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qemu / qemu / d3764db87531cd53849ccee9b2f72aede90ccf5b / . / migration / migration.c
blob: 454cd4ec1f230ab7b278b975b0aef405b0a6d3b8 [file] [log] [blame]
/*
* 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.
*
* Contributions after 2012-01-13 are licensed under the terms of the
* GNU GPL, version 2 or (at your option) any later version.
*/
#include "qemu/osdep.h"
#include "qemu/cutils.h"
#include "qemu/error-report.h"
#include "qemu/main-loop.h"
#include "migration/blocker.h"
#include "exec.h"
#include "fd.h"
#include "file.h"
#include "socket.h"
#include "sysemu/runstate.h"
#include "sysemu/sysemu.h"
#include "sysemu/cpu-throttle.h"
#include "rdma.h"
#include "ram.h"
#include "ram-compress.h"
#include "migration/global_state.h"
#include "migration/misc.h"
#include "migration.h"
#include "migration-stats.h"
#include "savevm.h"
#include "qemu-file.h"
#include "channel.h"
#include "migration/vmstate.h"
#include "block/block.h"
#include "qapi/error.h"
#include "qapi/clone-visitor.h"
#include "qapi/qapi-visit-migration.h"
#include "qapi/qapi-visit-sockets.h"
#include "qapi/qapi-commands-migration.h"
#include "qapi/qapi-events-migration.h"
#include "qapi/qmp/qerror.h"
#include "qapi/qmp/qnull.h"
#include "qemu/rcu.h"
#include "block.h"
#include "postcopy-ram.h"
#include "qemu/thread.h"
#include "trace.h"
#include "exec/target_page.h"
#include "io/channel-buffer.h"
#include "io/channel-tls.h"
#include "migration/colo.h"
#include "hw/boards.h"
#include "monitor/monitor.h"
#include "net/announce.h"
#include "qemu/queue.h"
#include "multifd.h"
#include "threadinfo.h"
#include "qemu/yank.h"
#include "sysemu/cpus.h"
#include "yank_functions.h"
#include "sysemu/qtest.h"
#include "options.h"
#include "sysemu/dirtylimit.h"
#include "qemu/sockets.h"
static NotifierList migration_state_notifiers =
NOTIFIER_LIST_INITIALIZER(migration_state_notifiers);
/* Messages sent on the return path from destination to source */
enum mig_rp_message_type {
MIG_RP_MSG_INVALID = 0, /* Must be 0 */
MIG_RP_MSG_SHUT, /* sibling will not send any more RP messages */
MIG_RP_MSG_PONG, /* Response to a PING; data (seq: be32 ) */
MIG_RP_MSG_REQ_PAGES_ID, /* data (start: be64, len: be32, id: string) */
MIG_RP_MSG_REQ_PAGES, /* data (start: be64, len: be32) */
MIG_RP_MSG_RECV_BITMAP, /* send recved_bitmap back to source */
MIG_RP_MSG_RESUME_ACK, /* tell source that we are ready to resume */
MIG_RP_MSG_SWITCHOVER_ACK, /* Tell source it's OK to do switchover */
MIG_RP_MSG_MAX
};
/* When we add fault tolerance, we could have several
migrations at once. For now we don't need to add
dynamic creation of migration */
static MigrationState *current_migration;
static MigrationIncomingState *current_incoming;
static GSList *migration_blockers[MIG_MODE__MAX];
static bool migration_object_check(MigrationState *ms, Error **errp);
static int migration_maybe_pause(MigrationState *s,
int *current_active_state,
int new_state);
static void migrate_fd_cancel(MigrationState *s);
static bool close_return_path_on_source(MigrationState *s);
static void migration_downtime_start(MigrationState *s)
{
trace_vmstate_downtime_checkpoint("src-downtime-start");
s->downtime_start = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
}
static void migration_downtime_end(MigrationState *s)
{
int64_t now = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
/*
* If downtime already set, should mean that postcopy already set it,
* then that should be the real downtime already.
*/
if (!s->downtime) {
s->downtime = now - s->downtime_start;
}
trace_vmstate_downtime_checkpoint("src-downtime-end");
}
static bool migration_needs_multiple_sockets(void)
{
return migrate_multifd() || migrate_postcopy_preempt();
}
static bool transport_supports_multi_channels(SocketAddress *saddr)
{
return saddr->type == SOCKET_ADDRESS_TYPE_INET ||
saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
saddr->type == SOCKET_ADDRESS_TYPE_VSOCK;
}
static bool
migration_channels_and_transport_compatible(MigrationAddress *addr,
Error **errp)
{
if (migration_needs_multiple_sockets() &&
(addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) &&
!transport_supports_multi_channels(&addr->u.socket)) {
error_setg(errp, "Migration requires multi-channel URIs (e.g. tcp)");
return false;
}
return true;
}
static gint page_request_addr_cmp(gconstpointer ap, gconstpointer bp)
{
uintptr_t a = (uintptr_t) ap, b = (uintptr_t) bp;
return (a > b) - (a < b);
}
int migration_stop_vm(RunState state)
{
int ret = vm_stop_force_state(state);
trace_vmstate_downtime_checkpoint("src-vm-stopped");
return ret;
}
void migration_object_init(void)
{
/* This can only be called once. */
assert(!current_migration);
current_migration = MIGRATION_OBJ(object_new(TYPE_MIGRATION));
/*
* Init the migrate incoming object as well no matter whether
* we'll use it or not.
*/
assert(!current_incoming);
current_incoming = g_new0(MigrationIncomingState, 1);
current_incoming->state = MIGRATION_STATUS_NONE;
current_incoming->postcopy_remote_fds =
g_array_new(FALSE, TRUE, sizeof(struct PostCopyFD));
qemu_mutex_init(&current_incoming->rp_mutex);
qemu_mutex_init(&current_incoming->postcopy_prio_thread_mutex);
qemu_event_init(&current_incoming->main_thread_load_event, false);
qemu_sem_init(&current_incoming->postcopy_pause_sem_dst, 0);
qemu_sem_init(&current_incoming->postcopy_pause_sem_fault, 0);
qemu_sem_init(&current_incoming->postcopy_pause_sem_fast_load, 0);
qemu_sem_init(&current_incoming->postcopy_qemufile_dst_done, 0);
qemu_mutex_init(&current_incoming->page_request_mutex);
qemu_cond_init(&current_incoming->page_request_cond);
current_incoming->page_requested = g_tree_new(page_request_addr_cmp);
migration_object_check(current_migration, &error_fatal);
blk_mig_init();
ram_mig_init();
dirty_bitmap_mig_init();
}
void migration_cancel(const Error *error)
{
if (error) {
migrate_set_error(current_migration, error);
}
if (migrate_dirty_limit()) {
qmp_cancel_vcpu_dirty_limit(false, -1, NULL);
}
migrate_fd_cancel(current_migration);
}
void migration_shutdown(void)
{
/*
* When the QEMU main thread exit, the COLO thread
* may wait a semaphore. So, we should wakeup the
* COLO thread before migration shutdown.
*/
colo_shutdown();
/*
* Cancel the current migration - that will (eventually)
* stop the migration using this structure
*/
migration_cancel(NULL);
object_unref(OBJECT(current_migration));
/*
* Cancel outgoing migration of dirty bitmaps. It should
* at least unref used block nodes.
*/
dirty_bitmap_mig_cancel_outgoing();
/*
* Cancel incoming migration of dirty bitmaps. Dirty bitmaps
* are non-critical data, and their loss never considered as
* something serious.
*/
dirty_bitmap_mig_cancel_incoming();
}
/* For outgoing */
MigrationState *migrate_get_current(void)
{
/* This can only be called after the object created. */
assert(current_migration);
return current_migration;
}
MigrationIncomingState *migration_incoming_get_current(void)
{
assert(current_incoming);
return current_incoming;
}
void migration_incoming_transport_cleanup(MigrationIncomingState *mis)
{
if (mis->socket_address_list) {
qapi_free_SocketAddressList(mis->socket_address_list);
mis->socket_address_list = NULL;
}
if (mis->transport_cleanup) {
mis->transport_cleanup(mis->transport_data);
mis->transport_data = mis->transport_cleanup = NULL;
}
}
void migration_incoming_state_destroy(void)
{
struct MigrationIncomingState *mis = migration_incoming_get_current();
multifd_load_cleanup();
compress_threads_load_cleanup();
if (mis->to_src_file) {
/* Tell source that we are done */
migrate_send_rp_shut(mis, qemu_file_get_error(mis->from_src_file) != 0);
qemu_fclose(mis->to_src_file);
mis->to_src_file = NULL;
}
if (mis->from_src_file) {
migration_ioc_unregister_yank_from_file(mis->from_src_file);
qemu_fclose(mis->from_src_file);
mis->from_src_file = NULL;
}
if (mis->postcopy_remote_fds) {
g_array_free(mis->postcopy_remote_fds, TRUE);
mis->postcopy_remote_fds = NULL;
}
migration_incoming_transport_cleanup(mis);
qemu_event_reset(&mis->main_thread_load_event);
if (mis->page_requested) {
g_tree_destroy(mis->page_requested);
mis->page_requested = NULL;
}
if (mis->postcopy_qemufile_dst) {
migration_ioc_unregister_yank_from_file(mis->postcopy_qemufile_dst);
qemu_fclose(mis->postcopy_qemufile_dst);
mis->postcopy_qemufile_dst = NULL;
}
yank_unregister_instance(MIGRATION_YANK_INSTANCE);
}
static void migrate_generate_event(int new_state)
{
if (migrate_events()) {
qapi_event_send_migration(new_state);
}
}
/*
* Send a message on the return channel back to the source
* of the migration.
*/
static int migrate_send_rp_message(MigrationIncomingState *mis,
enum mig_rp_message_type message_type,
uint16_t len, void *data)
{
int ret = 0;
trace_migrate_send_rp_message((int)message_type, len);
QEMU_LOCK_GUARD(&mis->rp_mutex);
/*
* It's possible that the file handle got lost due to network
* failures.
*/
if (!mis->to_src_file) {
ret = -EIO;
return ret;
}
qemu_put_be16(mis->to_src_file, (unsigned int)message_type);
qemu_put_be16(mis->to_src_file, len);
qemu_put_buffer(mis->to_src_file, data, len);
return qemu_fflush(mis->to_src_file);
}
/* Request one page from the source VM at the given start address.
* rb: the RAMBlock to request the page in
* Start: Address offset within the RB
* Len: Length in bytes required - must be a multiple of pagesize
*/
int migrate_send_rp_message_req_pages(MigrationIncomingState *mis,
RAMBlock *rb, ram_addr_t start)
{
uint8_t bufc[12 + 1 + 255]; /* start (8), len (4), rbname up to 256 */
size_t msglen = 12; /* start + len */
size_t len = qemu_ram_pagesize(rb);
enum mig_rp_message_type msg_type;
const char *rbname;
int rbname_len;
*(uint64_t *)bufc = cpu_to_be64((uint64_t)start);
*(uint32_t *)(bufc + 8) = cpu_to_be32((uint32_t)len);
/*
* We maintain the last ramblock that we requested for page. Note that we
* don't need locking because this function will only be called within the
* postcopy ram fault thread.
*/
if (rb != mis->last_rb) {
mis->last_rb = rb;
rbname = qemu_ram_get_idstr(rb);
rbname_len = strlen(rbname);
assert(rbname_len < 256);
bufc[msglen++] = rbname_len;
memcpy(bufc + msglen, rbname, rbname_len);
msglen += rbname_len;
msg_type = MIG_RP_MSG_REQ_PAGES_ID;
} else {
msg_type = MIG_RP_MSG_REQ_PAGES;
}
return migrate_send_rp_message(mis, msg_type, msglen, bufc);
}
int migrate_send_rp_req_pages(MigrationIncomingState *mis,
RAMBlock *rb, ram_addr_t start, uint64_t haddr)
{
void *aligned = (void *)(uintptr_t)ROUND_DOWN(haddr, qemu_ram_pagesize(rb));
bool received = false;
WITH_QEMU_LOCK_GUARD(&mis->page_request_mutex) {
received = ramblock_recv_bitmap_test_byte_offset(rb, start);
if (!received && !g_tree_lookup(mis->page_requested, aligned)) {
/*
* The page has not been received, and it's not yet in the page
* request list. Queue it. Set the value of element to 1, so that
* things like g_tree_lookup() will return TRUE (1) when found.
*/
g_tree_insert(mis->page_requested, aligned, (gpointer)1);
qatomic_inc(&mis->page_requested_count);
trace_postcopy_page_req_add(aligned, mis->page_requested_count);
}
}
/*
* If the page is there, skip sending the message. We don't even need the
* lock because as long as the page arrived, it'll be there forever.
