/* * QEMU live migration * * Copyright IBM, Corp. 2008 * * Authors: * Anthony Liguori <aliguori@us.ibm.com> * * This work is licensed under the terms of the GNU GPL, version 2. See * the COPYING file in the top-level directory. * */ #ifndef QEMU_MIGRATION_H #define QEMU_MIGRATION_H #include "exec/cpu-common.h" #include "hw/qdev-core.h" #include "qapi/qapi-types-migration.h" #include "qapi/qmp/json-writer.h" #include "qemu/thread.h" #include "qemu/coroutine.h" #include "io/channel.h" #include "io/channel-buffer.h" #include "net/announce.h" #include "qom/object.h" #include "postcopy-ram.h" #include "sysemu/runstate.h" #include "migration/misc.h" struct PostcopyBlocktimeContext; #define MIGRATION_RESUME_ACK_VALUE (1) /* * 1<<6=64 pages -> 256K chunk when page size is 4K. This gives us * the benefit that all the chunks are 64 pages aligned then the * bitmaps are always aligned to LONG. */ #define CLEAR_BITMAP_SHIFT_MIN 6 /* * 1<<18=256K pages -> 1G chunk when page size is 4K. This is the * default value to use if no one specified. */ #define CLEAR_BITMAP_SHIFT_DEFAULT 18 /* * 1<<31=2G pages -> 8T chunk when page size is 4K. This should be * big enough and make sure we won't overflow easily. */ #define CLEAR_BITMAP_SHIFT_MAX 31 /* This is an abstraction of a "temp huge page" for postcopy's purpose */ typedef struct { /* * This points to a temporary huge page as a buffer for UFFDIO_COPY. It's * mmap()ed and needs to be freed when cleanup. */ void *tmp_huge_page; /* * This points to the host page we're going to install for this temp page. * It tells us after we've received the whole page, where we should put it. */ void *host_addr; /* Number of small pages copied (in size of TARGET_PAGE_SIZE) */ unsigned int target_pages; /* Whether this page contains all zeros */ bool all_zero; } PostcopyTmpPage; typedef enum { PREEMPT_THREAD_NONE = 0, PREEMPT_THREAD_CREATED, PREEMPT_THREAD_QUIT, } PreemptThreadStatus; /* State for the incoming migration */ struct MigrationIncomingState { QEMUFile *from_src_file; /* Previously received RAM's RAMBlock pointer */ RAMBlock *last_recv_block[RAM_CHANNEL_MAX]; /* A hook to allow cleanup at the end of incoming migration */ void *transport_data; void (*transport_cleanup)(void *data); /* * Used to sync thread creations. Note that we can't create threads in * parallel with this sem. */ QemuSemaphore thread_sync_sem; /* * Free at the start of the main state load, set as the main thread finishes * loading state. */ QemuEvent main_thread_load_event; /* For network announces */ AnnounceTimer announce_timer; size_t largest_page_size; bool have_fault_thread; QemuThread fault_thread; /* Set this when we want the fault thread to quit */ bool fault_thread_quit; bool have_listen_thread; QemuThread listen_thread; /* For the kernel to send us notifications */ int userfault_fd; /* To notify the fault_thread to wake, e.g., when need to quit */ int userfault_event_fd; QEMUFile *to_src_file; QemuMutex rp_mutex; /* We send replies from multiple threads */ /* RAMBlock of last request sent to source */ RAMBlock *last_rb; /* * Number of postcopy channels including the default precopy channel, so * vanilla postcopy will only contain one channel which contain both * precopy and postcopy streams. * * This is calculated when the src requests to enable postcopy but before * it starts. Its value can depend on e.g. whether postcopy preemption is * enabled. */ unsigned int postcopy_channels; /* QEMUFile for postcopy only; it'll be handled by a separate thread */ QEMUFile *postcopy_qemufile_dst; /* * When postcopy_qemufile_dst is properly setup, this sem is posted. * One can wait on this semaphore to wait until the preempt channel is * properly setup. */ QemuSemaphore postcopy_qemufile_dst_done; /* Postcopy priority thread is used to receive postcopy requested pages */ QemuThread postcopy_prio_thread; /* * Always set by the main vm load thread only, but can be read by the * postcopy preempt thread. "volatile" makes sure all reads will be * up-to-date across cores. */ volatile PreemptThreadStatus preempt_thread_status; /* * Used to sync between the ram load main thread and the fast ram load * thread. It protects postcopy_qemufile_dst, which is the postcopy * fast channel. * * The ram fast load thread will