/* * QEMU System Emulator * * Copyright (c) 2003-2008 Fabrice Bellard * Copyright (c) 2011-2015 Red Hat Inc * * Authors: * Juan Quintela * * 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/osdep.h" #include "cpu.h" #include #include "qemu/cutils.h" #include "qemu/bitops.h" #include "qemu/bitmap.h" #include "qemu/main-loop.h" #include "xbzrle.h" #include "ram.h" #include "migration.h" #include "socket.h" #include "migration/register.h" #include "migration/misc.h" #include "qemu-file.h" #include "postcopy-ram.h" #include "migration/page_cache.h" #include "qemu/error-report.h" #include "qapi/error.h" #include "qapi/qapi-events-migration.h" #include "qapi/qmp/qerror.h" #include "trace.h" #include "exec/ram_addr.h" #include "exec/target_page.h" #include "qemu/rcu_queue.h" #include "migration/colo.h" #include "migration/block.h" #include "sysemu/sysemu.h" #include "qemu/uuid.h" #include "savevm.h" /***********************************************************/ /* ram save/restore */ /* RAM_SAVE_FLAG_ZERO used to be named RAM_SAVE_FLAG_COMPRESS, it * worked for pages that where filled with the same char. We switched * it to only search for the zero value. And to avoid confusion with * RAM_SSAVE_FLAG_COMPRESS_PAGE just rename it. */ #define RAM_SAVE_FLAG_FULL 0x01 /* Obsolete, not used anymore */ #define RAM_SAVE_FLAG_ZERO 0x02 #define RAM_SAVE_FLAG_MEM_SIZE 0x04 #define RAM_SAVE_FLAG_PAGE 0x08 #define RAM_SAVE_FLAG_EOS 0x10 #define RAM_SAVE_FLAG_CONTINUE 0x20 #define RAM_SAVE_FLAG_XBZRLE 0x40 /* 0x80 is reserved in migration.h start with 0x100 next */ #define RAM_SAVE_FLAG_COMPRESS_PAGE 0x100 static inline bool is_zero_range(uint8_t *p, uint64_t size) { return buffer_is_zero(p, size); } XBZRLECacheStats xbzrle_counters; /* struct contains XBZRLE cache and a static page used by the compression */ static struct { /* buffer used for XBZRLE encoding */ uint8_t *encoded_buf; /* buffer for storing page content */ uint8_t *current_buf; /* Cache for XBZRLE, Protected by lock. */ PageCache *cache; QemuMutex lock; /* it will store a page full of zeros */ uint8_t *zero_target_page; /* buffer used for XBZRLE decoding */ uint8_t *decoded_buf; } XBZRLE; static void XBZRLE_cache_lock(void) { if (migrate_use_xbzrle()) qemu_mutex_lock(&XBZRLE.lock); } static void XBZRLE_cache_unlock(void) { if (migrate_use_xbzrle()) qemu_mutex_unlock(&XBZRLE.lock); } /** * xbzrle_cache_resize: resize the xbzrle cache * * This function is called from qmp_migrate_set_cache_size in main * thread, possibly while a migration is in progress. A running * migration may be using the cache and might finish during this call, * hence changes to the cache are protected by XBZRLE.lock(). * * Returns 0 for success or -1 for error * * @new_size: new cache size * @errp: set *errp if the check failed, with reason */ int xbzrle_cache_resize(int64_t new_size, Error **errp) { PageCache *new_cache; int64_t ret = 0; /* Check for truncation */ if (new_size != (size_t)new_size) { error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size", "exceeding address space"); return -1; } if (new_size == migrate_xbzrle_cache_size()) { /* nothing to do */ return 0; } XBZRLE_cache_lock(); if (XBZRLE.cache != NULL) { new_cache = cache_init(new_size, TARGET_PAGE_SIZE, errp); if (!new_cache) { ret = -1; goto out; } cache_fini(XBZRLE.cache); XBZRLE.cache = new_cache; } out: XBZRLE_cache_unlock(); return ret; } /* Should be holding either ram_list.mutex, or the RCU lock. */ #define RAMBLOCK_FOREACH_MIGRATABLE(block) \ RAMBLOCK_FOREACH(block) \ if (!qemu_ram_is_migratable(block)) {} else static void ramblock_recv_map_init(void) { RAMBlock *rb; RAMBLOCK_FOREACH_MIGRATABLE(rb) { assert(!rb->receivedmap); rb->receivedmap = bitmap_new(rb->max_length >> qemu_target_page_bits()); } } int ramblock_recv_bitmap_test(RAMBlock *rb, void *host_addr) { return test_bit(ramblock_recv_bitmap_offset(host_addr, rb), rb->receivedmap); } bool ramblock_recv_bitmap_test_byte_offset(RAMBlock *rb, uint64_t byte_offset) { return test_bit(byte_offset >> TARGET_PAGE_BITS, rb->receivedmap); } void ramblock_recv_bitmap_set(RAMBlock *rb, void *host_addr) { set_bit_atomic(ramblock_recv_bitmap_offset(host_addr, rb), rb->receivedmap); } void ramblock_recv_bitmap_set_range(RAMBlock *rb, void *host_addr, size_t nr) { bitmap_set_atomic(rb->receivedmap, ramblock_recv_bitmap_offset(host_addr, rb), 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); g_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 */ struct RAMSrcPageRequest { RAMBlock *rb; hwaddr offset; hwaddr len; QSIMPLEQ_ENTRY(RAMSrcPageRequest) next_req; }; /* State of RAM for migration */ struct RAMState { /* QEMUFile used for this migration */ QEMUFile *f; /* Last block that we have visited searching for dirty pages */ RAMBlock *last_seen_block; /* Last block from where we have sent data */ RAMBlock *last_sent_block; /* Last dirty target page we have sent */ ram_addr_t last_page; /* last ram version we have seen */ uint32_t last_version; /* We are in the first round */ bool ram_bulk_stage; /* How many times we have dirty too many pages */ int dirty_rate_high_cnt; /* these variables are used for bitmap sync */ /* last time we did a full bitmap_sync */ int64_t time_last_bitmap_sync; /* bytes transferred at start_time */ uint64_t bytes_xfer_prev; /* number of dirty pages since start_time */ uint64_t num_dirty_pages_period; /* xbzrle misses since the beginning of the period */ uint64_t xbzrle_cache_miss_prev; /* number of iterations at the beginning of period */ uint64_t iterations_prev; /* Iterations since start */ uint64_t iterations; /* number of dirty bits in the bitmap */ uint64_t migration_dirty_pages; /* protects modification of the bitmap */ QemuMutex bitmap_mutex; /* The RAMBlock used in the last src_page_requests */ RAMBlock *last_req_rb; /* Queue of outstanding page requests from the destination */ QemuMutex src_page_req_mutex; QSIMPLEQ_HEAD(src_page_requests, RAMSrcPageRequest) src_page_requests; }; typedef struct RAMState RAMState; static RAMState *ram_state; uint64_t ram_bytes_remaining(void) { return ram_state ? (ram_state->migration_dirty_pages * TARGET_PAGE_SIZE) : 0; } MigrationStats ram_counters; /* used by the search for pages to send */ struct PageSearchStatus { /* Current block being searched */ RAMBlock *block; /* Current page to search from */ unsigned long page; /* Set once we wrap around */ bool complete_round; }; typedef struct PageSearchStatus PageSearchStatus; struct CompressParam { bool done; bool quit; QEMUFile *file; QemuMutex mutex; QemuCond cond; RAMBlock *block; ram_addr_t offset; /* internally used fields */ z_stream stream; uint8_t *originbuf; }; typedef struct CompressParam CompressParam; struct DecompressParam { bool done; bool quit; QemuMutex mutex; QemuCond cond; void *des; uint8_t *compbuf; int len; z_stream stream; }; typedef struct DecompressParam DecompressParam; static CompressParam *comp_param; static QemuThread *compress_threads; /* comp_done_cond is used to wake up the migration thread when * one of the compression threads has finished the compression. * comp_done_lock is used to co-work with comp_done_cond. */ static QemuMutex comp_done_lock; static QemuCond comp_done_cond; /* The empty QEMUFileOps will be used by file in CompressParam */ static const QEMUFileOps empty_ops = { }; static QEMUFile *decomp_file; static DecompressParam *decomp_param; static QemuThread *decompress_threads; static QemuMutex decomp_done_lock; static QemuCond decomp_done_cond; static int do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock *block, ram_addr_t offset, uint8_t *source_buf); static void *do_data_compress(void *opaque) { CompressParam *param = opaque; RAMBlock *block; ram_addr_t offset; qemu_mutex_lock(¶m->mutex); while (!param->quit) { if (param->block) { block = param->block; offset = param->offset; param->block = NULL; qemu_mutex_unlock(¶m->mutex); do_compress_ram_page(param->file, ¶m->stream, block, offset, param->originbuf); qemu_mutex_lock(&comp_done_lock); param->done = true; qemu_cond_signal(&comp_done_cond); qemu_mutex_unlock(&comp_done_lock); qemu_mutex_lock(¶m->mutex); } else { qemu_cond_wait(¶m->cond, ¶m->mutex); } } qemu_mutex_unlock(¶m->mutex); return NULL; } static inline void terminate_compression_threads(void) { int idx, thread_count; thread_count = migrate_compress_threads(); for (idx = 0; idx < thread_count; idx++) { qemu_mutex_lock(&comp_param[idx].mutex); comp_param[idx].quit = true; qemu_cond_signal(&comp_param[idx].cond); qemu_mutex_unlock(&comp_param[idx].mutex); } } static void compress_threads_save_cleanup(void) { int i, thread_count; if (!migrate_use_compression()) { return; } terminate_compression_threads(); thread_count = migrate_compress_threads(); for (i = 0; i < thread_count; i++) { /* * we use it as a indicator which shows if the thread is * properly init'd or not */ if (!comp_param[i].file) { break; } qemu_thread_join(compress_threads + i); qemu_mutex_destroy(&comp_param[i].mutex); qemu_cond_destroy(&comp_param[i].cond); deflateEnd(&comp_param[i].stream); g_free(comp_param[i].originbuf); qemu_fclose(comp_param[i].file); comp_param[i].file = NULL; } qemu_mutex_destroy(&comp_done_lock); qemu_cond_destroy(&comp_done_cond); g_free(compress_threads); g_free(comp_param); compress_threads = NULL; comp_param = NULL; } static int compress_threads_save_setup(void) { int i, thread_count; if (!migrate_use_compression()) { return 0; } thread_count = migrate_compress_threads(); compress_threads = g_new0(QemuThread, thread_count); comp_param = g_new0(CompressParam, thread_count); qemu_cond_init(&comp_done_cond); qemu_mutex_init(&comp_done_lock); for (i = 0; i < thread_count; i++) { comp_param[i].originbuf = g_try_malloc(TARGET_PAGE_SIZE); if (!comp_param[i].originbuf) { goto exit; } if (deflateInit(&comp_param[i].stream, migrate_compress_level()) != Z_OK) { g_free(comp_param[i].originbuf); goto exit; } /* comp_param[i].file is just used as a dummy buffer to save data, * set its ops to empty. */ comp_param[i].file = qemu_fopen_ops(NULL, &empty_ops); comp_param[i].done = true; comp_param[i].quit = false; qemu_mutex_init(&comp_param[i].mutex); qemu_cond_init(&comp_param[i].cond); qemu_thread_create(compress_threads + i, "compress", do_data_compress, comp_param + i, QEMU_THREAD_JOINABLE); } return 0; exit: compress_threads_save_cleanup(); return -1; } /* Multiple fd's */ #define MULTIFD_MAGIC 0x11223344U #define MULTIFD_VERSION 1 typedef struct { uint32_t magic; uint32_t version; unsigned char uuid[16]; /* QemuUUID */ uint8_t id; } __attribute__((packed)) MultiFDInit_t; typedef struct { /* this fields are not changed once the thread is created */ /* channel number */ uint8_t id; /* channel thread name */ char *name; /* channel thread id */ QemuThread thread; /* communication channel */ QIOChannel *c; /* sem where to wait for more work */ QemuSemaphore sem; /* this mutex protects the following parameters */ QemuMutex mutex; /* is this channel thread running */ bool running; /* should this thread finish */ bool quit; } MultiFDSendParams; typedef struct { /* this fields are not changed once the thread is created */ /* channel number */ uint8_t id; /* channel thread name */ char *name; /* channel thread id */ QemuThread thread; /* communication channel */ QIOChannel *c; /* sem where to wait for more work */ QemuSemaphore sem; /* this mutex protects the following parameters */ QemuMutex mutex; /* is this channel thread running */ bool running; /* should this thread finish */ bool quit; } MultiFDRecvParams; static int multifd_send_initial_packet(MultiFDSendParams *p, Error **errp) { MultiFDInit_t msg; int ret; msg.magic = cpu_to_be32(MULTIFD_MAGIC); msg.version = cpu_to_be32(MULTIFD_VERSION); msg.id = p->id; memcpy(msg.uuid, &qemu_uuid.data, sizeof(msg.uuid)); ret = qio_channel_write_all(p->c, (char *)&msg, sizeof(msg), errp); if (ret != 0) { return -1; } return 0; } static int multifd_recv_initial_packet(QIOChannel *c, Error **errp) { MultiFDInit_t msg; int ret; ret = qio_channel_read_all(c, (char *)&msg, sizeof(msg), errp); if (ret != 0) { return -1; } be32_to_cpus(&msg.magic); be32_to_cpus(&msg.version); if (msg.magic != MULTIFD_MAGIC) { error_setg(errp, "multifd: received packet magic %x " "expected %x", msg.magic, MULTIFD_MAGIC); return -1; } if (msg.version != MULTIFD_VERSION) { error_setg(errp, "multifd: received packet version %d " "expected %d", msg.version, MULTIFD_VERSION); return -1; } if (memcmp(msg.uuid, &qemu_uuid, sizeof(qemu_uuid))) { char *uuid = qemu_uuid_unparse_strdup(&qemu_uuid); char *msg_uuid = qemu_uuid_unparse_strdup((const QemuUUID *)msg.uuid); error_setg(errp, "multifd: received uuid '%s' and expected " "uuid '%s' for channel %hhd", msg_uuid, uuid, msg.id); g_free(uuid); g_free(msg_uuid); return -1; } if (msg.id > migrate_multifd_channels()) { error_setg(errp, "multifd: received channel version %d " "expected %d", msg.version, MULTIFD_VERSION); return -1; } return msg.id; } struct { MultiFDSendParams *params; /* number of created threads */ int count; } *multifd_send_state; static void multifd_send_terminate_threads(Error *err) { int i; if (err) { MigrationState *s = migrate_get_current(); migrate_set_error(s, err); if (s->state == MIGRATION_STATUS_SETUP || s->state == MIGRATION_STATUS_PRE_SWITCHOVER || s->state == MIGRATION_STATUS_DEVICE || s->state == MIGRATION_STATUS_ACTIVE) { migrate_set_state(&s->state, s->state, MIGRATION_STATUS_FAILED); } } for (i = 0; i < migrate_multifd_channels(); i++) { MultiFDSendParams *p = &multifd_send_state->params[i]; qemu_mutex_lock(&p->mutex); p->quit = true; qemu_sem_post(&p->sem); qemu_mutex_unlock(&p->mutex); } } int multifd_save_cleanup(Error **errp) { int i; int ret = 0; if (!migrate_use_multifd()) { return 0; } multifd_send_terminate_threads(NULL); for (i = 0; i < migrate_multifd_channels(); i++) { MultiFDSendParams *p = &multifd_send_state->params[i]; if (p->running) { qemu_thread_join(&p->thread); } socket_send_channel_destroy(p->c); p->c = NULL; qemu_mutex_destroy(&p->mutex); qemu_sem_destroy(&p->sem); g_free(p->name); p->name = NULL; } g_free(multifd_send_state->params); multifd_send_state->params = NULL; g_free(multifd_send_state); multifd_send_state = NULL; return ret; } static void *multifd_send_thread(void *opaque) { MultiFDSendParams *p = opaque; Error *local_err = NULL; if (multifd_send_initial_packet(p, &local_err) < 0) { goto out; } while (true) { qemu_mutex_lock(&p->mutex); if (p->quit) { qemu_mutex_unlock(&p->mutex); break; } qemu_mutex_unlock(&p->mutex); qemu_sem_wait(&p->sem); } out: if (local_err) { multifd_send_terminate_threads(local_err); } qemu_mutex_lock(&p->mutex); p->running = false; qemu_mutex_unlock(&p->mutex); return NULL; } static void multifd_new_send_channel_async(QIOTask *task, gpointer opaque) { MultiFDSendParams *p = opaque; QIOChannel *sioc = QIO_CHANNEL(qio_task_get_source(task)); Error *local_err = NULL; if (qio_task_propagate_error(task, &local_err)) { if (multifd_save_cleanup(&local_err) != 0) { migrate_set_error(migrate_get_current(), local_err); } } else { p->c = QIO_CHANNEL(sioc); qio_channel_set_delay(p->c, false); p->running = true; qemu_thread_create(&p->thread, p->name, multifd_send_thread, p, QEMU_THREAD_JOINABLE); atomic_inc(&multifd_send_state->count); } } int multifd_save_setup(void) { int thread_count; uint8_t i; if (!migrate_use_multifd()) { return 0; } thread_count = migrate_multifd_channels(); multifd_send_state = g_malloc0(sizeof(*multifd_send_state)); multifd_send_state->params = g_new0(MultiFDSendParams, thread_count); atomic_set(&multifd_send_state->count, 0); for (i = 0; i < thread_count; i++) { MultiFDSendParams *p = &multifd_send_state->params[i]; qemu_mutex_init(&p->mutex); qemu_sem_init(&p->sem, 0); p->quit = false; p->id = i; p->name = g_strdup_printf("multifdsend_%d", i); socket_send_channel_create(multifd_new_send_channel_async, p); } return 0; } struct { MultiFDRecvParams *params; /* number of created threads */ int count; } *multifd_recv_state; static void multifd_recv_terminate_threads(Error *err) { int i; if (err) { MigrationState *s = migrate_get_current(); migrate_set_error(s, err); if (s->state == MIGRATION_STATUS_SETUP || s->state == MIGRATION_STATUS_ACTIVE) { migrate_set_state(&s->state, s->state, MIGRATION_STATUS_FAILED); } } for (i = 0; i < migrate_multifd_channels(); i++) { MultiFDRecvParams *p = &multifd_recv_state->params[i]; qemu_mutex_lock(&p->mutex); p->quit = true; qemu_sem_post(&p->sem); qemu_mutex_unlock(&p->mutex); } } int multifd_load_cleanup(Error **errp) { int i; int ret = 0; if (!migrate_use_multifd()) { return 0; } multifd_recv_terminate_threads(NULL); for (i = 0; i < migrate_multifd_channels(); i++) { MultiFDRecvParams *p = &multifd_recv_state->params[i]; if (p->running) { qemu_thread_join(&p->thread); } object_unref(OBJECT(p->c)); p->c = NULL; qemu_mutex_destroy(&p->mutex); qemu_sem_destroy(&p->sem); g_free(p->name); p->name = NULL; } g_free(multifd_recv_state->params); multifd_recv_state->params = NULL; g_free(multifd_recv_state); multifd_recv_state = NULL; return ret; } static void *multifd_recv_thread(void *opaque) { MultiFDRecvParams *p = opaque; while (true) { qemu_mutex_lock(&p->mutex); if (p->quit) { qemu_mutex_unlock(&p->mutex); break; } qemu_mutex_unlock(&p->mutex); qemu_sem_wait(&p->sem); } qemu_mutex_lock(&p->mutex); p->running = false; qemu_mutex_unlock(&p->mutex); return NULL; } int multifd_load_setup(void) { int thread_count; uint8_t i; if (!migrate_use_multifd()) { return 0; } thread_count = migrate_multifd_channels(); multifd_recv_state = g_malloc0(sizeof(*multifd_recv_state)); multifd_recv_state->params = g_new0(MultiFDRecvParams, thread_count); atomic_set(&multifd_recv_state->count, 0); for (i = 0; i < thread_count; i++) { MultiFDRecvParams *p = &multifd_recv_state->params[i]; qemu_mutex_init(&p->mutex); qemu_sem_init(&p->sem, 0); p->quit = false; p->id = i; p->name = g_strdup_printf("multifdrecv_%d", i); } return 0; } bool multifd_recv_all_channels_created(void) { int thread_count = migrate_multifd_channels(); if (!migrate_use_multifd()) { return true; } return thread_count == atomic_read(&multifd_recv_state->count); } void multifd_recv_new_channel(QIOChannel *ioc) { MultiFDRecvParams *p; Error *local_err = NULL; int id; id = multifd_recv_initial_packet(ioc, &local_err); if (id < 0) { multifd_recv_terminate_threads(local_err); return; } p = &multifd_recv_state->params[id]; if (p->c != NULL) { error_setg(&local_err, "multifd: received id '%d' already setup'", id); multifd_recv_terminate_threads(local_err); return; } p->c = ioc; object_ref(OBJECT(ioc)); p->running = true; qemu_thread_create(&p->thread, p->name, multifd_recv_thread, p, QEMU_THREAD_JOINABLE); atomic_inc(&multifd_recv_state->count); if (multifd_recv_state->count == migrate_multifd_channels()) { migration_incoming_process(); } } /** * save_page_header: write page header to wire * * If this is the 1st block, it also writes the block identification * * Returns the number of bytes written * * @f: QEMUFile where to send the data * @block: block that contains the page we want to send * @offset: offset inside the block for the page * in the lower bits, it contains flags */ static size_t save_page_header(RAMState *rs, QEMUFile *f, RAMBlock *block, ram_addr_t offset) { size_t size, len; if (block == rs->last_sent_block) { offset |= RAM_SAVE_FLAG_CONTINUE; } qemu_put_be64(f, offset); size = 8; if (!