*/
if (received) {
return 0;
}
return migrate_send_rp_message_req_pages(mis, rb, start);
}
static bool migration_colo_enabled;
bool migration_incoming_colo_enabled(void)
{
return migration_colo_enabled;
}
void migration_incoming_disable_colo(void)
{
ram_block_discard_disable(false);
migration_colo_enabled = false;
}
int migration_incoming_enable_colo(void)
{
#ifndef CONFIG_REPLICATION
error_report("ENABLE_COLO command come in migration stream, but COLO "
"module is not built in");
return -ENOTSUP;
#endif
if (!migrate_colo()) {
error_report("ENABLE_COLO command come in migration stream, but c-colo "
"capability is not set");
return -EINVAL;
}
if (ram_block_discard_disable(true)) {
error_report("COLO: cannot disable RAM discard");
return -EBUSY;
}
migration_colo_enabled = true;
return 0;
}
void migrate_add_address(SocketAddress *address)
{
MigrationIncomingState *mis = migration_incoming_get_current();
QAPI_LIST_PREPEND(mis->socket_address_list,
QAPI_CLONE(SocketAddress, address));
}
bool migrate_uri_parse(const char *uri, MigrationChannel **channel,
Error **errp)
{
g_autoptr(MigrationChannel) val = g_new0(MigrationChannel, 1);
g_autoptr(MigrationAddress) addr = g_new0(MigrationAddress, 1);
InetSocketAddress *isock = &addr->u.rdma;
strList **tail = &addr->u.exec.args;
if (strstart(uri, "exec:", NULL)) {
addr->transport = MIGRATION_ADDRESS_TYPE_EXEC;
#ifdef WIN32
QAPI_LIST_APPEND(tail, g_strdup(exec_get_cmd_path()));
QAPI_LIST_APPEND(tail, g_strdup("/c"));
#else
QAPI_LIST_APPEND(tail, g_strdup("/bin/sh"));
QAPI_LIST_APPEND(tail, g_strdup("-c"));
#endif
QAPI_LIST_APPEND(tail, g_strdup(uri + strlen("exec:")));
} else if (strstart(uri, "rdma:", NULL)) {
if (inet_parse(isock, uri + strlen("rdma:"), errp)) {
qapi_free_InetSocketAddress(isock);
return false;
}
addr->transport = MIGRATION_ADDRESS_TYPE_RDMA;
} else if (strstart(uri, "tcp:", NULL) ||
strstart(uri, "unix:", NULL) ||
strstart(uri, "vsock:", NULL) ||
strstart(uri, "fd:", NULL)) {
addr->transport = MIGRATION_ADDRESS_TYPE_SOCKET;
SocketAddress *saddr = socket_parse(uri, errp);
if (!saddr) {
return false;
}
addr->u.socket.type = saddr->type;
addr->u.socket.u = saddr->u;
/* Don't free the objects inside; their ownership moved to "addr" */
g_free(saddr);
} else if (strstart(uri, "file:", NULL)) {
addr->transport = MIGRATION_ADDRESS_TYPE_FILE;
addr->u.file.filename = g_strdup(uri + strlen("file:"));
if (file_parse_offset(addr->u.file.filename, &addr->u.file.offset,
errp)) {
return false;
}
} else {
error_setg(errp, "unknown migration protocol: %s", uri);
return false;
}
val->channel_type = MIGRATION_CHANNEL_TYPE_MAIN;
val->addr = g_steal_pointer(&addr);
*channel = g_steal_pointer(&val);
return true;
}
static void qemu_start_incoming_migration(const char *uri, bool has_channels,
MigrationChannelList *channels,
Error **errp)
{
g_autoptr(MigrationChannel) channel = NULL;
MigrationAddress *addr = NULL;
MigrationIncomingState *mis = migration_incoming_get_current();
/*
* Having preliminary checks for uri and channel
*/
if (uri && has_channels) {
error_setg(errp, "'uri' and 'channels' arguments are mutually "
"exclusive; exactly one of the two should be present in "
"'migrate-incoming' qmp command ");
return;
} else if (channels) {
/* To verify that Migrate channel list has only item */
if (channels->next) {
error_setg(errp, "Channel list has more than one entries");
return;
}
addr = channels->value->addr;
} else if (uri) {
/* caller uses the old URI syntax */
if (!migrate_uri_parse(uri, &channel, errp)) {
return;
}
addr = channel->addr;
} else {
error_setg(errp, "neither 'uri' or 'channels' argument are "
"specified in 'migrate-incoming' qmp command ");
return;
}
/* transport mechanism not suitable for migration? */
if (!migration_channels_and_transport_compatible(addr, errp)) {
return;
}
migrate_set_state(&mis->state, MIGRATION_STATUS_NONE,
MIGRATION_STATUS_SETUP);
if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
SocketAddress *saddr = &addr->u.socket;
if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
saddr->type == SOCKET_ADDRESS_TYPE_VSOCK) {
socket_start_incoming_migration(saddr, errp);
} else if (saddr->type == SOCKET_ADDRESS_TYPE_FD) {
fd_start_incoming_migration(saddr->u.fd.str, errp);
}
#ifdef CONFIG_RDMA
} else if (addr->transport == MIGRATION_ADDRESS_TYPE_RDMA) {
if (migrate_compress()) {
error_setg(errp, "RDMA and compression can't be used together");
return;
}
if (migrate_xbzrle()) {
error_setg(errp, "RDMA and XBZRLE can't be used together");
return;
}
if (migrate_multifd()) {
error_setg(errp, "RDMA and multifd can't be used together");
return;
}
rdma_start_incoming_migration(&addr->u.rdma, errp);
#endif
} else if (addr->transport == MIGRATION_ADDRESS_TYPE_EXEC) {
exec_start_incoming_migration(addr->u.exec.args, errp);
} else if (addr->transport == MIGRATION_ADDRESS_TYPE_FILE) {
file_start_incoming_migration(&addr->u.file, errp);
} else {
error_setg(errp, "unknown migration protocol: %s", uri);
}
}
static void process_incoming_migration_bh(void *opaque)
{
Error *local_err = NULL;
MigrationIncomingState *mis = opaque;
trace_vmstate_downtime_checkpoint("dst-precopy-bh-enter");
/* If capability late_block_activate is set:
* Only fire up the block code now if we're going to restart the
* VM, else 'cont' will do it.
* This causes file locking to happen; so we don't want it to happen
* unless we really are starting the VM.
*/
if (!migrate_late_block_activate() ||
(autostart && (!global_state_received() ||
runstate_is_live(global_state_get_runstate())))) {
/* Make sure all file formats throw away their mutable metadata.
* If we get an error here, just don't restart the VM yet. */
bdrv_activate_all(&local_err);
if (local_err) {
error_report_err(local_err);
local_err = NULL;
autostart = false;
}
}
/*
* This must happen after all error conditions are dealt with and
* we're sure the VM is going to be running on this host.
*/
qemu_announce_self(&mis->announce_timer, migrate_announce_params());
trace_vmstate_downtime_checkpoint("dst-precopy-bh-announced");
multifd_load_shutdown();
dirty_bitmap_mig_before_vm_start();
if (!global_state_received() ||
runstate_is_live(global_state_get_runstate())) {
if (autostart) {
vm_start();
} else {
runstate_set(RUN_STATE_PAUSED);
}
} else if (migration_incoming_colo_enabled()) {
migration_incoming_disable_colo();
vm_start();
} else {
runstate_set(global_state_get_runstate());
}
trace_vmstate_downtime_checkpoint("dst-precopy-bh-vm-started");
/*
* This must happen after any state changes since as soon as an external
* observer sees this event they might start to prod at the VM assuming
* it's ready to use.
*/
migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
MIGRATION_STATUS_COMPLETED);
qemu_bh_delete(mis->bh);
migration_incoming_state_destroy();
}
static void coroutine_fn
process_incoming_migration_co(void *opaque)
{
MigrationIncomingState *mis = migration_incoming_get_current();
PostcopyState ps;
int ret;
assert(mis->from_src_file);
if (compress_threads_load_setup(mis->from_src_file)) {
error_report("Failed to setup decompress threads");
goto fail;
}
mis->largest_page_size = qemu_ram_pagesize_largest();
postcopy_state_set(POSTCOPY_INCOMING_NONE);
migrate_set_state(&mis->state, MIGRATION_STATUS_SETUP,
MIGRATION_STATUS_ACTIVE);
mis->loadvm_co = qemu_coroutine_self();
ret = qemu_loadvm_state(mis->from_src_file);
mis->loadvm_co = NULL;
trace_vmstate_downtime_checkpoint("dst-precopy-loadvm-completed");
ps = postcopy_state_get();
trace_process_incoming_migration_co_end(ret, ps);
if (ps != POSTCOPY_INCOMING_NONE) {
if (ps == POSTCOPY_INCOMING_ADVISE) {
/*
* Where a migration had postcopy enabled (and thus went to advise)
* but managed to complete within the precopy period, we can use
* the normal exit.
*/
postcopy_ram_incoming_cleanup(mis);
} else if (ret >= 0) {
/*
* Postcopy was started, cleanup should happen at the end of the
* postcopy thread.
*/
trace_process_incoming_migration_co_postcopy_end_main();
return;
}
/* Else if something went wrong then just fall out of the normal exit */
}
if (ret < 0) {
error_report("load of migration failed: %s", strerror(-ret));
goto fail;
}
if (colo_incoming_co() < 0) {
goto fail;
}
mis->bh = qemu_bh_new(process_incoming_migration_bh, mis);
qemu_bh_schedule(mis->bh);
return;
fail:
migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
MIGRATION_STATUS_FAILED);
qemu_fclose(mis->from_src_file);
multifd_load_cleanup();
compress_threads_load_cleanup();
exit(EXIT_FAILURE);
}
/**
* migration_incoming_setup: Setup incoming migration
* @f: file for main migration channel
*/
static void migration_incoming_setup(QEMUFile *f)
{
MigrationIncomingState *mis = migration_incoming_get_current();
if (!mis->from_src_file) {
mis->from_src_file = f;
}
qemu_file_set_blocking(f, false);
}
void migration_incoming_process(void)
{
Coroutine *co = qemu_coroutine_create(process_incoming_migration_co, NULL);
qemu_coroutine_enter(co);
}
/* Returns true if recovered from a paused migration, otherwise false */
static bool postcopy_try_recover(void)
{
MigrationIncomingState *mis = migration_incoming_get_current();
if (mis->state == MIGRATION_STATUS_POSTCOPY_PAUSED) {
/* Resumed from a paused postcopy migration */
/* This should be set already in migration_incoming_setup() */
assert(mis->from_src_file);
/* Postcopy has standalone thread to do vm load */
qemu_file_set_blocking(mis->from_src_file, true);
/* Re-configure the return path */
mis->to_src_file = qemu_file_get_return_path(mis->from_src_file);
migrate_set_state(&mis->state, MIGRATION_STATUS_POSTCOPY_PAUSED,
MIGRATION_STATUS_POSTCOPY_RECOVER);
/*
* Here, we only wake up the main loading thread (while the
* rest threads will still be waiting), so that we can receive
* commands from source now, and answer it if needed. The
* rest threads will be woken up afterwards until we are sure
* that source is ready to reply to page requests.
*/
qemu_sem_post(&mis->postcopy_pause_sem_dst);
return true;
}
return false;
}
void migration_fd_process_incoming(QEMUFile *f)
{
migration_incoming_setup(f);
if (postcopy_try_recover()) {
return;
}
migration_incoming_process();
}
/*
* Returns true when we want to start a new incoming migration process,
* false otherwise.
*/
static bool migration_should_start_incoming(bool main_channel)
{
/* Multifd doesn't start unless all channels are established */
if (migrate_multifd()) {
return migration_has_all_channels();
}
/* Preempt channel only starts when the main channel is created */
if (migrate_postcopy_preempt()) {
return main_channel;
}
/*
* For all the rest types of migration, we should only reach here when
* it's the main channel that's being created, and we should always
* proceed with this channel.
*/
assert(main_channel);
return true;
}
void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
{
MigrationIncomingState *mis = migration_incoming_get_current();
Error *local_err = NULL;
QEMUFile *f;
bool default_channel = true;
uint32_t channel_magic = 0;
int ret = 0;
if (migrate_multifd() && !migrate_postcopy_ram() &&
qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_READ_MSG_PEEK)) {
/*
* With multiple channels, it is possible that we receive channels
* out of order on destination side, causing incorrect mapping of
* source channels on destination side. Check channel MAGIC to
* decide type of channel. Please note this is best effort, postcopy
* preempt channel does not send any magic number so avoid it for
* postcopy live migration. Also tls live migration already does
* tls handshake while initializing main channel so with tls this
* issue is not possible.
*/
ret = migration_channel_read_peek(ioc, (void *)&channel_magic,
sizeof(channel_magic), errp);
if (ret != 0) {
return;
}
default_channel = (channel_magic == cpu_to_be32(QEMU_VM_FILE_MAGIC));
} else {
default_channel = !mis->from_src_file;
}
if (multifd_load_setup(errp) != 0) {
return;
}
if (default_channel) {
f = qemu_file_new_input(ioc);
migration_incoming_setup(f);
} else {
/* Multiple connections */
assert(migration_needs_multiple_sockets());
if (migrate_multifd()) {
multifd_recv_new_channel(ioc, &local_err);
} else {
assert(migrate_postcopy_preempt());
f = qemu_file_new_input(ioc);
postcopy_preempt_new_channel(mis, f);
}
if (local_err) {
error_propagate(errp, local_err);
return;
}
}
if (migration_should_start_incoming(default_channel)) {
/* If it's a recovery, we're done */
if (postcopy_try_recover()) {
return;
}
migration_incoming_process();
}
}
/**
* @migration_has_all_channels: We have received all channels that we need
*
* Returns true when we have got connections to all the channels that
* we need for migration.
*/
bool migration_has_all_channels(void)
{
MigrationIncomingState *mis = migration_incoming_get_current();
if (!mis->from_src_file) {
return false;
}
if (migrate_multifd()) {
return multifd_recv_all_channels_created();
}
if (migrate_postcopy_preempt()) {
return mis->postcopy_qemufile_dst != NULL;
}
return true;
}
int migrate_send_rp_switchover_ack(MigrationIncomingState *mis)
{
return migrate_send_rp_message(mis, MIG_RP_MSG_SWITCHOVER_ACK, 0, NULL);
}
/*
* Send a 'SHUT' message on the return channel with the given value
* to indicate that we've finished with the RP. Non-0 value indicates
* error.