take it mostly for the whole lifecycle * because it needs to continuously read data from the channel, and * it'll only release this mutex if postcopy is interrupted, so that * the ram load main thread will take this mutex over and properly * release the broken channel. */ QemuMutex postcopy_prio_thread_mutex; /* * An array of temp host huge pages to be used, one for each postcopy * channel. */ PostcopyTmpPage *postcopy_tmp_pages; /* This is shared for all postcopy channels */ void *postcopy_tmp_zero_page; /* PostCopyFD's for external userfaultfds & handlers of shared memory */ GArray *postcopy_remote_fds; MigrationStatus state; /* * The incoming migration coroutine, non-NULL during qemu_loadvm_state(). * Used to wake the migration incoming coroutine from rdma code. How much is * it safe - it's a question. */ Coroutine *loadvm_co; /* The coroutine we should enter (back) after failover */ Coroutine *colo_incoming_co; QemuSemaphore colo_incoming_sem; /* * PostcopyBlocktimeContext to keep information for postcopy * live migration, to calculate vCPU block time * */ struct PostcopyBlocktimeContext *blocktime_ctx; /* notify PAUSED postcopy incoming migrations to try to continue */ QemuSemaphore postcopy_pause_sem_dst; QemuSemaphore postcopy_pause_sem_fault; /* * This semaphore is used to allow the ram fast load thread (only when * postcopy preempt is enabled) fall into sleep when there's network * interruption detected. When the recovery is done, the main load * thread will kick the fast ram load thread using this semaphore. */ QemuSemaphore postcopy_pause_sem_fast_load; /* List of listening socket addresses */ SocketAddressList *socket_address_list; /* A tree of pages that we requested to the source VM */ GTree *page_requested; /* * For postcopy only, count the number of requested page faults that * still haven't been resolved. */ int page_requested_count; /* * The mutex helps to maintain the requested pages that we sent to the * source, IOW, to guarantee coherent between the page_requests tree and * the per-ramblock receivedmap. Note! This does not guarantee consistency * of the real page copy procedures (using UFFDIO_[ZERO]COPY). E.g., even * if one bit in receivedmap is cleared, UFFDIO_COPY could have happened * for that page already. This is intended so that the mutex won't * serialize and blocked by slow operations like UFFDIO_* ioctls. However * this should be enough to make sure the page_requested tree always * contains valid information. */ QemuMutex page_request_mutex; /* * If postcopy preempt is enabled, there is a chance that the main * thread finished loading its data before the preempt channel has * finished loading the urgent pages. If that happens, the two threads * will use this condvar to synchronize, so the main thread will always * wait until all pages received. */ QemuCond page_request_cond; /* * Number of devices that have yet to approve switchover. When this reaches * zero an ACK that it's OK to do switchover is sent to the source. No lock * is needed as this field is updated serially. */ unsigned int switchover_ack_pending_num; /* Do exit on incoming migration failure */ bool exit_on_error; }; MigrationIncomingState *migration_incoming_get_current(void); void migration_incoming_state_destroy(void); void migration_incoming_transport_cleanup(MigrationIncomingState *mis); /* * Functions to work with blocktime context */ void fill_destination_postcopy_migration_info(MigrationInfo *info); #define TYPE_MIGRATION "migration" typedef struct MigrationClass MigrationClass; DECLARE_OBJ_CHECKERS(MigrationState, MigrationClass, MIGRATION_OBJ, TYPE_MIGRATION) struct MigrationClass { /*< private >*/ DeviceClass parent_class; }; struct MigrationState { /*< private >*/ DeviceState parent_obj; /*< public >*/ QemuThread thread; /* Protected by qemu_file_lock */ QEMUFile *to_dst_file; /* Postcopy specific transfer channel */ QEMUFile *postcopy_qemufile_src; /* * It is posted when the preempt channel is established. Note: this is * used for both the start or recover of a postcopy migration. We'll * post to this sem every time a new preempt channel is created in the * main thread, and we keep post() and wait() in pair. */ QemuSemaphore postcopy_qemufile_src_sem; QIOChannelBuffer *bioc; /* * Protects