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      1 /*
      2  * Block driver for Connectix / Microsoft Virtual PC images
      3  *
      4  * Copyright (c) 2005 Alex Beregszaszi
      5  * Copyright (c) 2009 Kevin Wolf <kwolf (at) suse.de>
      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-common.h"
     26 #include "block_int.h"
     27 #include "module.h"
     28 
     29 /**************************************************************/
     30 
     31 #define HEADER_SIZE 512
     32 
     33 //#define CACHE
     34 
     35 enum vhd_type {
     36     VHD_FIXED           = 2,
     37     VHD_DYNAMIC         = 3,
     38     VHD_DIFFERENCING    = 4,
     39 };
     40 
     41 // Seconds since Jan 1, 2000 0:00:00 (UTC)
     42 #define VHD_TIMESTAMP_BASE 946684800
     43 
     44 // always big-endian
     45 struct vhd_footer {
     46     char        creator[8]; // "conectix"
     47     uint32_t    features;
     48     uint32_t    version;
     49 
     50     // Offset of next header structure, 0xFFFFFFFF if none
     51     uint64_t    data_offset;
     52 
     53     // Seconds since Jan 1, 2000 0:00:00 (UTC)
     54     uint32_t    timestamp;
     55 
     56     char        creator_app[4]; // "vpc "
     57     uint16_t    major;
     58     uint16_t    minor;
     59     char        creator_os[4]; // "Wi2k"
     60 
     61     uint64_t    orig_size;
     62     uint64_t    size;
     63 
     64     uint16_t    cyls;
     65     uint8_t     heads;
     66     uint8_t     secs_per_cyl;
     67 
     68     uint32_t    type;
     69 
     70     // Checksum of the Hard Disk Footer ("one's complement of the sum of all
     71     // the bytes in the footer without the checksum field")
     72     uint32_t    checksum;
     73 
     74     // UUID used to identify a parent hard disk (backing file)
     75     uint8_t     uuid[16];
     76 
     77     uint8_t     in_saved_state;
     78 };
     79 
     80 struct vhd_dyndisk_header {
     81     char        magic[8]; // "cxsparse"
     82 
     83     // Offset of next header structure, 0xFFFFFFFF if none
     84     uint64_t    data_offset;
     85 
     86     // Offset of the Block Allocation Table (BAT)
     87     uint64_t    table_offset;
     88 
     89     uint32_t    version;
     90     uint32_t    max_table_entries; // 32bit/entry
     91 
     92     // 2 MB by default, must be a power of two
     93     uint32_t    block_size;
     94 
     95     uint32_t    checksum;
     96     uint8_t     parent_uuid[16];
     97     uint32_t    parent_timestamp;
     98     uint32_t    reserved;
     99 
    100     // Backing file name (in UTF-16)
    101     uint8_t     parent_name[512];
    102 
    103     struct {
    104         uint32_t    platform;
    105         uint32_t    data_space;
    106         uint32_t    data_length;
    107         uint32_t    reserved;
    108         uint64_t    data_offset;
    109     } parent_locator[8];
    110 };
    111 
    112 typedef struct BDRVVPCState {
    113     BlockDriverState *hd;
    114 
    115     uint8_t footer_buf[HEADER_SIZE];
    116     uint64_t free_data_block_offset;
    117     int max_table_entries;
    118     uint32_t *pagetable;
    119     uint64_t bat_offset;
    120     uint64_t last_bitmap_offset;
    121 
    122     uint32_t block_size;
    123     uint32_t bitmap_size;
    124 
    125 #ifdef CACHE
    126     uint8_t *pageentry_u8;
    127     uint32_t *pageentry_u32;
    128     uint16_t *pageentry_u16;
    129 
    130     uint64_t last_bitmap;
    131 #endif
    132 } BDRVVPCState;
    133 
    134 static uint32_t vpc_checksum(uint8_t* buf, size_t size)
    135 {
    136     uint32_t res = 0;
