qemu/migration/migration.h
Peter Xu b062106d3a migration: Remove old preempt code around state maintainance
With the new code to send pages in rp-return thread, there's little help to
keep lots of the old code on maintaining the preempt state in migration
thread, because the new way should always be faster..

Then if we'll always send pages in the rp-return thread anyway, we don't
need those logic to maintain preempt state anymore because now we serialize
things using the mutex directly instead of using those fields.

It's very unfortunate to have those code for a short period, but that's
still one intermediate step that we noticed the next bottleneck on the
migration thread.  Now what we can do best is to drop unnecessary code as
long as the new code is stable to reduce the burden.  It's actually a good
thing because the new "sending page in rp-return thread" model is (IMHO)
even cleaner and with better performance.

Remove the old code that was responsible for maintaining preempt states, at
the meantime also remove x-postcopy-preempt-break-huge parameter because
with concurrent sender threads we don't really need to break-huge anymore.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-12-15 10:30:37 +01:00

477 lines
16 KiB
C

/*
* 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 "qemu/thread.h"
#include "qemu/coroutine_int.h"
#include "io/channel.h"
#include "io/channel-buffer.h"
#include "net/announce.h"
#include "qom/object.h"
#include "postcopy-ram.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;
/* 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;
/* Postcopy priority thread is used to receive postcopy requested pages */
QemuThread postcopy_prio_thread;
bool postcopy_prio_thread_created;
/*
* 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;
QEMUBH *bh;
int state;
bool have_colo_incoming_thread;
QemuThread colo_incoming_thread;
/* The coroutine we should enter (back) after failover */
Coroutine *migration_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 debugging purpose only, but would be nice to keep */
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;
};
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;
QEMUBH *vm_start_bh;
QEMUBH *cleanup_bh;
/* 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
*/
int64_t threshold_size;
/* params from 'migrate-set-parameters' */
MigrationParameters parameters;
int state;
/* State related to return path */
struct {
/* Protected by qemu_file_lock */
QEMUFile *from_dst_file;
QemuThread rp_thread;
bool error;
/*
* 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;
QemuSemaphore rp_sem;
} 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 enabled_capabilities[MIGRATION_CAPABILITY__MAX];
int64_t setup_time;
/*
* Whether guest was running when we enter the completion stage.
* If migration is interrupted by any reason, we need to continue
* running the guest on source.
*/
bool vm_was_running;
/* Flag set once the migration has been asked to enter postcopy */
bool start_postcopy;
/* Flag set after postcopy has sent the device state */
bool postcopy_after_devices;
/* 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;
/* Do we have to clean up -b/-i from old migrate parameters */
/* This feature is deprecated and will be removed */
bool must_remove_block_options;
/*
* 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;
QemuSemaphore postcopy_pause_rp_sem;
/*
* Whether we abort the migration if decompression errors are
* detected at the destination. It is left at false for qemu
* older than 3.0, since only newer qemu sends streams that
* do not trigger spurious decompression errors.
*/
bool decompress_error_check;
/*
* 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;
};
void migrate_set_state(int *state, int old_state, int new_state);
void migration_fd_process_incoming(QEMUFile *f, Error **errp);
void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp);
void migration_incoming_process(void);
bool migration_has_all_channels(void);
uint64_t migrate_max_downtime(void);
void migrate_set_error(MigrationState *s, const Error *error);
void migrate_fd_error(MigrationState *s, const Error *error);
void migrate_fd_connect(MigrationState *s, Error *error_in);
bool migration_is_setup_or_active(int state);
bool migration_is_running(int state);
void migrate_init(MigrationState *s);
bool migration_is_blocked(Error **errp);
/* True if outgoing migration has entered postcopy phase */
bool migration_in_postcopy(void);
MigrationState *migrate_get_current(void);
bool migrate_postcopy(void);
bool migrate_release_ram(void);
bool migrate_postcopy_ram(void);
bool migrate_zero_blocks(void);
bool migrate_dirty_bitmaps(void);
bool migrate_ignore_shared(void);
bool migrate_validate_uuid(void);
bool migrate_auto_converge(void);
bool migrate_use_multifd(void);
bool migrate_pause_before_switchover(void);
int migrate_multifd_channels(void);
MultiFDCompression migrate_multifd_compression(void);
int migrate_multifd_zlib_level(void);
int migrate_multifd_zstd_level(void);
#ifdef CONFIG_LINUX
bool migrate_use_zero_copy_send(void);
#else
#define migrate_use_zero_copy_send() (false)
#endif
int migrate_use_tls(void);
int migrate_use_xbzrle(void);
uint64_t migrate_xbzrle_cache_size(void);
bool migrate_colo_enabled(void);
bool migrate_use_block(void);
bool migrate_use_block_incremental(void);
int migrate_max_cpu_throttle(void);
bool migrate_use_return_path(void);
uint64_t ram_get_total_transferred_pages(void);
bool migrate_use_compression(void);
int migrate_compress_level(void);
int migrate_compress_threads(void);
int migrate_compress_wait_thread(void);
int migrate_decompress_threads(void);
bool migrate_use_events(void);
bool migrate_postcopy_blocktime(void);
bool migrate_background_snapshot(void);
bool migrate_postcopy_preempt(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);
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);
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_cancel(const Error *error);
void populate_vfio_info(MigrationInfo *info);
void postcopy_temp_page_reset(PostcopyTmpPage *tmp_page);
bool migrate_multi_channels_is_allowed(void);
void migrate_protocol_allow_multi_channels(bool allow);
#endif