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qemu/block/vpc.c

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/*
* Block driver for Connectix / Microsoft Virtual PC images
*
* Copyright (c) 2005 Alex Beregszaszi
* Copyright (c) 2009 Kevin Wolf <kwolf@suse.de>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu-common.h"
#include "block_int.h"
#include "module.h"
#include "migration.h"
/**************************************************************/
#define HEADER_SIZE 512
//#define CACHE
enum vhd_type {
VHD_FIXED = 2,
VHD_DYNAMIC = 3,
VHD_DIFFERENCING = 4,
};
// Seconds since Jan 1, 2000 0:00:00 (UTC)
#define VHD_TIMESTAMP_BASE 946684800
// always big-endian
struct vhd_footer {
char creator[8]; // "conectix"
uint32_t features;
uint32_t version;
// Offset of next header structure, 0xFFFFFFFF if none
uint64_t data_offset;
// Seconds since Jan 1, 2000 0:00:00 (UTC)
uint32_t timestamp;
char creator_app[4]; // "vpc "
uint16_t major;
uint16_t minor;
char creator_os[4]; // "Wi2k"
uint64_t orig_size;
uint64_t size;
uint16_t cyls;
uint8_t heads;
uint8_t secs_per_cyl;
uint32_t type;
// Checksum of the Hard Disk Footer ("one's complement of the sum of all
// the bytes in the footer without the checksum field")
uint32_t checksum;
// UUID used to identify a parent hard disk (backing file)
uint8_t uuid[16];
uint8_t in_saved_state;
};
struct vhd_dyndisk_header {
char magic[8]; // "cxsparse"
// Offset of next header structure, 0xFFFFFFFF if none
uint64_t data_offset;
// Offset of the Block Allocation Table (BAT)
uint64_t table_offset;
uint32_t version;
uint32_t max_table_entries; // 32bit/entry
// 2 MB by default, must be a power of two
uint32_t block_size;
uint32_t checksum;
uint8_t parent_uuid[16];
uint32_t parent_timestamp;
uint32_t reserved;
// Backing file name (in UTF-16)
uint8_t parent_name[512];
struct {
uint32_t platform;
uint32_t data_space;
uint32_t data_length;
uint32_t reserved;
uint64_t data_offset;
} parent_locator[8];
};
typedef struct BDRVVPCState {
CoMutex lock;
uint8_t footer_buf[HEADER_SIZE];
uint64_t free_data_block_offset;
int max_table_entries;
uint32_t *pagetable;
uint64_t bat_offset;
uint64_t last_bitmap_offset;
uint32_t block_size;
uint32_t bitmap_size;
#ifdef CACHE
uint8_t *pageentry_u8;
uint32_t *pageentry_u32;
uint16_t *pageentry_u16;
uint64_t last_bitmap;
#endif
Error *migration_blocker;
} BDRVVPCState;
static uint32_t vpc_checksum(uint8_t* buf, size_t size)
{
uint32_t res = 0;
int i;
for (i = 0; i < size; i++)
res += buf[i];
return ~res;
}
static int vpc_probe(const uint8_t *buf, int buf_size, const char *filename)
{
if (buf_size >= 8 && !strncmp((char *)buf, "conectix", 8))
return 100;
return 0;
}
static int vpc_open(BlockDriverState *bs, int flags)
{
BDRVVPCState *s = bs->opaque;
int i;
struct vhd_footer* footer;
struct vhd_dyndisk_header* dyndisk_header;
uint8_t buf[HEADER_SIZE];
uint32_t checksum;
int err = -1;
int disk_type = VHD_DYNAMIC;