    137     int i;
    138 
    139     for (i = 0; i < size; i++)
    140         res += buf[i];
    141 
    142     return ~res;
    143 }
    144 
    145 
    146 static int vpc_probe(const uint8_t *buf, int buf_size, const char *filename)
    147 {
    148     if (buf_size >= 8 && !strncmp((char *)buf, "conectix", 8))
    149 	return 100;
    150     return 0;
    151 }
    152 
    153 static int vpc_open(BlockDriverState *bs, int flags)
    154 {
    155     BDRVVPCState *s = bs->opaque;
    156     int i;
    157     struct vhd_footer* footer;
    158     struct vhd_dyndisk_header* dyndisk_header;
    159     uint8_t buf[HEADER_SIZE];
    160     uint32_t checksum;
    161 
    162     if (bdrv_pread(bs->file, 0, s->footer_buf, HEADER_SIZE) != HEADER_SIZE)
    163         goto fail;
    164 
    165     footer = (struct vhd_footer*) s->footer_buf;
    166     if (strncmp(footer->creator, "conectix", 8))
    167         goto fail;
    168 
    169     checksum = be32_to_cpu(footer->checksum);
    170     footer->checksum = 0;
    171     if (vpc_checksum(s->footer_buf, HEADER_SIZE) != checksum)
    172         fprintf(stderr, "block-vpc: The header checksum of '%s' is "
    173             "incorrect.\n", bs->filename);
    174 
    175     // The visible size of a image in Virtual PC depends on the geometry
    176     // rather than on the size stored in the footer (the size in the footer
    177     // is too large usually)
    178     bs->total_sectors = (int64_t)
    179         be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl;
    180 
    181     if (bdrv_pread(bs->file, be64_to_cpu(footer->data_offset), buf, HEADER_SIZE)
    182             != HEADER_SIZE)
    183         goto fail;
    184 
    185     dyndisk_header = (struct vhd_dyndisk_header*) buf;
    186 
    187     if (strncmp(dyndisk_header->magic, "cxsparse", 8))
    188         goto fail;
    189 
    190 
    191     s->block_size = be32_to_cpu(dyndisk_header->block_size);
    192     s->bitmap_size = ((s->block_size / (8 * 512)) + 511) & ~511;
    193 
    194     s->max_table_entries = be32_to_cpu(dyndisk_header->max_table_entries);
    195     s->pagetable = qemu_malloc(s->max_table_entries * 4);
    196 
    197     s->bat_offset = be64_to_cpu(dyndisk_header->table_offset);
    198     if (bdrv_pread(bs->file, s->bat_offset, s->pagetable,
    199             s->max_table_entries * 4) != s->max_table_entries * 4)
    200 	    goto fail;
    201 
    202     s->free_data_block_offset =
    203         (s->bat_offset + (s->max_table_entries * 4) + 511) & ~511;
    204 
    205     for (i = 0; i < s->max_table_entries; i++) {
    206         be32_to_cpus(&s->pagetable[i]);
    207         if (s->pagetable[i] != 0xFFFFFFFF) {
    208             int64_t next = (512 * (int64_t) s->pagetable[i]) +
    209                 s->bitmap_size + s->block_size;
    210 
    211             if (next> s->free_data_block_offset)
    212                 s->free_data_block_offset = next;
    213         }
    214     }
    215 
    216     s->last_bitmap_offset = (int64_t) -1;
    217 
    218 #ifdef CACHE
    219     s->pageentry_u8 = qemu_malloc(512);
    220     s->pageentry_u32 = s->pageentry_u8;
    221     s->pageentry_u16 = s->pageentry_u8;
    222     s->last_pagetable = -1;
    223 #endif
    224 
    225     return 0;
    226  fail:
    227     return -1;
    228 }
    229 
    230 /*
    231  * Returns the absolute byte offset of the given sector in the image file.
    232  * If the sector is not allocated, -1 is returned instead.
    233  *
    234  * The parameter write must be 1 if the offset will be used for a write
    235  * operation (the block bitmaps is updated then), 0 otherwise.