*/
void migrate_send_rp_shut(MigrationIncomingState *mis,
uint32_t value)
{
uint32_t buf;
buf = cpu_to_be32(value);
migrate_send_rp_message(mis, MIG_RP_MSG_SHUT, sizeof(buf), &buf);
}
/*
* Send a 'PONG' message on the return channel with the given value
* (normally in response to a 'PING')
*/
void migrate_send_rp_pong(MigrationIncomingState *mis,
uint32_t value)
{
uint32_t buf;
buf = cpu_to_be32(value);
migrate_send_rp_message(mis, MIG_RP_MSG_PONG, sizeof(buf), &buf);
}
void migrate_send_rp_recv_bitmap(MigrationIncomingState *mis,
char *block_name)
{
char buf[512];
int len;
int64_t res;
/*
* First, we send the header part. It contains only the len of
* idstr, and the idstr itself.
*/
len = strlen(block_name);
buf[0] = len;
memcpy(buf + 1, block_name, len);
if (mis->state != MIGRATION_STATUS_POSTCOPY_RECOVER) {
error_report("%s: MSG_RP_RECV_BITMAP only used for recovery",
__func__);
return;
}
migrate_send_rp_message(mis, MIG_RP_MSG_RECV_BITMAP, len + 1, buf);
/*
* Next, we dump the received bitmap to the stream.
*
* TODO: currently we are safe since we are the only one that is
* using the to_src_file handle (fault thread is still paused),
* and it's ok even not taking the mutex. However the best way is
* to take the lock before sending the message header, and release
* the lock after sending the bitmap.
*/
qemu_mutex_lock(&mis->rp_mutex);
res = ramblock_recv_bitmap_send(mis->to_src_file, block_name);
qemu_mutex_unlock(&mis->rp_mutex);
trace_migrate_send_rp_recv_bitmap(block_name, res);
}
void migrate_send_rp_resume_ack(MigrationIncomingState *mis, uint32_t value)
{
uint32_t buf;
buf = cpu_to_be32(value);
migrate_send_rp_message(mis, MIG_RP_MSG_RESUME_ACK, sizeof(buf), &buf);
}
/*
* Return true if we're already in the middle of a migration
* (i.e. any of the active or setup states)
*/
bool migration_is_setup_or_active(int state)
{
switch (state) {
case MIGRATION_STATUS_ACTIVE:
case MIGRATION_STATUS_POSTCOPY_ACTIVE:
case MIGRATION_STATUS_POSTCOPY_PAUSED:
case MIGRATION_STATUS_POSTCOPY_RECOVER:
case MIGRATION_STATUS_SETUP:
case MIGRATION_STATUS_PRE_SWITCHOVER:
case MIGRATION_STATUS_DEVICE:
case MIGRATION_STATUS_WAIT_UNPLUG:
case MIGRATION_STATUS_COLO:
return true;
default:
return false;
}
}
bool migration_is_running(int state)
{
switch (state) {
case MIGRATION_STATUS_ACTIVE:
case MIGRATION_STATUS_POSTCOPY_ACTIVE:
case MIGRATION_STATUS_POSTCOPY_PAUSED:
case MIGRATION_STATUS_POSTCOPY_RECOVER:
case MIGRATION_STATUS_SETUP:
case MIGRATION_STATUS_PRE_SWITCHOVER:
case MIGRATION_STATUS_DEVICE:
case MIGRATION_STATUS_WAIT_UNPLUG:
case MIGRATION_STATUS_CANCELLING:
return true;
default:
return false;
}
}
static bool migrate_show_downtime(MigrationState *s)
{
return (s->state == MIGRATION_STATUS_COMPLETED) || migration_in_postcopy();
}
static void populate_time_info(MigrationInfo *info, MigrationState *s)
{
info->has_status = true;
info->has_setup_time = true;
info->setup_time = s->setup_time;
if (s->state == MIGRATION_STATUS_COMPLETED) {
info->has_total_time = true;
info->total_time = s->total_time;
} else {
info->has_total_time = true;
info->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) -
s->start_time;
}
if (migrate_show_downtime(s)) {
info->has_downtime = true;
info->downtime = s->downtime;
} else {
info->has_expected_downtime = true;
info->expected_downtime = s->expected_downtime;
}
}
static void populate_ram_info(MigrationInfo *info, MigrationState *s)
{
size_t page_size = qemu_target_page_size();
info->ram = g_malloc0(sizeof(*info->ram));
info->ram->transferred = migration_transferred_bytes();
info->ram->total = ram_bytes_total();
info->ram->duplicate = stat64_get(&mig_stats.zero_pages);
/* legacy value. It is not used anymore */
info->ram->skipped = 0;
info->ram->normal = stat64_get(&mig_stats.normal_pages);
info->ram->normal_bytes = info->ram->normal * page_size;
info->ram->mbps = s->mbps;
info->ram->dirty_sync_count =
stat64_get(&mig_stats.dirty_sync_count);
info->ram->dirty_sync_missed_zero_copy =
stat64_get(&mig_stats.dirty_sync_missed_zero_copy);
info->ram->postcopy_requests =
stat64_get(&mig_stats.postcopy_requests);
info->ram->page_size = page_size;
info->ram->multifd_bytes = stat64_get(&mig_stats.multifd_bytes);
info->ram->pages_per_second = s->pages_per_second;
info->ram->precopy_bytes = stat64_get(&mig_stats.precopy_bytes);
info->ram->downtime_bytes = stat64_get(&mig_stats.downtime_bytes);
info->ram->postcopy_bytes = stat64_get(&mig_stats.postcopy_bytes);
if (migrate_xbzrle()) {
info->xbzrle_cache = g_malloc0(sizeof(*info->xbzrle_cache));
info->xbzrle_cache->cache_size = migrate_xbzrle_cache_size();
info->xbzrle_cache->bytes = xbzrle_counters.bytes;
info->xbzrle_cache->pages = xbzrle_counters.pages;
info->xbzrle_cache->cache_miss = xbzrle_counters.cache_miss;
info->xbzrle_cache->cache_miss_rate = xbzrle_counters.cache_miss_rate;
info->xbzrle_cache->encoding_rate = xbzrle_counters.encoding_rate;
info->xbzrle_cache->overflow = xbzrle_counters.overflow;
}
populate_compress(info);
if (cpu_throttle_active()) {
info->has_cpu_throttle_percentage = true;
info->cpu_throttle_percentage = cpu_throttle_get_percentage();
}
if (s->state != MIGRATION_STATUS_COMPLETED) {
info->ram->remaining = ram_bytes_remaining();
info->ram->dirty_pages_rate =
stat64_get(&mig_stats.dirty_pages_rate);
}
if (migrate_dirty_limit() && dirtylimit_in_service()) {
info->has_dirty_limit_throttle_time_per_round = true;
info->dirty_limit_throttle_time_per_round =
dirtylimit_throttle_time_per_round();
info->has_dirty_limit_ring_full_time = true;
info->dirty_limit_ring_full_time = dirtylimit_ring_full_time();
}
}
static void populate_disk_info(MigrationInfo *info)
{
if (blk_mig_active()) {
info->disk = g_malloc0(sizeof(*info->disk));
info->disk->transferred = blk_mig_bytes_transferred();
info->disk->remaining = blk_mig_bytes_remaining();
info->disk->total = blk_mig_bytes_total();
}
}
static void fill_source_migration_info(MigrationInfo *info)
{
MigrationState *s = migrate_get_current();
int state = qatomic_read(&s->state);
GSList *cur_blocker = migration_blockers[migrate_mode()];
info->blocked_reasons = NULL;
/*
* There are two types of reasons a migration might be blocked;
* a) devices marked in VMState as non-migratable, and
* b) Explicit migration blockers
* We need to add both of them here.
*/
qemu_savevm_non_migratable_list(&info->blocked_reasons);
while (cur_blocker) {
QAPI_LIST_PREPEND(info->blocked_reasons,
g_strdup(error_get_pretty(cur_blocker->data)));
cur_blocker = g_slist_next(cur_blocker);
}
info->has_blocked_reasons = info->blocked_reasons != NULL;
switch (state) {
case MIGRATION_STATUS_NONE:
/* no migration has happened ever */
/* do not overwrite destination migration status */
return;
case MIGRATION_STATUS_SETUP:
info->has_status = true;
info->has_total_time = false;
break;
case MIGRATION_STATUS_ACTIVE:
case MIGRATION_STATUS_CANCELLING:
case MIGRATION_STATUS_POSTCOPY_ACTIVE:
case MIGRATION_STATUS_PRE_SWITCHOVER:
case MIGRATION_STATUS_DEVICE:
case MIGRATION_STATUS_POSTCOPY_PAUSED:
case MIGRATION_STATUS_POSTCOPY_RECOVER:
/* TODO add some postcopy stats */
populate_time_info(info, s);
populate_ram_info(info, s);
populate_disk_info(info);
migration_populate_vfio_info(info);
break;
case MIGRATION_STATUS_COLO:
info->has_status = true;
/* TODO: display COLO specific information (checkpoint info etc.) */
break;
case MIGRATION_STATUS_COMPLETED:
populate_time_info(info, s);
populate_ram_info(info, s);
migration_populate_vfio_info(info);
break;
case MIGRATION_STATUS_FAILED:
info->has_status = true;
break;
case MIGRATION_STATUS_CANCELLED:
info->has_status = true;
break;
case MIGRATION_STATUS_WAIT_UNPLUG:
info->has_status = true;
break;
}
info->status = state;
QEMU_LOCK_GUARD(&s->error_mutex);
if (s->error) {
info->error_desc = g_strdup(error_get_pretty(s->error));
}
}
static void fill_destination_migration_info(MigrationInfo *info)
{
MigrationIncomingState *mis = migration_incoming_get_current();
if (mis->socket_address_list) {
info->has_socket_address = true;
info->socket_address =
QAPI_CLONE(SocketAddressList, mis->socket_address_list);
}
switch (mis->state) {
case MIGRATION_STATUS_NONE:
return;
case MIGRATION_STATUS_SETUP:
case MIGRATION_STATUS_CANCELLING:
case MIGRATION_STATUS_CANCELLED:
case MIGRATION_STATUS_ACTIVE:
case MIGRATION_STATUS_POSTCOPY_ACTIVE:
case MIGRATION_STATUS_POSTCOPY_PAUSED:
case MIGRATION_STATUS_POSTCOPY_RECOVER:
case MIGRATION_STATUS_FAILED:
case MIGRATION_STATUS_COLO:
info->has_status = true;
break;
case MIGRATION_STATUS_COMPLETED:
info->has_status = true;
fill_destination_postcopy_migration_info(info);
break;
}
info->status = mis->state;
}
MigrationInfo *qmp_query_migrate(Error **errp)
{
MigrationInfo *info = g_malloc0(sizeof(*info));
fill_destination_migration_info(info);
fill_source_migration_info(info);
return info;
}
void qmp_migrate_start_postcopy(Error **errp)
{
MigrationState *s = migrate_get_current();
if (!migrate_postcopy()) {
error_setg(errp, "Enable postcopy with migrate_set_capability before"
" the start of migration");
return;
}
if (s->state == MIGRATION_STATUS_NONE) {
error_setg(errp, "Postcopy must be started after migration has been"
" started");
return;
}
/*
* we don't error if migration has finished since that would be racy
* with issuing this command.
*/
qatomic_set(&s->start_postcopy, true);
}
/* shared migration helpers */
void migrate_set_state(int *state, int old_state, int new_state)
{
assert(new_state < MIGRATION_STATUS__MAX);
if (qatomic_cmpxchg(state, old_state, new_state) == old_state) {
trace_migrate_set_state(MigrationStatus_str(new_state));
migrate_generate_event(new_state);
}
}
static void migrate_fd_cleanup(MigrationState *s)
{
qemu_bh_delete(s->cleanup_bh);
s->cleanup_bh = NULL;
g_free(s->hostname);
s->hostname = NULL;
json_writer_free(s->vmdesc);
s->vmdesc = NULL;
qemu_savevm_state_cleanup();
if (s->to_dst_file) {
QEMUFile *tmp;
trace_migrate_fd_cleanup();
qemu_mutex_unlock_iothread();
if (s->migration_thread_running) {
qemu_thread_join(&s->thread);
s->migration_thread_running = false;
}
qemu_mutex_lock_iothread();
multifd_save_cleanup();
qemu_mutex_lock(&s->qemu_file_lock);
tmp = s->to_dst_file;
s->to_dst_file = NULL;
qemu_mutex_unlock(&s->qemu_file_lock);
/*
* Close the file handle without the lock to make sure the
* critical section won't block for long.
*/
migration_ioc_unregister_yank_from_file(tmp);
qemu_fclose(tmp);
}
/*
* We already cleaned up to_dst_file, so errors from the return
* path might be due to that, ignore them.