to_dst_file/from_dst_file pointers. We need to make sure we * won't yield or hang during the critical section, since this lock will be * used in OOB command handler. */ QemuMutex qemu_file_lock; /* * Used to allow urgent requests to override rate limiting. */ QemuSemaphore rate_limit_sem; /* pages already send at the beginning of current iteration */ uint64_t iteration_initial_pages; /* pages transferred per second */ double pages_per_second; /* bytes already send at the beginning of current iteration */ uint64_t iteration_initial_bytes; /* time at the start of current iteration */ int64_t iteration_start_time; /* * The final stage happens when the remaining data is smaller than * this threshold; it's calculated from the requested downtime and * measured bandwidth, or avail-switchover-bandwidth if specified. */ uint64_t threshold_size; /* params from 'migrate-set-parameters' */ MigrationParameters parameters; MigrationStatus state; /* State related to return path */ struct { /* Protected by qemu_file_lock */ QEMUFile *from_dst_file; QemuThread rp_thread; /* * We can also check non-zero of rp_thread, but there's no "official" * way to do this, so this bool makes it slightly more elegant. * Checking from_dst_file for this is racy because from_dst_file will * be cleared in the rp_thread! */ bool rp_thread_created; /* * Used to synchronize between migration main thread and return * path thread. The migration thread can wait() on this sem, while * other threads (e.g., return path thread) can kick it using a * post(). */ QemuSemaphore rp_sem; /* * We post to this when we got one PONG from dest. So far it's an * easy way to know the main channel has successfully established * on dest QEMU. */ QemuSemaphore rp_pong_acks; } rp_state; double mbps; /* Timestamp when recent migration starts (ms) */ int64_t start_time; /* Total time used by latest migration (ms) */ int64_t total_time; /* Timestamp when VM is down (ms) to migrate the last stuff */ int64_t downtime_start; int64_t downtime; int64_t expected_downtime; bool capabilities[MIGRATION_CAPABILITY__MAX]; int64_t setup_time; /* * State before stopping the vm by vm_stop_force_state(). * If migration is interrupted by any reason, we need to continue * running the guest on source if it was running or restore its stopped * state. */ RunState vm_old_state; /* Flag set once the migration has been asked to enter postcopy */ bool start_postcopy; /* Flag set once the migration thread is running (and needs joining) */ bool migration_thread_running; /* Flag set once the migration thread called bdrv_inactivate_all */ bool block_inactive; /* Migration is waiting for guest to unplug device */ QemuSemaphore wait_unplug_sem; /* Migration is paused due to pause-before-switchover */ QemuSemaphore pause_sem; /* The semaphore is used to notify COLO thread that failover is finished */ QemuSemaphore colo_exit_sem; /* The event is used to notify COLO thread to do checkpoint */ QemuEvent colo_checkpoint_event; int64_t colo_checkpoint_time; QEMUTimer *colo_delay_timer; /* The first error that has occurred. We used the mutex to be able to return the 1st error message */ Error *error; /* mutex to protect errp */ QemuMutex error_mutex; /* * Global switch on whether we need to store the global state * during migration. */ bool store_global_state; /* Whether we send QEMU_VM_CONFIGURATION during migration */ bool send_configuration; /* Whether we send section footer during migration */ bool send_section_footer; /* Needed by postcopy-pause state */ QemuSemaphore postcopy_pause_sem; /* * This variable only affects behavior when postcopy preempt mode is * enabled. * * When set: * * - postcopy preempt src QEMU instance will generate an EOS message at * the end of migration to shut the preempt channel on dest side. * * - postcopy preempt channel will be created at the setup phase on src QEMU. * * When clear: * * - postcopy preempt src QEMU instance will _not_ generate an EOS * message at the end of migration, the dest qemu will shutdown the * channel itself. * * - postcopy preempt channel will be created at the switching phase * from precopy -> postcopy (to avoid race condition of misordered * creation of channels). * * NOTE: See message-id <ZBoShWArKDPpX/D7@work-vm> on qemu-devel * mailing