    236  */
    237 static inline int64_t get_sector_offset(BlockDriverState *bs,
    238     int64_t sector_num, int write)
    239 {
    240     BDRVVPCState *s = bs->opaque;
    241     uint64_t offset = sector_num * 512;
    242     uint64_t bitmap_offset, block_offset;
    243     uint32_t pagetable_index, pageentry_index;
    244 
    245     pagetable_index = offset / s->block_size;
    246     pageentry_index = (offset % s->block_size) / 512;
    247 
    248     if (pagetable_index >= s->max_table_entries || s->pagetable[pagetable_index] == 0xffffffff)
    249         return -1; // not allocated
    250 
    251     bitmap_offset = 512 * (uint64_t) s->pagetable[pagetable_index];
    252     block_offset = bitmap_offset + s->bitmap_size + (512 * pageentry_index);
    253 
    254     // We must ensure that we don't write to any sectors which are marked as
    255     // unused in the bitmap. We get away with setting all bits in the block
    256     // bitmap each time we write to a new block. This might cause Virtual PC to
    257     // miss sparse read optimization, but it's not a problem in terms of
    258     // correctness.
    259     if (write && (s->last_bitmap_offset != bitmap_offset)) {
    260         uint8_t bitmap[s->bitmap_size];
    261 
    262         s->last_bitmap_offset = bitmap_offset;
    263         memset(bitmap, 0xff, s->bitmap_size);
    264         bdrv_pwrite_sync(bs->file, bitmap_offset, bitmap, s->bitmap_size);
    265     }
    266 
    267 //    printf("sector: %" PRIx64 ", index: %x, offset: %x, bioff: %" PRIx64 ", bloff: %" PRIx64 "\n",
    268 //	sector_num, pagetable_index, pageentry_index,
    269 //	bitmap_offset, block_offset);
    270 
    271 // disabled by reason
    272 #if 0
    273 #ifdef CACHE
    274     if (bitmap_offset != s->last_bitmap)
    275     {
    276 	lseek(s->fd, bitmap_offset, SEEK_SET);
    277 
    278 	s->last_bitmap = bitmap_offset;
    279 
    280 	// Scary! Bitmap is stored as big endian 32bit entries,
    281 	// while we used to look it up byte by byte
    282 	read(s->fd, s->pageentry_u8, 512);
    283 	for (i = 0; i < 128; i++)
    284 	    be32_to_cpus(&s->pageentry_u32[i]);
    285     }
    286 
    287     if ((s->pageentry_u8[pageentry_index / 8] >> (pageentry_index % 8)) & 1)
    288 	return -1;
    289 #else
    290     lseek(s->fd, bitmap_offset + (pageentry_index / 8), SEEK_SET);
    291 
    292     read(s->fd, &bitmap_entry, 1);
    293 
    294     if ((bitmap_entry >> (pageentry_index % 8)) & 1)
    295 	return -1; // not allocated
    296 #endif
    297 #endif
    298 
    299     return block_offset;
    300 }
    301 
    302 /*
    303  * Writes the footer to the end of the image file. This is needed when the
    304  * file grows as it overwrites the old footer
    305  *
    306  * Returns 0 on success and < 0 on error
    307  */
    308 static int rewrite_footer(BlockDriverState* bs)
    309 {
    310     int ret;
    311     BDRVVPCState *s = bs->opaque;
    312     int64_t offset = s->free_data_block_offset;
    313 
    314     ret = bdrv_pwrite_sync(bs->file, offset, s->footer_buf, HEADER_SIZE);
    315     if (ret < 0)
    316         return ret;
    317 
    318     return 0;
    319 }
    320 
    321 /*
    322  * Allocates a new block. This involves writing a new footer and updating
    323  * the Block Allocation Table to use the space at the old end of the image
    324  * file (overwriting the old footer)
    325  *
    326  * Returns the sectors' offset in the image file on success and < 0 on error
    327  */
    328 static int64_t alloc_block(BlockDriverState* bs, int64_t sector_num)
    329 {
    330     BDRVVPCState *s = bs->opaque;
    331     int64_t bat_offset;
    332     uint32_t index, bat_value;
    333     int ret;
    334     uint8_t bitmap[s->bitmap_size];
    335 
    336     // Check if sector_num is valid