*/
close_return_path_on_source(s);
assert(!migration_is_active(s));
if (s->state == MIGRATION_STATUS_CANCELLING) {
migrate_set_state(&s->state, MIGRATION_STATUS_CANCELLING,
MIGRATION_STATUS_CANCELLED);
}
if (s->error) {
/* It is used on info migrate. We can't free it */
error_report_err(error_copy(s->error));
}
migration_call_notifiers(s);
block_cleanup_parameters();
yank_unregister_instance(MIGRATION_YANK_INSTANCE);
}
static void migrate_fd_cleanup_schedule(MigrationState *s)
{
/*
* Ref the state for bh, because it may be called when
* there're already no other refs
*/
object_ref(OBJECT(s));
qemu_bh_schedule(s->cleanup_bh);
}
static void migrate_fd_cleanup_bh(void *opaque)
{
MigrationState *s = opaque;
migrate_fd_cleanup(s);
object_unref(OBJECT(s));
}
void migrate_set_error(MigrationState *s, const Error *error)
{
QEMU_LOCK_GUARD(&s->error_mutex);
if (!s->error) {
s->error = error_copy(error);
}
}
bool migrate_has_error(MigrationState *s)
{
/* The lock is not helpful here, but still follow the rule */
QEMU_LOCK_GUARD(&s->error_mutex);
return qatomic_read(&s->error);
}
static void migrate_error_free(MigrationState *s)
{
QEMU_LOCK_GUARD(&s->error_mutex);
if (s->error) {
error_free(s->error);
s->error = NULL;
}
}
static void migrate_fd_error(MigrationState *s, const Error *error)
{
trace_migrate_fd_error(error_get_pretty(error));
assert(s->to_dst_file == NULL);
migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
MIGRATION_STATUS_FAILED);
migrate_set_error(s, error);
}
static void migrate_fd_cancel(MigrationState *s)
{
int old_state ;
trace_migrate_fd_cancel();
WITH_QEMU_LOCK_GUARD(&s->qemu_file_lock) {
if (s->rp_state.from_dst_file) {
/* shutdown the rp socket, so causing the rp thread to shutdown */
qemu_file_shutdown(s->rp_state.from_dst_file);
}
}
do {
old_state = s->state;
if (!migration_is_running(old_state)) {
break;
}
/* If the migration is paused, kick it out of the pause */
if (old_state == MIGRATION_STATUS_PRE_SWITCHOVER) {
qemu_sem_post(&s->pause_sem);
}
migrate_set_state(&s->state, old_state, MIGRATION_STATUS_CANCELLING);
} while (s->state != MIGRATION_STATUS_CANCELLING);
/*
* If we're unlucky the migration code might be stuck somewhere in a
* send/write while the network has failed and is waiting to timeout;
* if we've got shutdown(2) available then we can force it to quit.
*/
if (s->state == MIGRATION_STATUS_CANCELLING) {
WITH_QEMU_LOCK_GUARD(&s->qemu_file_lock) {
if (s->to_dst_file) {
qemu_file_shutdown(s->to_dst_file);
}
}
}
if (s->state == MIGRATION_STATUS_CANCELLING && s->block_inactive) {
Error *local_err = NULL;
bdrv_activate_all(&local_err);
if (local_err) {
error_report_err(local_err);
} else {
s->block_inactive = false;
}
}
}
void migration_add_notifier(Notifier *notify,
void (*func)(Notifier *notifier, void *data))
{
notify->notify = func;
notifier_list_add(&migration_state_notifiers, notify);
}
void migration_remove_notifier(Notifier *notify)
{
if (notify->notify) {
notifier_remove(notify);
notify->notify = NULL;
}
}
void migration_call_notifiers(MigrationState *s)
{
notifier_list_notify(&migration_state_notifiers, s);
}
bool migration_in_setup(MigrationState *s)
{
return s->state == MIGRATION_STATUS_SETUP;
}
bool migration_has_finished(MigrationState *s)
{
return s->state == MIGRATION_STATUS_COMPLETED;
}
bool migration_has_failed(MigrationState *s)
{
return (s->state == MIGRATION_STATUS_CANCELLED ||
s->state == MIGRATION_STATUS_FAILED);
}
bool migration_in_postcopy(void)
{
MigrationState *s = migrate_get_current();
switch (s->state) {
case MIGRATION_STATUS_POSTCOPY_ACTIVE:
case MIGRATION_STATUS_POSTCOPY_PAUSED:
case MIGRATION_STATUS_POSTCOPY_RECOVER:
return true;
default:
return false;
}
}
bool migration_postcopy_is_alive(int state)
{
switch (state) {
case MIGRATION_STATUS_POSTCOPY_ACTIVE:
case MIGRATION_STATUS_POSTCOPY_RECOVER:
return true;
default:
return false;
}
}
bool migration_in_postcopy_after_devices(MigrationState *s)
{
return migration_in_postcopy() && s->postcopy_after_devices;
}
bool migration_in_incoming_postcopy(void)
{
PostcopyState ps = postcopy_state_get();
return ps >= POSTCOPY_INCOMING_DISCARD && ps < POSTCOPY_INCOMING_END;
}
bool migration_incoming_postcopy_advised(void)
{
PostcopyState ps = postcopy_state_get();
return ps >= POSTCOPY_INCOMING_ADVISE && ps < POSTCOPY_INCOMING_END;
}
bool migration_in_bg_snapshot(void)
{
MigrationState *s = migrate_get_current();
return migrate_background_snapshot() &&
migration_is_setup_or_active(s->state);
}
bool migration_is_idle(void)
{
MigrationState *s = current_migration;
if (!s) {
return true;
}
switch (s->state) {
case MIGRATION_STATUS_NONE:
case MIGRATION_STATUS_CANCELLED:
case MIGRATION_STATUS_COMPLETED:
case MIGRATION_STATUS_FAILED:
return true;
case MIGRATION_STATUS_SETUP:
case MIGRATION_STATUS_CANCELLING:
case MIGRATION_STATUS_ACTIVE:
case MIGRATION_STATUS_POSTCOPY_ACTIVE:
case MIGRATION_STATUS_COLO:
case MIGRATION_STATUS_PRE_SWITCHOVER:
case MIGRATION_STATUS_DEVICE:
case MIGRATION_STATUS_WAIT_UNPLUG:
return false;
case MIGRATION_STATUS__MAX:
g_assert_not_reached();
}
return false;
}
bool migration_is_active(MigrationState *s)
{
return (s->state == MIGRATION_STATUS_ACTIVE ||
s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE);
}
int migrate_init(MigrationState *s, Error **errp)
{
int ret;
ret = qemu_savevm_state_prepare(errp);
if (ret) {
return ret;
}
/*
* Reinitialise all migration state, except
* parameters/capabilities that the user set, and
* locks.
*/
s->cleanup_bh = 0;
s->vm_start_bh = 0;
s->to_dst_file = NULL;
s->state = MIGRATION_STATUS_NONE;
s->rp_state.from_dst_file = NULL;
s->mbps = 0.0;
s->pages_per_second = 0.0;
s->downtime = 0;
s->expected_downtime = 0;
s->setup_time = 0;
s->start_postcopy = false;
s->postcopy_after_devices = false;
s->migration_thread_running = false;
error_free(s->error);
s->error = NULL;
s->vmdesc = NULL;
migrate_set_state(&s->state, MIGRATION_STATUS_NONE, MIGRATION_STATUS_SETUP);
s->start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
s->total_time = 0;
s->vm_old_state = -1;
s->iteration_initial_bytes = 0;
s->threshold_size = 0;
s->switchover_acked = false;
s->rdma_migration = false;
/*
* set mig_stats memory to zero for a new migration
*/
memset(&mig_stats, 0, sizeof(mig_stats));
migration_reset_vfio_bytes_transferred();
return 0;
}
static bool is_busy(Error **reasonp, Error **errp)
{
ERRP_GUARD();
/* Snapshots are similar to migrations, so check RUN_STATE_SAVE_VM too. */
if (runstate_check(RUN_STATE_SAVE_VM) || !migration_is_idle()) {
error_propagate_prepend(errp, *reasonp,
"disallowing migration blocker "
"(migration/snapshot in progress) for: ");
*reasonp = NULL;
return true;
}
return false;
}
static bool is_only_migratable(Error **reasonp, Error **errp, int modes)
{
ERRP_GUARD();
if (only_migratable && (modes & BIT(MIG_MODE_NORMAL))) {
error_propagate_prepend(errp, *reasonp,
"disallowing migration blocker "
"(--only-migratable) for: ");
*reasonp = NULL;
return true;
}
return false;
}
static int get_modes(MigMode mode, va_list ap)
{
int modes = 0;
while (mode != -1 && mode != MIG_MODE_ALL) {
assert(mode >= MIG_MODE_NORMAL && mode < MIG_MODE__MAX);
modes |= BIT(mode);
mode = va_arg(ap, MigMode);
}
if (mode == MIG_MODE_ALL) {
modes = BIT(MIG_MODE__MAX) - 1;
}
return modes;
}
static int add_blockers(Error **reasonp, Error **errp, int modes)
{
for (MigMode mode = 0; mode < MIG_MODE__MAX; mode++) {
if (modes & BIT(mode)) {
migration_blockers[mode] = g_slist_prepend(migration_blockers[mode],
*reasonp);
}
}
return 0;
}
int migrate_add_blocker(Error **reasonp, Error **errp)
{
return migrate_add_blocker_modes(reasonp, errp, MIG_MODE_ALL);
}
int migrate_add_blocker_normal(Error **reasonp, Error **errp)
{
return migrate_add_blocker_modes(reasonp, errp, MIG_MODE_NORMAL, -1);
}
int migrate_add_blocker_modes(Error **reasonp, Error **errp, MigMode mode, ...)
{
int modes;
va_list ap;
va_start(ap, mode);
modes = get_modes(mode, ap);
va_end(ap);
if (is_only_migratable(reasonp, errp, modes)) {
return -EACCES;
} else if (is_busy(reasonp, errp)) {
return -EBUSY;
}
return add_blockers(reasonp, errp, modes);
}
int migrate_add_blocker_internal(Error **reasonp, Error **errp)
{
int modes = BIT(MIG_MODE__MAX) - 1;
if (is_busy(reasonp, errp)) {
return -EBUSY;
}
return add_blockers(reasonp, errp, modes);
}
void migrate_del_blocker(Error **reasonp)
{
if (*reasonp) {
for (MigMode mode = 0; mode < MIG_MODE__MAX; mode++) {
migration_blockers[mode] = g_slist_remove(migration_blockers[mode],
*reasonp);
}
error_free(*reasonp);
*reasonp = NULL;
}
}
void qmp_migrate_incoming(const char *uri, bool has_channels,
MigrationChannelList *channels, Error **errp)
{
Error *local_err = NULL;
static bool once = true;
if (!once) {
error_setg(errp, "The incoming migration has already been started");
return;
}
if (!runstate_check(RUN_STATE_INMIGRATE)) {
error_setg(errp, "'-incoming' was not specified on the command line");
return;
}
if (!yank_register_instance(MIGRATION_YANK_INSTANCE, errp)) {
return;
}
qemu_start_incoming_migration(uri, has_channels, channels, &local_err);
if (local_err) {
yank_unregister_instance(MIGRATION_YANK_INSTANCE);
error_propagate(errp, local_err);
return;
}
once = false;
}
void qmp_migrate_recover(const char *uri, Error **errp)
{
MigrationIncomingState *mis = migration_incoming_get_current();
/*
* Don't even bother to use ERRP_GUARD() as it _must_ always be set by
* callers (no one should ignore a recover failure); if there is, it's a
* programming error.
*/
assert(errp);
if (mis->state != MIGRATION_STATUS_POSTCOPY_PAUSED) {
error_setg(errp, "Migrate recover can only be run "
"when postcopy is paused.");
return;
}
/* If there's an existing transport, release it */
migration_incoming_transport_cleanup(mis);
/*
* Note that this call will never start a real migration; it will
* only re-setup the migration stream and poke existing migration
* to continue using that newly established channel.
*/
qemu_start_incoming_migration(uri, false, NULL, errp);
}
void qmp_migrate_pause(Error **errp)
{
MigrationState *ms = migrate_get_current();
MigrationIncomingState *mis = migration_incoming_get_current();
int ret = 0;
if (migration_postcopy_is_alive(ms->state)) {
/* Source side, during postcopy */
Error *error = NULL;
/* Tell the core migration that we're pausing */
error_setg(&error, "Postcopy migration is paused by the user");
migrate_set_error(ms, error);
error_free(error);
qemu_mutex_lock(&ms->qemu_file_lock);
if (ms->to_dst_file) {
ret = qemu_file_shutdown(ms->to_dst_file);
}
qemu_mutex_unlock(&ms->qemu_file_lock);
if (ret) {
error_setg(errp, "Failed to pause source migration");
}
/*
* Kick the migration thread out of any waiting windows (on behalf
* of the rp thread).
*/
migration_rp_kick(ms);
return;
}
if (migration_postcopy_is_alive(mis->state)) {
ret = qemu_file_shutdown(mis->from_src_file);
if (ret) {
error_setg(errp, "Failed to pause destination migration");
}
return;
}
error_setg(errp, "migrate-pause is currently only supported "
"during postcopy-active or postcopy-recover state");
}
bool migration_is_blocked(Error **errp)
{
GSList *blockers = migration_blockers[migrate_mode()];
if (qemu_savevm_state_blocked(errp)) {
return true;
}
if (blockers) {
error_propagate(errp, error_copy(blockers->data));
return true;
}
return false;
}
/* Returns true if continue to migrate, or false if error detected */
static bool migrate_prepare(MigrationState *s, bool blk, bool blk_inc,
bool resume, Error **errp)
{
if (blk_inc) {
warn_report("parameter 'inc' is deprecated;"
" use blockdev-mirror with NBD instead");
}
if (blk) {
warn_report("parameter 'blk' is deprecated;"
" use blockdev-mirror with NBD instead");
}
if (resume) {
if (s->state != MIGRATION_STATUS_POSTCOPY_PAUSED) {
error_setg(errp, "Cannot resume if there is no "
"paused migration");
return false;
}
/*
* Postcopy recovery won't work well with release-ram
* capability since release-ram will drop the page buffer as
* long as the page is put into the send buffer. So if there
* is a network failure happened, any page buffers that have
* not yet reached the destination VM but have already been
* sent from the source VM will be lost forever. Let's refuse
* the client from resuming such a postcopy migration.
* Luckily release-ram was designed to only be used when src
* and destination VMs are on the same host, so it should be
* fine.