list for more information on the possible race. Everyone * should probably just keep this value untouched after set by the * machine type (or the default). */ bool preempt_pre_7_2; /* * flush every channel after each section sent. * * This assures that we can't mix pages from one iteration through * ram pages with pages for the following iteration. We really * only need to do this flush after we have go through all the * dirty pages. For historical reasons, we do that after each * section. This is suboptimal (we flush too many times). * Default value is false. (since 8.1) */ bool multifd_flush_after_each_section; /* * This decides the size of guest memory chunk that will be used * to track dirty bitmap clearing. The size of memory chunk will * be GUEST_PAGE_SIZE << N. Say, N=0 means we will clear dirty * bitmap for each page to send (1<<0=1); N=10 means we will clear * dirty bitmap only once for 1<<10=1K continuous guest pages * (which is in 4M chunk). */ uint8_t clear_bitmap_shift; /* * This save hostname when out-going migration starts */ char *hostname; /* QEMU_VM_VMDESCRIPTION content filled for all non-iterable devices. */ JSONWriter *vmdesc; /* * Indicates whether an ACK from the destination that it's OK to do * switchover has been received. */ bool switchover_acked; /* Is this a rdma migration */ bool rdma_migration; }; void migrate_set_state(MigrationStatus *state, MigrationStatus old_state, MigrationStatus new_state); void migration_fd_process_incoming(QEMUFile *f); void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp); void migration_incoming_process(void); bool migration_has_all_channels(void); void migrate_set_error(MigrationState *s, const Error *error); bool migrate_has_error(MigrationState *s); void migrate_fd_connect(MigrationState *s, Error *error_in); int migration_call_notifiers(MigrationState *s, MigrationEventType type, Error **errp); int migrate_init(MigrationState *s, Error **errp); bool migration_is_blocked(Error **errp); /* True if outgoing migration has entered postcopy phase */ bool migration_in_postcopy(void); bool migration_postcopy_is_alive(MigrationStatus state); MigrationState *migrate_get_current(void); bool migration_has_failed(MigrationState *); bool migrate_mode_is_cpr(MigrationState *); uint64_t ram_get_total_transferred_pages(void); /* Sending on the return path - generic and then for each message type */ void migrate_send_rp_shut(MigrationIncomingState *mis, uint32_t value); void migrate_send_rp_pong(MigrationIncomingState *mis, uint32_t value); int migrate_send_rp_req_pages(MigrationIncomingState *mis, RAMBlock *rb, ram_addr_t start, uint64_t haddr); int migrate_send_rp_message_req_pages(MigrationIncomingState *mis, RAMBlock *rb, ram_addr_t start); void migrate_send_rp_recv_bitmap(MigrationIncomingState *mis, char *block_name); void migrate_send_rp_resume_ack(MigrationIncomingState *mis, uint32_t value); int migrate_send_rp_switchover_ack(MigrationIncomingState *mis); void dirty_bitmap_mig_before_vm_start(void); void dirty_bitmap_mig_cancel_outgoing(void); void dirty_bitmap_mig_cancel_incoming(void); bool check_dirty_bitmap_mig_alias_map(const BitmapMigrationNodeAliasList *bbm, Error **errp); void migrate_add_address(SocketAddress *address); bool migrate_uri_parse(const char *uri, MigrationChannel **channel, Error **errp); int foreach_not_ignored_block(RAMBlockIterFunc func, void *opaque); #define qemu_ram_foreach_block \ #warning "Use foreach_not_ignored_block in migration code" void migration_make_urgent_request(void); void migration_consume_urgent_request(void); bool migration_rate_limit(void); void migration_bh_schedule(QEMUBHFunc *cb, void *opaque); void migration_cancel(const Error *error); void migration_populate_vfio_info(MigrationInfo *info); void migration_reset_vfio_bytes_transferred(void); void postcopy_temp_page_reset(PostcopyTmpPage *tmp_page); /* * Migration thread waiting for return path thread. Return non-zero if an * error is detected. */ int migration_rp_wait(MigrationState *s); /* * Kick the migration thread waiting for return path messages. NOTE: the * name can be slightly confusing (when read as "kick the rp thread"), just * to remember the target is always the migration thread. */ void migration_rp_kick(MigrationState *s); #endif