diff options
Diffstat (limited to 'migration/ram.c')
| -rw-r--r-- | migration/ram.c | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/migration/ram.c b/migration/ram.c index cb14399ef9..5542843adc 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -190,6 +190,70 @@ void ramblock_recv_bitmap_set_range(RAMBlock *rb, void *host_addr, nr); } +#define RAMBLOCK_RECV_BITMAP_ENDING (0x0123456789abcdefULL) + +/* + * Format: bitmap_size (8 bytes) + whole_bitmap (N bytes). + * + * Returns >0 if success with sent bytes, or <0 if error. + */ +int64_t ramblock_recv_bitmap_send(QEMUFile *file, + const char *block_name) +{ + RAMBlock *block = qemu_ram_block_by_name(block_name); + unsigned long *le_bitmap, nbits; + uint64_t size; + + if (!block) { + error_report("%s: invalid block name: %s", __func__, block_name); + return -1; + } + + nbits = block->used_length >> TARGET_PAGE_BITS; + + /* + * Make sure the tmp bitmap buffer is big enough, e.g., on 32bit + * machines we may need 4 more bytes for padding (see below + * comment). So extend it a bit before hand. + */ + le_bitmap = bitmap_new(nbits + BITS_PER_LONG); + + /* + * Always use little endian when sending the bitmap. This is + * required that when source and destination VMs are not using the + * same endianess. (Note: big endian won't work.) + */ + bitmap_to_le(le_bitmap, block->receivedmap, nbits); + + /* Size of the bitmap, in bytes */ + size = nbits / 8; + + /* + * size is always aligned to 8 bytes for 64bit machines, but it + * may not be true for 32bit machines. We need this padding to + * make sure the migration can survive even between 32bit and + * 64bit machines. + */ + size = ROUND_UP(size, 8); + + qemu_put_be64(file, size); + qemu_put_buffer(file, (const uint8_t *)le_bitmap, size); + /* + * Mark as an end, in case the middle part is screwed up due to + * some "misterious" reason. + */ + qemu_put_be64(file, RAMBLOCK_RECV_BITMAP_ENDING); + qemu_fflush(file); + + free(le_bitmap); + + if (qemu_file_get_error(file)) { + return qemu_file_get_error(file); + } + + return size + sizeof(size); +} + /* * An outstanding page request, on the source, having been received * and queued @@ -3300,6 +3364,86 @@ static bool ram_has_postcopy(void *opaque) return migrate_postcopy_ram(); } +/* + * Read the received bitmap, revert it as the initial dirty bitmap. + * This is only used when the postcopy migration is paused but wants + * to resume from a middle point. + */ +int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *block) +{ + int ret = -EINVAL; + QEMUFile *file = s->rp_state.from_dst_file; + unsigned long *le_bitmap, nbits = block->used_length >> TARGET_PAGE_BITS; + uint64_t local_size = nbits / 8; + uint64_t size, end_mark; + + trace_ram_dirty_bitmap_reload_begin(block->idstr); + + if (s->state != MIGRATION_STATUS_POSTCOPY_RECOVER) { + error_report("%s: incorrect state %s", __func__, + MigrationStatus_str(s->state)); + return -EINVAL; + } + + /* + * Note: see comments in ramblock_recv_bitmap_send() on why we + * need the endianess convertion, and the paddings. + */ + local_size = ROUND_UP(local_size, 8); + + /* Add paddings */ + le_bitmap = bitmap_new(nbits + BITS_PER_LONG); + + size = qemu_get_be64(file); + + /* The size of the bitmap should match with our ramblock */ + if (size != local_size) { + error_report("%s: ramblock '%s' bitmap size mismatch " + "(0x%"PRIx64" != 0x%"PRIx64")", __func__, + block->idstr, size, local_size); + ret = -EINVAL; + goto out; + } + + size = qemu_get_buffer(file, (uint8_t *)le_bitmap, local_size); + end_mark = qemu_get_be64(file); + + ret = qemu_file_get_error(file); + if (ret || size != local_size) { + error_report("%s: read bitmap failed for ramblock '%s': %d" + " (size 0x%"PRIx64", got: 0x%"PRIx64")", + __func__, block->idstr, ret, local_size, size); + ret = -EIO; + goto out; + } + + if (end_mark != RAMBLOCK_RECV_BITMAP_ENDING) { + error_report("%s: ramblock '%s' end mark incorrect: 0x%"PRIu64, + __func__, block->idstr, end_mark); + ret = -EINVAL; + goto out; + } + + /* + * Endianess convertion. We are during postcopy (though paused). + * The dirty bitmap won't change. We can directly modify it. + */ + bitmap_from_le(block->bmap, le_bitmap, nbits); + + /* + * What we received is "received bitmap". Revert it as the initial + * dirty bitmap for this ramblock. + */ + bitmap_complement(block->bmap, block->bmap, nbits); + + trace_ram_dirty_bitmap_reload_complete(block->idstr); + + ret = 0; +out: + free(le_bitmap); + return ret; +} + static SaveVMHandlers savevm_ram_handlers = { .save_setup = ram_save_setup, .save_live_iterate = ram_save_iterate, |