(offset & RAM_SAVE_FLAG_CONTINUE)) { len = strlen(block->idstr); qemu_put_byte(f, len); qemu_put_buffer(f, (uint8_t *)block->idstr, len); size += 1 + len; rs->last_sent_block = block; } return size; } /** * mig_throttle_guest_down: throotle down the guest * * Reduce amount of guest cpu execution to hopefully slow down memory * writes. If guest dirty memory rate is reduced below the rate at * which we can transfer pages to the destination then we should be * able to complete migration. Some workloads dirty memory way too * fast and will not effectively converge, even with auto-converge. */ static void mig_throttle_guest_down(void) { MigrationState *s = migrate_get_current(); uint64_t pct_initial = s->parameters.cpu_throttle_initial; uint64_t pct_icrement = s->parameters.cpu_throttle_increment; /* We have not started throttling yet. Let's start it. */ if (!cpu_throttle_active()) { cpu_throttle_set(pct_initial); } else { /* Throttling already on, just increase the rate */ cpu_throttle_set(cpu_throttle_get_percentage() + pct_icrement); } } /** * xbzrle_cache_zero_page: insert a zero page in the XBZRLE cache * * @rs: current RAM state * @current_addr: address for the zero page * * Update the xbzrle cache to reflect a page that's been sent as all 0. * The important thing is that a stale (not-yet-0'd) page be replaced * by the new data. * As a bonus, if the page wasn't in the cache it gets added so that * when a small write is made into the 0'd page it gets XBZRLE sent. */ static void xbzrle_cache_zero_page(RAMState *rs, ram_addr_t current_addr) { if (rs->ram_bulk_stage || !migrate_use_xbzrle()) { return; } /* We don't care if this fails to allocate a new cache page * as long as it updated an old one */ cache_insert(XBZRLE.cache, current_addr, XBZRLE.zero_target_page, ram_counters.dirty_sync_count); } #define ENCODING_FLAG_XBZRLE 0x1 /** * save_xbzrle_page: compress and send current page * * Returns: 1 means that we wrote the page * 0 means that page is identical to the one already sent * -1 means that xbzrle would be longer than normal * * @rs: current RAM state * @current_data: pointer to the address of the page contents * @current_addr: addr of the page * @block: block that contains the page we want to send * @offset: offset inside the block for the page * @last_stage: if we are at the completion stage */ static int save_xbzrle_page(RAMState *rs, uint8_t **current_data, ram_addr_t current_addr, RAMBlock *block, ram_addr_t offset, bool last_stage) { int encoded_len = 0, bytes_xbzrle; uint8_t *prev_cached_page; if (!cache_is_cached(XBZRLE.cache, current_addr, ram_counters.dirty_sync_count)) { xbzrle_counters.cache_miss++; if (!last_stage) { if (cache_insert(XBZRLE.cache, current_addr, *current_data, ram_counters.dirty_sync_count) == -1) { return -1; } else { /* update *current_data when the page has been inserted into cache */ *current_data = get_cached_data(XBZRLE.cache, current_addr); } } return -1; } prev_cached_page = get_cached_data(XBZRLE.cache, current_addr); /* save current buffer into memory */ memcpy(XBZRLE.current_buf, *current_data, TARGET_PAGE_SIZE); /* XBZRLE encoding (if there is no overflow) */ encoded_len = xbzrle_encode_buffer(prev_cached_page, XBZRLE.current_buf, TARGET_PAGE_SIZE, XBZRLE.encoded_buf, TARGET_PAGE_SIZE); if (encoded_len == 0) { trace_save_xbzrle_page_skipping(); return 0; } else if (encoded_len == -1) { trace_save_xbzrle_page_overflow(); xbzrle_counters.overflow++; /* update data in the cache */ if (!last_stage) { memcpy(prev_cached_page, *current_data, TARGET_PAGE_SIZE); *current_data = prev_cached_page; } return -1; } /* we need to update the data in the cache, in order to get the same data */ if (!last_stage) { memcpy(prev_cached_page, XBZRLE.current_buf, TARGET_PAGE_SIZE); } /* Send XBZRLE based compressed page */ bytes_xbzrle = save_page_header(rs, rs->f, block, offset | RAM_SAVE_FLAG_XBZRLE); qemu_put_byte(rs->f, ENCODING_FLAG_XBZRLE); qemu_put_be16(rs->f, encoded_len); qemu_put_buffer(rs->f, XBZRLE.encoded_buf, encoded_len); bytes_xbzrle += encoded_len + 1 + 2; xbzrle_counters.pages++; xbzrle_counters.bytes += bytes_xbzrle; ram_counters.transferred += bytes_xbzrle; return 1; } /** * migration_bitmap_find_dirty: find the next dirty page from start * * Called with rcu_read_lock() to protect migration_bitmap * * Returns the byte offset within memory region of the start of a dirty page * * @rs: current RAM state * @rb: RAMBlock where to search for dirty pages * @start: page where we start the search */ static inline unsigned long migration_bitmap_find_dirty(RAMState *rs, RAMBlock *rb, unsigned long start) { unsigned long size = rb->used_length >> TARGET_PAGE_BITS; unsigned long *bitmap = rb->bmap; unsigned long next; if (!qemu_ram_is_migratable(rb)) { return size; } if (rs->ram_bulk_stage && start > 0) { next = start + 1; } else { next = find_next_bit(bitmap, size, start); } return next; } static inline bool migration_bitmap_clear_dirty(RAMState *rs, RAMBlock *rb, unsigned long page) { bool ret; ret = test_and_clear_bit(page, rb->bmap); if (ret) { rs->migration_dirty_pages--; } return ret; } static void migration_bitmap_sync_range(RAMState *rs, RAMBlock *rb, ram_addr_t start, ram_addr_t length) { rs->migration_dirty_pages += cpu_physical_memory_sync_dirty_bitmap(rb, start, length, &rs->num_dirty_pages_period); } /** * ram_pagesize_summary: calculate all the pagesizes of a VM * * Returns a summary bitmap of the page sizes of all RAMBlocks * * For VMs with just normal pages this is equivalent to the host page * size. If it's got some huge pages then it's the OR of all the * different page sizes. */ uint64_t ram_pagesize_summary(void) { RAMBlock *block; uint64_t summary = 0; RAMBLOCK_FOREACH_MIGRATABLE(block) { summary |= block->page_size; } return summary; } static void migration_bitmap_sync(RAMState *rs) { RAMBlock *block; int64_t end_time; uint64_t bytes_xfer_now; ram_counters.dirty_sync_count++; if (!rs->time_last_bitmap_sync) { rs->time_last_bitmap_sync = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); } trace_migration_bitmap_sync_start(); memory_global_dirty_log_sync(); qemu_mutex_lock(&rs->bitmap_mutex); rcu_read_lock(); RAMBLOCK_FOREACH_MIGRATABLE(block) { migration_bitmap_sync_range(rs, block, 0, block->used_length); } rcu_read_unlock(); qemu_mutex_unlock(&rs->bitmap_mutex); trace_migration_bitmap_sync_end(rs->num_dirty_pages_period); end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); /* more than 1 second = 1000 millisecons */ if (end_time > rs->time_last_bitmap_sync + 1000) { /* calculate period counters */ ram_counters.dirty_pages_rate = rs->num_dirty_pages_period * 1000 / (end_time - rs->time_last_bitmap_sync); bytes_xfer_now = ram_counters.transferred; /* During block migration the auto-converge logic incorrectly detects * that ram migration makes no progress. Avoid this by disabling the * throttling logic during the bulk phase of block migration. */ if (migrate_auto_converge() && !blk_mig_bulk_active()) { /* The following detection logic can be refined later. For now: Check to see if the dirtied bytes is 50% more than the approx. amount of bytes that just got transferred since the last time we were in this routine. If that happens twice, start or increase throttling */ if ((rs->num_dirty_pages_period * TARGET_PAGE_SIZE > (bytes_xfer_now - rs->bytes_xfer_prev) / 2) && (++rs->dirty_rate_high_cnt >= 2)) { trace_migration_throttle(); rs->dirty_rate_high_cnt = 0; mig_throttle_guest_down(); } } if (migrate_use_xbzrle()) { if (rs->iterations_prev != rs->iterations) { xbzrle_counters.cache_miss_rate = (double)(xbzrle_counters.cache_miss - rs->xbzrle_cache_miss_prev) / (rs->iterations - rs->iterations_prev); } rs->iterations_prev = rs->iterations; rs->xbzrle_cache_miss_prev = xbzrle_counters.cache_miss; } /* reset period counters */ rs->time_last_bitmap_sync = end_time; rs->num_dirty_pages_period = 0; rs->bytes_xfer_prev = bytes_xfer_now; } if (migrate_use_events()) { qapi_event_send_migration_pass(ram_counters.dirty_sync_count, NULL); } } /** * save_zero_page: send the zero page to the stream * * Returns the number of pages written. * * @rs: current RAM state * @block: block that contains the page we want to send * @offset: offset inside the block for the page */ static int save_zero_page(RAMState *rs, RAMBlock *block, ram_addr_t offset) { uint8_t *p = block->host + offset; int pages = -1; if (is_zero_range(p, TARGET_PAGE_SIZE)) { ram_counters.duplicate++; ram_counters.transferred += save_page_header(rs, rs->f, block, offset | RAM_SAVE_FLAG_ZERO); qemu_put_byte(rs->f, 0); ram_counters.transferred += 1; pages = 1; } return pages; } static void ram_release_pages(const char *rbname, uint64_t offset, int pages) { if (!migrate_release_ram() || !migration_in_postcopy()) { return; } ram_discard_range(rbname, offset, pages << TARGET_PAGE_BITS); } /* * @pages: the number of pages written by the control path, * < 0 - error * > 0 - number of pages written * * Return true if the pages has been saved, otherwise false is returned. */ static bool control_save_page(RAMState *rs, RAMBlock *block, ram_addr_t offset, int *pages) { uint64_t bytes_xmit = 0; int ret; *pages = -1; ret = ram_control_save_page(rs->f, block->offset, offset, TARGET_PAGE_SIZE, &bytes_xmit); if (ret == RAM_SAVE_CONTROL_NOT_SUPP) { return false; } if (bytes_xmit) { ram_counters.transferred += bytes_xmit; *pages = 1; } if (ret == RAM_SAVE_CONTROL_DELAYED) { return true; } if (bytes_xmit > 0) { ram_counters.normal++; } else if (bytes_xmit == 0) { ram_counters.duplicate++; } return true; } /* * directly send the page to the stream * * Returns the number of pages written. * * @rs: current RAM state * @block: block that contains the page we want to send * @offset: offset inside the block for the page * @buf: the page to be sent * @async: send to page asyncly */ static int save_normal_page(RAMState *rs, RAMBlock *block, ram_addr_t offset, uint8_t *buf, bool async) { ram_counters.transferred += save_page_header(rs, rs->f, block, offset | RAM_SAVE_FLAG_PAGE); if (async) { qemu_put_buffer_async(rs->f, buf, TARGET_PAGE_SIZE, migrate_release_ram() & migration_in_postcopy()); } else { qemu_put_buffer(rs->f, buf, TARGET_PAGE_SIZE); } ram_counters.transferred += TARGET_PAGE_SIZE; ram_counters.normal++; return 1; } /** * ram_save_page: send the given page to the stream * * Returns the number of pages written. * < 0 - error * >=0 - Number of pages written - this might legally be 0 * if xbzrle noticed the page was the same. * * @rs: current RAM state * @block: block that contains the page we want to send * @offset: offset inside the block for the page * @last_stage: if we are at the completion stage */ static int ram_save_page(RAMState *rs, PageSearchStatus *pss, bool last_stage) { int pages = -1; uint8_t *p; bool send_async = true; RAMBlock *block = pss->block; ram_addr_t offset = pss->page << TARGET_PAGE_BITS; ram_addr_t current_addr = block->offset + offset; p = block->host + offset; trace_ram_save_page(block->idstr, (uint64_t)offset, p); XBZRLE_cache_lock(); if (!rs->ram_bulk_stage && !migration_in_postcopy() && migrate_use_xbzrle()) { pages = save_xbzrle_page(rs, &p, current_addr, block, offset, last_stage); if (!last_stage) { /* Can't send this cached data async, since the cache page * might get updated before it gets to the wire */ send_async = false; } } /* XBZRLE overflow or normal page */ if (pages == -1) { pages = save_normal_page(rs, block, offset, p, send_async); } XBZRLE_cache_unlock(); return pages; } static int do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock *block, ram_addr_t offset, uint8_t *source_buf) { RAMState *rs = ram_state; int bytes_sent, blen; uint8_t *p = block->host + (offset & TARGET_PAGE_MASK); bytes_sent = save_page_header(rs, f, block, offset | RAM_SAVE_FLAG_COMPRESS_PAGE); /* * copy it to a internal buffer to avoid it being modified by VM * so that we can catch up the error during compression and * decompression */ memcpy(source_buf, p, TARGET_PAGE_SIZE); blen = qemu_put_compression_data(f, stream, source_buf, TARGET_PAGE_SIZE); if (blen < 0) { bytes_sent = 0; qemu_file_set_error(migrate_get_current()->to_dst_file, blen); error_report("compressed data failed!"); } else { bytes_sent += blen; ram_release_pages(block->idstr, offset & TARGET_PAGE_MASK, 1); } return bytes_sent; } static void flush_compressed_data(RAMState *rs) { int idx, len, thread_count; if (!migrate_use_compression()) { return; } thread_count = migrate_compress_threads(); qemu_mutex_lock(&comp_done_lock); for (idx = 0; idx < thread_count; idx++) { while (!comp_param[idx].done) { qemu_cond_wait(&comp_done_cond, &comp_done_lock); } } qemu_mutex_unlock(&comp_done_lock); for (idx = 0; idx < thread_count; idx++) { qemu_mutex_lock(&comp_param[idx].mutex); if (!comp_param[idx].quit) { len = qemu_put_qemu_file(rs->f, comp_param[idx].file); ram_counters.transferred += len; } qemu_mutex_unlock(&comp_param[idx].mutex); } } static inline void set_compress_params(CompressParam *param, RAMBlock *block, ram_addr_t offset) { param->block = block; param->offset = offset; } static int compress_page_with_multi_thread(RAMState *rs, RAMBlock *block, ram_addr_t offset) { int idx, thread_count, bytes_xmit = -1, pages = -1; thread_count = migrate_compress_threads(); qemu_mutex_lock(&comp_done_lock); while (true) { for (idx = 0; idx < thread_count; idx++) { if (comp_param[idx].done) { comp_param[idx].done = false; bytes_xmit = qemu_put_qemu_file(rs->f, comp_param[idx].file); qemu_mutex_lock(&comp_param[idx].mutex); set_compress_params(&comp_param[idx], block, offset); qemu_cond_signal(&comp_param[idx].cond); qemu_mutex_unlock(&comp_param[idx].mutex); pages = 1; ram_counters.normal++; ram_counters.transferred += bytes_xmit; break; } } if (pages > 0) { break; } else { qemu_cond_wait(&comp_done_cond, &comp_done_lock); } } qemu_mutex_unlock(&comp_done_lock); return pages; } /** * find_dirty_block: find the next dirty page and update any state * associated with the search process. * * Returns if a page is found * * @rs: current RAM state * @pss: data about the state of the current dirty page scan * @again: set to false if the search has scanned the whole of RAM */ static bool find_dirty_block(RAMState *rs, PageSearchStatus *pss, bool *again) { pss->page = migration_bitmap_find_dirty(rs, pss->block, pss->page); if (pss->complete_round && pss->block == rs->last_seen_block && pss->page >= rs->last_page) { /* * We've been once around the RAM and haven't found anything. * Give up. */ *again = false; return false; } if ((pss->page << TARGET_PAGE_BITS) >= pss->block->used_length) { /* Didn't find anything in this RAM Block */ pss->page = 0; pss->block = QLIST_NEXT_RCU(pss->block, next); if (!pss->block) { /* Hit the end of the list */ pss->block = QLIST_FIRST_RCU(&ram_list.blocks); /* Flag that we've looped */ pss->complete_round = true; rs->ram_bulk_stage = false; if (migrate_use_xbzrle()) { /* If xbzrle is on, stop using the data compression at this * point. In theory, xbzrle can do better than compression. */ flush_compressed_data(rs); } } /* Didn't find anything this time, but try again on the new block */ *again = true; return false; } else { /* Can go around again, but... */ *again = true; /* We've found something so probably don't need to */ return true; } } /** * unqueue_page: gets a page of the queue * * Helper for 'get_queued_page' - gets a page off the queue * * Returns the block of the page (or NULL if none available) * * @rs: current RAM state * @offset: used to return the offset within the RAMBlock */ static RAMBlock *unqueue_page(RAMState *rs, ram_addr_t *offset) { RAMBlock *block = NULL; qemu_mutex_lock(&rs->src_page_req_mutex); if (!QSIMPLEQ_EMPTY(&rs->src_page_requests)) { struct RAMSrcPageRequest *entry = QSIMPLEQ_FIRST(&rs->src_page_requests); block = entry->rb; *offset = entry->offset; if (entry->len > TARGET_PAGE_SIZE) { entry->len -= TARGET_PAGE_SIZE; entry->offset += TARGET_PAGE_SIZE; } else { memory_region_unref(block->mr); QSIMPLEQ_REMOVE_HEAD(&rs->src_page_requests, next_req); g_free(entry); } } qemu_mutex_unlock(&rs->src_page_req_mutex); return block; } /** * get_queued_page: unqueue a page from the postocpy requests * * Skips pages that are already sent (!dirty) * * Returns if a queued page is found * * @rs: current RAM state * @pss: data about the state of the current dirty page scan */ static bool get_queued_page(RAMState *rs, PageSearchStatus *pss) { RAMBlock *block; ram_addr_t offset; bool dirty; do { block = unqueue_page(rs, &offset); /* * We're sending this page, and since it's postcopy nothing else * will dirty it, and we must make sure it doesn't get sent again * even if this queue request was received after the background * search already sent it. */ if (block) { unsigned long page; page = offset >> TARGET_PAGE_BITS; dirty = test_bit(page, block->bmap); if (!dirty) { trace_get_queued_page_not_dirty(block->idstr, (uint64_t)offset, page, test_bit(page, block->unsentmap)); } else { trace_get_queued_page(block->idstr, (uint64_t)offset, page); } } } while (block && !dirty); if (block) { /* * As soon as we start servicing pages out of order, then we have * to kill the bulk stage, since the bulk stage assumes * in (migration_bitmap_find_and_reset_dirty) that every page is * dirty, that's no longer true. */ rs->ram_bulk_stage = false; /* * We want the background search to continue from the queued page * since the guest is likely to want other pages near to the page * it just requested. */ pss->block = block; pss->page = offset >> TARGET_PAGE_BITS; } return !!block; } /** * migration_page_queue_free: drop any remaining pages in the ram * request queue * * It should be empty at the end anyway, but in error cases there may * be some left. in case that there is any page left, we drop it. * */ static void migration_page_queue_free(RAMState *rs) { struct RAMSrcPageRequest *mspr, *next_mspr; /* This queue generally should be empty - but in the case of a failed * migration might have some droppings in. */ rcu_read_lock(); QSIMPLEQ_FOREACH_SAFE(mspr, &rs->src_page_requests, next_req, next_mspr) { memory_region_unref(mspr->rb->mr); QSIMPLEQ_REMOVE_HEAD(&rs->src_page_requests, next_req); g_free(mspr); } rcu_read_unlock(); } /** * ram_save_queue_pages: queue the page for transmission * * A request from postcopy destination for example. * * Returns zero on success or negative on error * * @rbname: Name of the RAMBLock of the request. NULL means the * same that last one. * @start: starting address from the start of the RAMBlock * @len: length (in bytes) to send */ int ram_save_queue_pages(const char *rbname, ram_addr_t start, ram_addr_t len) { RAMBlock *ramblock; RAMState *rs = ram_state; ram_counters.postcopy_requests++; rcu_read_lock(); if (!rbname) { /* Reuse last RAMBlock */ ramblock = rs->last_req_rb; if (!ramblock) { /* * Shouldn't happen, we can't reuse the last RAMBlock if * it's the 1st request. */ error_report("ram_save_queue_pages no previous block"); goto err; } } else { ramblock = qemu_ram_block_by_name(rbname); if (!ramblock) { /* We shouldn't be asked for a non-existent RAMBlock */ error_report("ram_save_queue_pages no block '%s'", rbname); goto err; } rs->last_req_rb = ramblock; } trace_ram_save_queue_pages(ramblock->idstr, start, len); if (start+len > ramblock->used_length) { error_report("%s request overrun start=" RAM_ADDR_FMT " len=" RAM_ADDR_FMT " blocklen=" RAM_ADDR_FMT, __func__, start, len, ramblock->used_length); goto err; } struct RAMSrcPageRequest *new_entry = g_malloc0(sizeof(struct RAMSrcPageRequest)); new_entry->rb = ramblock; new_entry->offset = start; new_entry->len = len; memory_region_ref(ramblock->mr); qemu_mutex_lock(&rs->src_page_req_mutex); QSIMPLEQ_INSERT_TAIL(&rs->src_page_requests, new_entry, next_req); qemu_mutex_unlock(&rs->src_page_req_mutex); rcu_read_unlock(); return 0; err: rcu_read_unlock(); return -1; } static bool save_page_use_compression(RAMState *rs) { if (!migrate_use_compression()) { return false; } /* * If xbzrle is on, stop using the data compression after first * round of migration even if compression is enabled. In theory, * xbzrle can do better than compression. */ if (rs->ram_bulk_stage || !migrate_use_xbzrle()) { return true; } return false; } /** * ram_save_target_page: save one target page * * Returns the number of pages written * * @rs: current RAM state * @pss: data about the page we want to send * @last_stage: if we are at the completion stage */ static int ram_save_target_page(RAMState *rs, PageSearchStatus *pss, bool last_stage) { RAMBlock *block = pss->block; ram_addr_t offset = pss->page << TARGET_PAGE_BITS; int res; if (control_save_page(rs, block, offset, &res)) { return res; } /* * When starting the process of a new block, the first page of * the block should be sent out before other pages in the same * block, and all the pages in last block should have been sent * out, keeping this order is important, because the 