/* * Block driver for Hyper-V VHDX Images * * Copyright (c) 2013 Red Hat, Inc., * * Authors: * Jeff Cody * * This is based on the "VHDX Format Specification v0.95", published 4/12/2012 * by Microsoft: * https://www.microsoft.com/en-us/download/details.aspx?id=29681 * * This work is licensed under the terms of the GNU LGPL, version 2 or later. * See the COPYING.LIB file in the top-level directory. * */ #include "qemu-common.h" #include "block/block_int.h" #include "qemu/module.h" #include "qemu/crc32c.h" #include "block/vhdx.h" /* Several metadata and region table data entries are identified by * guids in a MS-specific GUID format. */ /* ------- Known Region Table GUIDs ---------------------- */ static const MSGUID bat_guid = { .data1 = 0x2dc27766, .data2 = 0xf623, .data3 = 0x4200, .data4 = { 0x9d, 0x64, 0x11, 0x5e, 0x9b, 0xfd, 0x4a, 0x08} }; static const MSGUID metadata_guid = { .data1 = 0x8b7ca206, .data2 = 0x4790, .data3 = 0x4b9a, .data4 = { 0xb8, 0xfe, 0x57, 0x5f, 0x05, 0x0f, 0x88, 0x6e} }; /* ------- Known Metadata Entry GUIDs ---------------------- */ static const MSGUID file_param_guid = { .data1 = 0xcaa16737, .data2 = 0xfa36, .data3 = 0x4d43, .data4 = { 0xb3, 0xb6, 0x33, 0xf0, 0xaa, 0x44, 0xe7, 0x6b} }; static const MSGUID virtual_size_guid = { .data1 = 0x2FA54224, .data2 = 0xcd1b, .data3 = 0x4876, .data4 = { 0xb2, 0x11, 0x5d, 0xbe, 0xd8, 0x3b, 0xf4, 0xb8} }; static const MSGUID page83_guid = { .data1 = 0xbeca12ab, .data2 = 0xb2e6, .data3 = 0x4523, .data4 = { 0x93, 0xef, 0xc3, 0x09, 0xe0, 0x00, 0xc7, 0x46} }; static const MSGUID phys_sector_guid = { .data1 = 0xcda348c7, .data2 = 0x445d, .data3 = 0x4471, .data4 = { 0x9c, 0xc9, 0xe9, 0x88, 0x52, 0x51, 0xc5, 0x56} }; static const MSGUID parent_locator_guid = { .data1 = 0xa8d35f2d, .data2 = 0xb30b, .data3 = 0x454d, .data4 = { 0xab, 0xf7, 0xd3, 0xd8, 0x48, 0x34, 0xab, 0x0c} }; static const MSGUID logical_sector_guid = { .data1 = 0x8141bf1d, .data2 = 0xa96f, .data3 = 0x4709, .data4 = { 0xba, 0x47, 0xf2, 0x33, 0xa8, 0xfa, 0xab, 0x5f} }; /* Each parent type must have a valid GUID; this is for parent images * of type 'VHDX'. If we were to allow e.g. a QCOW2 parent, we would * need to make up our own QCOW2 GUID type */ static const MSGUID parent_vhdx_guid = { .data1 = 0xb04aefb7, .data2 = 0xd19e, .data3 = 0x4a81, .data4 = { 0xb7, 0x89, 0x25, 0xb8, 0xe9, 0x44, 0x59, 0x13} }; #define META_FILE_PARAMETER_PRESENT 0x01 #define META_VIRTUAL_DISK_SIZE_PRESENT 0x02 #define META_PAGE_83_PRESENT 0x04 #define META_LOGICAL_SECTOR_SIZE_PRESENT 0x08 #define META_PHYS_SECTOR_SIZE_PRESENT 0x10 #define META_PARENT_LOCATOR_PRESENT 0x20 #define META_ALL_PRESENT \ (META_FILE_PARAMETER_PRESENT | META_VIRTUAL_DISK_SIZE_PRESENT | \ META_PAGE_83_PRESENT | META_LOGICAL_SECTOR_SIZE_PRESENT | \ META_PHYS_SECTOR_SIZE_PRESENT) typedef struct VHDXMetadataEntries { VHDXMetadataTableEntry file_parameters_entry; VHDXMetadataTableEntry virtual_disk_size_entry; VHDXMetadataTableEntry page83_data_entry; VHDXMetadataTableEntry logical_sector_size_entry; VHDXMetadataTableEntry phys_sector_size_entry; VHDXMetadataTableEntry parent_locator_entry; uint16_t present; } VHDXMetadataEntries; typedef struct VHDXSectorInfo { uint32_t bat_idx; /* BAT entry index */ uint32_t sectors_avail; /* sectors available in payload block */ uint32_t bytes_left; /* bytes left in the block after data to r/w */ uint32_t bytes_avail; /* bytes available in payload block */ uint64_t file_offset; /* absolute offset