    337     if ((sector_num < 0) || (sector_num > bs->total_sectors))
    338         return -1;
    339 
    340     // Write entry into in-memory BAT
    341     index = (sector_num * 512) / s->block_size;
    342     if (s->pagetable[index] != 0xFFFFFFFF)
    343         return -1;
    344 
    345     s->pagetable[index] = s->free_data_block_offset / 512;
    346 
    347     // Initialize the block's bitmap
    348     memset(bitmap, 0xff, s->bitmap_size);
    349     bdrv_pwrite_sync(bs->file, s->free_data_block_offset, bitmap,
    350         s->bitmap_size);
    351 
    352     // Write new footer (the old one will be overwritten)
    353     s->free_data_block_offset += s->block_size + s->bitmap_size;
    354     ret = rewrite_footer(bs);
    355     if (ret < 0)
    356         goto fail;
    357 
    358     // Write BAT entry to disk
    359     bat_offset = s->bat_offset + (4 * index);
    360     bat_value = be32_to_cpu(s->pagetable[index]);
    361     ret = bdrv_pwrite_sync(bs->file, bat_offset, &bat_value, 4);
    362     if (ret < 0)
    363         goto fail;
    364 
    365     return get_sector_offset(bs, sector_num, 0);
    366 
    367 fail:
    368     s->free_data_block_offset -= (s->block_size + s->bitmap_size);
    369     return -1;
    370 }
    371 
    372 static int vpc_read(BlockDriverState *bs, int64_t sector_num,
    373                     uint8_t *buf, int nb_sectors)
    374 {
    375     BDRVVPCState *s = bs->opaque;
    376     int ret;
    377     int64_t offset;
    378     int64_t sectors, sectors_per_block;
    379 
    380     while (nb_sectors > 0) {
    381         offset = get_sector_offset(bs, sector_num, 0);
    382 
    383         sectors_per_block = s->block_size >> BDRV_SECTOR_BITS;
    384         sectors = sectors_per_block - (sector_num % sectors_per_block);
    385         if (sectors > nb_sectors) {
    386             sectors = nb_sectors;
    387         }
    388 
    389         if (offset == -1) {
    390             memset(buf, 0, sectors * BDRV_SECTOR_SIZE);
    391         } else {
    392             ret = bdrv_pread(bs->file, offset, buf,
    393                 sectors * BDRV_SECTOR_SIZE);
    394             if (ret != sectors * BDRV_SECTOR_SIZE) {
    395                 return -1;
    396             }
    397         }
    398 
    399         nb_sectors -= sectors;
    400         sector_num += sectors;
    401         buf += sectors * BDRV_SECTOR_SIZE;
    402     }
    403     return 0;
    404 }
    405 
    406 static int vpc_write(BlockDriverState *bs, int64_t sector_num,
    407     const uint8_t *buf, int nb_sectors)
    408 {
    409     BDRVVPCState *s = bs->opaque;
    410     int64_t offset;
    411     int64_t sectors, sectors_per_block;
    412     int ret;
    413 
    414     while (nb_sectors > 0) {
    415         offset = get_sector_offset(bs, sector_num, 1);
    416 
    417         sectors_per_block = s->block_size >> BDRV_SECTOR_BITS;
    418         sectors = sectors_per_block - (sector_num % sectors_per_block);
    419         if (sectors > nb_sectors) {
    420             sectors = nb_sectors;
    421         }
    422 
    423         if (offset == -1) {
    424             offset = alloc_block(bs, sector_num);
    425             if (offset < 0)
    426                 return -1;
    427         }
    428 
    429         ret = bdrv_pwrite(bs->file, offset, buf, sectors * BDRV_SECTOR_SIZE);
    430         if (ret != sectors * BDRV_SECTOR_SIZE) {
    431             return -1;
    432         }
    433 
    434         nb_sectors -= sectors;
    435         sector_num += sectors;
    436         buf += sectors * BDRV_SECTOR_SIZE;
    437     }
    438 
    439     return 0;
    440 }
    441 
    442 
    443 /*
    444  * Calculates the number of cylinders, heads and sectors per cylinder
    445  * based on a given number of sectors. This is the algorithm described
    446  * in the VHD specification.