*/
if (migrate_release_ram()) {
error_setg(errp, "Postcopy recovery cannot work "
"when release-ram capability is set");
return false;
}
/* This is a resume, skip init status */
return true;
}
if (migration_is_running(s->state)) {
error_setg(errp, QERR_MIGRATION_ACTIVE);
return false;
}
if (runstate_check(RUN_STATE_INMIGRATE)) {
error_setg(errp, "Guest is waiting for an incoming migration");
return false;
}
if (runstate_check(RUN_STATE_POSTMIGRATE)) {
error_setg(errp, "Can't migrate the vm that was paused due to "
"previous migration");
return false;
}
if (migration_is_blocked(errp)) {
return false;
}
if (blk || blk_inc) {
if (migrate_colo()) {
error_setg(errp, "No disk migration is required in COLO mode");
return false;
}
if (migrate_block() || migrate_block_incremental()) {
error_setg(errp, "Command options are incompatible with "
"current migration capabilities");
return false;
}
if (!migrate_cap_set(MIGRATION_CAPABILITY_BLOCK, true, errp)) {
return false;
}
s->must_remove_block_options = true;
}
if (blk_inc) {
migrate_set_block_incremental(true);
}
if (migrate_init(s, errp)) {
return false;
}
return true;
}
void qmp_migrate(const char *uri, bool has_channels,
MigrationChannelList *channels, bool has_blk, bool blk,
bool has_inc, bool inc, bool has_detach, bool detach,
bool has_resume, bool resume, Error **errp)
{
bool resume_requested;
Error *local_err = NULL;
MigrationState *s = migrate_get_current();
g_autoptr(MigrationChannel) channel = NULL;
MigrationAddress *addr = NULL;
/*
* Having preliminary checks for uri and channel
*/
if (uri && has_channels) {
error_setg(errp, "'uri' and 'channels' arguments are mutually "
"exclusive; exactly one of the two should be present in "
"'migrate' qmp command ");
return;
} else if (channels) {
/* To verify that Migrate channel list has only item */
if (channels->next) {
error_setg(errp, "Channel list has more than one entries");
return;
}
addr = channels->value->addr;
} else if (uri) {
/* caller uses the old URI syntax */
if (!migrate_uri_parse(uri, &channel, errp)) {
return;
}
addr = channel->addr;
} else {
error_setg(errp, "neither 'uri' or 'channels' argument are "
"specified in 'migrate' qmp command ");
return;
}
/* transport mechanism not suitable for migration? */
if (!migration_channels_and_transport_compatible(addr, errp)) {
return;
}
resume_requested = has_resume && resume;
if (!migrate_prepare(s, has_blk && blk, has_inc && inc,
resume_requested, errp)) {
/* Error detected, put into errp */
return;
}
if (!resume_requested) {
if (!yank_register_instance(MIGRATION_YANK_INSTANCE, errp)) {
return;
}
}
if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
SocketAddress *saddr = &addr->u.socket;
if (saddr->type == SOCKET_ADDRESS_TYPE_INET ||
saddr->type == SOCKET_ADDRESS_TYPE_UNIX ||
saddr->type == SOCKET_ADDRESS_TYPE_VSOCK) {
socket_start_outgoing_migration(s, saddr, &local_err);
} else if (saddr->type == SOCKET_ADDRESS_TYPE_FD) {
fd_start_outgoing_migration(s, saddr->u.fd.str, &local_err);
}
#ifdef CONFIG_RDMA
} else if (addr->transport == MIGRATION_ADDRESS_TYPE_RDMA) {
rdma_start_outgoing_migration(s, &addr->u.rdma, &local_err);
#endif
} else if (addr->transport == MIGRATION_ADDRESS_TYPE_EXEC) {
exec_start_outgoing_migration(s, addr->u.exec.args, &local_err);
} else if (addr->transport == MIGRATION_ADDRESS_TYPE_FILE) {
file_start_outgoing_migration(s, &addr->u.file, &local_err);
} else {
error_setg(&local_err, QERR_INVALID_PARAMETER_VALUE, "uri",
"a valid migration protocol");
migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
MIGRATION_STATUS_FAILED);
block_cleanup_parameters();
}
if (local_err) {
if (!resume_requested) {
yank_unregister_instance(MIGRATION_YANK_INSTANCE);
}
migrate_fd_error(s, local_err);
error_propagate(errp, local_err);
return;
}
}
void qmp_migrate_cancel(Error **errp)
{
migration_cancel(NULL);
}
void qmp_migrate_continue(MigrationStatus state, Error **errp)
{
MigrationState *s = migrate_get_current();
if (s->state != state) {
error_setg(errp, "Migration not in expected state: %s",
MigrationStatus_str(s->state));
return;
}
qemu_sem_post(&s->pause_sem);
}
int migration_rp_wait(MigrationState *s)
{
/* If migration has failure already, ignore the wait */
if (migrate_has_error(s)) {
return -1;
}
qemu_sem_wait(&s->rp_state.rp_sem);
/* After wait, double check that there's no failure */
if (migrate_has_error(s)) {
return -1;
}
return 0;
}
void migration_rp_kick(MigrationState *s)
{
qemu_sem_post(&s->rp_state.rp_sem);
}
static struct rp_cmd_args {
ssize_t len; /* -1 = variable */
const char *name;
} rp_cmd_args[] = {
[MIG_RP_MSG_INVALID] = { .len = -1, .name = "INVALID" },
[MIG_RP_MSG_SHUT] = { .len = 4, .name = "SHUT" },
[MIG_RP_MSG_PONG] = { .len = 4, .name = "PONG" },
[MIG_RP_MSG_REQ_PAGES] = { .len = 12, .name = "REQ_PAGES" },
[MIG_RP_MSG_REQ_PAGES_ID] = { .len = -1, .name = "REQ_PAGES_ID" },
[MIG_RP_MSG_RECV_BITMAP] = { .len = -1, .name = "RECV_BITMAP" },
[MIG_RP_MSG_RESUME_ACK] = { .len = 4, .name = "RESUME_ACK" },
[MIG_RP_MSG_SWITCHOVER_ACK] = { .len = 0, .name = "SWITCHOVER_ACK" },
[MIG_RP_MSG_MAX] = { .len = -1, .name = "MAX" },
};
/*
* Process a request for pages received on the return path,
* We're allowed to send more than requested (e.g. to round to our page size)
* and we don't need to send pages that have already been sent.
*/
static void
migrate_handle_rp_req_pages(MigrationState *ms, const char* rbname,
ram_addr_t start, size_t len, Error **errp)
{
long our_host_ps = qemu_real_host_page_size();
trace_migrate_handle_rp_req_pages(rbname, start, len);
/*
* Since we currently insist on matching page sizes, just sanity check
* we're being asked for whole host pages.
*/
if (!QEMU_IS_ALIGNED(start, our_host_ps) ||
!QEMU_IS_ALIGNED(len, our_host_ps)) {
error_setg(errp, "MIG_RP_MSG_REQ_PAGES: Misaligned page request, start:"
RAM_ADDR_FMT " len: %zd", start, len);
return;
}
ram_save_queue_pages(rbname, start, len, errp);
}
static bool migrate_handle_rp_recv_bitmap(MigrationState *s, char *block_name,
Error **errp)
{
RAMBlock *block = qemu_ram_block_by_name(block_name);
if (!block) {
error_setg(errp, "MIG_RP_MSG_RECV_BITMAP has invalid block name '%s'",
block_name);
return false;
}
/* Fetch the received bitmap and refresh the dirty bitmap */
return ram_dirty_bitmap_reload(s, block, errp);
}
static bool migrate_handle_rp_resume_ack(MigrationState *s,
uint32_t value, Error **errp)
{
trace_source_return_path_thread_resume_ack(value);
if (value != MIGRATION_RESUME_ACK_VALUE) {
error_setg(errp, "illegal resume_ack value %"PRIu32, value);
return false;
}
/* Now both sides are active. */
migrate_set_state(&s->state, MIGRATION_STATUS_POSTCOPY_RECOVER,
MIGRATION_STATUS_POSTCOPY_ACTIVE);
/* Notify send thread that time to continue send pages */
migration_rp_kick(s);
return true;
}
/*
* Release ms->rp_state.from_dst_file (and postcopy_qemufile_src if
* existed) in a safe way.
*/
static void migration_release_dst_files(MigrationState *ms)
{
QEMUFile *file;
WITH_QEMU_LOCK_GUARD(&ms->qemu_file_lock) {
/*
* Reset the from_dst_file pointer first before releasing it, as we
* can't block within lock section
*/
file = ms->rp_state.from_dst_file;
ms->rp_state.from_dst_file = NULL;
}
/*
* Do the same to postcopy fast path socket too if there is. No
* locking needed because this qemufile should only be managed by
* return path thread.
*/
if (ms->postcopy_qemufile_src) {
migration_ioc_unregister_yank_from_file(ms->postcopy_qemufile_src);
qemu_file_shutdown(ms->postcopy_qemufile_src);
qemu_fclose(ms->postcopy_qemufile_src);
ms->postcopy_qemufile_src = NULL;
}
qemu_fclose(file);
}
/*
* Handles messages sent on the return path towards the source VM
*
*/
static void *source_return_path_thread(void *opaque)
{
MigrationState *ms = opaque;
QEMUFile *rp = ms->rp_state.from_dst_file;
uint16_t header_len, header_type;
uint8_t buf[512];
uint32_t tmp32, sibling_error;
ram_addr_t start = 0; /* =0 to silence warning */
size_t len = 0, expected_len;
Error *err = NULL;
int res;
trace_source_return_path_thread_entry();
rcu_register_thread();
while (migration_is_setup_or_active(ms->state)) {
trace_source_return_path_thread_loop_top();
header_type = qemu_get_be16(rp);
header_len = qemu_get_be16(rp);
if (qemu_file_get_error(rp)) {
qemu_file_get_error_obj(rp, &err);
goto out;
}
if (header_type >= MIG_RP_MSG_MAX ||
header_type == MIG_RP_MSG_INVALID) {
error_setg(&err, "Received invalid message 0x%04x length 0x%04x",
header_type, header_len);
goto out;
}
if ((rp_cmd_args[header_type].len != -1 &&
header_len != rp_cmd_args[header_type].len) ||
header_len > sizeof(buf)) {
error_setg(&err, "Received '%s' message (0x%04x) with"
"incorrect length %d expecting %zu",
rp_cmd_args[header_type].name, header_type, header_len,
(size_t)rp_cmd_args[header_type].len);
goto out;
}
/* We know we've got a valid header by this point */
res = qemu_get_buffer(rp, buf, header_len);
if (res != header_len) {
error_setg(&err, "Failed reading data for message 0x%04x"
" read %d expected %d",
header_type, res, header_len);
goto out;
}
/* OK, we have the message and the data */
switch (header_type) {
case MIG_RP_MSG_SHUT:
sibling_error = ldl_be_p(buf);
trace_source_return_path_thread_shut(sibling_error);
if (sibling_error) {
error_setg(&err, "Sibling indicated error %d", sibling_error);
}
/*
* We'll let the main thread deal with closing the RP
* we could do a shutdown(2) on it, but we're the only user
* anyway, so there's nothing gained.
*/
goto out;
case MIG_RP_MSG_PONG:
tmp32 = ldl_be_p(buf);
trace_source_return_path_thread_pong(tmp32);
qemu_sem_post(&ms->rp_state.rp_pong_acks);
break;
case MIG_RP_MSG_REQ_PAGES:
start = ldq_be_p(buf);
len = ldl_be_p(buf + 8);
migrate_handle_rp_req_pages(ms, NULL, start, len, &err);
if (err) {
goto out;
}
break;
case MIG_RP_MSG_REQ_PAGES_ID:
expected_len = 12 + 1; /* header + termination */
if (header_len >= expected_len) {
start = ldq_be_p(buf);
len = ldl_be_p(buf + 8);
/* Now we expect an idstr */
tmp32 = buf[12]; /* Length of the following idstr */
buf[13 + tmp32] = '\0';
expected_len += tmp32;
}
if (header_len != expected_len) {
error_setg(&err, "Req_Page_id with length %d expecting %zd",
header_len, expected_len);
goto out;
}
migrate_handle_rp_req_pages(ms, (char *)&buf[13], start, len,
&err);
if (err) {
goto out;
}
break;
case MIG_RP_MSG_RECV_BITMAP:
if (header_len < 1) {
error_setg(&err, "MIG_RP_MSG_RECV_BITMAP missing block name");
goto out;
}
/* Format: len (1B) + idstr (<255B). This ends the idstr. */
buf[buf[0] + 1] = '\0';
if (!migrate_handle_rp_recv_bitmap(ms, (char *)(buf + 1), &err)) {
goto out;
}
break;
case MIG_RP_MSG_RESUME_ACK:
tmp32 = ldl_be_p(buf);
if (!migrate_handle_rp_resume_ack(ms, tmp32, &err)) {
goto out;
}
break;
case MIG_RP_MSG_SWITCHOVER_ACK:
ms->switchover_acked = true;
trace_source_return_path_thread_switchover_acked();
break;
default:
break;
}
}
out:
if (err) {
migrate_set_error(ms, err);
error_free(err);
trace_source_return_path_thread_bad_end();
}
if (ms->state == MIGRATION_STATUS_POSTCOPY_RECOVER) {
/*
* this will be extremely unlikely: that we got yet another network
* issue during recovering of the 1st network failure.. during this
* period the main migration thread can be waiting on rp_sem for
* this thread to sync with the other side.
*
* When this happens, explicitly kick the migration thread out of
* RECOVER stage and back to PAUSED, so the admin can try
* everything again.