if (bdrv_pread(bs->file, 0, s->footer_buf, HEADER_SIZE) != HEADER_SIZE)
goto fail;
footer = (struct vhd_footer*) s->footer_buf;
if (strncmp(footer->creator, "conectix", 8)) {
int64_t offset = bdrv_getlength(bs->file);
if (offset < HEADER_SIZE) {
goto fail;
}
/* If a fixed disk, the footer is found only at the end of the file */
if (bdrv_pread(bs->file, offset-HEADER_SIZE, s->footer_buf, HEADER_SIZE)
!= HEADER_SIZE) {
goto fail;
}
if (strncmp(footer->creator, "conectix", 8)) {
goto fail;
}
disk_type = VHD_FIXED;
}
checksum = be32_to_cpu(footer->checksum);
footer->checksum = 0;
if (vpc_checksum(s->footer_buf, HEADER_SIZE) != checksum)
fprintf(stderr, "block-vpc: The header checksum of '%s' is "
"incorrect.\n", bs->filename);
/* Write 'checksum' back to footer, or else will leave it with zero. */
footer->checksum = be32_to_cpu(checksum);
// The visible size of a image in Virtual PC depends on the geometry
// rather than on the size stored in the footer (the size in the footer
// is too large usually)
bs->total_sectors = (int64_t)
be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl;
if (bs->total_sectors >= 65535 * 16 * 255) {
err = -EFBIG;
goto fail;
}
if (disk_type == VHD_DYNAMIC) {
if (bdrv_pread(bs->file, be64_to_cpu(footer->data_offset), buf,
HEADER_SIZE) != HEADER_SIZE) {
goto fail;
}
dyndisk_header = (struct vhd_dyndisk_header *) buf;
if (strncmp(dyndisk_header->magic, "cxsparse", 8)) {
goto fail;
}
s->block_size = be32_to_cpu(dyndisk_header->block_size);
s->bitmap_size = ((s->block_size / (8 * 512)) + 511) & ~511;
s->max_table_entries = be32_to_cpu(dyndisk_header->max_table_entries);
s->pagetable = g_malloc(s->max_table_entries * 4);
s->bat_offset = be64_to_cpu(dyndisk_header->table_offset);
if (bdrv_pread(bs->file, s->bat_offset, s->pagetable,
s->max_table_entries * 4) != s->max_table_entries * 4) {
goto fail;
}
s->free_data_block_offset =
(s->bat_offset + (s->max_table_entries * 4) + 511) & ~511;
for (i = 0; i < s->max_table_entries; i++) {
be32_to_cpus(&s->pagetable[i]);
if (s->pagetable[i] != 0xFFFFFFFF) {
int64_t next = (512 * (int64_t) s->pagetable[i]) +
s->bitmap_size + s->block_size;
if (next > s->free_data_block_offset) {
s->free_data_block_offset = next;
}
}
}
s->last_bitmap_offset = (int64_t) -1;
#ifdef CACHE
s->pageentry_u8 = g_malloc(512);
s->pageentry_u32 = s->pageentry_u8;
s->pageentry_u16 = s->pageentry_u8;
s->last_pagetable = -1;
#endif
}
qemu_co_mutex_init(&s->lock);
/* Disable migration when VHD images are used */
error_set(&s->migration_blocker,
QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED,
"vpc", bs->device_name, "live migration");
migrate_add_blocker(s->migration_blocker);
return 0;
fail:
return err;
}
/*
* Returns the absolute byte offset of the given sector in the image file.
* If the sector is not allocated, -1 is returned instead.
*
* The parameter write must be 1 if the offset will be used for a write
* operation (the block bitmaps is updated then), 0 otherwise.