    447  *
    448  * Note that the geometry doesn't always exactly match total_sectors but
    449  * may round it down.
    450  *
    451  * Returns 0 on success, -EFBIG if the size is larger than 127 GB
    452  */
    453 static int calculate_geometry(int64_t total_sectors, uint16_t* cyls,
    454     uint8_t* heads, uint8_t* secs_per_cyl)
    455 {
    456     uint32_t cyls_times_heads;
    457 
    458     if (total_sectors > 65535 * 16 * 255)
    459         return -EFBIG;
    460 
    461     if (total_sectors > 65535 * 16 * 63) {
    462         *secs_per_cyl = 255;
    463         *heads = 16;
    464         cyls_times_heads = total_sectors / *secs_per_cyl;
    465     } else {
    466         *secs_per_cyl = 17;
    467         cyls_times_heads = total_sectors / *secs_per_cyl;
    468         *heads = (cyls_times_heads + 1023) / 1024;
    469 
    470         if (*heads < 4)
    471             *heads = 4;
    472 
    473         if (cyls_times_heads >= (*heads * 1024) || *heads > 16) {
    474             *secs_per_cyl = 31;
    475             *heads = 16;
    476             cyls_times_heads = total_sectors / *secs_per_cyl;
    477         }
    478 
    479         if (cyls_times_heads >= (*heads * 1024)) {
    480             *secs_per_cyl = 63;
    481             *heads = 16;
    482             cyls_times_heads = total_sectors / *secs_per_cyl;
    483         }
    484     }
    485 
    486     *cyls = cyls_times_heads / *heads;
    487 
    488     return 0;
    489 }
    490 
    491 static int vpc_create(const char *filename, QEMUOptionParameter *options)
    492 {
    493     uint8_t buf[1024];
    494     struct vhd_footer* footer = (struct vhd_footer*) buf;
    495     struct vhd_dyndisk_header* dyndisk_header =
    496         (struct vhd_dyndisk_header*) buf;
    497     int fd, i;
    498     uint16_t cyls = 0;
    499     uint8_t heads = 0;
    500     uint8_t secs_per_cyl = 0;
    501     size_t block_size, num_bat_entries;
    502     int64_t total_sectors = 0;
    503 
    504     // Read out options
    505     while (options && options->name) {
    506         if (!strcmp(options->name, "size")) {
    507             total_sectors = options->value.n / 512;
    508         }
    509         options++;
    510     }
    511 
    512     // Create the file
    513     fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
    514     if (fd < 0)
    515         return -EIO;
    516 
    517     /* Calculate matching total_size and geometry. Increase the number of
    518        sectors requested until we get enough (or fail). */
    519     for (i = 0; total_sectors > (int64_t)cyls * heads * secs_per_cyl; i++) {
    520         if (calculate_geometry(total_sectors + i,
    521                                &cyls, &heads, &secs_per_cyl)) {
    522             return -EFBIG;
    523         }
    524     }
    525     total_sectors = (int64_t) cyls * heads * secs_per_cyl;
    526 
    527     // Prepare the Hard Disk Footer
    528     memset(buf, 0, 1024);
    529 
    530     memcpy(footer->creator, "conectix", 8);
    531     // TODO Check if "qemu" creator_app is ok for VPC
    532     memcpy(footer->creator_app, "qemu", 4);
    533     memcpy(footer->creator_os, "Wi2k", 4);
    534 
    535     footer->features = be32_to_cpu(0x02);
    536     footer->version = be32_to_cpu(0x00010000);
    537     footer->data_offset = be64_to_cpu(HEADER_SIZE);