*/
migration_rp_kick(ms);
}
trace_source_return_path_thread_end();
rcu_unregister_thread();
return NULL;
}
static int open_return_path_on_source(MigrationState *ms)
{
ms->rp_state.from_dst_file = qemu_file_get_return_path(ms->to_dst_file);
if (!ms->rp_state.from_dst_file) {
return -1;
}
trace_open_return_path_on_source();
qemu_thread_create(&ms->rp_state.rp_thread, "return path",
source_return_path_thread, ms, QEMU_THREAD_JOINABLE);
ms->rp_state.rp_thread_created = true;
trace_open_return_path_on_source_continue();
return 0;
}
/* Return true if error detected, or false otherwise */
static bool close_return_path_on_source(MigrationState *ms)
{
if (!ms->rp_state.rp_thread_created) {
return false;
}
trace_migration_return_path_end_before();
/*
* If this is a normal exit then the destination will send a SHUT
* and the rp_thread will exit, however if there's an error we
* need to cause it to exit. shutdown(2), if we have it, will
* cause it to unblock if it's stuck waiting for the destination.
*/
WITH_QEMU_LOCK_GUARD(&ms->qemu_file_lock) {
if (ms->to_dst_file && ms->rp_state.from_dst_file &&
qemu_file_get_error(ms->to_dst_file)) {
qemu_file_shutdown(ms->rp_state.from_dst_file);
}
}
qemu_thread_join(&ms->rp_state.rp_thread);
ms->rp_state.rp_thread_created = false;
migration_release_dst_files(ms);
trace_migration_return_path_end_after();
/* Return path will persist the error in MigrationState when quit */
return migrate_has_error(ms);
}
static inline void
migration_wait_main_channel(MigrationState *ms)
{
/* Wait until one PONG message received */
qemu_sem_wait(&ms->rp_state.rp_pong_acks);
}
/*
* Switch from normal iteration to postcopy
* Returns non-0 on error
*/
static int postcopy_start(MigrationState *ms, Error **errp)
{
int ret;
QIOChannelBuffer *bioc;
QEMUFile *fb;
uint64_t bandwidth = migrate_max_postcopy_bandwidth();
bool restart_block = false;
int cur_state = MIGRATION_STATUS_ACTIVE;
if (migrate_postcopy_preempt()) {
migration_wait_main_channel(ms);
if (postcopy_preempt_establish_channel(ms)) {
migrate_set_state(&ms->state, ms->state, MIGRATION_STATUS_FAILED);
return -1;
}
}
if (!migrate_pause_before_switchover()) {
migrate_set_state(&ms->state, MIGRATION_STATUS_ACTIVE,
MIGRATION_STATUS_POSTCOPY_ACTIVE);
}
trace_postcopy_start();
qemu_mutex_lock_iothread();
trace_postcopy_start_set_run();
migration_downtime_start(ms);
global_state_store();
ret = migration_stop_vm(RUN_STATE_FINISH_MIGRATE);
if (ret < 0) {
goto fail;
}
ret = migration_maybe_pause(ms, &cur_state,
MIGRATION_STATUS_POSTCOPY_ACTIVE);
if (ret < 0) {
goto fail;
}
ret = bdrv_inactivate_all();
if (ret < 0) {
goto fail;
}
restart_block = true;
/*
* Cause any non-postcopiable, but iterative devices to
* send out their final data.
*/
qemu_savevm_state_complete_precopy(ms->to_dst_file, true, false);
/*
* in Finish migrate and with the io-lock held everything should
* be quiet, but we've potentially still got dirty pages and we
* need to tell the destination to throw any pages it's already received
* that are dirty
*/
if (migrate_postcopy_ram()) {
ram_postcopy_send_discard_bitmap(ms);
}
/*
* send rest of state - note things that are doing postcopy
* will notice we're in POSTCOPY_ACTIVE and not actually
* wrap their state up here
*/
migration_rate_set(bandwidth);
if (migrate_postcopy_ram()) {
/* Ping just for debugging, helps line traces up */
qemu_savevm_send_ping(ms->to_dst_file, 2);
}
/*
* While loading the device state we may trigger page transfer
* requests and the fd must be free to process those, and thus
* the destination must read the whole device state off the fd before
* it starts processing it. Unfortunately the ad-hoc migration format
* doesn't allow the destination to know the size to read without fully
* parsing it through each devices load-state code (especially the open
* coded devices that use get/put).
* So we wrap the device state up in a package with a length at the start;
* to do this we use a qemu_buf to hold the whole of the device state.
*/
bioc = qio_channel_buffer_new(4096);
qio_channel_set_name(QIO_CHANNEL(bioc), "migration-postcopy-buffer");
fb = qemu_file_new_output(QIO_CHANNEL(bioc));
object_unref(OBJECT(bioc));
/*
* Make sure the receiver can get incoming pages before we send the rest
* of the state
*/
qemu_savevm_send_postcopy_listen(fb);
qemu_savevm_state_complete_precopy(fb, false, false);
if (migrate_postcopy_ram()) {
qemu_savevm_send_ping(fb, 3);
}
qemu_savevm_send_postcopy_run(fb);
/* <><> end of stuff going into the package */
/* Last point of recovery; as soon as we send the package the destination
* can open devices and potentially start running.
* Lets just check again we've not got any errors.
*/
ret = qemu_file_get_error(ms->to_dst_file);
if (ret) {
error_setg(errp, "postcopy_start: Migration stream errored (pre package)");
goto fail_closefb;
}
restart_block = false;
/* Now send that blob */
if (qemu_savevm_send_packaged(ms->to_dst_file, bioc->data, bioc->usage)) {
goto fail_closefb;
}
qemu_fclose(fb);
/* Send a notify to give a chance for anything that needs to happen
* at the transition to postcopy and after the device state; in particular
* spice needs to trigger a transition now
*/
ms->postcopy_after_devices = true;
migration_call_notifiers(ms);
migration_downtime_end(ms);
qemu_mutex_unlock_iothread();
if (migrate_postcopy_ram()) {
/*
* Although this ping is just for debug, it could potentially be
* used for getting a better measurement of downtime at the source.
*/
qemu_savevm_send_ping(ms->to_dst_file, 4);
}
if (migrate_release_ram()) {
ram_postcopy_migrated_memory_release(ms);
}
ret = qemu_file_get_error(ms->to_dst_file);
if (ret) {
error_setg(errp, "postcopy_start: Migration stream errored");
migrate_set_state(&ms->state, MIGRATION_STATUS_POSTCOPY_ACTIVE,
MIGRATION_STATUS_FAILED);
}
trace_postcopy_preempt_enabled(migrate_postcopy_preempt());
return ret;
fail_closefb:
qemu_fclose(fb);
fail:
migrate_set_state(&ms->state, MIGRATION_STATUS_POSTCOPY_ACTIVE,
MIGRATION_STATUS_FAILED);
if (restart_block) {
/* A failure happened early enough that we know the destination hasn't
* accessed block devices, so we're safe to recover.
*/
Error *local_err = NULL;
bdrv_activate_all(&local_err);
if (local_err) {
error_report_err(local_err);
}
}
qemu_mutex_unlock_iothread();
return -1;
}
/**
* migration_maybe_pause: Pause if required to by
* migrate_pause_before_switchover called with the iothread locked
* Returns: 0 on success
*/
static int migration_maybe_pause(MigrationState *s,
int *current_active_state,
int new_state)
{
if (!migrate_pause_before_switchover()) {
return 0;
}
/* Since leaving this state is not atomic with posting the semaphore
* it's possible that someone could have issued multiple migrate_continue
* and the semaphore is incorrectly positive at this point;
* the docs say it's undefined to reinit a semaphore that's already
* init'd, so use timedwait to eat up any existing posts.
*/
while (qemu_sem_timedwait(&s->pause_sem, 1) == 0) {
/* This block intentionally left blank */
}
/*
* If the migration is cancelled when it is in the completion phase,
* the migration state is set to MIGRATION_STATUS_CANCELLING.
* So we don't need to wait a semaphore, otherwise we would always
* wait for the 'pause_sem' semaphore.
*/
if (s->state != MIGRATION_STATUS_CANCELLING) {
qemu_mutex_unlock_iothread();
migrate_set_state(&s->state, *current_active_state,
MIGRATION_STATUS_PRE_SWITCHOVER);
qemu_sem_wait(&s->pause_sem);
migrate_set_state(&s->state, MIGRATION_STATUS_PRE_SWITCHOVER,
new_state);
*current_active_state = new_state;
qemu_mutex_lock_iothread();
}
return s->state == new_state ? 0 : -EINVAL;
}
static int migration_completion_precopy(MigrationState *s,
int *current_active_state)
{
int ret;
qemu_mutex_lock_iothread();
migration_downtime_start(s);
s->vm_old_state = runstate_get();
global_state_store();
ret = migration_stop_vm(RUN_STATE_FINISH_MIGRATE);
trace_migration_completion_vm_stop(ret);
if (ret < 0) {
goto out_unlock;
}
ret = migration_maybe_pause(s, current_active_state,
MIGRATION_STATUS_DEVICE);
if (ret < 0) {
goto out_unlock;
}
/*
* Inactivate disks except in COLO, and track that we have done so in order
* to remember to reactivate them if migration fails or is cancelled.
*/
s->block_inactive = !migrate_colo();
migration_rate_set(RATE_LIMIT_DISABLED);
ret = qemu_savevm_state_complete_precopy(s->to_dst_file, false,
s->block_inactive);
out_unlock:
qemu_mutex_unlock_iothread();
return ret;
}
static void migration_completion_postcopy(MigrationState *s)
{
trace_migration_completion_postcopy_end();
qemu_mutex_lock_iothread();
qemu_savevm_state_complete_postcopy(s->to_dst_file);
qemu_mutex_unlock_iothread();
/*
* Shutdown the postcopy fast path thread. This is only needed when dest
* QEMU binary is old (7.1/7.2). QEMU 8.0+ doesn't need this.
*/
if (migrate_postcopy_preempt() && s->preempt_pre_7_2) {
postcopy_preempt_shutdown_file(s);
}
trace_migration_completion_postcopy_end_after_complete();
}
static void migration_completion_failed(MigrationState *s,
int current_active_state)
{
if (s->block_inactive && (s->state == MIGRATION_STATUS_ACTIVE ||
s->state == MIGRATION_STATUS_DEVICE)) {
/*
* If not doing postcopy, vm_start() will be called: let's
* regain control on images.
*/
Error *local_err = NULL;
qemu_mutex_lock_iothread();
bdrv_activate_all(&local_err);
if (local_err) {
error_report_err(local_err);
} else {
s->block_inactive = false;
}
qemu_mutex_unlock_iothread();
}
migrate_set_state(&s->state, current_active_state,
MIGRATION_STATUS_FAILED);
}
/**
* migration_completion: Used by migration_thread when there's not much left.
* The caller 'breaks' the loop when this returns.
*
* @s: Current migration state
*/
static void migration_completion(MigrationState *s)
{
int ret = 0;
int current_active_state = s->state;
if (s->state == MIGRATION_STATUS_ACTIVE) {
ret = migration_completion_precopy(s, &current_active_state);
} else if (s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE) {
migration_completion_postcopy(s);
} else {
ret = -1;
}
if (ret < 0) {
goto fail;
}
if (close_return_path_on_source(s)) {
goto fail;
}
if (qemu_file_get_error(s->to_dst_file)) {
trace_migration_completion_file_err();
goto fail;
}
if (migrate_colo() && s->state == MIGRATION_STATUS_ACTIVE) {
/* COLO does not support postcopy */
migrate_set_state(&s->state, MIGRATION_STATUS_ACTIVE,
MIGRATION_STATUS_COLO);
} else {
migrate_set_state(&s->state, current_active_state,
MIGRATION_STATUS_COMPLETED);
}
return;
fail:
migration_completion_failed(s, current_active_state);
}
/**
* bg_migration_completion: Used by bg_migration_thread when after all the
* RAM has been saved. The caller 'breaks' the loop when this returns.
*
* @s: Current migration state
*/
static void bg_migration_completion(MigrationState *s)
{
int current_active_state = s->state;
if (s->state == MIGRATION_STATUS_ACTIVE) {
/*
* By this moment we have RAM content saved into the migration stream.
* The next step is to flush the non-RAM content (device state)
* right after the ram content. The device state has been stored into
* the temporary buffer before RAM saving started.
*/
qemu_put_buffer(s->to_dst_file, s->bioc->data, s->bioc->usage);
qemu_fflush(s->to_dst_file);
} else if (s->state == MIGRATION_STATUS_CANCELLING) {
goto fail;
}
if (qemu_file_get_error(s->to_dst_file)) {
trace_migration_completion_file_err();
goto fail;
}
migrate_set_state(&s->state, current_active_state,
MIGRATION_STATUS_COMPLETED);
return;
fail:
migrate_set_state(&s->state, current_active_state,
MIGRATION_STATUS_FAILED);
}
typedef enum MigThrError {
/* No error detected */
MIG_THR_ERR_NONE = 0,
/* Detected error, but resumed successfully */
MIG_THR_ERR_RECOVERED = 1,
/* Detected fatal error, need to exit */
MIG_THR_ERR_FATAL = 2,
} MigThrError;
static int postcopy_resume_handshake(MigrationState *s)
{
qemu_savevm_send_postcopy_resume(s->to_dst_file);
while (s->state == MIGRATION_STATUS_POSTCOPY_RECOVER) {
if (migration_rp_wait(s)) {
return -1;
}
}
if (s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE) {
return 0;
}
return -1;
}
/* Return zero if success, or <0 for error */
static int postcopy_do_resume(MigrationState *s)
{
int ret;
/*
* Call all the resume_prepare() hooks, so that modules can be
* ready for the migration resume.
