1 /*
2 * Block driver for the various disk image formats used by Bochs
3 * Currently only for "growing" type in read-only mode
4 *
5 * Copyright (c) 2005 Alex Beregszaszi
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
23 * THE SOFTWARE.
24 */
25 #include "qemu/osdep.h"
26 #include "qapi/error.h"
27 #include "block/block-io.h"
28 #include "block/block_int.h"
29 #include "qemu/module.h"
30 #include "qemu/bswap.h"
31 #include "qemu/error-report.h"
32
33 /**************************************************************/
34
35 #define HEADER_MAGIC "Bochs Virtual HD Image"
36 #define HEADER_VERSION 0x00020000
37 #define HEADER_V1 0x00010000
38 #define HEADER_SIZE 512
39
40 #define REDOLOG_TYPE "Redolog"
41 #define GROWING_TYPE "Growing"
42
43 // not allocated: 0xffffffff
44
45 // always little-endian
46 struct bochs_header {
47 char magic[32]; /* "Bochs Virtual HD Image" */
48 char type[16]; /* "Redolog" */
49 char subtype[16]; /* "Undoable" / "Volatile" / "Growing" */
50 uint32_t version;
51 uint32_t header; /* size of header */
52
53 uint32_t catalog; /* num of entries */
54 uint32_t bitmap; /* bitmap size */
55 uint32_t extent; /* extent size */
56
57 union {
58 struct {
59 uint32_t reserved; /* for ??? */
60 uint64_t disk; /* disk size */
61 char padding[HEADER_SIZE - 64 - 20 - 12];
62 } QEMU_PACKED redolog;
63 struct {
64 uint64_t disk; /* disk size */
65 char padding[HEADER_SIZE - 64 - 20 - 8];
66 } QEMU_PACKED redolog_v1;
67 char padding[HEADER_SIZE - 64 - 20];
68 } extra;
69 } QEMU_PACKED;
70
71 typedef struct BDRVBochsState {
72 CoMutex lock;
73 uint32_t *catalog_bitmap;
74 uint32_t catalog_size;
75
76 uint32_t data_offset;
77
78 uint32_t bitmap_blocks;
79 uint32_t extent_blocks;
80 uint32_t extent_size;
81 } BDRVBochsState;
82
bochs_probe(const uint8_t * buf,int buf_size,const char * filename)83 static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename)
84 {
85 const struct bochs_header *bochs = (const void *)buf;
86
87 if (buf_size < HEADER_SIZE)
88 return 0;
89
90 if (!strcmp(bochs->magic, HEADER_MAGIC) &&
91 !strcmp(bochs->type, REDOLOG_TYPE) &&
92 !strcmp(bochs->subtype, GROWING_TYPE) &&
93 ((le32_to_cpu(bochs->version) == HEADER_VERSION) ||
94 (le32_to_cpu(bochs->version) == HEADER_V1)))
95 return 100;
96
97 return 0;
98 }
99
bochs_open(BlockDriverState * bs,QDict * options,int flags,Error ** errp)100 static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
101 Error **errp)
102 {
103 BDRVBochsState *s = bs->opaque;
104 uint32_t i;
105 struct bochs_header bochs;
106 int ret;
107
108 GLOBAL_STATE_CODE();
109
110 /* No write support yet */
111 bdrv_graph_rdlock_main_loop();
112 ret = bdrv_apply_auto_read_only(bs, NULL, errp);
113 bdrv_graph_rdunlock_main_loop();
114 if (ret < 0) {
115 return ret;
116 }
117
118 ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
119 if (ret < 0) {
120 return ret;
121 }
122
123 GRAPH_RDLOCK_GUARD_MAINLOOP();
124
125 ret = bdrv_pread(bs->file, 0, sizeof(bochs), &bochs, 0);
126 if (ret < 0) {
127 return ret;
128 }
129
130 if (strcmp(bochs.magic, HEADER_MAGIC) ||
131 strcmp(bochs.type, REDOLOG_TYPE) ||
132 strcmp(bochs.subtype, GROWING_TYPE) ||
133 ((le32_to_cpu(bochs.version) != HEADER_VERSION) &&
134 (le32_to_cpu(bochs.version) != HEADER_V1))) {
135 error_setg(errp, "Image not in Bochs format");
136 return -EINVAL;
137 }
138
139 if (le32_to_cpu(bochs.version) == HEADER_V1) {
140 bs->total_sectors = le64_to_cpu(bochs.extra.redolog_v1.disk) / 512;
141 } else {
142 bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
143 }
144
145 /* Limit to 1M entries to avoid unbounded allocation. This is what is
146 * needed for the largest image that bximage can create (~8 TB). */
147 s->catalog_size = le32_to_cpu(bochs.catalog);
148 if (s->catalog_size > 0x100000) {
149 error_setg(errp, "Catalog size is too large");
150 return -EFBIG;
151 }
152
153 s->catalog_bitmap = g_try_new(uint32_t, s->catalog_size);
154 if (s->catalog_size && s->catalog_bitmap == NULL) {
155 error_setg(errp, "Could not allocate memory for catalog");
156 return -ENOMEM;
157 }
158
159 ret = bdrv_pread(bs->file, le32_to_cpu(bochs.header), s->catalog_size * 4,
160 s->catalog_bitmap, 0);
161 if (ret < 0) {
162 goto fail;
163 }
164
165 for (i = 0; i < s->catalog_size; i++)
166 le32_to_cpus(&s->catalog_bitmap[i]);
167
168 s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4);
169