    538     footer->timestamp = be32_to_cpu(time(NULL) - VHD_TIMESTAMP_BASE);
    539 
    540     // Version of Virtual PC 2007
    541     footer->major = be16_to_cpu(0x0005);
    542     footer->minor =be16_to_cpu(0x0003);
    543 
    544     footer->orig_size = be64_to_cpu(total_sectors * 512);
    545     footer->size = be64_to_cpu(total_sectors * 512);
    546 
    547     footer->cyls = be16_to_cpu(cyls);
    548     footer->heads = heads;
    549     footer->secs_per_cyl = secs_per_cyl;
    550 
    551     footer->type = be32_to_cpu(VHD_DYNAMIC);
    552 
    553     // TODO uuid is missing
    554 
    555     footer->checksum = be32_to_cpu(vpc_checksum(buf, HEADER_SIZE));
    556 
    557     // Write the footer (twice: at the beginning and at the end)
    558     block_size = 0x200000;
    559     num_bat_entries = (total_sectors + block_size / 512) / (block_size / 512);
    560 
    561     if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE)
    562         return -EIO;
    563 
    564     if (lseek(fd, 1536 + ((num_bat_entries * 4 + 511) & ~511), SEEK_SET) < 0)
    565         return -EIO;
    566     if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE)
    567         return -EIO;
    568 
    569     // Write the initial BAT
    570     if (lseek(fd, 3 * 512, SEEK_SET) < 0)
    571         return -EIO;
    572 
    573     memset(buf, 0xFF, 512);
    574     for (i = 0; i < (num_bat_entries * 4 + 511) / 512; i++)
    575         if (write(fd, buf, 512) != 512)
    576             return -EIO;
    577 
    578 
    579     // Prepare the Dynamic Disk Header
    580     memset(buf, 0, 1024);
    581 
    582     memcpy(dyndisk_header->magic, "cxsparse", 8);
    583 
    584     dyndisk_header->data_offset = be64_to_cpu(0xFFFFFFFF);
    585     dyndisk_header->table_offset = be64_to_cpu(3 * 512);
    586     dyndisk_header->version = be32_to_cpu(0x00010000);
    587     dyndisk_header->block_size = be32_to_cpu(block_size);
    588     dyndisk_header->max_table_entries = be32_to_cpu(num_bat_entries);
    589 
    590     dyndisk_header->checksum = be32_to_cpu(vpc_checksum(buf, 1024));
    591 
    592     // Write the header
    593     if (lseek(fd, 512, SEEK_SET) < 0)
    594         return -EIO;
    595     if (write(fd, buf, 1024) != 1024)
    596         return -EIO;
    597 
    598     close(fd);
    599     return 0;
    600 }
    601 
    602 static void vpc_close(BlockDriverState *bs)
    603 {
    604     BDRVVPCState *s = bs->opaque;
    605     qemu_free(s->pagetable);
    606 #ifdef CACHE
    607     qemu_free(s->pageentry_u8);
    608 #endif
    609 }
    610 
    611 static QEMUOptionParameter vpc_create_options[] = {
    612     {
    613         .name = BLOCK_OPT_SIZE,
    614         .type = OPT_SIZE,
    615         .help = "Virtual disk size"
    616     },
    617     { NULL }
    618 };
    619 
    620 static BlockDriver bdrv_vpc = {
    621     .format_name	= "vpc",
    622     .instance_size	= sizeof(BDRVVPCState),
    623     .bdrv_probe		= vpc_probe,
    624     .bdrv_open		= vpc_open,
    625     .bdrv_read		= vpc_read,
    626     .bdrv_write		= vpc_write,
    627     .bdrv_close		= vpc_close,
    628     .bdrv_create	= vpc_create,
    629 
    630     .create_options = vpc_create_options,
    631 };
    632 
    633 static void bdrv_vpc_init(void)
    634 {
    635     bdrv_register(&bdrv_vpc);
    636 }
    637 
    638 block_init(bdrv_vpc_init);
    639