'cont' flag * is used to avoid resending the block name. */ if (block != rs->last_sent_block && save_page_use_compression(rs)) { flush_compressed_data(rs); } res = save_zero_page(rs, block, offset); if (res > 0) { /* Must let xbzrle know, otherwise a previous (now 0'd) cached * page would be stale */ if (!save_page_use_compression(rs)) { XBZRLE_cache_lock(); xbzrle_cache_zero_page(rs, block->offset + offset); XBZRLE_cache_unlock(); } ram_release_pages(block->idstr, offset, res); return res; } /* * Make sure the first page is sent out before other pages. * * we post it as normal page as compression will take much * CPU resource. */ if (block == rs->last_sent_block && save_page_use_compression(rs)) { return compress_page_with_multi_thread(rs, block, offset); } return ram_save_page(rs, pss, last_stage); } /** * ram_save_host_page: save a whole host page * * Starting at *offset send pages up to the end of the current host * page. It's valid for the initial offset to point into the middle of * a host page in which case the remainder of the hostpage is sent. * Only dirty target pages are sent. Note that the host page size may * be a huge page for this block. * The saving stops at the boundary of the used_length of the block * if the RAMBlock isn't a multiple of the host page size. * * Returns the number of pages written or negative on error * * @rs: current RAM state * @ms: current migration state * @pss: data about the page we want to send * @last_stage: if we are at the completion stage */ static int ram_save_host_page(RAMState *rs, PageSearchStatus *pss, bool last_stage) { int tmppages, pages = 0; size_t pagesize_bits = qemu_ram_pagesize(pss->block) >> TARGET_PAGE_BITS; if (!qemu_ram_is_migratable(pss->block)) { error_report("block %s should not be migrated !", pss->block->idstr); return 0; } do { /* Check the pages is dirty and if it is send it */ if (!migration_bitmap_clear_dirty(rs, pss->block, pss->page)) { pss->page++; continue; } tmppages = ram_save_target_page(rs, pss, last_stage); if (tmppages < 0) { return tmppages; } pages += tmppages; if (pss->block->unsentmap) { clear_bit(pss->page, pss->block->unsentmap); } pss->page++; } while ((pss->page & (pagesize_bits - 1)) && offset_in_ramblock(pss->block, pss->page << TARGET_PAGE_BITS)); /* The offset we leave with is the last one we looked at */ pss->page--; return pages; } /** * ram_find_and_save_block: finds a dirty page and sends it to f * * Called within an RCU critical section. * * Returns the number of pages written where zero means no dirty pages * * @rs: current RAM state * @last_stage: if we are at the completion stage * * On systems where host-page-size > target-page-size it will send all the * pages in a host page that are dirty. */ static int ram_find_and_save_block(RAMState *rs, bool last_stage) { PageSearchStatus pss; int pages = 0; bool again, found; /* No dirty page as there is zero RAM */ if (!ram_bytes_total()) { return pages; } pss.block = rs->last_seen_block; pss.page = rs->last_page; pss.complete_round = false; if (!pss.block) { pss.block = QLIST_FIRST_RCU(&ram_list.blocks); } do { again = true; found = get_queued_page(rs, &pss); if (!found) { /* priority queue empty, so just search for something dirty */ found = find_dirty_block(rs, &pss, &again); } if (found) { pages = ram_save_host_page(rs, &pss, last_stage); } } while (!pages && again); rs->last_seen_block = pss.block; rs->last_page = pss.page; return pages; } void acct_update_position(QEMUFile *f, size_t size, bool zero) { uint64_t pages = size / TARGET_PAGE_SIZE; if (zero) { ram_counters.duplicate += pages; } else { ram_counters.normal += pages; ram_counters.transferred += size; qemu_update_position(f, size); } } uint64_t ram_bytes_total(void) { RAMBlock *block; uint64_t total = 0; rcu_read_lock(); RAMBLOCK_FOREACH_MIGRATABLE(block) { total += block->used_length; } rcu_read_unlock(); return total; } static void xbzrle_load_setup(void) { XBZRLE.decoded_buf = g_malloc(TARGET_PAGE_SIZE); } static void xbzrle_load_cleanup(void) { g_free(XBZRLE.decoded_buf); XBZRLE.decoded_buf = NULL; } static void ram_state_cleanup(RAMState **rsp) { if (*rsp) { migration_page_queue_free(*rsp); qemu_mutex_destroy(&(*rsp)->bitmap_mutex); qemu_mutex_destroy(&(*rsp)->src_page_req_mutex); g_free(*rsp); *rsp = NULL; } } static void xbzrle_cleanup(void) { XBZRLE_cache_lock(); if (XBZRLE.cache) { cache_fini(XBZRLE.cache); g_free(XBZRLE.encoded_buf); g_free(XBZRLE.current_buf); g_free(XBZRLE.zero_target_page); XBZRLE.cache = NULL; XBZRLE.encoded_buf = NULL; XBZRLE.current_buf = NULL; XBZRLE.zero_target_page = NULL; } XBZRLE_cache_unlock(); } static void ram_save_cleanup(void *opaque) { RAMState **rsp = opaque; RAMBlock *block; /* caller have hold iothread lock or is in a bh, so there is * no writing race against this migration_bitmap */ memory_global_dirty_log_stop(); RAMBLOCK_FOREACH_MIGRATABLE(block) { g_free(block->bmap); block->bmap = NULL; g_free(block->unsentmap); block->unsentmap = NULL; } xbzrle_cleanup(); compress_threads_save_cleanup(); ram_state_cleanup(rsp); } static void ram_state_reset(RAMState *rs) { rs->last_seen_block = NULL; rs->last_sent_block = NULL; rs->last_page = 0; rs->last_version = ram_list.version; rs->ram_bulk_stage = true; } #define MAX_WAIT 50 /* ms, half buffered_file limit */ /* * 'expected' is the value you expect the bitmap mostly to be full * of; it won't bother printing lines that are all this value. * If 'todump' is null the migration bitmap is dumped. */ void ram_debug_dump_bitmap(unsigned long *todump, bool expected, unsigned long pages) { int64_t cur; int64_t linelen = 128; char linebuf[129]; for (cur = 0; cur < pages; cur += linelen) { int64_t curb; bool found = false; /* * Last line; catch the case where the line length * is longer than remaining ram */ if (cur + linelen > pages) { linelen = pages - cur; } for (curb = 0; curb < linelen; curb++) { bool thisbit = test_bit(cur + curb, todump); linebuf[curb] = thisbit ? '1' : '.'; found = found || (thisbit != expected); } if (found) { linebuf[curb] = '\0'; fprintf(stderr, "0x%08" PRIx64 " : %s\n", cur, linebuf); } } } /* **** functions for postcopy ***** */ void ram_postcopy_migrated_memory_release(MigrationState *ms) { struct RAMBlock *block; RAMBLOCK_FOREACH_MIGRATABLE(block) { unsigned long *bitmap = block->bmap; unsigned long range = block->used_length >> TARGET_PAGE_BITS; unsigned long run_start = find_next_zero_bit(bitmap, range, 0); while (run_start < range) { unsigned long run_end = find_next_bit(bitmap, range, run_start + 1); ram_discard_range(block->idstr, run_start << TARGET_PAGE_BITS, (run_end - run_start) << TARGET_PAGE_BITS); run_start = find_next_zero_bit(bitmap, range, run_end + 1); } } } /** * postcopy_send_discard_bm_ram: discard a RAMBlock * * Returns zero on success * * Callback from postcopy_each_ram_send_discard for each RAMBlock * Note: At this point the 'unsentmap' is the processed bitmap combined * with the dirtymap; so a '1' means it's either dirty or unsent. * * @ms: current migration state * @pds: state for postcopy * @start: RAMBlock starting page * @length: RAMBlock size */ static int postcopy_send_discard_bm_ram(MigrationState *ms, PostcopyDiscardState *pds, RAMBlock *block) { unsigned long end = block->used_length >> TARGET_PAGE_BITS; unsigned long current; unsigned long *unsentmap = block->unsentmap; for (current = 0; current < end; ) { unsigned long one = find_next_bit(unsentmap, end, current); if (one <= end) { unsigned long zero = find_next_zero_bit(unsentmap, end, one + 1); unsigned long discard_length; if (zero >= end) { discard_length = end - one; } else { discard_length = zero - one; } if (discard_length) { postcopy_discard_send_range(ms, pds, one, discard_length); } current = one + discard_length; } else { current = one; } } return 0; } /** * postcopy_each_ram_send_discard: discard all RAMBlocks * * Returns 0 for success or negative for error * * Utility for the outgoing postcopy code. * Calls postcopy_send_discard_bm_ram for each RAMBlock * passing it bitmap indexes and name. * (qemu_ram_foreach_block ends up passing unscaled lengths * which would mean postcopy code would have to deal with target page) * * @ms: current migration state */ static int postcopy_each_ram_send_discard(MigrationState *ms) { struct RAMBlock *block; int ret; RAMBLOCK_FOREACH_MIGRATABLE(block) { PostcopyDiscardState *pds = postcopy_discard_send_init(ms, block->idstr); /* * Postcopy sends chunks of bitmap over the wire, but it * just needs indexes at this point, avoids it having * target page specific code. */ ret = postcopy_send_discard_bm_ram(ms, pds, block); postcopy_discard_send_finish(ms, pds); if (ret) { return ret; } } return 0; } /** * postcopy_chunk_hostpages_pass: canocalize bitmap in hostpages * * Helper for postcopy_chunk_hostpages; it's called twice to * canonicalize the two bitmaps, that are similar, but one is * inverted. * * Postcopy requires that all target pages in a hostpage are dirty or * clean, not a mix. This function canonicalizes the bitmaps. * * @ms: current migration state * @unsent_pass: if true we need to canonicalize partially unsent host pages * otherwise we need to canonicalize partially dirty host pages * @block: block that contains the page we want to canonicalize * @pds: state for postcopy */ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass, RAMBlock *block, PostcopyDiscardState *pds) { RAMState *rs = ram_state; unsigned long *bitmap = block->bmap; unsigned long *unsentmap = block->unsentmap; unsigned int host_ratio = block->page_size / TARGET_PAGE_SIZE; unsigned long pages = block->used_length >> TARGET_PAGE_BITS; unsigned long run_start; if (block->page_size == TARGET_PAGE_SIZE) { /* Easy case - TPS==HPS for a non-huge page RAMBlock */ return; } if (unsent_pass) { /* Find a sent page */ run_start = find_next_zero_bit(unsentmap, pages, 0); } else { /* Find a dirty page */ run_start = find_next_bit(bitmap, pages, 0); } while (run_start < pages) { bool do_fixup = false; unsigned long fixup_start_addr; unsigned long host_offset; /* * If the start of this run of pages