LXR qemu/block/bochs.c

   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 "qemu-common.h"
  28#include "block/block_int.h"
  29#include "qemu/module.h"
  30#include "qemu/bswap.h"
  31
  32/**************************************************************/
  33
  34#define HEADER_MAGIC "Bochs Virtual HD Image"
  35#define HEADER_VERSION 0x00020000
  36#define HEADER_V1 0x00010000
  37#define HEADER_SIZE 512
  38
  39#define REDOLOG_TYPE "Redolog"
  40#define GROWING_TYPE "Growing"
  41
  42// not allocated: 0xffffffff
  43
  44// always little-endian
  45struct bochs_header {
  46    char magic[32];     /* "Bochs Virtual HD Image" */
  47    char type[16];      /* "Redolog" */
  48    char subtype[16];   /* "Undoable" / "Volatile" / "Growing" */
  49    uint32_t version;
  50    uint32_t header;    /* size of header */
  51
  52    uint32_t catalog;   /* num of entries */
  53    uint32_t bitmap;    /* bitmap size */
  54    uint32_t extent;    /* extent size */
  55
  56    union {
  57        struct {
  58            uint32_t reserved;  /* for ??? */
  59            uint64_t disk;      /* disk size */
  60            char padding[HEADER_SIZE - 64 - 20 - 12];
  61        } QEMU_PACKED redolog;
  62        struct {
  63            uint64_t disk;      /* disk size */
  64            char padding[HEADER_SIZE - 64 - 20 - 8];
  65        } QEMU_PACKED redolog_v1;
  66        char padding[HEADER_SIZE - 64 - 20];
  67    } extra;
  68} QEMU_PACKED;
  69
  70typedef struct BDRVBochsState {
  71    CoMutex lock;
  72    uint32_t *catalog_bitmap;
  73    uint32_t catalog_size;
  74
  75    uint32_t data_offset;
  76
  77    uint32_t bitmap_blocks;
  78    uint32_t extent_blocks;
  79    uint32_t extent_size;
  80} BDRVBochsState;
  81
  82static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename)
  83{
  84    const struct bochs_header *bochs = (const void *)buf;
  85
  86    if (buf_size < HEADER_SIZE)
  87        return 0;
  88
  89    if (!strcmp(bochs->magic, HEADER_MAGIC) &&
  90        !strcmp(bochs->type, REDOLOG_TYPE) &&
  91        !strcmp(bochs->subtype, GROWING_TYPE) &&
  92        ((le32_to_cpu(bochs->version) == HEADER_VERSION) ||
  93        (le32_to_cpu(bochs->version) == HEADER_V1)))
  94        return 100;
  95
  96    return 0;
  97}
  98
  99static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
 100                      Error **errp)
 101{
 102    BDRVBochsState *s = bs->opaque;
 103    uint32_t i;
 104    struct bochs_header bochs;
 105    int ret;
 106
 107    bs->read_only = true; /* no write support yet */
 108
 109    ret = bdrv_pread(bs->file, 0, &bochs, sizeof(bochs));
 110    if (ret < 0) {
 111        return ret;
 112    }
 113
 114    if (strcmp(bochs.magic, HEADER_MAGIC) ||
 115        strcmp(bochs.type, REDOLOG_TYPE) ||
 116        strcmp(bochs.subtype, GROWING_TYPE) ||
 117        ((le32_to_cpu(bochs.version) != HEADER_VERSION) &&
 118        (le32_to_cpu(bochs.version) != HEADER_V1))) {
 119        error_setg(errp, "Image not in Bochs format");
 120        return -EINVAL;
 121    }
 122
 123    if (le32_to_cpu(bochs.version) == HEADER_V1) {
 124        bs->total_sectors = le64_to_cpu(bochs.extra.redolog_v1.disk) / 512;
 125    } else {
 126        bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
 127    }
 128
 129    /* Limit to 1M entries to avoid unbounded allocation. This is what is
 130     * needed for the largest image that bximage can create (~8 TB). */
 131    s->catalog_size = le32_to_cpu(bochs.catalog);
 132    if (s->catalog_size > 0x100000) {
 133        error_setg(errp, "Catalog size is too large");
 134        return -EFBIG;
 135    }
 136
 137    s->catalog_bitmap = g_try_new(uint32_t, s->catalog_size);
 138    if (s->catalog_size && s->catalog_bitmap == NULL) {
 139        error_setg(errp, "Could not allocate memory for catalog");
 140        return -ENOMEM;
 141    }
 142
 143    ret = bdrv_pread(bs->file, le32_to_cpu(bochs.header), s->catalog_bitmap,
 144                     s->catalog_size * 4);
 145    if (ret < 0) {
 146        goto fail;
 147    }
 148
 149    for (i = 0; i < s->catalog_size; i++)
 150        le32_to_cpus(&s->catalog_bitmap[i]);
 151
 152    s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4);
 153
 154    s->bitmap_blocks = 1 + (le32_to_cpu(bochs.bitmap) - 1) / 512;
 155    s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512;
 156
 157    s->extent_size = le32_to_cpu(bochs.extent);
 158    if (s->extent_size < BDRV_SECTOR_SIZE) {