in bytes, in file */ uint64_t block_offset; /* block offset, in bytes */ } VHDXSectorInfo; typedef struct BDRVVHDXState { CoMutex lock; int curr_header; VHDXHeader *headers[2]; VHDXRegionTableHeader rt; VHDXRegionTableEntry bat_rt; /* region table for the BAT */ VHDXRegionTableEntry metadata_rt; /* region table for the metadata */ VHDXMetadataTableHeader metadata_hdr; VHDXMetadataEntries metadata_entries; VHDXFileParameters params; uint32_t block_size; uint32_t block_size_bits; uint32_t sectors_per_block; uint32_t sectors_per_block_bits; uint64_t virtual_disk_size; uint32_t logical_sector_size; uint32_t physical_sector_size; uint64_t chunk_ratio; uint32_t chunk_ratio_bits; uint32_t logical_sector_size_bits; uint32_t bat_entries; VHDXBatEntry *bat; uint64_t bat_offset; VHDXParentLocatorHeader parent_header; VHDXParentLocatorEntry *parent_entries; } BDRVVHDXState; uint32_t vhdx_checksum_calc(uint32_t crc, uint8_t *buf, size_t size, int crc_offset) { uint32_t crc_new; uint32_t crc_orig; assert(buf != NULL); if (crc_offset > 0) { memcpy(&crc_orig, buf + crc_offset, sizeof(crc_orig)); memset(buf + crc_offset, 0, sizeof(crc_orig)); } crc_new = crc32c(crc, buf, size); if (crc_offset > 0) { memcpy(buf + crc_offset, &crc_orig, sizeof(crc_orig)); } return crc_new; } /* Validates the checksum of the buffer, with an in-place CRC. * * Zero is substituted during crc calculation for the original crc field, * and the crc field is restored afterwards. But the buffer will be modifed * during the calculation, so this may not be not suitable for multi-threaded * use. * * crc_offset: byte offset in buf of the buffer crc * buf: buffer pointer * size: size of buffer (must be > crc_offset+4) * * returns true if checksum is valid, false otherwise */ bool vhdx_checksum_is_valid(uint8_t *buf, size_t size, int crc_offset) { uint32_t crc_orig; uint32_t crc; assert(buf != NULL); assert(size > (crc_offset + 4)); memcpy(&crc_orig, buf + crc_offset, sizeof(crc_orig)); crc_orig = le32_to_cpu(crc_orig); crc = vhdx_checksum_calc(0xffffffff, buf, size, crc_offset); return crc == crc_orig; } /* * Per the MS VHDX Specification, for every VHDX file: * - The header section is fixed size - 1 MB * - The header section is always the first "object" * - The first 64KB of the header is the File Identifier * - The first uint64 (8 bytes) is the VHDX Signature ("vhdxfile") * - The following 512 bytes constitute a UTF-16 string identifiying the * software that created the file, and is optional and diagnostic only. * * Therefore, we probe by looking for the vhdxfile signature "vhdxfile" */ static int vhdx_probe(const uint8_t *buf, int buf_size, const char *filename) { if (buf_size >= 8 && !memcmp(buf, "vhdxfile", 8)) { return 100; } return 0; } /* All VHDX structures on disk are little endian */ static void vhdx_header_le_import(VHDXHeader *h) { assert(h != NULL); le32_to_cpus(&h->signature); le32_to_cpus(&h->checksum); le64_to_cpus(&h->sequence_number); leguid_to_cpus(&h->file_write_guid); leguid_to_cpus(&h->data_write_guid); leguid_to_cpus(&h->log_guid); le16_to_cpus(&h->log_version); le16_to_cpus(&h->version); le32_to_cpus(&h->log_length); le64_to_cpus(&h->log_offset); } /* opens the specified header block from the VHDX file header section */ static int vhdx_parse_header(BlockDriverState *bs, BDRVVHDXState *s) { int ret = 0; VHDXHeader *header1; VHDXHeader *header2; bool h1_valid = false; bool h2_valid = false; uint64_t h1_seq = 0; uint64_t