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migration: Add helper to get target runstate

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In 99% cases, after QEMU migrates to dest host, it tries to detect the
target VM runstate using global_state_get_runstate().

There's one outlier so far which is Xen that won't send global state.
That's the major reason why global_state_received() check was always there
together with global_state_get_runstate().

However it's utterly confusing why global_state_received() has anything to
do with "let's start VM or not".

Provide a helper to explain it, then we have an unified entry for getting
the target dest QEMU runstate after migration.

Suggested-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20241206230838.1111496-2-peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
This commit is contained in:
Peter Xu 2024-12-06 18:08:33 -05:00 committed by Fabiano Rosas
parent b93d897ea2
commit 7815f69867
1 changed files with 17 additions and 4 deletions
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21
migration/migration.c
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@ -135,6 +135,21 @@ static bool migration_needs_multiple_sockets(void)
return migrate_multifd() || migrate_postcopy_preempt(); return migrate_multifd() || migrate_postcopy_preempt();
} }
static RunState migration_get_target_runstate(void)
{
/*
* When the global state is not migrated, it means we don't know the
* runstate of the src QEMU. We don't have much choice but assuming
* the VM is running. NOTE: this is pretty rare case, so far only Xen
* uses it.
*/
if (!global_state_received()) {
return RUN_STATE_RUNNING;
}
return global_state_get_runstate();
}
static bool transport_supports_multi_channels(MigrationAddress *addr) static bool transport_supports_multi_channels(MigrationAddress *addr)
{ {
if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) { if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) {
@ -735,8 +750,7 @@ static void process_incoming_migration_bh(void *opaque)
* unless we really are starting the VM. * unless we really are starting the VM.
*/ */
if (!migrate_late_block_activate() || if (!migrate_late_block_activate() ||
(autostart && (!global_state_received() || (autostart && runstate_is_live(migration_get_target_runstate()))) {
runstate_is_live(global_state_get_runstate())))) {
/* Make sure all file formats throw away their mutable metadata. /* Make sure all file formats throw away their mutable metadata.
* If we get an error here, just don't restart the VM yet. */ * If we get an error here, just don't restart the VM yet. */
bdrv_activate_all(&local_err); bdrv_activate_all(&local_err);
@ -759,8 +773,7 @@ static void process_incoming_migration_bh(void *opaque)
dirty_bitmap_mig_before_vm_start(); dirty_bitmap_mig_before_vm_start();
if (!global_state_received() || if (runstate_is_live(migration_get_target_runstate())) {
runstate_is_live(global_state_get_runstate())) {
if (autostart) { if (autostart) {
vm_start(); vm_start();
} else { } else {