCOW2_CLUSTER_NORMAL,
255     QCOW2_CLUSTER_COMPRESSED,
256     QCOW2_CLUSTER_ZERO
257 };
258 
259 #define L1E_OFFSET_MASK 0x00ffffffffffff00ULL
260 #define L2E_OFFSET_MASK 0x00ffffffffffff00ULL
261 #define L2E_COMPRESSED_OFFSET_SIZE_MASK 0x3fffffffffffffffULL
262 
263 #define REFT_OFFSET_MASK 0xffffffffffffff00ULL
264 
265 static inline int size_to_clusters(BDRVQcowState *s, int64_t size)
266 {
267     return (size + (s->cluster_size - 1)) >> s->cluster_bits;
268 }
269 
270 static inline int size_to_l1(BDRVQcowState *s, int64_t size)
271 {
272     int shift = s->cluster_bits + s->l2_bits;
273     return (size + (1ULL << shift) - 1) >> shift;
274 }
275 
276 static inline int64_t align_offset(int64_t offset, int n)
277 {
278     offset = (offset + n - 1) & ~(n - 1);
279     return offset;
280 }
281 
282 static inline int qcow2_get_cluster_type(uint64_t l2_entry)
283 {
284     if (l2_entry & QCOW_OFLAG_COMPRESSED) {
285         return QCOW2_CLUSTER_COMPRESSED;
286     } else if (l2_entry & QCOW_OFLAG_ZERO) {
287         return QCOW2_CLUSTER_ZERO;
288     } else if (!(l2_entry & L2E_OFFSET_MASK)) {
289         return QCOW2_CLUSTER_UNALLOCATED;
290     } else {
291         return QCOW2_CLUSTER_NORMAL;
292     }
293 }
294 
295 /* Check whether refcounts are eager or lazy */
296 static inline bool qcow2_need_accurate_refcounts(BDRVQcowState *s)
297 {
298     return !(s->incompatible_features & QCOW2_INCOMPAT_DIRTY);
299 }
300 
301 // FIXME Need qcow2_ prefix to global functions
302 
303 /* qcow2.c functions */
304 int qcow2_backing_read1(BlockDriverState *bs, QEMUIOVector *qiov,
305                   int64_t sector_num, int nb_sectors);
306 
307 int qcow2_mark_dirty(BlockDriverState *bs);
308 int qcow2_update_header(BlockDriverState *bs);
309 
310 /* qcow2-refcount.c functions */
311 int qcow2_refcount_init(BlockDriverState *bs);
312 void qcow2_refcount_close(BlockDriverState *bs);
313 
314 int64_t qcow2_alloc_clusters(BlockDriverState *bs, int64_t size);
315 int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
316     int nb_clusters);
317 int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size);
318 void qcow2_free_clusters(BlockDriverState *bs,
319     int64_t offset, int64_t size);
320 void qcow2_free_any_clusters(BlockDriverState *bs,
321     uint64_t cluster_offset, int nb_clusters);
322 
323 int qcow2_update_snapshot_refcount(BlockDriverState *bs,
324     int64_t l1_table_offset, int l1_size, int addend);
325 
326 int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
327                           BdrvCheckMode fix);
328 
329 /* qcow2-cluster.c functions */
330 int qcow2_grow_l1_table(BlockDriverState *bs, int min_size, bool exact_size);
331 void qcow2_l2_cache_reset(BlockDriverState *bs);
332 int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset);
333 void qcow2_encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
334                      uint8_t *out_buf, const uint8_t *in_buf,
335                      int nb_sectors, int enc,
336                      const AES_KEY *key);
337 
338 int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
339     int *num, uint64_t *cluster_offset);
340 int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
341     int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta **m);
342 uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
343                                          uint64_t offset,
344                                          int compressed_size);
345 
346 int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m);
347 int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset,
348     int nb_sectors);
349 int qcow2_zero_clusters(BlockDriverState *bs, uint64_t offset, int nb_sectors);
350 
351 /* qcow2-snapshot.c functions */
352 int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info);
353 int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id);
354 int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id);
355 int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab);
356 int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name);
357 
358 void qcow2_free_snapshots(BlockDriverState *bs);
359 int qcow2_read_snapshots(BlockDriverState *bs);
360 
361 /* qcow2-cache.c functions */
362 Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables);
363 int qcow2_cache_destroy(BlockDriverState* bs, Qcow2Cache *c);
364 
365 void qcow2_cache_entry_mark_dirty(Qcow2Cache *c, void *table);
366 int qcow2_cache_flush(BlockDriverState *bs, Qcow2Cache *c);
367 int qcow2_cache_set_dependency(BlockDriverState *bs, Qcow2Cache *c,
368     Qcow2Cache *dependency);
369 void qcow2_cache_depends_on_flush(Qcow2Cache *c);
370 
371 int qcow2_cache_get(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
372     void **table);
373 int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
374     void **table);
375 int qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table);
376 
377 #endif
378