170 s->bitmap_blocks = 1 + (le32_to_cpu(bochs.bitmap) - 1) / 512;
171 s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512;
172
173 s->extent_size = le32_to_cpu(bochs.extent);
174 if (s->extent_size < BDRV_SECTOR_SIZE) {
175 /* bximage actually never creates extents smaller than 4k */
176 error_setg(errp, "Extent size must be at least 512");
177 ret = -EINVAL;
178 goto fail;
179 } else if (!is_power_of_2(s->extent_size)) {
180 error_setg(errp, "Extent size %" PRIu32 " is not a power of two",
181 s->extent_size);
182 ret = -EINVAL;
183 goto fail;
184 } else if (s->extent_size > 0x800000) {
185 error_setg(errp, "Extent size %" PRIu32 " is too large",
186 s->extent_size);
187 ret = -EINVAL;
188 goto fail;
189 }
190
191 if (s->catalog_size < DIV_ROUND_UP(bs->total_sectors,
192 s->extent_size / BDRV_SECTOR_SIZE))
193 {
194 error_setg(errp, "Catalog size is too small for this disk size");
195 ret = -EINVAL;
196 goto fail;
197 }
198
199 qemu_co_mutex_init(&s->lock);
200 return 0;
201
202 fail:
203 g_free(s->catalog_bitmap);
204 return ret;
205 }
206
bochs_refresh_limits(BlockDriverState * bs,Error ** errp)207 static void bochs_refresh_limits(BlockDriverState *bs, Error **errp)
208 {
209 bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
210 }
211
212 static int64_t coroutine_fn GRAPH_RDLOCK
seek_to_sector(BlockDriverState * bs,int64_t sector_num)213 seek_to_sector(BlockDriverState *bs, int64_t sector_num)
214 {
215 BDRVBochsState *s = bs->opaque;
216 uint64_t offset = sector_num * 512;
217 uint64_t extent_index, extent_offset, bitmap_offset;
218 char bitmap_entry;
219 int ret;
220
221 // seek to sector
222 extent_index = offset / s->extent_size;
223 extent_offset = (offset % s->extent_size) / 512;
224
225 if (s->catalog_bitmap[extent_index] == 0xffffffff) {
226 return 0; /* not allocated */
227 }
228
229 bitmap_offset = s->data_offset +
230 (512 * (uint64_t) s->catalog_bitmap[extent_index] *
231 (s->extent_blocks + s->bitmap_blocks));
232
233 /* read in bitmap for current extent */
234 ret = bdrv_co_pread(bs->file, bitmap_offset + (extent_offset / 8), 1,
235 &bitmap_entry, 0);
236 if (ret < 0) {
237 return ret;
238 }
239
240 if (!((bitmap_entry >> (extent_offset % 8)) & 1)) {
241 return 0; /* not allocated */
242 }
243
244 return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
245 }
246
247 static int coroutine_fn GRAPH_RDLOCK
bochs_co_preadv(BlockDriverState * bs,int64_t offset,int64_t bytes,QEMUIOVector * qiov,BdrvRequestFlags flags)248 bochs_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
249 QEMUIOVector *qiov, BdrvRequestFlags flags)
250 {
251 BDRVBochsState *s = bs->opaque;
252 uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
253 int nb_sectors = bytes >> BDRV_SECTOR_BITS;
254 uint64_t bytes_done = 0;
255 QEMUIOVector local_qiov;
256 int ret;
257
258 assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE));
259 assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE));
260
261 qemu_iovec_init(&local_qiov, qiov->niov);
262 qemu_co_mutex_lock(&s->lock);
263
264 while (nb_sectors > 0) {
265 int64_t block_offset = seek_to_sector(bs, sector_num);
266 if (block_offset < 0) {
267 ret = block_offset;
268 goto fail;
269 }
270
271 qemu_iovec_reset(&local_qiov);
272 qemu_iovec_concat(&local_qiov, qiov, bytes_done, 512);
273
274 if (block_offset > 0) {
275 ret = bdrv_co_preadv(bs->file, block_offset, 512,
276 &local_qiov, 0);
277 if (ret < 0) {
278 goto fail;
279 }
280 } else {
281 qemu_iovec_memset(&local_qiov, 0, 0, 512);
282 }
283 nb_sectors--;
284 sector_num++;
285 bytes_done += 512;
286 }
287
288 ret = 0;
289 fail:
290 qemu_co_mutex_unlock(&s->lock);
291 qemu_iovec_destroy(&local_qiov);
292
293 return ret;
294 }
295
bochs_close(BlockDriverState * bs)296 static void bochs_close(BlockDriverState *bs)
297 {
298 BDRVBochsState *s = bs->opaque;
299 g_free(s->catalog_bitmap);
300 }
301
302 static BlockDriver bdrv_bochs = {
303 .format_name = "bochs",
304 .instance_size = sizeof(BDRVBochsState),
305 .bdrv_probe = bochs_probe,
306 .bdrv_open = bochs_open,
307 .bdrv_child_perm = bdrv_default_perms,
308 .bdrv_refresh_limits = bochs_refresh_limits,
309 .bdrv_co_preadv = bochs_co_preadv,
310 .bdrv_close = bochs_close,
311 .is_format = true,
312 };
313
bdrv_bochs_init(void)314 static void bdrv_bochs_init(void)
315 {
316 bdrv_register(&bdrv_bochs);
317 }
318
319 block_init(bdrv_bochs_init);
320