*/
static inline int64_t get_sector_offset(BlockDriverState *bs,
int64_t sector_num, int write)
{
BDRVVPCState *s = bs->opaque;
uint64_t offset = sector_num * 512;
uint64_t bitmap_offset, block_offset;
uint32_t pagetable_index, pageentry_index;
pagetable_index = offset / s->block_size;
pageentry_index = (offset % s->block_size) / 512;
if (pagetable_index >= s->max_table_entries || s->pagetable[pagetable_index] == 0xffffffff)
return -1; // not allocated
bitmap_offset = 512 * (uint64_t) s->pagetable[pagetable_index];
block_offset = bitmap_offset + s->bitmap_size + (512 * pageentry_index);
// We must ensure that we don't write to any sectors which are marked as
// unused in the bitmap. We get away with setting all bits in the block
// bitmap each time we write to a new block. This might cause Virtual PC to
// miss sparse read optimization, but it's not a problem in terms of
// correctness.
if (write && (s->last_bitmap_offset != bitmap_offset)) {
uint8_t bitmap[s->bitmap_size];
s->last_bitmap_offset = bitmap_offset;
memset(bitmap, 0xff, s->bitmap_size);
bdrv_pwrite_sync(bs->file, bitmap_offset, bitmap, s->bitmap_size);
}
// printf("sector: %" PRIx64 ", index: %x, offset: %x, bioff: %" PRIx64 ", bloff: %" PRIx64 "\n",
// sector_num, pagetable_index, pageentry_index,
// bitmap_offset, block_offset);
// disabled by reason
#if 0
#ifdef CACHE
if (bitmap_offset != s->last_bitmap)
{
lseek(s->fd, bitmap_offset, SEEK_SET);
s->last_bitmap = bitmap_offset;
// Scary! Bitmap is stored as big endian 32bit entries,
// while we used to look it up byte by byte
read(s->fd, s->pageentry_u8, 512);
for (i = 0; i < 128; i++)
be32_to_cpus(&s->pageentry_u32[i]);
}
if ((s->pageentry_u8[pageentry_index / 8] >> (pageentry_index % 8)) & 1)
return -1;
#else
lseek(s->fd, bitmap_offset + (pageentry_index / 8), SEEK_SET);
read(s->fd, &bitmap_entry, 1);
if ((bitmap_entry >> (pageentry_index % 8)) & 1)
return -1; // not allocated
#endif
#endif
return block_offset;
}
/*
* Writes the footer to the end of the image file. This is needed when the
* file grows as it overwrites the old footer
*
* Returns 0 on success and < 0 on error
*/
static int rewrite_footer(BlockDriverState* bs)
{
int ret;
BDRVVPCState *s = bs->opaque;
int64_t offset = s->free_data_block_offset;
ret = bdrv_pwrite_sync(bs->file, offset, s->footer_buf, HEADER_SIZE);
if (ret < 0)
return ret;
return 0;
}
/*
* Allocates a new block. This involves writing a new footer and updating
* the Block Allocation Table to use the space at the old end of the image
* file (overwriting the old footer)
*
* Returns the sectors' offset in the image file on success and < 0 on error
*/
static int64_t alloc_block(BlockDriverState* bs, int64_t sector_num)
{
BDRVVPCState *s = bs->opaque;
int64_t bat_offset;
uint32_t index, bat_value;
int ret;
uint8_t bitmap[s->bitmap_size];
// Check if sector_num is valid
if ((sector_num < 0) || (sector_num > bs->total_sectors))
return -1;
// Write entry into in-memory BAT
index = (sector_num * 512) / s->block_size;
if (s->pagetable[index] != 0xFFFFFFFF)
return -1;
s->pagetable[index] = s->free_data_block_offset / 512;
// Initialize the block's bitmap