is in the middle of a host * page, then we need to fixup this host page. */ host_offset = run_start % host_ratio; if (host_offset) { do_fixup = true; run_start -= host_offset; fixup_start_addr = run_start; /* For the next pass */ run_start = run_start + host_ratio; } else { /* Find the end of this run */ unsigned long run_end; if (unsent_pass) { run_end = find_next_bit(unsentmap, pages, run_start + 1); } else { run_end = find_next_zero_bit(bitmap, pages, run_start + 1); } /* * If the end isn't at the start of a host page, then the * run doesn't finish at the end of a host page * and we need to discard. */ host_offset = run_end % host_ratio; if (host_offset) { do_fixup = true; fixup_start_addr = run_end - host_offset; /* * This host page has gone, the next loop iteration starts * from after the fixup */ run_start = fixup_start_addr + host_ratio; } else { /* * No discards on this iteration, next loop starts from * next sent/dirty page */ run_start = run_end + 1; } } if (do_fixup) { unsigned long page; /* Tell the destination to discard this page */ if (unsent_pass || !test_bit(fixup_start_addr, unsentmap)) { /* For the unsent_pass we: * discard partially sent pages * For the !unsent_pass (dirty) we: * discard partially dirty pages that were sent * (any partially sent pages were already discarded * by the previous unsent_pass) */ postcopy_discard_send_range(ms, pds, fixup_start_addr, host_ratio); } /* Clean up the bitmap */ for (page = fixup_start_addr; page < fixup_start_addr + host_ratio; page++) { /* All pages in this host page are now not sent */ set_bit(page, unsentmap); /* * Remark them as dirty, updating the count for any pages * that weren't previously dirty. */ rs->migration_dirty_pages += !test_and_set_bit(page, bitmap); } } if (unsent_pass) { /* Find the next sent page for the next iteration */ run_start = find_next_zero_bit(unsentmap, pages, run_start); } else { /* Find the next dirty page for the next iteration */ run_start = find_next_bit(bitmap, pages, run_start); } } } /** * postcopy_chuck_hostpages: discrad any partially sent host page * * Utility for the outgoing postcopy code. * * Discard any partially sent host-page size chunks, mark any partially * dirty host-page size chunks as all dirty. In this case the host-page * is the host-page for the particular RAMBlock, i.e. it might be a huge page * * Returns zero on success * * @ms: current migration state * @block: block we want to work with */ static int postcopy_chunk_hostpages(MigrationState *ms, RAMBlock *block) { PostcopyDiscardState *pds = postcopy_discard_send_init(ms, block->idstr); /* First pass: Discard all partially sent host pages */ postcopy_chunk_hostpages_pass(ms, true, block, pds); /* * Second pass: Ensure that all partially dirty host pages are made * fully dirty. */ postcopy_chunk_hostpages_pass(ms, false, block, pds); postcopy_discard_send_finish(ms, pds); return 0; } /** * ram_postcopy_send_discard_bitmap: transmit the discard bitmap * * Returns zero on success * * Transmit the set of pages to be discarded after precopy to the target * these are pages that: * a) Have been previously transmitted but are now dirty again * b) Pages that have never been transmitted, this ensures that * any pages on the destination that have been mapped by background * tasks get discarded (transparent huge pages is the specific concern) * Hopefully this is pretty sparse * * @ms: current migration state */ int ram_postcopy_send_discard_bitmap(MigrationState *ms) { RAMState *rs = ram_state; RAMBlock *block; int ret; rcu_read_lock(); /* This should be our last sync, the src is now paused */ migration_bitmap_sync(rs); /* Easiest way to make sure we don't resume in the middle of a host-page */ rs->last_seen_block = NULL; rs->last_sent_block = NULL; rs->last_page = 0; RAMBLOCK_FOREACH_MIGRATABLE(block) { unsigned long pages = block->used_length >> TARGET_PAGE_BITS; unsigned long *bitmap = block->bmap; unsigned long *unsentmap = block->unsentmap; if (!unsentmap) { /* We don't have a safe way to resize the sentmap, so * if the bitmap was resized it will be NULL at this * point. */ error_report("migration ram resized during precopy phase"); rcu_read_unlock(); return -EINVAL; } /* Deal with TPS != HPS and huge pages */ ret = postcopy_chunk_hostpages(ms, block); if (ret) { rcu_read_unlock(); return ret; } /* * Update the unsentmap to be unsentmap = unsentmap | dirty */ bitmap_or(unsentmap, unsentmap, bitmap, pages); #ifdef DEBUG_POSTCOPY ram_debug_dump_bitmap(unsentmap, true, pages); #endif } trace_ram_postcopy_send_discard_bitmap(); ret = postcopy_each_ram_send_discard(ms); rcu_read_unlock(); return ret; } /** * ram_discard_range: discard dirtied pages at the beginning of postcopy * * Returns zero on success * * @rbname: name of the RAMBlock of the request. NULL means the * same that last one. * @start: RAMBlock starting page * @length: RAMBlock size */ int ram_discard_range(const char *rbname, uint64_t start, size_t length) { int ret = -1; trace_ram_discard_range(rbname, start, length); rcu_read_lock(); RAMBlock *rb = qemu_ram_block_by_name(rbname); if (!rb) { error_report("ram_discard_range: Failed to find block '%s'", rbname); goto err; } bitmap_clear(rb->receivedmap, start >> qemu_target_page_bits(), length >> qemu_target_page_bits()); ret = ram_block_discard_range(rb, start, length); err: rcu_read_unlock(); return ret; } /* * For every allocation, we will try not to crash the VM if the * allocation failed. */ static int xbzrle_init(void) { Error *local_err = NULL; if (!migrate_use_xbzrle()) { return 0; } XBZRLE_cache_lock(); XBZRLE.zero_target_page = g_try_malloc0(TARGET_PAGE_SIZE); if (!XBZRLE.zero_target_page) { error_report("%s: Error allocating zero page", __func__); goto err_out; } XBZRLE.cache = cache_init(migrate_xbzrle_cache_size(), TARGET_PAGE_SIZE, &local_err); if (!XBZRLE.cache) { error_report_err(local_err); goto free_zero_page; } XBZRLE.encoded_buf = g_try_malloc0(TARGET_PAGE_SIZE); if (!XBZRLE.encoded_buf) { error_report("%s: Error allocating encoded_buf", __func__); goto free_cache; } XBZRLE.current_buf = g_try_malloc(TARGET_PAGE_SIZE); if (!XBZRLE.current_buf) { error_report("%s: Error allocating current_buf", __func__); goto free_encoded_buf; } /* We are all good */ XBZRLE_cache_unlock(); return 0; free_encoded_buf: g_free(XBZRLE.encoded_buf); XBZRLE.encoded_buf = NULL; free_cache: cache_fini(XBZRLE.cache); XBZRLE.cache = NULL; free_zero_page: g_free(XBZRLE.zero_target_page); XBZRLE.zero_target_page = NULL; err_out: XBZRLE_cache_unlock(); return -ENOMEM; } static int ram_state_init(RAMState **rsp) { *rsp = g_try_new0(RAMState, 1); if (!*rsp) { error_report("%s: Init ramstate fail", __func__); return -1; } qemu_mutex_init(&(*rsp)->bitmap_mutex); qemu_mutex_init(&(*rsp)->src_page_req_mutex); QSIMPLEQ_INIT(&(*rsp)->src_page_requests); /* * Count the total number of pages used by ram blocks not including any * gaps due to alignment or unplugs. */ (*rsp)->migration_dirty_pages = ram_bytes_total() >> TARGET_PAGE_BITS; ram_state_reset(*rsp); return 0; } static void ram_list_init_bitmaps(void) { RAMBlock *block; unsigned long pages; /* Skip setting bitmap if there is no RAM */ if (ram_bytes_total()) { RAMBLOCK_FOREACH_MIGRATABLE(block) { pages = block->max_length >> TARGET_PAGE_BITS; block->bmap = bitmap_new(pages); bitmap_set(block->bmap, 0, pages); if (migrate_postcopy_ram()) { block->unsentmap = bitmap_new(pages); bitmap_set(block->unsentmap, 0, pages); } } } } static void ram_init_bitmaps(RAMState *rs) { /* For memory_global_dirty_log_start below. */ qemu_mutex_lock_iothread(); qemu_mutex_lock_ramlist(); rcu_read_lock(); ram_list_init_bitmaps(); memory_global_dirty_log_start(); migration_bitmap_sync(rs); rcu_read_unlock(); qemu_mutex_unlock_ramlist(); qemu_mutex_unlock_iothread(); } static int ram_init_all(RAMState **rsp) { if (ram_state_init(rsp)) { return -1; } if (xbzrle_init()) { ram_state_cleanup(rsp); return -1; } ram_init_bitmaps(*rsp); return 0; } static void ram_state_resume_prepare(RAMState *rs, QEMUFile *out) { RAMBlock *block; uint64_t pages = 0; /* * Postcopy is not using xbzrle/compression, so no need for that. * Also, since source are already halted, we don't need to care * about dirty page logging as well. */ RAMBLOCK_FOREACH(block) { pages += bitmap_count_one(block->bmap, block->used_length >> TARGET_PAGE_BITS); } /* This may not be aligned with current bitmaps. Recalculate. */ rs->migration_dirty_pages = pages; rs->last_seen_block = NULL; rs->last_sent_block = NULL; rs->last_page = 0; rs->last_version = ram_list.version; /* * Disable the bulk stage, otherwise we'll resend the whole RAM no * matter what we have sent. */ rs->ram_bulk_stage = false; /* Update RAMState cache of output QEMUFile */ rs->f = out; trace_ram_state_resume_prepare(pages); } /* * Each of ram_save_setup, ram_save_iterate and ram_save_complete has * long-running RCU critical section. When rcu-reclaims in the code * start to become numerous it will be necessary to reduce the * granularity of these critical sections. */ /** * ram_save_setup: Setup RAM for migration * * Returns zero to indicate success and negative for error * * @f: QEMUFile where to send the data * @opaque: RAMState pointer */ static int ram_save_setup(QEMUFile *f, void *opaque) { RAMState **rsp = opaque; RAMBlock *block; if (compress_threads_save_setup()) { return -1; } /* migration has already setup the bitmap, reuse it. */ if (!migration_in_colo_state()) { if (ram_init_all(rsp) != 0) { compress_threads_save_cleanup(); return -1; } } (*rsp)->f = f; rcu_read_lock(); qemu_put_be64(f, ram_bytes_total() | RAM_SAVE_FLAG_MEM_SIZE); RAMBLOCK_FOREACH_MIGRATABLE(block) { qemu_put_byte(f, strlen(block->idstr)); qemu_put_buffer(f, (uint8_t *)block->idstr, strlen(block->idstr)); qemu_put_be64(f, block->used_length); if (migrate_postcopy_ram() && block->page_size != qemu_host_page_size) { qemu_put_be64(f, block->page_size); } } rcu_read_unlock(); ram_control_before_iterate(f, RAM_CONTROL_SETUP); ram_control_after_iterate(f, RAM_CONTROL_SETUP); qemu_put_be64(f, RAM_SAVE_FLAG_EOS); return 