*/
ret = qemu_savevm_state_resume_prepare(s);
if (ret) {
error_report("%s: resume_prepare() failure detected: %d",
__func__, ret);
return ret;
}
/*
* If preempt is enabled, re-establish the preempt channel. Note that
* we do it after resume prepare to make sure the main channel will be
* created before the preempt channel. E.g. with weak network, the
* dest QEMU may get messed up with the preempt and main channels on
* the order of connection setup. This guarantees the correct order.
*/
ret = postcopy_preempt_establish_channel(s);
if (ret) {
error_report("%s: postcopy_preempt_establish_channel(): %d",
__func__, ret);
return ret;
}
/*
* Last handshake with destination on the resume (destination will
* switch to postcopy-active afterwards)
*/
ret = postcopy_resume_handshake(s);
if (ret) {
error_report("%s: handshake failed: %d", __func__, ret);
return ret;
}
return 0;
}
/*
* We don't return until we are in a safe state to continue current
* postcopy migration. Returns MIG_THR_ERR_RECOVERED if recovered, or
* MIG_THR_ERR_FATAL if unrecovery failure happened.
*/
static MigThrError postcopy_pause(MigrationState *s)
{
assert(s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE);
while (true) {
QEMUFile *file;
/*
* Current channel is possibly broken. Release it. Note that this is
* guaranteed even without lock because to_dst_file should only be
* modified by the migration thread. That also guarantees that the
* unregister of yank is safe too without the lock. It should be safe
* even to be within the qemu_file_lock, but we didn't do that to avoid
* taking more mutex (yank_lock) within qemu_file_lock. TL;DR: we make
* the qemu_file_lock critical section as small as possible.
*/
assert(s->to_dst_file);
migration_ioc_unregister_yank_from_file(s->to_dst_file);
qemu_mutex_lock(&s->qemu_file_lock);
file = s->to_dst_file;
s->to_dst_file = NULL;
qemu_mutex_unlock(&s->qemu_file_lock);
qemu_file_shutdown(file);
qemu_fclose(file);
/*
* We're already pausing, so ignore any errors on the return
* path and just wait for the thread to finish. It will be
* re-created when we resume.
*/
close_return_path_on_source(s);
migrate_set_state(&s->state, s->state,
MIGRATION_STATUS_POSTCOPY_PAUSED);
error_report("Detected IO failure for postcopy. "
"Migration paused.");
/*
* We wait until things fixed up. Then someone will setup the
* status back for us.
*/
while (s->state == MIGRATION_STATUS_POSTCOPY_PAUSED) {
qemu_sem_wait(&s->postcopy_pause_sem);
}
if (s->state == MIGRATION_STATUS_POSTCOPY_RECOVER) {
/* Woken up by a recover procedure. Give it a shot */
/* Do the resume logic */
if (postcopy_do_resume(s) == 0) {
/* Let's continue! */
trace_postcopy_pause_continued();
return MIG_THR_ERR_RECOVERED;
} else {
/*
* Something wrong happened during the recovery, let's
* pause again. Pause is always better than throwing
* data away.
*/
continue;
}
} else {
/* This is not right... Time to quit. */
return MIG_THR_ERR_FATAL;
}
}
}
static MigThrError migration_detect_error(MigrationState *s)
{
int ret;
int state = s->state;
Error *local_error = NULL;
if (state == MIGRATION_STATUS_CANCELLING ||
state == MIGRATION_STATUS_CANCELLED) {
/* End the migration, but don't set the state to failed */
return MIG_THR_ERR_FATAL;
}
/*
* Try to detect any file errors. Note that postcopy_qemufile_src will
* be NULL when postcopy preempt is not enabled.
*/
ret = qemu_file_get_error_obj_any(s->to_dst_file,
s->postcopy_qemufile_src,
&local_error);
if (!ret) {
/* Everything is fine */
assert(!local_error);
return MIG_THR_ERR_NONE;
}
if (local_error) {
migrate_set_error(s, local_error);
error_free(local_error);
}
if (state == MIGRATION_STATUS_POSTCOPY_ACTIVE && ret) {
/*
* For postcopy, we allow the network to be down for a
* while. After that, it can be continued by a
* recovery phase.
*/
return postcopy_pause(s);
} else {
/*
* For precopy (or postcopy with error outside IO), we fail
* with no time.
*/
migrate_set_state(&s->state, state, MIGRATION_STATUS_FAILED);
trace_migration_thread_file_err();
/* Time to stop the migration, now. */
return MIG_THR_ERR_FATAL;
}
}
static void migration_calculate_complete(MigrationState *s)
{
uint64_t bytes = migration_transferred_bytes();
int64_t end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
int64_t transfer_time;
migration_downtime_end(s);
s->total_time = end_time - s->start_time;
transfer_time = s->total_time - s->setup_time;
if (transfer_time) {
s->mbps = ((double) bytes * 8.0) / transfer_time / 1000;
}
}
static void update_iteration_initial_status(MigrationState *s)
{
/*
* Update these three fields at the same time to avoid mismatch info lead
* wrong speed calculation.
*/
s->iteration_start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
s->iteration_initial_bytes = migration_transferred_bytes();
s->iteration_initial_pages = ram_get_total_transferred_pages();
}
static void migration_update_counters(MigrationState *s,
int64_t current_time)
{
uint64_t transferred, transferred_pages, time_spent;
uint64_t current_bytes; /* bytes transferred since the beginning */
uint64_t switchover_bw;
/* Expected bandwidth when switching over to destination QEMU */
double expected_bw_per_ms;
double bandwidth;
if (current_time < s->iteration_start_time + BUFFER_DELAY) {
return;
}
switchover_bw = migrate_avail_switchover_bandwidth();
current_bytes = migration_transferred_bytes();
transferred = current_bytes - s->iteration_initial_bytes;
time_spent = current_time - s->iteration_start_time;
bandwidth = (double)transferred / time_spent;
if (switchover_bw) {
/*
* If the user specified a switchover bandwidth, let's trust the
* user so that can be more accurate than what we estimated.
*/
expected_bw_per_ms = switchover_bw / 1000;
} else {
/* If the user doesn't specify bandwidth, we use the estimated */
expected_bw_per_ms = bandwidth;
}
s->threshold_size = expected_bw_per_ms * migrate_downtime_limit();
s->mbps = (((double) transferred * 8.0) /
((double) time_spent / 1000.0)) / 1000.0 / 1000.0;
transferred_pages = ram_get_total_transferred_pages() -
s->iteration_initial_pages;
s->pages_per_second = (double) transferred_pages /
(((double) time_spent / 1000.0));
/*
* if we haven't sent anything, we don't want to
* recalculate. 10000 is a small enough number for our purposes
*/
if (stat64_get(&mig_stats.dirty_pages_rate) &&
transferred > 10000) {
s->expected_downtime =
stat64_get(&mig_stats.dirty_bytes_last_sync) / expected_bw_per_ms;
}
migration_rate_reset();
update_iteration_initial_status(s);
trace_migrate_transferred(transferred, time_spent,
/* Both in unit bytes/ms */
bandwidth, switchover_bw / 1000,
s->threshold_size);
}
static bool migration_can_switchover(MigrationState *s)
{
if (!migrate_switchover_ack()) {
return true;
}
/* No reason to wait for switchover ACK if VM is stopped */
if (!runstate_is_running()) {
return true;
}
return s->switchover_acked;
}
/* Migration thread iteration status */
typedef enum {
MIG_ITERATE_RESUME, /* Resume current iteration */
MIG_ITERATE_SKIP, /* Skip current iteration */
MIG_ITERATE_BREAK, /* Break the loop */
} MigIterateState;
/*
* Return true if continue to the next iteration directly, false
* otherwise.
*/
static MigIterateState migration_iteration_run(MigrationState *s)
{
uint64_t must_precopy, can_postcopy;
Error *local_err = NULL;
bool in_postcopy = s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE;
bool can_switchover = migration_can_switchover(s);
qemu_savevm_state_pending_estimate(&must_precopy, &can_postcopy);
uint64_t pending_size = must_precopy + can_postcopy;
trace_migrate_pending_estimate(pending_size, must_precopy, can_postcopy);
if (must_precopy <= s->threshold_size) {
qemu_savevm_state_pending_exact(&must_precopy, &can_postcopy);
pending_size = must_precopy + can_postcopy;
trace_migrate_pending_exact(pending_size, must_precopy, can_postcopy);
}
if ((!pending_size || pending_size < s->threshold_size) && can_switchover) {
trace_migration_thread_low_pending(pending_size);
migration_completion(s);
return MIG_ITERATE_BREAK;
}
/* Still a significant amount to transfer */
if (!in_postcopy && must_precopy <= s->threshold_size && can_switchover &&
qatomic_read(&s->start_postcopy)) {
if (postcopy_start(s, &local_err)) {
migrate_set_error(s, local_err);
error_report_err(local_err);
}
return MIG_ITERATE_SKIP;
}
/* Just another iteration step */
qemu_savevm_state_iterate(s->to_dst_file, in_postcopy);
return MIG_ITERATE_RESUME;
}
static void migration_iteration_finish(MigrationState *s)
{
/* If we enabled cpu throttling for auto-converge, turn it off. */
cpu_throttle_stop();
qemu_mutex_lock_iothread();
switch (s->state) {
case MIGRATION_STATUS_COMPLETED:
migration_calculate_complete(s);
runstate_set(RUN_STATE_POSTMIGRATE);
break;
case MIGRATION_STATUS_COLO:
assert(migrate_colo());
migrate_start_colo_process(s);
s->vm_old_state = RUN_STATE_RUNNING;
/* Fallthrough */
case MIGRATION_STATUS_FAILED:
case MIGRATION_STATUS_CANCELLED:
case MIGRATION_STATUS_CANCELLING:
if (runstate_is_live(s->vm_old_state)) {
if (!runstate_check(RUN_STATE_SHUTDOWN)) {
vm_start();
}
} else {
if (runstate_check(RUN_STATE_FINISH_MIGRATE)) {
runstate_set(s->vm_old_state);
}
}
break;
default:
/* Should not reach here, but if so, forgive the VM. */
error_report("%s: Unknown ending state %d", __func__, s->state);
break;
}
migrate_fd_cleanup_schedule(s);
qemu_mutex_unlock_iothread();
}
static void bg_migration_iteration_finish(MigrationState *s)
{
/*
* Stop tracking RAM writes - un-protect memory, un-register UFFD
* memory ranges, flush kernel wait queues and wake up threads
* waiting for write fault to be resolved.
*/
ram_write_tracking_stop();
qemu_mutex_lock_iothread();
switch (s->state) {
case MIGRATION_STATUS_COMPLETED:
migration_calculate_complete(s);
break;
case MIGRATION_STATUS_ACTIVE:
case MIGRATION_STATUS_FAILED:
case MIGRATION_STATUS_CANCELLED:
case MIGRATION_STATUS_CANCELLING:
break;
default:
/* Should not reach here, but if so, forgive the VM. */
error_report("%s: Unknown ending state %d", __func__, s->state);
break;
}
migrate_fd_cleanup_schedule(s);
qemu_mutex_unlock_iothread();
}
/*
* Return true if continue to the next iteration directly, false
* otherwise.
*/
static MigIterateState bg_migration_iteration_run(MigrationState *s)
{
int res;
res = qemu_savevm_state_iterate(s->to_dst_file, false);
if (res > 0) {
bg_migration_completion(s);
return MIG_ITERATE_BREAK;
}
return MIG_ITERATE_RESUME;
}
void migration_make_urgent_request(void)
{
qemu_sem_post(&migrate_get_current()->rate_limit_sem);
}
void migration_consume_urgent_request(void)
{
qemu_sem_wait(&migrate_get_current()->rate_limit_sem);
}
/* Returns true if the rate limiting was broken by an urgent request */
bool migration_rate_limit(void)
{
int64_t now = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
MigrationState *s = migrate_get_current();
bool urgent = false;
migration_update_counters(s, now);
if (migration_rate_exceeded(s->to_dst_file)) {
if (qemu_file_get_error(s->to_dst_file)) {
return false;
}
/*
* Wait for a delay to do rate limiting OR
* something urgent to post the semaphore.
*/
int ms = s->iteration_start_time + BUFFER_DELAY - now;
trace_migration_rate_limit_pre(ms);
if (qemu_sem_timedwait(&s->rate_limit_sem, ms) == 0) {
/*
* We were woken by one or more urgent things but
* the timedwait will have consumed one of them.
* The service routine for the urgent wake will dec
* the semaphore itself for each item it consumes,
* so add this one we just eat back.
*/
qemu_sem_post(&s->rate_limit_sem);
urgent = true;
}
trace_migration_rate_limit_post(urgent);
}
return urgent;
}
/*
* if failover devices are present, wait they are completely
* unplugged
*/
static void qemu_savevm_wait_unplug(MigrationState *s, int old_state,
int new_state)
{
if (qemu_savevm_state_guest_unplug_pending()) {
migrate_set_state(&s->state, old_state, MIGRATION_STATUS_WAIT_UNPLUG);
while (s->state == MIGRATION_STATUS_WAIT_UNPLUG &&
qemu_savevm_state_guest_unplug_pending()) {
qemu_sem_timedwait(&s->wait_unplug_sem, 250);
}
if (s->state != MIGRATION_STATUS_WAIT_UNPLUG) {
int timeout = 120; /* 30 seconds */
/*
* migration has been canceled
* but as we have started an unplug we must wait the end
* to be able to plug back the card
*/
while (timeout-- && qemu_savevm_state_guest_unplug_pending()) {
qemu_sem_timedwait(&s->wait_unplug_sem, 250);
}
if (qemu_savevm_state_guest_unplug_pending() &&
!qtest_enabled()) {
warn_report("migration: partially unplugged device on "
"failure");
}
}
migrate_set_state(&s->state, MIGRATION_STATUS_WAIT_UNPLUG, new_state);
} else {
migrate_set_state(&s->state, old_state, new_state);
}
}
/*
* Master migration thread on the source VM.