h2_seq = 0; uint8_t *buffer; header1 = qemu_blockalign(bs, sizeof(VHDXHeader)); header2 = qemu_blockalign(bs, sizeof(VHDXHeader)); buffer = qemu_blockalign(bs, VHDX_HEADER_SIZE); s->headers[0] = header1; s->headers[1] = header2; /* We have to read the whole VHDX_HEADER_SIZE instead of * sizeof(VHDXHeader), because the checksum is over the whole * region */ ret = bdrv_pread(bs->file, VHDX_HEADER1_OFFSET, buffer, VHDX_HEADER_SIZE); if (ret < 0) { goto fail; } /* copy over just the relevant portion that we need */ memcpy(header1, buffer, sizeof(VHDXHeader)); vhdx_header_le_import(header1); if (vhdx_checksum_is_valid(buffer, VHDX_HEADER_SIZE, 4) && !memcmp(&header1->signature, "head", 4) && header1->version == 1) { h1_seq = header1->sequence_number; h1_valid = true; } ret = bdrv_pread(bs->file, VHDX_HEADER2_OFFSET, buffer, VHDX_HEADER_SIZE); if (ret < 0) { goto fail; } /* copy over just the relevant portion that we need */ memcpy(header2, buffer, sizeof(VHDXHeader)); vhdx_header_le_import(header2); if (vhdx_checksum_is_valid(buffer, VHDX_HEADER_SIZE, 4) && !memcmp(&header2->signature, "head", 4) && header2->version == 1) { h2_seq = header2->sequence_number; h2_valid = true; } /* If there is only 1 valid header (or no valid headers), we * don't care what the sequence numbers are */ if (h1_valid && !h2_valid) { s->curr_header = 0; } else if (!h1_valid && h2_valid) { s->curr_header = 1; } else if (!h1_valid && !h2_valid) { ret = -EINVAL; goto fail; } else { /* If both headers are valid, then we choose the active one by the * highest sequence number. If the sequence numbers are equal, that is * invalid */ if (h1_seq > h2_seq) { s->curr_header = 0; } else if (h2_seq > h1_seq) { s->curr_header = 1; } else { ret = -EINVAL; goto fail; } } ret = 0; goto exit; fail: qerror_report(ERROR_CLASS_GENERIC_ERROR, "No valid VHDX header found"); qemu_vfree(header1); qemu_vfree(header2); s->headers[0] = NULL; s->headers[1] = NULL; exit: qemu_vfree(buffer); return ret; } static int vhdx_open_region_tables(BlockDriverState *bs, BDRVVHDXState *s) { int ret = 0; uint8_t *buffer; int offset = 0; VHDXRegionTableEntry rt_entry; uint32_t i; bool bat_rt_found = false; bool metadata_rt_found = false; /* We have to read the whole 64KB block, because the crc32 is over the * whole block */ buffer = qemu_blockalign(bs, VHDX_HEADER_BLOCK_SIZE); ret = bdrv_pread(bs->file, VHDX_REGION_TABLE_OFFSET, buffer, VHDX_HEADER_BLOCK_SIZE); if (ret < 0) { goto fail; } memcpy(&s->rt, buffer, sizeof(s->rt)); le32_to_cpus(&s->rt.signature); le32_to_cpus(&s->rt.checksum); le32_to_cpus(&s->rt.entry_count); le32_to_cpus(&s->rt.reserved); offset += sizeof(s->rt); if (!vhdx_checksum_is_valid(buffer, VHDX_HEADER_BLOCK_SIZE, 4) || memcmp(&s->rt.signature, "regi", 4)) { ret = -EINVAL; goto fail; } /* Per spec, maximum region table entry count is 2047 */ if (s->rt.entry_count > 2047) { ret = -EINVAL; goto fail; } for (i = 0; i < s->rt.entry_count; i++) { memcpy(&rt_entry, buffer + offset, sizeof(rt_entry)); offset += sizeof(rt_entry); leguid_to_cpus(&rt_entry.guid); le64_to_cpus(&rt_entry.file_offset); le32_to_cpus(&rt_entry.length); le32_to_cpus(&rt_entry.data_bits); /* see if we recognize the entry */ if (guid_eq(rt_entry.guid, bat_guid)) { /* must be unique; if we have already found it this is invalid */ if (bat_rt_found) { ret = -EINVAL; goto fail; } bat_rt_found = true; s->bat_rt = rt_entry; continue; } if (guid_eq(rt_entry.guid, metadata_guid)) { /* must