0; } /** * ram_save_iterate: iterative stage for migration * * Returns zero to indicate success and negative for error * * @f: QEMUFile where to send the data * @opaque: RAMState pointer */ static int ram_save_iterate(QEMUFile *f, void *opaque) { RAMState **temp = opaque; RAMState *rs = *temp; int ret; int i; int64_t t0; int done = 0; if (blk_mig_bulk_active()) { /* Avoid transferring ram during bulk phase of block migration as * the bulk phase will usually take a long time and transferring * ram updates during that time is pointless. */ goto out; } rcu_read_lock(); if (ram_list.version != rs->last_version) { ram_state_reset(rs); } /* Read version before ram_list.blocks */ smp_rmb(); ram_control_before_iterate(f, RAM_CONTROL_ROUND); t0 = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); i = 0; while ((ret = qemu_file_rate_limit(f)) == 0) { int pages; pages = ram_find_and_save_block(rs, false); /* no more pages to sent */ if (pages == 0) { done = 1; break; } rs->iterations++; /* we want to check in the 1st loop, just in case it was the 1st time and we had to sync the dirty bitmap. qemu_get_clock_ns() is a bit expensive, so we only check each some iterations */ if ((i & 63) == 0) { uint64_t t1 = (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - t0) / 1000000; if (t1 > MAX_WAIT) { trace_ram_save_iterate_big_wait(t1, i); break; } } i++; } flush_compressed_data(rs); rcu_read_unlock(); /* * Must occur before EOS (or any QEMUFile operation) * because of RDMA protocol. */ ram_control_after_iterate(f, RAM_CONTROL_ROUND); out: qemu_put_be64(f, RAM_SAVE_FLAG_EOS); ram_counters.transferred += 8; ret = qemu_file_get_error(f); if (ret < 0) { return ret; } return done; } /** * ram_save_complete: function called to send the remaining amount of ram * * Returns zero to indicate success * * Called with iothread lock * * @f: QEMUFile where to send the data * @opaque: RAMState pointer */ static int ram_save_complete(QEMUFile *f, void *opaque) { RAMState **temp = opaque; RAMState *rs = *temp; rcu_read_lock(); if (!migration_in_postcopy()) { migration_bitmap_sync(rs); } ram_control_before_iterate(f, RAM_CONTROL_FINISH); /* try transferring iterative blocks of memory */ /* flush all remaining blocks regardless of rate limiting */ while (true) { int pages; pages = ram_find_and_save_block(rs, !migration_in_colo_state()); /* no more blocks to sent */ if (pages == 0) { break; } } flush_compressed_data(rs); ram_control_after_iterate(f, RAM_CONTROL_FINISH); rcu_read_unlock(); qemu_put_be64(f, RAM_SAVE_FLAG_EOS); return 0; } static void ram_save_pending(QEMUFile *f, void *opaque, uint64_t max_size, uint64_t *res_precopy_only, uint64_t *res_compatible, uint64_t *res_postcopy_only) { RAMState **temp = opaque; RAMState *rs = *temp; uint64_t remaining_size; remaining_size = rs->migration_dirty_pages * TARGET_PAGE_SIZE; if (!migration_in_postcopy() && remaining_size < max_size) { qemu_mutex_lock_iothread(); rcu_read_lock(); migration_bitmap_sync(rs); rcu_read_unlock(); qemu_mutex_unlock_iothread(); remaining_size = rs->migration_dirty_pages * TARGET_PAGE_SIZE; } if (migrate_postcopy_ram()) { /* We can do postcopy, and all the data is postcopiable */ *res_compatible += remaining_size; } else { *res_precopy_only += remaining_size; } } static int load_xbzrle(QEMUFile *f, ram_addr_t addr, void *host) { unsigned int xh_len; int xh_flags; uint8_t *loaded_data; /* extract RLE header */ xh_flags = qemu_get_byte(f); xh_len = qemu_get_be16(f); if (xh_flags != ENCODING_FLAG_XBZRLE) { error_report("Failed to load XBZRLE page - wrong compression!"); return -1; } if (xh_len > TARGET_PAGE_SIZE) { error_report("Failed to load XBZRLE page - len overflow!"); return -1; } loaded_data = XBZRLE.decoded_buf; /* load data and decode */ /* it can change loaded_data to point to an internal buffer */ qemu_get_buffer_in_place(f, &loaded_data, xh_len); /* decode RLE */ if (xbzrle_decode_buffer(loaded_data, xh_len, host, TARGET_PAGE_SIZE) == -1) { error_report("Failed to load XBZRLE page - decode error!"); return -1; } return 0; } /** * ram_block_from_stream: read a RAMBlock id from the migration stream * * Must be called from within a rcu critical section. * * Returns a pointer from within the RCU-protected ram_list. * * @f: QEMUFile where to read the data from * @flags: Page flags (mostly to see if it's a continuation of previous block) */ static inline RAMBlock *ram_block_from_stream(QEMUFile *f, int flags) { static RAMBlock *block = NULL; char id[256]; uint8_t len; if (flags & RAM_SAVE_FLAG_CONTINUE) { if (!block) { error_report("Ack, bad migration stream!"); return NULL; } return block; } len = qemu_get_byte(f); qemu_get_buffer(f, (uint8_t *)id, len); id[len] = 0; block = qemu_ram_block_by_name(id); if (!block) { error_report("Can't find block %s", id); return NULL; } if (!qemu_ram_is_migratable(block)) { error_report("block %s should not be migrated !", id); return NULL; } return block; } static inline void *host_from_ram_block_offset(RAMBlock *block, ram_addr_t offset) { if (!offset_in_ramblock(block, offset)) { return NULL; } return block->host + offset; } /** * ram_handle_compressed: handle the zero page case * * If a page (or a whole RDMA chunk) has been * determined to be zero, then zap it. * * @host: host address for the zero page * @ch: what the page is filled from. We only support zero * @size: size of the zero page */ void ram_handle_compressed(void *host, uint8_t ch, uint64_t size) { if (ch != 0 || !is_zero_range(host, size)) { memset(host, ch, size); } } /* return the size after decompression, or negative value on error */ static int qemu_uncompress_data(z_stream *stream, uint8_t *dest, size_t dest_len, const uint8_t *source, size_t source_len) { int err; err = inflateReset(stream); if (err != Z_OK) { return -1; } stream->avail_in = source_len; stream->next_in = (uint8_t *)source; stream->avail_out = dest_len; stream->next_out = dest; err = inflate(stream, Z_NO_FLUSH); if (err != Z_STREAM_END) { return -1; } return stream->total_out; } static void *do_data_decompress(void *opaque) { DecompressParam *param = opaque; unsigned long pagesize; uint8_t *des; int len, ret; qemu_mutex_lock(¶m->mutex); while (!param->quit) { if (param->des) { des = param->des; len = param->len; param->des = 0; qemu_mutex_unlock(¶m->mutex); pagesize = TARGET_PAGE_SIZE; ret = qemu_uncompress_data(¶m->stream, des, pagesize, param->compbuf, len); if (ret < 0 && migrate_get_current()->decompress_error_check) { error_report("decompress data failed"); qemu_file_set_error(decomp_file, ret); } qemu_mutex_lock(&decomp_done_lock); param->done = true; qemu_cond_signal(&decomp_done_cond); qemu_mutex_unlock(&decomp_done_lock); qemu_mutex_lock(¶m->mutex); } else { qemu_cond_wait(¶m->cond, ¶m->mutex); } } qemu_mutex_unlock(¶m->mutex); return NULL; } static int wait_for_decompress_done(void) { int idx, thread_count; if (!migrate_use_compression()) { return 0; } thread_count = migrate_decompress_threads(); qemu_mutex_lock(&decomp_done_lock); for (idx = 0; idx < thread_count; idx++) { while (!decomp_param[idx].done) { qemu_cond_wait(&decomp_done_cond, &decomp_done_lock); } } qemu_mutex_unlock(&decomp_done_lock); return qemu_file_get_error(decomp_file); } static void compress_threads_load_cleanup(void) { int i, thread_count; if (!migrate_use_compression()) { return; } thread_count = migrate_decompress_threads(); for (i = 0; i < thread_count; i++) { /* * we use it as a indicator which shows if the thread is * properly init'd or not */ if (!decomp_param[i].compbuf) { break; } qemu_mutex_lock(&decomp_param[i].mutex); decomp_param[i].quit = true; qemu_cond_signal(&decomp_param[i].cond); qemu_mutex_unlock(&decomp_param[i].mutex); } for (i = 0; i < thread_count; i++) { if (!decomp_param[i].compbuf) { break; } qemu_thread_join(decompress_threads + i); qemu_mutex_destroy(&decomp_param[i].mutex); qemu_cond_destroy(&decomp_param[i].cond); inflateEnd(&decomp_param[i].stream); g_free(decomp_param[i].compbuf); decomp_param[i].compbuf = NULL; } g_free(decompress_threads); g_free(decomp_param); decompress_threads = NULL; decomp_param = NULL; decomp_file = NULL; } static int compress_threads_load_setup(QEMUFile *f) { int i, thread_count; if (!migrate_use_compression()) { return 0; } thread_count = migrate_decompress_threads(); decompress_threads = g_new0(QemuThread, thread_count); decomp_param = g_new0(DecompressParam, thread_count); qemu_mutex_init(&decomp_done_lock); qemu_cond_init(&decomp_done_cond); decomp_file = f; for (i = 0; i < thread_count; i++) { if (inflateInit(&decomp_param[i].stream) != Z_OK) { goto exit; } decomp_param[i].compbuf = g_malloc0(compressBound(TARGET_PAGE_SIZE)); qemu_mutex_init(&decomp_param[i].mutex); qemu_cond_init(&decomp_param[i].cond); decomp_param[i].done = true; decomp_param[i].quit = false; qemu_thread_create(decompress_threads + i, "decompress", do_data_decompress, decomp_param + i, QEMU_THREAD_JOINABLE); } return 0; exit: compress_threads_load_cleanup(); return -1; } static void decompress_data_with_multi_threads(QEMUFile *f, void *host, int len) { int idx, thread_count; thread_count = migrate_decompress_threads(); qemu_mutex_lock(&decomp_done_lock); while (true) { for (idx = 0; idx < thread_count; idx++) { if (decomp_param[idx].done) { decomp_param[idx].done = false; qemu_mutex_lock(&decomp_param[idx].mutex); qemu_get_buffer(f, decomp_param[idx].compbuf, len); decomp_param[idx].des = host; decomp_param[idx].len = len; qemu_cond_signal(&decomp_param[idx].cond); qemu_mutex_unlock(&decomp_param[idx].mutex); break; } } if (idx < thread_count) { break; } else { qemu_cond_wait(&decomp_done_cond, &decomp_done_lock); } } qemu_mutex_unlock(&decomp_done_lock); } /** * ram_load_setup: Setup RAM for migration incoming side * * Returns zero to indicate success and negative for error * * @f: QEMUFile where to receive the data * @opaque: RAMState pointer */ static int ram_load_setup(QEMUFile *f, void *opaque) { if (compress_threads_load_setup(f)) { return -1; } xbzrle_load_setup(); ramblock_recv_map_init(); return 0; } static int ram_load_cleanup(void *opaque) { RAMBlock *rb; xbzrle_load_cleanup(); compress_threads_load_cleanup(); RAMBLOCK_FOREACH_MIGRATABLE(rb) { g_free(rb->receivedmap); rb->receivedmap = NULL; } return 0; } /** * ram_postcopy_incoming_init: allocate postcopy data structures * * Returns 0 for success and negative if there was one error * * @mis: current migration incoming state * * Allocate data structures etc needed by incoming migration with * postcopy-ram. postcopy-ram's similarly names * postcopy_ram_incoming_init does the work. */ int ram_postcopy_incoming_init(MigrationIncomingState *mis) { unsigned long ram_pages = last_ram_page(); return postcopy_ram_incoming_init(mis, ram_pages); } /** * ram_load_postcopy: load a page in postcopy case * * Returns 0 for success or -errno in case of error * * Called in postcopy mode by ram_load(). * rcu_read_lock is taken prior to this being called. * * @f: QEMUFile where to send the data */ static int ram_load_postcopy(QEMUFile *f) { int flags = 0, ret = 0; bool place_needed = false; bool matching_page_sizes = false; MigrationIncomingState *mis = migration_incoming_get_current(); /* Temporary page that is later 'placed' */ void *postcopy_host_page = postcopy_get_tmp_page(mis); void *last_host = NULL; bool all_zero = false; while (!ret && !