qmp: handle stop/cont in INMIGRATE state
Right now, stop followed by an incoming migration will let the virtual machine start. cont before an incoming migration instead will fail. This is bad because the actual behavior is not predictable; it is racy with respect to the start of the incoming migration. That's because incoming migration is blocking, and thus will delay the processing of stop/cont until the end of the migration. In addition, there's nothing that really prevents the user from typing the block device's passwords before incoming migration is done, so returning the DeviceEncrypted error is also helpful in the QMP case. Both things can be fixed by just toggling the autostart variable when stop/cont are called in INMIGRATE state. Note that libvirt is currently working around the race by looping if the MigrationExpected answer is returned. After this patch, the command will return right away without ever raising an error. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
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@ -22,15 +22,11 @@
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# @KVMMissingCap: the requested operation can't be fulfilled because a
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# required KVM capability is missing
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#
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# @MigrationExpected: the requested operation can't be fulfilled because a
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# migration process is expected
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#
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# Since: 1.2
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##
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{ 'enum': 'ErrorClass',
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'data': [ 'GenericError', 'CommandNotFound', 'DeviceEncrypted',
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'DeviceNotActive', 'DeviceNotFound', 'KVMMissingCap',
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'MigrationExpected' ] }
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'DeviceNotActive', 'DeviceNotFound', 'KVMMissingCap' ] }
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##
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# @add_client
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@ -149,7 +145,11 @@
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#
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# @finish-migrate: guest is paused to finish the migration process
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#
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# @inmigrate: guest is paused waiting for an incoming migration
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# @inmigrate: guest is paused waiting for an incoming migration. Note
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# that this state does not tell whether the machine will start at the
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# end of the migration. This depends on the command-line -S option and
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# any invocation of 'stop' or 'cont' that has happened since QEMU was
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# started.
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#
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# @internal-error: An internal error that prevents further guest execution
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# has occurred
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@ -1210,7 +1210,9 @@
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# Since: 0.14.0
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#
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# Notes: This function will succeed even if the guest is already in the stopped
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# state
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# state. In "inmigrate" state, it will ensure that the guest
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# remains paused once migration finishes, as if the -S option was
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# passed on the command line.
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##
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{ 'command': 'stop' }
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@ -1299,11 +1301,14 @@
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# Since: 0.14.0
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#
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# Returns: If successful, nothing
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# If the QEMU is waiting for an incoming migration, MigrationExpected
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# If QEMU was started with an encrypted block device and a key has
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# not yet been set, DeviceEncrypted.
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#
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# Notes: This command will succeed if the guest is currently running.
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# Notes: This command will succeed if the guest is currently running. It
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# will also succeed if the guest is in the "inmigrate" state; in
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# this case, the effect of the command is to make sure the guest
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# starts once migration finishes, removing the effect of the -S
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# command line option if it was passed.
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##
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{ 'command': 'cont' }
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3
qerror.h
3
qerror.h
@ -165,9 +165,6 @@ void assert_no_error(Error *err);
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#define QERR_MIGRATION_NOT_SUPPORTED \
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ERROR_CLASS_GENERIC_ERROR, "State blocked by non-migratable device '%s'"
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#define QERR_MIGRATION_EXPECTED \
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ERROR_CLASS_MIGRATION_EXPECTED, "An incoming migration is expected before this command can be executed"
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#define QERR_MISSING_PARAMETER \
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ERROR_CLASS_GENERIC_ERROR, "Parameter '%s' is missing"
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13
qmp.c
13
qmp.c
@ -85,8 +85,12 @@ void qmp_quit(Error **err)
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void qmp_stop(Error **errp)
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{
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if (runstate_check(RUN_STATE_INMIGRATE)) {
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autostart = 0;
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} else {
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vm_stop(RUN_STATE_PAUSED);
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}
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}
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void qmp_system_reset(Error **errp)
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{
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@ -144,10 +148,7 @@ void qmp_cont(Error **errp)
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{
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Error *local_err = NULL;
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if (runstate_check(RUN_STATE_INMIGRATE)) {
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error_set(errp, QERR_MIGRATION_EXPECTED);
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return;
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} else if (runstate_check(RUN_STATE_INTERNAL_ERROR) ||
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if (runstate_check(RUN_STATE_INTERNAL_ERROR) ||
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runstate_check(RUN_STATE_SHUTDOWN)) {
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error_set(errp, QERR_RESET_REQUIRED);
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return;
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@ -162,8 +163,12 @@ void qmp_cont(Error **errp)
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return;
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}
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if (runstate_check(RUN_STATE_INMIGRATE)) {
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autostart = 1;
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} else {
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vm_start();
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}
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}
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void qmp_system_wakeup(Error **errp)
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{
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