be unique; if we have already found it this is invalid */ if (metadata_rt_found) { ret = -EINVAL; goto fail; } metadata_rt_found = true; s->metadata_rt = rt_entry; continue; } if (rt_entry.data_bits & VHDX_REGION_ENTRY_REQUIRED) { /* cannot read vhdx file - required region table entry that * we do not understand. per spec, we must fail to open */ ret = -ENOTSUP; goto fail; } } ret = 0; fail: qemu_vfree(buffer); return ret; } /* Metadata initial parser * * This loads all the metadata entry fields. This may cause additional * fields to be processed (e.g. parent locator, etc..). * * There are 5 Metadata items that are always required: * - File Parameters (block size, has a parent) * - Virtual Disk Size (size, in bytes, of the virtual drive) * - Page 83 Data (scsi page 83 guid) * - Logical Sector Size (logical sector size in bytes, either 512 or * 4096. We only support 512 currently) * - Physical Sector Size (512 or 4096) * * Also, if the File Parameters indicate this is a differencing file, * we must also look for the Parent Locator metadata item. */ static int vhdx_parse_metadata(BlockDriverState *bs, BDRVVHDXState *s) { int ret = 0; uint8_t *buffer; int offset = 0; uint32_t i = 0; VHDXMetadataTableEntry md_entry; buffer = qemu_blockalign(bs, VHDX_METADATA_TABLE_MAX_SIZE); ret = bdrv_pread(bs->file, s->metadata_rt.file_offset, buffer, VHDX_METADATA_TABLE_MAX_SIZE); if (ret < 0) { goto exit; } memcpy(&s->metadata_hdr, buffer, sizeof(s->metadata_hdr)); offset += sizeof(s->metadata_hdr); le64_to_cpus(&s->metadata_hdr.signature); le16_to_cpus(&s->metadata_hdr.reserved); le16_to_cpus(&s->metadata_hdr.entry_count); if (memcmp(&s->metadata_hdr.signature, "metadata", 8)) { ret = -EINVAL; goto exit; } s->metadata_entries.present = 0; if ((s->metadata_hdr.entry_count * sizeof(md_entry)) > (VHDX_METADATA_TABLE_MAX_SIZE - offset)) { ret = -EINVAL; goto exit; } for (i = 0; i < s->metadata_hdr.entry_count; i++) { memcpy(&md_entry, buffer + offset, sizeof(md_entry)); offset += sizeof(md_entry); leguid_to_cpus(&md_entry.item_id); le32_to_cpus(&md_entry.offset); le32_to_cpus(&md_entry.length); le32_to_cpus(&md_entry.data_bits); le32_to_cpus(&md_entry.reserved2); if (guid_eq(md_entry.item_id, file_param_guid)) { if (s->metadata_entries.present & META_FILE_PARAMETER_PRESENT) { ret = -EINVAL; goto exit; } s->metadata_entries.file_parameters_entry = md_entry; s->metadata_entries.present |= META_FILE_PARAMETER_PRESENT; continue; } if (guid_eq(md_entry.item_id, virtual_size_guid)) { if (s->metadata_entries.present & META_VIRTUAL_DISK_SIZE_PRESENT) { ret = -EINVAL; goto exit; } s->metadata_entries.virtual_disk_size_entry = md_entry; s->metadata_entries.present |= META_VIRTUAL_DISK_SIZE_PRESENT; continue; } if (guid_eq(md_entry.item_id, page83_guid)) { if (s->metadata_entries.present & META_PAGE_83_PRESENT) { ret = -EINVAL; goto exit; } s->metadata_entries.page83_data_entry = md_entry; s->metadata_entries.present |= META_PAGE_83_PRESENT; continue; } if (guid_eq(md_entry.item_id, logical_sector_guid)) { if (s->metadata_entries.present & META_LOGICAL_SECTOR_SIZE_PRESENT) { ret = -EINVAL; goto exit; } s->metadata_entries.logical_sector_size_entry = md_entry; s->metadata_entries.present |= META_LOGICAL_SECTOR_SIZE_PRESENT; continue; } if (guid_eq(md_entry.item_id, phys_sector_guid)) { if (s->metadata_entries.present & META_PHYS_SECTOR_SIZE_PRESENT) { ret = -EINVAL; goto exit; } s->metadata_entries.phys_sector_size_entry = md_entry; s->metadata_entries.present |= META_PHYS_SECTOR_SIZE_PRESENT; continue; } if (guid_eq(md_entry.item_id, parent_locator_guid)) { if (s->metadata_entries.present & META_PARENT_LOCATOR_PRESENT) { ret = -EINVAL; goto exit; } s->metadata_entries.parent_locator_entry = md_entry; s->metadata_entries.present |= META_PARENT_LOCATOR_PRESENT; continue; } if (md_entry.data_bits & VHDX_META_FLAGS_IS_REQUIRED) { /* cannot read vhdx file - required region table entry that * we do not understand. per spec, we must fail to open */ ret = -ENOTSUP; goto exit; } } if (s->metadata_entries.present != META_ALL_PRESENT) { ret = -ENOTSUP; goto exit; } ret = bdrv_pread(bs->file, s->metadata_entries.file_parameters_entry.offset + s->metadata_rt.file_offset, &s->params, sizeof(s->params)); if (ret < 0) { goto exit; } le32_to_cpus(&s->params.block_size); le32_to_cpus(&s->params.data_bits); /* We now have the file parameters, so we can tell if this is a * differencing file (i.e.. has_parent), is dynamic or fixed * sized (leave_blocks_allocated), and the block size */ /* The parent locator required iff the file parameters has_parent set */ if (s->params.data_bits & VHDX_PARAMS_HAS_PARENT) { if (s->metadata_entries.present & META_PARENT_LOCATOR_PRESENT) { /* TODO: parse parent locator fields */ ret = -ENOTSUP; /* temp, until differencing files are supported */ goto exit; } else { /* if has_parent is set, but there is not parent locator present, * then that is an invalid combination */ ret = -EINVAL; goto exit; } } /* determine virtual disk size, logical sector size, * and phys sector size */ ret = bdrv_pread(bs->file, s->metadata_entries.virtual_disk_size_entry.offset + s->metadata_rt.file_offset, &s->virtual_disk_size, sizeof(uint64_t)); if (ret < 0) { goto exit; } ret = bdrv_pread(bs->file, s->metadata_entries.logical_sector_size_entry.offset + s->metadata_rt.file_offset, &s->logical_sector_size, sizeof(uint32_t)); if (ret < 0) { goto exit; } ret = bdrv_pread(bs->file, s->metadata_entries.phys_sector_size_entry.offset + s->metadata_rt.file_offset, &s->physical_sector_size, sizeof(uint32_t)); if (ret < 0) { goto exit; } le64_to_cpus(&s->virtual_disk_size); le32_to_cpus(&s->logical_sector_size); le32_to_cpus(&s->physical_sector_size); if (s->logical_sector_size == 0 || s->params.block_size == 0) { ret = -EINVAL; goto exit; } /* both block_size and sector_size are guaranteed powers of 2 */ s->sectors_per_block = s->params.block_size / s->logical_sector_size; s->chunk_ratio = (VHDX_MAX_SECTORS_PER_BLOCK) * (uint64_t)s->logical_sector_size / (uint64_t)s->params.block_size; /* These values are ones we will want to use for division / multiplication * later on, and they are all guaranteed (per the spec) to be powers of 2, * so we can take advantage of that for shift operations during * reads/writes */ if (s->logical_sector_size & (s->logical_sector_size - 1)) { ret = -EINVAL; goto exit; } if (s->sectors_per_block & (s->sectors_per_block - 1)) { ret = -EINVAL; goto exit; } if (s->chunk_ratio & (s->chunk_ratio - 1)) { ret = -EINVAL; goto exit; } s->block_size = s->params.block_size; if (s->block_size & (s->block_size - 1)) { ret = -EINVAL; goto exit; } s->logical_sector_size_bits = 31 - clz32(s->logical_sector_size); s->sectors_per_block_bits = 31 - clz32(s->sectors_per_block); s->chunk_ratio_bits = 63 - clz64(s->chunk_ratio); s->block_size_bits = 31 - clz32(s->block_size); ret = 0; exit: qemu_vfree(buffer); return