 159        /* bximage actually never creates extents smaller than 4k */
 160        error_setg(errp, "Extent size must be at least 512");
 161        ret = -EINVAL;
 162        goto fail;
 163    } else if (!is_power_of_2(s->extent_size)) {
 164        error_setg(errp, "Extent size %" PRIu32 " is not a power of two",
 165                   s->extent_size);
 166        ret = -EINVAL;
 167        goto fail;
 168    } else if (s->extent_size > 0x800000) {
 169        error_setg(errp, "Extent size %" PRIu32 " is too large",
 170                   s->extent_size);
 171        ret = -EINVAL;
 172        goto fail;
 173    }
 174
 175    if (s->catalog_size < DIV_ROUND_UP(bs->total_sectors,
 176                                       s->extent_size / BDRV_SECTOR_SIZE))
 177    {
 178        error_setg(errp, "Catalog size is too small for this disk size");
 179        ret = -EINVAL;
 180        goto fail;
 181    }
 182
 183    qemu_co_mutex_init(&s->lock);
 184    return 0;
 185
 186fail:
 187    g_free(s->catalog_bitmap);
 188    return ret;
 189}
 190
 191static void bochs_refresh_limits(BlockDriverState *bs, Error **errp)
 192{
 193    bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
 194}
 195
 196static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num)
 197{
 198    BDRVBochsState *s = bs->opaque;
 199    uint64_t offset = sector_num * 512;
 200    uint64_t extent_index, extent_offset, bitmap_offset;
 201    char bitmap_entry;
 202    int ret;
 203
 204    // seek to sector
 205    extent_index = offset / s->extent_size;
 206    extent_offset = (offset % s->extent_size) / 512;
 207
 208    if (s->catalog_bitmap[extent_index] == 0xffffffff) {
 209        return 0; /* not allocated */
 210    }
 211
 212    bitmap_offset = s->data_offset +
 213        (512 * (uint64_t) s->catalog_bitmap[extent_index] *
 214        (s->extent_blocks + s->bitmap_blocks));
 215
 216    /* read in bitmap for current extent */
 217    ret = bdrv_pread(bs->file, bitmap_offset + (extent_offset / 8),
 218                     &bitmap_entry, 1);
 219    if (ret < 0) {
 220        return ret;
 221    }
 222
 223    if (!((bitmap_entry >> (extent_offset % 8)) & 1)) {
 224        return 0; /* not allocated */
 225    }
 226
 227    return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
 228}
 229
 230static int coroutine_fn
 231bochs_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 232                QEMUIOVector *qiov, int flags)
 233{
 234    BDRVBochsState *s = bs->opaque;
 235    uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
 236    int nb_sectors = bytes >> BDRV_SECTOR_BITS;
 237    uint64_t bytes_done = 0;
 238    QEMUIOVector local_qiov;
 239    int ret;
 240
 241    assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
 242    assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
 243
 244    qemu_iovec_init(&local_qiov, qiov->niov);
 245    qemu_co_mutex_lock(&s->lock);
 246
 247    while (nb_sectors > 0) {
 248        int64_t block_offset = seek_to_sector(bs, sector_num);
 249        if (block_offset < 0) {
 250            ret = block_offset;
 251            goto fail;
 252        }
 253
 254        qemu_iovec_reset(&local_qiov);
 255        qemu_iovec_concat(&local_qiov, qiov, bytes_done, 512);
 256
 257        if (block_offset > 0) {
 258            ret = bdrv_co_preadv(bs->file, block_offset, 512,
 259                                 &local_qiov, 0);
 260            if (ret < 0) {
 261                goto fail;
 262            }
 263        } else {
 264            qemu_iovec_memset(&local_qiov, 0, 0, 512);
 265        }
 266        nb_sectors--;
 267        sector_num++;
 268        bytes_done += 512;
 269    }
 270
 271    ret = 0;
 272fail:
 273    qemu_co_mutex_unlock(&s->lock);
 274    qemu_iovec_destroy(&local_qiov);
 275
 276    return ret;
 277}
 278
 279static void bochs_close(BlockDriverState *bs)
 280{
 281    BDRVBochsState *s = bs->opaque;
 282    g_free(s->catalog_bitmap);
 283}
 284
 285static BlockDriver bdrv_bochs = {
 286    .format_name        = "bochs",
 287    .instance_size      = sizeof(BDRVBochsState),
 288    .bdrv_probe         = bochs_probe,
 289    .bdrv_open          = bochs_open,
 290    .bdrv_refresh_limits = bochs_refresh_limits,
 291    .bdrv_co_preadv = bochs_co_preadv,
 292    .bdrv_close         = bochs_close,
 293};
 294
 295static void bdrv_bochs_init(void)
 296{
 297    bdrv_register(&bdrv_bochs);
 298}
 299
 300block_init(bdrv_bochs_init);
 301