(flags & RAM_SAVE_FLAG_EOS)) { ram_addr_t addr; void *host = NULL; void *page_buffer = NULL; void *place_source = NULL; RAMBlock *block = NULL; uint8_t ch; addr = qemu_get_be64(f); /* * If qemu file error, we should stop here, and then "addr" * may be invalid */ ret = qemu_file_get_error(f); if (ret) { break; } flags = addr & ~TARGET_PAGE_MASK; addr &= TARGET_PAGE_MASK; trace_ram_load_postcopy_loop((uint64_t)addr, flags); place_needed = false; if (flags & (RAM_SAVE_FLAG_ZERO | RAM_SAVE_FLAG_PAGE)) { block = ram_block_from_stream(f, flags); host = host_from_ram_block_offset(block, addr); if (!host) { error_report("Illegal RAM offset " RAM_ADDR_FMT, addr); ret = -EINVAL; break; } matching_page_sizes = block->page_size == TARGET_PAGE_SIZE; /* * Postcopy requires that we place whole host pages atomically; * these may be huge pages for RAMBlocks that are backed by * hugetlbfs. * To make it atomic, the data is read into a temporary page * that's moved into place later. * The migration protocol uses, possibly smaller, target-pages * however the source ensures it always sends all the components * of a host page in order. */ page_buffer = postcopy_host_page + ((uintptr_t)host & (block->page_size - 1)); /* If all TP are zero then we can optimise the place */ if (!((uintptr_t)host & (block->page_size - 1))) { all_zero = true; } else { /* not the 1st TP within the HP */ if (host != (last_host + TARGET_PAGE_SIZE)) { error_report("Non-sequential target page %p/%p", host, last_host); ret = -EINVAL; break; } } /* * If it's the last part of a host page then we place the host * page */ place_needed = (((uintptr_t)host + TARGET_PAGE_SIZE) & (block->page_size - 1)) == 0; place_source = postcopy_host_page; } last_host = host; switch (flags & ~RAM_SAVE_FLAG_CONTINUE) { case RAM_SAVE_FLAG_ZERO: ch = qemu_get_byte(f); memset(page_buffer, ch, TARGET_PAGE_SIZE); if (ch) { all_zero = false; } break; case RAM_SAVE_FLAG_PAGE: all_zero = false; if (!place_needed || !matching_page_sizes) { qemu_get_buffer(f, page_buffer, TARGET_PAGE_SIZE); } else { /* Avoids the qemu_file copy during postcopy, which is * going to do a copy later; can only do it when we * do this read in one go (matching page sizes) */ qemu_get_buffer_in_place(f, (uint8_t **)&place_source, TARGET_PAGE_SIZE); } break; case RAM_SAVE_FLAG_EOS: /* normal exit */ break; default: error_report("Unknown combination of migration flags: %#x" " (postcopy mode)", flags); ret = -EINVAL; break; } /* Detect for any possible file errors */ if (!ret && qemu_file_get_error(f)) { ret = qemu_file_get_error(f); } if (!ret && place_needed) { /* This gets called at the last target page in the host page */ void *place_dest = host + TARGET_PAGE_SIZE - block->page_size; if (all_zero) { ret = postcopy_place_page_zero(mis, place_dest, block); } else { ret = postcopy_place_page(mis, place_dest, place_source, block); } } } return ret; } static bool postcopy_is_advised(void) { PostcopyState ps = postcopy_state_get(); return ps >= POSTCOPY_INCOMING_ADVISE && ps < POSTCOPY_INCOMING_END; } static bool postcopy_is_running(void) { PostcopyState ps = postcopy_state_get(); return ps >= POSTCOPY_INCOMING_LISTENING && ps < POSTCOPY_INCOMING_END; } static int ram_load(QEMUFile *f, void *opaque, int version_id) { int flags = 0, ret = 0, invalid_flags = 0; static uint64_t seq_iter; int len = 0; /* * If system is running in postcopy mode, page inserts to host memory must * be atomic */ bool postcopy_running = postcopy_is_running(); /* ADVISE is earlier, it shows the source has the postcopy capability on */ bool postcopy_advised = postcopy_is_advised(); seq_iter++; if (version_id != 4) { ret = -EINVAL; } if (!migrate_use_compression()) { invalid_flags |= RAM_SAVE_FLAG_COMPRESS_PAGE; } /* This RCU critical section can be very long running. * When RCU reclaims in the code start to become numerous, * it will be necessary to reduce the granularity of this * critical section. */ rcu_read_lock(); if (postcopy_running) { ret = ram_load_postcopy(f); } while (!postcopy_running && !ret && !(flags & RAM_SAVE_FLAG_EOS)) { ram_addr_t addr, total_ram_bytes; void *host = NULL; uint8_t ch; addr = qemu_get_be64(f); flags = addr & ~TARGET_PAGE_MASK; addr &= TARGET_PAGE_MASK; if (flags & invalid_flags) { if (flags & invalid_flags & RAM_SAVE_FLAG_COMPRESS_PAGE) { error_report("Received an unexpected compressed page"); } ret = -EINVAL; break; } if (flags & (RAM_SAVE_FLAG_ZERO | RAM_SAVE_FLAG_PAGE | RAM_SAVE_FLAG_COMPRESS_PAGE | RAM_SAVE_FLAG_XBZRLE)) { RAMBlock *block = ram_block_from_stream(f, flags); host = host_from_ram_block_offset(block, addr); if (!host) { error_report("Illegal RAM offset " RAM_ADDR_FMT, addr); ret = -EINVAL; break; } ramblock_recv_bitmap_set(block, host); trace_ram_load_loop(block->idstr, (uint64_t)addr, flags, host); } switch (flags & ~RAM_SAVE_FLAG_CONTINUE) { case RAM_SAVE_FLAG_MEM_SIZE: /* Synchronize RAM block list */ total_ram_bytes = addr; while (!ret && total_ram_bytes) { RAMBlock *block; char id[256]; ram_addr_t length; len = qemu_get_byte(f); qemu_get_buffer(f, (uint8_t *)id, len); id[len] = 0; length = qemu_get_be64(f); block = qemu_ram_block_by_name(id); if (block && !qemu_ram_is_migratable(block)) { error_report("block %s should not be migrated !", id); ret = -EINVAL; } else if (block) { if (length != block->used_length) { Error *local_err = NULL; ret = qemu_ram_resize(block, length, &local_err); if (local_err) { error_report_err(local_err); } } /* For postcopy we need to check hugepage sizes match */ if (postcopy_advised && block->page_size != qemu_host_page_size) { uint64_t remote_page_size = qemu_get_be64(f); if (remote_page_size != block->page_size) { error_report("Mismatched RAM page size %s " "(local) %zd != %" PRId64, id, block->page_size, remote_page_size); ret = -EINVAL; } } ram_control_load_hook(f, RAM_CONTROL_BLOCK_REG, block->idstr); } else { error_report("Unknown ramblock \"%s\", cannot " "accept migration", id); ret = -EINVAL; } total_ram_bytes -= length; } break; case RAM_SAVE_FLAG_ZERO: ch = qemu_get_byte(f); ram_handle_compressed(host, ch, TARGET_PAGE_SIZE); break; case RAM_SAVE_FLAG_PAGE: qemu_get_buffer(f, host, TARGET_PAGE_SIZE); break; case RAM_SAVE_FLAG_COMPRESS_PAGE: len = qemu_get_be32(f); if (len < 0 || len > compressBound(TARGET_PAGE_SIZE)) { error_report("Invalid compressed data length: %d", len); ret = -EINVAL; break; } decompress_data_with_multi_threads(f, host, len); break; case RAM_SAVE_FLAG_XBZRLE: if (load_xbzrle(f, addr, host) < 0) { error_report("Failed to decompress XBZRLE page at " RAM_ADDR_FMT, addr); ret = -EINVAL; break; } break; case RAM_SAVE_FLAG_EOS: /* normal exit */ break; default: if (flags & RAM_SAVE_FLAG_HOOK) { ram_control_load_hook(f, RAM_CONTROL_HOOK, NULL); } else { error_report("Unknown combination of migration flags: %#x", flags); ret = -EINVAL; } } if (!ret) { ret = qemu_file_get_error(f); } } ret |= wait_for_decompress_done(); rcu_read_unlock(); trace_ram_load_complete(ret, seq_iter); return ret; } static bool ram_has_postcopy(void *opaque) { return migrate_postcopy_ram(); } /* Sync all the dirty bitmap with destination VM. */ static int ram_dirty_bitmap_sync_all(MigrationState *s, RAMState *rs) { RAMBlock *block; QEMUFile *file = s->to_dst_file; int ramblock_count = 0; trace_ram_dirty_bitmap_sync_start(); RAMBLOCK_FOREACH(block) { qemu_savevm_send_recv_bitmap(file, block->idstr); trace_ram_dirty_bitmap_request(block->idstr); ramblock_count++; } trace_ram_dirty_bitmap_sync_wait(); /* Wait until all the ramblocks' dirty bitmap synced */ while (ramblock_count--) { qemu_sem_wait(&s->rp_state.rp_sem); } trace_ram_dirty_bitmap_sync_complete(); return 0; } static void ram_dirty_bitmap_reload_notify(MigrationState *s) { qemu_sem_post(&s->rp_state.rp_sem); } /* * 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); /* * We succeeded to sync bitmap for current ramblock. If this is * the last one to sync, we need to notify the main send thread. */ ram_dirty_bitmap_reload_notify(s); ret = 0; out: g_free(le_bitmap); return ret; } static int ram_resume_prepare(MigrationState *s, void *opaque) { RAMState *rs = *(RAMState **)opaque; int ret; ret = ram_dirty_bitmap_sync_all(s, rs); if (ret) { return ret; } ram_state_resume_prepare(rs, s->to_dst_file); return 0; } static SaveVMHandlers savevm_ram_handlers = { .save_setup = ram_save_setup, .save_live_iterate = ram_save_iterate, .save_live_complete_postcopy = ram_save_complete, .save_live_complete_precopy = ram_save_complete, .has_postcopy = ram_has_postcopy, .save_live_pending = ram_save_pending, .load_state = ram_load, .save_cleanup = ram_save_cleanup, .load_setup = ram_load_setup, .load_cleanup = ram_load_cleanup, .resume_prepare = ram_resume_prepare, }; void ram_mig_init(void) { qemu_mutex_init(&XBZRLE.lock); register_savevm_live(NULL, "ram", 0, 4, &savevm_ram_handlers, &ram_state); }