ret; } /* Parse the replay log. Per the VHDX spec, if the log is present * it must be replayed prior to opening the file, even read-only. * * If read-only, we must replay the log in RAM (or refuse to open * a dirty VHDX file read-only */ static int vhdx_parse_log(BlockDriverState *bs, BDRVVHDXState *s) { int ret = 0; int i; VHDXHeader *hdr; hdr = s->headers[s->curr_header]; /* either the log guid, or log length is zero, * then a replay log is present */ for (i = 0; i < sizeof(hdr->log_guid.data4); i++) { ret |= hdr->log_guid.data4[i]; } if (hdr->log_guid.data1 == 0 && hdr->log_guid.data2 == 0 && hdr->log_guid.data3 == 0 && ret == 0) { goto exit; } /* per spec, only log version of 0 is supported */ if (hdr->log_version != 0) { ret = -EINVAL; goto exit; } if (hdr->log_length == 0) { goto exit; } /* We currently do not support images with logs to replay */ ret = -ENOTSUP; exit: return ret; } static int vhdx_open(BlockDriverState *bs, QDict *options, int flags) { BDRVVHDXState *s = bs->opaque; int ret = 0; uint32_t i; uint64_t signature; uint32_t data_blocks_cnt, bitmap_blocks_cnt; s->bat = NULL; qemu_co_mutex_init(&s->lock); /* validate the file signature */ ret = bdrv_pread(bs->file, 0, &signature, sizeof(uint64_t)); if (ret < 0) { goto fail; } if (memcmp(&signature, "vhdxfile", 8)) { ret = -EINVAL; goto fail; } ret = vhdx_parse_header(bs, s); if (ret) { goto fail; } ret = vhdx_parse_log(bs, s); if (ret) { goto fail; } ret = vhdx_open_region_tables(bs, s); if (ret) { goto fail; } ret = vhdx_parse_metadata(bs, s); if (ret) { goto fail; } s->block_size = s->params.block_size; /* the VHDX spec dictates that virtual_disk_size is always a multiple of * logical_sector_size */ bs->total_sectors = s->virtual_disk_size >> s->logical_sector_size_bits; data_blocks_cnt = s->virtual_disk_size >> s->block_size_bits; if (s->virtual_disk_size - (data_blocks_cnt << s->block_size_bits)) { data_blocks_cnt++; } bitmap_blocks_cnt = data_blocks_cnt >> s->chunk_ratio_bits; if (data_blocks_cnt - (bitmap_blocks_cnt << s->chunk_ratio_bits)) { bitmap_blocks_cnt++; } if (s->parent_entries) { s->bat_entries = bitmap_blocks_cnt * (s->chunk_ratio + 1); } else { s->bat_entries = data_blocks_cnt + ((data_blocks_cnt - 1) >> s->chunk_ratio_bits); } s->bat_offset = s->bat_rt.file_offset; if (s->bat_entries > s->bat_rt.length / sizeof(VHDXBatEntry)) { /* BAT allocation is not large enough for all entries */ ret = -EINVAL; goto fail; } s->bat = qemu_blockalign(bs, s->bat_rt.length); ret = bdrv_pread(bs->file, s->bat_offset, s->bat, s->bat_rt.length); if (ret < 0) { goto fail; } for (i = 0; i < s->bat_entries; i++) { le64_to_cpus(&s->bat[i]); } if (flags & BDRV_O_RDWR) { ret = -ENOTSUP; goto fail; } /* TODO: differencing files, write */ return 0; fail: qemu_vfree(s->headers[0]); qemu_vfree(s->headers[1]); qemu_vfree(s->bat); qemu_vfree(s->parent_entries); return ret; } static int vhdx_reopen_prepare(BDRVReopenState *state, BlockReopenQueue *queue, Error **errp) { return 0; } /* * Perform sector to block offset translations, to get various * sector and file offsets into the image. See VHDXSectorInfo */ static void vhdx_block_translate(BDRVVHDXState *s, int64_t sector_num, int nb_sectors, VHDXSectorInfo *sinfo) { uint32_t block_offset; sinfo->bat_idx = sector_num >> s->sectors_per_block_bits; /* effectively a modulo - this gives us the offset into the block * (in sector sizes) for our sector number */ block_offset = sector_num - (sinfo->bat_idx << s->sectors_per_block_bits); /* the chunk ratio gives us the interleaving of the sector * bitmaps, so we need to advance our page block index by the * sector bitmaps entry number */ sinfo->bat_idx += sinfo->bat_idx >> s->chunk_ratio_bits; /* the number of sectors we can read/write in this cycle */ sinfo->sectors_avail = s->sectors_per_block - block_offset; sinfo->bytes_left = sinfo->sectors_avail << s->logical_sector_size_bits; if (sinfo->sectors_avail > nb_sectors) { sinfo->sectors_avail = nb_sectors; } sinfo->bytes_avail = sinfo->sectors_avail << s->logical_sector_size_bits; sinfo->file_offset = s->bat[sinfo->bat_idx] >> VHDX_BAT_FILE_OFF_BITS; sinfo->block_offset = block_offset << s->logical_sector_size_bits; /* The file offset must be past the header section, so must be > 0 */ if (sinfo->file_offset == 0) { return; } /* block offset is the offset in vhdx logical sectors, in * the payload data block. Convert that to a byte offset * in the block, and add in the payload data block offset * in the file, in bytes, to get the final read address */ sinfo->file_offset <<= 20; /* now in bytes, rather than 1MB units */ sinfo->file_offset += sinfo->block_offset; } static coroutine_fn int vhdx_co_readv(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) { BDRVVHDXState *s = bs->opaque; int ret = 0; VHDXSectorInfo sinfo; uint64_t bytes_done = 0; QEMUIOVector hd_qiov; qemu_iovec_init(&hd_qiov, qiov->niov); qemu_co_mutex_lock(&s->lock); while (nb_sectors > 0) { /* We are a differencing file, so we need to inspect the sector bitmap * to see if we have the data or not */ if (s->params.data_bits & VHDX_PARAMS_HAS_PARENT) { /* not supported yet */ ret = -ENOTSUP; goto exit; } else { vhdx_block_translate(s, sector_num, nb_sectors, &sinfo); qemu_iovec_reset(&hd_qiov); qemu_iovec_concat(&hd_qiov, qiov, bytes_done, sinfo.bytes_avail); /* check the payload block state */ switch (s->bat[sinfo.bat_idx] & VHDX_BAT_STATE_BIT_MASK) { case PAYLOAD_BLOCK_NOT_PRESENT: /* fall through */ case PAYLOAD_BLOCK_UNDEFINED: /* fall through */ case PAYLOAD_BLOCK_UNMAPPED: /* fall through */ case PAYLOAD_BLOCK_ZERO: /* return zero */ qemu_iovec_memset(&hd_qiov, 0, 0, sinfo.bytes_avail); break; case PAYLOAD_BLOCK_FULL_PRESENT: qemu_co_mutex_unlock(&s->lock); ret = bdrv_co_readv(bs->file, sinfo.file_offset >> BDRV_SECTOR_BITS, sinfo.sectors_avail, &hd_qiov); qemu_co_mutex_lock(&s->lock); if (ret < 0) { goto exit; } break; case PAYLOAD_BLOCK_PARTIALLY_PRESENT: /* we don't yet support difference files, fall through * to error */ default: ret = -EIO; goto exit; break; } nb_sectors -= sinfo.sectors_avail; sector_num += sinfo.sectors_avail; bytes_done += sinfo.bytes_avail; } } ret = 0; exit: qemu_co_mutex_unlock(&s->lock); qemu_iovec_destroy(&hd_qiov); return ret; } static coroutine_fn int vhdx_co_writev(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) { return -ENOTSUP; } static void vhdx_close(BlockDriverState *bs) { BDRVVHDXState *s = bs->opaque; qemu_vfree(s->headers[0]); qemu_vfree(s->headers[1]); qemu_vfree(s->bat); qemu_vfree(s->parent_entries); } static BlockDriver bdrv_vhdx = { .format_name = "vhdx", .instance_size = sizeof(BDRVVHDXState), .bdrv_probe = vhdx_probe, .bdrv_open = vhdx_open, .bdrv_close = vhdx_close, .bdrv_reopen_prepare = vhdx_reopen_prepare, .bdrv_co_readv = vhdx_co_readv, .bdrv_co_writev = vhdx_co_writev, }; static void bdrv_vhdx_init(void) { bdrv_register(&bdrv_vhdx); } block_init(bdrv_vhdx_init);