memset(bitmap, 0xff, s->bitmap_size);
ret = bdrv_pwrite_sync(bs->file, s->free_data_block_offset, bitmap,
s->bitmap_size);
if (ret < 0) {
return ret;
}
// Write new footer (the old one will be overwritten)
s->free_data_block_offset += s->block_size + s->bitmap_size;
ret = rewrite_footer(bs);
if (ret < 0)
goto fail;
// Write BAT entry to disk
bat_offset = s->bat_offset + (4 * index);
bat_value = be32_to_cpu(s->pagetable[index]);
ret = bdrv_pwrite_sync(bs->file, bat_offset, &bat_value, 4);
if (ret < 0)
goto fail;
return get_sector_offset(bs, sector_num, 0);
fail:
s->free_data_block_offset -= (s->block_size + s->bitmap_size);
return -1;
}
static int vpc_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
BDRVVPCState *s = bs->opaque;
int ret;
int64_t offset;
int64_t sectors, sectors_per_block;
struct vhd_footer *footer = (struct vhd_footer *) s->footer_buf;
if (cpu_to_be32(footer->type) == VHD_FIXED) {
return bdrv_read(bs->file, sector_num, buf, nb_sectors);
}
while (nb_sectors > 0) {
offset = get_sector_offset(bs, sector_num, 0);
sectors_per_block = s->block_size >> BDRV_SECTOR_BITS;
sectors = sectors_per_block - (sector_num % sectors_per_block);
if (sectors > nb_sectors) {
sectors = nb_sectors;
}
if (offset == -1) {
memset(buf, 0, sectors * BDRV_SECTOR_SIZE);
} else {
ret = bdrv_pread(bs->file, offset, buf,
sectors * BDRV_SECTOR_SIZE);
if (ret != sectors * BDRV_SECTOR_SIZE) {
return -1;
}
}
nb_sectors -= sectors;
sector_num += sectors;
buf += sectors * BDRV_SECTOR_SIZE;
}
return 0;
}
static coroutine_fn int vpc_co_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
int ret;
BDRVVPCState *s = bs->opaque;
qemu_co_mutex_lock(&s->lock);
ret = vpc_read(bs, sector_num, buf, nb_sectors);
qemu_co_mutex_unlock(&s->lock);
return ret;
}
static int vpc_write(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
BDRVVPCState *s = bs->opaque;
int64_t offset;
int64_t sectors, sectors_per_block;
int ret;
struct vhd_footer *footer = (struct vhd_footer *) s->footer_buf;
if (cpu_to_be32(footer->type) == VHD_FIXED) {
return bdrv_write(bs->file, sector_num, buf, nb_sectors);
}
while (nb_sectors > 0) {
offset = get_sector_offset(bs, sector_num, 1);
sectors_per_block = s->block_size >> BDRV_SECTOR_BITS;
sectors = sectors_per_block - (sector_num % sectors_per_block);
if (sectors > nb_sectors) {
sectors = nb_sectors;
}
if (offset == -1) {
offset = alloc_block(bs, sector_num);
if (offset < 0)
return -1;
}
ret = bdrv_pwrite(bs->file, offset, buf, sectors * BDRV_SECTOR_SIZE);
if (ret != sectors * BDRV_SECTOR_SIZE) {
return -1;
}
nb_sectors -= sectors;
sector_num += sectors;
buf += sectors * BDRV_SECTOR_SIZE;
}
return 0;
}
static coroutine_fn int vpc_co_write(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
int ret;
BDRVVPCState *s = bs->opaque;
qemu_co_mutex_lock(&s->lock);
ret = vpc_write(bs, sector_num, buf, nb_sectors);
qemu_co_mutex_unlock(&s->lock);
return ret;
}
/*
* Calculates the number of cylinders, heads and sectors per cylinder
* based on a given number of sectors. This is the algorithm described
* in the VHD specification.
*
* Note that the geometry doesn't always exactly match total_sectors but
* may round it down.