* It drives the migration and pumps the data down the outgoing channel.
*/
static void *migration_thread(void *opaque)
{
MigrationState *s = opaque;
MigrationThread *thread = NULL;
int64_t setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST);
MigThrError thr_error;
bool urgent = false;
thread = migration_threads_add("live_migration", qemu_get_thread_id());
rcu_register_thread();
object_ref(OBJECT(s));
update_iteration_initial_status(s);
qemu_mutex_lock_iothread();
qemu_savevm_state_header(s->to_dst_file);
qemu_mutex_unlock_iothread();
/*
* If we opened the return path, we need to make sure dst has it
* opened as well.
*/
if (s->rp_state.rp_thread_created) {
/* Now tell the dest that it should open its end so it can reply */
qemu_savevm_send_open_return_path(s->to_dst_file);
/* And do a ping that will make stuff easier to debug */
qemu_savevm_send_ping(s->to_dst_file, 1);
}
if (migrate_postcopy()) {
/*
* Tell the destination that we *might* want to do postcopy later;
* if the other end can't do postcopy it should fail now, nice and
* early.
*/
qemu_savevm_send_postcopy_advise(s->to_dst_file);
}
if (migrate_colo()) {
/* Notify migration destination that we enable COLO */
qemu_savevm_send_colo_enable(s->to_dst_file);
}
qemu_mutex_lock_iothread();
qemu_savevm_state_setup(s->to_dst_file);
qemu_mutex_unlock_iothread();
qemu_savevm_wait_unplug(s, MIGRATION_STATUS_SETUP,
MIGRATION_STATUS_ACTIVE);
s->setup_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) - setup_start;
trace_migration_thread_setup_complete();
while (migration_is_active(s)) {
if (urgent || !migration_rate_exceeded(s->to_dst_file)) {
MigIterateState iter_state = migration_iteration_run(s);
if (iter_state == MIG_ITERATE_SKIP) {
continue;
} else if (iter_state == MIG_ITERATE_BREAK) {
break;
}
}
/*
* Try to detect any kind of failures, and see whether we
* should stop the migration now.
*/
thr_error = migration_detect_error(s);
if (thr_error == MIG_THR_ERR_FATAL) {
/* Stop migration */
break;
} else if (thr_error == MIG_THR_ERR_RECOVERED) {
/*
* Just recovered from a e.g. network failure, reset all
* the local variables. This is important to avoid
* breaking transferred_bytes and bandwidth calculation
*/
update_iteration_initial_status(s);
}
urgent = migration_rate_limit();
}
trace_migration_thread_after_loop();
migration_iteration_finish(s);
object_unref(OBJECT(s));
rcu_unregister_thread();
migration_threads_remove(thread);
return NULL;
}
static void bg_migration_vm_start_bh(void *opaque)
{
MigrationState *s = opaque;
qemu_bh_delete(s->vm_start_bh);
s->vm_start_bh = NULL;
vm_resume(s->vm_old_state);
migration_downtime_end(s);
}
/**
* Background snapshot thread, based on live migration code.
* This is an alternative implementation of live migration mechanism
* introduced specifically to support background snapshots.
*
* It takes advantage of userfault_fd write protection mechanism introduced
* in v5.7 kernel. Compared to existing dirty page logging migration much
* lesser stream traffic is produced resulting in smaller snapshot images,
* simply cause of no page duplicates can get into the stream.
*
* Another key point is that generated vmstate stream reflects machine state
* 'frozen' at the beginning of snapshot creation compared to dirty page logging
* mechanism, which effectively results in that saved snapshot is the state of VM
* at the end of the process.
*/
static void *bg_migration_thread(void *opaque)
{
MigrationState *s = opaque;
int64_t setup_start;
MigThrError thr_error;
QEMUFile *fb;
bool early_fail = true;
rcu_register_thread();
object_ref(OBJECT(s));
migration_rate_set(RATE_LIMIT_DISABLED);
setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST);
/*
* We want to save vmstate for the moment when migration has been
* initiated but also we want to save RAM content while VM is running.
* The RAM content should appear first in the vmstate. So, we first
* stash the non-RAM part of the vmstate to the temporary buffer,
* then write RAM part of the vmstate to the migration stream
* with vCPUs running and, finally, write stashed non-RAM part of
* the vmstate from the buffer to the migration stream.
*/
s->bioc = qio_channel_buffer_new(512 * 1024);
qio_channel_set_name(QIO_CHANNEL(s->bioc), "vmstate-buffer");
fb = qemu_file_new_output(QIO_CHANNEL(s->bioc));
object_unref(OBJECT(s->bioc));
update_iteration_initial_status(s);
/*
* Prepare for tracking memory writes with UFFD-WP - populate
* RAM pages before protecting.
*/
#ifdef __linux__
ram_write_tracking_prepare();
#endif
qemu_mutex_lock_iothread();
qemu_savevm_state_header(s->to_dst_file);
qemu_savevm_state_setup(s->to_dst_file);
qemu_mutex_unlock_iothread();
qemu_savevm_wait_unplug(s, MIGRATION_STATUS_SETUP,
MIGRATION_STATUS_ACTIVE);
s->setup_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) - setup_start;
trace_migration_thread_setup_complete();
migration_downtime_start(s);
qemu_mutex_lock_iothread();
s->vm_old_state = runstate_get();
global_state_store();
/* Forcibly stop VM before saving state of vCPUs and devices */
if (migration_stop_vm(RUN_STATE_PAUSED)) {
goto fail;
}
/*
* Put vCPUs in sync with shadow context structures, then
* save their state to channel-buffer along with devices.
*/
cpu_synchronize_all_states();
if (qemu_savevm_state_complete_precopy_non_iterable(fb, false, false)) {
goto fail;
}
/*
* Since we are going to get non-iterable state data directly
* from s->bioc->data, explicit flush is needed here.
*/
qemu_fflush(fb);
/* Now initialize UFFD context and start tracking RAM writes */
if (ram_write_tracking_start()) {
goto fail;
}
early_fail = false;
/*
* Start VM from BH handler to avoid write-fault lock here.
* UFFD-WP protection for the whole RAM is already enabled so
* calling VM state change notifiers from vm_start() would initiate
* writes to virtio VQs memory which is in write-protected region.
*/
s->vm_start_bh = qemu_bh_new(bg_migration_vm_start_bh, s);
qemu_bh_schedule(s->vm_start_bh);
qemu_mutex_unlock_iothread();
while (migration_is_active(s)) {
MigIterateState iter_state = bg_migration_iteration_run(s);
if (iter_state == MIG_ITERATE_SKIP) {
continue;
} else if (iter_state == MIG_ITERATE_BREAK) {
break;
}
/*
* Try to detect any kind of failures, and see whether we
* should stop the migration now.
*/
thr_error = migration_detect_error(s);
if (thr_error == MIG_THR_ERR_FATAL) {
/* Stop migration */
break;
}
migration_update_counters(s, qemu_clock_get_ms(QEMU_CLOCK_REALTIME));
}
trace_migration_thread_after_loop();
fail:
if (early_fail) {
migrate_set_state(&s->state, MIGRATION_STATUS_ACTIVE,
MIGRATION_STATUS_FAILED);
qemu_mutex_unlock_iothread();
}
bg_migration_iteration_finish(s);
qemu_fclose(fb);
object_unref(OBJECT(s));
rcu_unregister_thread();
return NULL;
}
void migrate_fd_connect(MigrationState *s, Error *error_in)
{
Error *local_err = NULL;
uint64_t rate_limit;
bool resume = s->state == MIGRATION_STATUS_POSTCOPY_PAUSED;
/*
* If there's a previous error, free it and prepare for another one.
* Meanwhile if migration completes successfully, there won't have an error
* dumped when calling migrate_fd_cleanup().
*/
migrate_error_free(s);
s->expected_downtime = migrate_downtime_limit();
if (resume) {
assert(s->cleanup_bh);
} else {
assert(!s->cleanup_bh);
s->cleanup_bh = qemu_bh_new(migrate_fd_cleanup_bh, s);
}
if (error_in) {
migrate_fd_error(s, error_in);
if (resume) {
/*
* Don't do cleanup for resume if channel is invalid, but only dump
* the error. We wait for another channel connect from the user.
* The error_report still gives HMP user a hint on what failed.
* It's normally done in migrate_fd_cleanup(), but call it here
* explicitly.
*/
error_report_err(error_copy(s->error));
} else {
migrate_fd_cleanup(s);
}
return;
}
if (resume) {
/* This is a resumed migration */
rate_limit = migrate_max_postcopy_bandwidth();
} else {
/* This is a fresh new migration */
rate_limit = migrate_max_bandwidth();
/* Notify before starting migration thread */
migration_call_notifiers(s);
}
migration_rate_set(rate_limit);
qemu_file_set_blocking(s->to_dst_file, true);
/*
* Open the return path. For postcopy, it is used exclusively. For
* precopy, only if user specified "return-path" capability would
* QEMU uses the return path.
*/
if (migrate_postcopy_ram() || migrate_return_path()) {
if (open_return_path_on_source(s)) {
error_setg(&local_err, "Unable to open return-path for postcopy");
migrate_set_state(&s->state, s->state, MIGRATION_STATUS_FAILED);
migrate_set_error(s, local_err);
error_report_err(local_err);
migrate_fd_cleanup(s);
return;
}
}
/*
* This needs to be done before resuming a postcopy. Note: for newer
* QEMUs we will delay the channel creation until postcopy_start(), to
* avoid disorder of channel creations.
*/
if (migrate_postcopy_preempt() && s->preempt_pre_7_2) {
postcopy_preempt_setup(s);
}
if (resume) {
/* Wakeup the main migration thread to do the recovery */
migrate_set_state(&s->state, MIGRATION_STATUS_POSTCOPY_PAUSED,
MIGRATION_STATUS_POSTCOPY_RECOVER);
qemu_sem_post(&s->postcopy_pause_sem);
return;
}
if (multifd_save_setup(&local_err) != 0) {
migrate_set_error(s, local_err);
error_report_err(local_err);
migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
MIGRATION_STATUS_FAILED);
migrate_fd_cleanup(s);
return;
}
if (migrate_background_snapshot()) {
qemu_thread_create(&s->thread, "bg_snapshot",
bg_migration_thread, s, QEMU_THREAD_JOINABLE);
} else {
qemu_thread_create(&s->thread, "live_migration",
migration_thread, s, QEMU_THREAD_JOINABLE);
}
s->migration_thread_running = true;
}
static void migration_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
dc->user_creatable = false;
device_class_set_props(dc, migration_properties);
}
static void migration_instance_finalize(Object *obj)
{
MigrationState *ms = MIGRATION_OBJ(obj);
qemu_mutex_destroy(&ms->error_mutex);
qemu_mutex_destroy(&ms->qemu_file_lock);
qemu_sem_destroy(&ms->wait_unplug_sem);
qemu_sem_destroy(&ms->rate_limit_sem);
qemu_sem_destroy(&ms->pause_sem);
qemu_sem_destroy(&ms->postcopy_pause_sem);
qemu_sem_destroy(&ms->rp_state.rp_sem);
qemu_sem_destroy(&ms->rp_state.rp_pong_acks);
qemu_sem_destroy(&ms->postcopy_qemufile_src_sem);
error_free(ms->error);
}
static void migration_instance_init(Object *obj)
{
MigrationState *ms = MIGRATION_OBJ(obj);
ms->state = MIGRATION_STATUS_NONE;
ms->mbps = -1;
ms->pages_per_second = -1;
qemu_sem_init(&ms->pause_sem, 0);
qemu_mutex_init(&ms->error_mutex);
migrate_params_init(&ms->parameters);
qemu_sem_init(&ms->postcopy_pause_sem, 0);
qemu_sem_init(&ms->rp_state.rp_sem, 0);
qemu_sem_init(&ms->rp_state.rp_pong_acks, 0);
qemu_sem_init(&ms->rate_limit_sem, 0);
qemu_sem_init(&ms->wait_unplug_sem, 0);
qemu_sem_init(&ms->postcopy_qemufile_src_sem, 0);
qemu_mutex_init(&ms->qemu_file_lock);
}
/*
* Return true if check pass, false otherwise. Error will be put
* inside errp if provided.
*/
static bool migration_object_check(MigrationState *ms, Error **errp)
{
/* Assuming all off */
bool old_caps[MIGRATION_CAPABILITY__MAX] = { 0 };
if (!migrate_params_check(&ms->parameters, errp)) {
return false;
}
return migrate_caps_check(old_caps, ms->capabilities, errp);
}
static const TypeInfo migration_type = {
.name = TYPE_MIGRATION,
/*
* NOTE: TYPE_MIGRATION is not really a device, as the object is
* not created using qdev_new(), it is not attached to the qdev
* device tree, and it is never realized.
*
* TODO: Make this TYPE_OBJECT once QOM provides something like
* TYPE_DEVICE's "-global" properties.
*/
.parent = TYPE_DEVICE,
.class_init = migration_class_init,
.class_size = sizeof(MigrationClass),
.instance_size = sizeof(MigrationState),
.instance_init = migration_instance_init,
.instance_finalize = migration_instance_finalize,
};
static void register_migration_types(void)
{
type_register_static(&migration_type);
}
type_init(register_migration_types);