*
* Returns 0 on success, -EFBIG if the size is larger than 127 GB
*/
static int calculate_geometry(int64_t total_sectors, uint16_t* cyls,
uint8_t* heads, uint8_t* secs_per_cyl)
{
uint32_t cyls_times_heads;
if (total_sectors > 65535 * 16 * 255)
return -EFBIG;
if (total_sectors > 65535 * 16 * 63) {
*secs_per_cyl = 255;
*heads = 16;
cyls_times_heads = total_sectors / *secs_per_cyl;
} else {
*secs_per_cyl = 17;
cyls_times_heads = total_sectors / *secs_per_cyl;
*heads = (cyls_times_heads + 1023) / 1024;
if (*heads < 4)
*heads = 4;
if (cyls_times_heads >= (*heads * 1024) || *heads > 16) {
*secs_per_cyl = 31;
*heads = 16;
cyls_times_heads = total_sectors / *secs_per_cyl;
}
if (cyls_times_heads >= (*heads * 1024)) {
*secs_per_cyl = 63;
*heads = 16;
cyls_times_heads = total_sectors / *secs_per_cyl;
}
}
*cyls = cyls_times_heads / *heads;
return 0;
}
static int create_dynamic_disk(int fd, uint8_t *buf, int64_t total_sectors)
{
struct vhd_dyndisk_header* dyndisk_header =
(struct vhd_dyndisk_header*) buf;
size_t block_size, num_bat_entries;
int i;
int ret = -EIO;
// Write the footer (twice: at the beginning and at the end)
block_size = 0x200000;
num_bat_entries = (total_sectors + block_size / 512) / (block_size / 512);
if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE) {
goto fail;
}
if (lseek(fd, 1536 + ((num_bat_entries * 4 + 511) & ~511), SEEK_SET) < 0) {
goto fail;
}
if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE) {
goto fail;
}
// Write the initial BAT
if (lseek(fd, 3 * 512, SEEK_SET) < 0) {
goto fail;
}
memset(buf, 0xFF, 512);
for (i = 0; i < (num_bat_entries * 4 + 511) / 512; i++) {
if (write(fd, buf, 512) != 512) {
goto fail;
}
}
// Prepare the Dynamic Disk Header
memset(buf, 0, 1024);
memcpy(dyndisk_header->magic, "cxsparse", 8);
/*
* Note: The spec is actually wrong here for data_offset, it says
* 0xFFFFFFFF, but MS tools expect all 64 bits to be set.
*/
dyndisk_header->data_offset = be64_to_cpu(0xFFFFFFFFFFFFFFFFULL);
dyndisk_header->table_offset = be64_to_cpu(3 * 512);
dyndisk_header->version = be32_to_cpu(0x00010000);
dyndisk_header->block_size = be32_to_cpu(block_size);
dyndisk_header->max_table_entries = be32_to_cpu(num_bat_entries);
dyndisk_header->checksum = be32_to_cpu(vpc_checksum(buf, 1024));
// Write the header
if (lseek(fd, 512, SEEK_SET) < 0) {
goto fail;
}
if (write(fd, buf, 1024) != 1024) {
goto fail;
}
ret = 0;
fail:
return ret;
}
static int create_fixed_disk(int fd, uint8_t *buf, int64_t total_size)
{
int ret = -EIO;
/* Add footer to total size */
total_size += 512;
if (ftruncate(fd, total_size) != 0) {
ret = -errno;
goto fail;
}
if (lseek(fd, -512, SEEK_END) < 0) {
goto fail;
}
if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE) {
goto fail;
}
ret = 0;
fail:
return ret;
}
static int vpc_create(const char *filename, QEMUOptionParameter *options)
{
uint8_t buf[1024];
struct vhd_footer *footer = (struct vhd_footer *) buf;
QEMUOptionParameter *disk_type_param;
int fd, i;
uint16_t cyls = 0;
uint8_t heads = 0;
uint8_t secs_per_cyl = 0;
int64_t total_sectors;
int64_t total_size;
int disk_type;
int ret = -EIO;
/* Read out options */
total_size = get_option_parameter(options, BLOCK_OPT_SIZE)->value.n;
disk_type_param = get_option_parameter(options, BLOCK_OPT_SUBFMT);
if (disk_type_param && disk_type_param->value.s) {
if (!strcmp(disk_type_param->value.s, "dynamic")) {
disk_type = VHD_DYNAMIC;
} else if (!strcmp(disk_type_param->value.s, "fixed")) {
disk_type = VHD_FIXED;
} else {
return -EINVAL;
}
} else {
disk_type = VHD_DYNAMIC;
}
/* Create the file */
fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
if (fd < 0) {
return -EIO;
}
/*
* Calculate matching total_size and geometry. Increase the number of
* sectors requested until we get enough (or fail). This ensures that
* qemu-img convert doesn't truncate images, but rather rounds up.
*/
total_sectors = total_size / BDRV_SECTOR_SIZE;
for (i = 0; total_sectors > (int64_t)cyls * heads * secs_per_cyl; i++) {
if (calculate_geometry(total_sectors + i, &cyls, &heads,
&secs_per_cyl))
{
ret = -EFBIG;
goto fail;
}
}
total_sectors = (int64_t) cyls * heads * secs_per_cyl;
/* Prepare the Hard Disk Footer */
memset(buf, 0, 1024);
memcpy(footer->creator, "conectix", 8);
/* TODO Check if "qemu" creator_app is ok for VPC */
memcpy(footer->creator_app, "qemu", 4);
memcpy(footer->creator_os, "Wi2k", 4);
footer->features = be32_to_cpu(0x02);
footer->version = be32_to_cpu(0x00010000);
if (disk_type == VHD_DYNAMIC) {
footer->data_offset = be64_to_cpu(HEADER_SIZE);
} else {
footer->data_offset = be64_to_cpu(0xFFFFFFFFFFFFFFFFULL);
}
footer->timestamp = be32_to_cpu(time(NULL) - VHD_TIMESTAMP_BASE);
/* Version of Virtual PC 2007 */
footer->major = be16_to_cpu(0x0005);
footer->minor = be16_to_cpu(0x0003);
if (disk_type == VHD_DYNAMIC) {
footer->orig_size = be64_to_cpu(total_sectors * 512);
footer->size = be64_to_cpu(total_sectors * 512);
} else {
footer->orig_size = be64_to_cpu(total_size);
footer->size = be64_to_cpu(total_size);
}
footer->cyls = be16_to_cpu(cyls);
footer->heads = heads;
footer->secs_per_cyl = secs_per_cyl;
footer->type = be32_to_cpu(disk_type);
/* TODO uuid is missing */
footer->checksum = be32_to_cpu(vpc_checksum(buf, HEADER_SIZE));
if (disk_type == VHD_DYNAMIC) {
ret = create_dynamic_disk(fd, buf, total_sectors);
} else {
ret = create_fixed_disk(fd, buf, total_size);
}
fail:
close(fd);
return ret;
}
static void vpc_close(BlockDriverState *bs)
{
BDRVVPCState *s = bs->opaque;
g_free(s->pagetable);
#ifdef CACHE
g_free(s->pageentry_u8);
#endif
migrate_del_blocker(s->migration_blocker);
error_free(s->migration_blocker);
}
static QEMUOptionParameter vpc_create_options[] = {
{
.name = BLOCK_OPT_SIZE,
.type = OPT_SIZE,
.help = "Virtual disk size"
},
{
.name = BLOCK_OPT_SUBFMT,
.type = OPT_STRING,
.help =
"Type of virtual hard disk format. Supported formats are "
"{dynamic (default) | fixed} "
},
{ NULL }
};
static BlockDriver bdrv_vpc = {
.format_name = "vpc",
.instance_size = sizeof(BDRVVPCState),
.bdrv_probe = vpc_probe,
.bdrv_open = vpc_open,
.bdrv_close = vpc_close,
.bdrv_create = vpc_create,
.bdrv_read = vpc_co_read,
.bdrv_write = vpc_co_write,
.create_options = vpc_create_options,
};
static void bdrv_vpc_init(void)
{
bdrv_register(&bdrv_vpc);
}
block_init(bdrv_vpc_init);
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