[libvirt] [PATCH v2 1/1] qemu: hide details of fake reboot
Nikolay Shirokovskiy
nshirokovskiy at virtuozzo.com
Thu Dec 19 10:50:19 UTC 2019
If we use fake reboot then domain goes thru running->shutdown->running
state changes with shutdown state only for short period of time. At
least this is implementation details leaking into API. And also there is
one real case when this is not convinient. I'm doing a backup with the
help of temporary block snapshot (with the help of qemu's API which is
used in the newly created libvirt's backup API). If guest is shutdowned
I want to continue to backup so I don't kill the process and domain is
in shutdown state. Later when backup is finished I want to destroy qemu
process. So I check if it is in shutdowned state and destroy it if it
is. Now if instead of shutdown domain got fake reboot then I can destroy
process in the middle of fake reboot process.
After shutdown event we also get stop event and now as domain state is
running it will be transitioned to paused state and back to running
later. Though this is not critical for the described case I guess it is
better not to leak these details to user too. So let's leave domain in
running state on stop event if fake reboot is in process.
Reconnection code handles this patch without modification. It detects
that qemu is not running due to shutdown and then calls qemuProcessShutdownOrReboot
which reboots as fake reboot flag is set.
Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy at virtuozzo.com>
---
Changes from v1[1]:
- rebase on current master
- add comments
- use special flag to check if we should go paused or not*
- add notes about reconnection to commit message
* Using just fake reboot flag is not reliable. What if ACPI shutdown is
ignored by guest? Reboot flag will remain set and now domain state
will remain running on plain pause.
[1] https://www.redhat.com/archives/libvir-list/2019-October/msg01827.html
src/qemu/qemu_domain.h | 1 +
src/qemu/qemu_process.c | 61 ++++++++++++++++++++++++-----------------
2 files changed, 37 insertions(+), 25 deletions(-)
diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index a32852047c..a39b9546ae 100644
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -319,6 +319,7 @@ struct _qemuDomainObjPrivate {
char *lockState;
bool fakeReboot;
+ bool pausedShutdown;
virTristateBool allowReboot;
int jobs_queued;
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 7e1db50e8f..3e5fe3b6de 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -505,6 +505,7 @@ qemuProcessFakeReboot(void *opaque)
qemuDomainObjEndJob(driver, vm);
cleanup:
+ priv->pausedShutdown = false;
if (ret == -1)
ignore_value(qemuProcessKill(vm, VIR_QEMU_PROCESS_KILL_FORCE));
virDomainObjEndAPI(&vm);
@@ -528,6 +529,7 @@ qemuProcessShutdownOrReboot(virQEMUDriverPtr driver,
vm) < 0) {
VIR_ERROR(_("Failed to create reboot thread, killing domain"));
ignore_value(qemuProcessKill(vm, VIR_QEMU_PROCESS_KILL_NOWAIT));
+ priv->pausedShutdown = false;
virObjectUnref(vm);
}
} else {
@@ -589,35 +591,41 @@ qemuProcessHandleShutdown(qemuMonitorPtr mon G_GNUC_UNUSED,
goto unlock;
}
- VIR_DEBUG("Transitioned guest %s to shutdown state",
- vm->def->name);
- virDomainObjSetState(vm,
- VIR_DOMAIN_SHUTDOWN,
- VIR_DOMAIN_SHUTDOWN_UNKNOWN);
+ /* In case of fake reboot qemu shutdown state is transient so don't
+ * change domain state nor send events. */
+ if (!priv->fakeReboot) {
+ VIR_DEBUG("Transitioned guest %s to shutdown state",
+ vm->def->name);
+ virDomainObjSetState(vm,
+ VIR_DOMAIN_SHUTDOWN,
+ VIR_DOMAIN_SHUTDOWN_UNKNOWN);
- switch (guest_initiated) {
- case VIR_TRISTATE_BOOL_YES:
- detail = VIR_DOMAIN_EVENT_SHUTDOWN_GUEST;
- break;
+ switch (guest_initiated) {
+ case VIR_TRISTATE_BOOL_YES:
+ detail = VIR_DOMAIN_EVENT_SHUTDOWN_GUEST;
+ break;
- case VIR_TRISTATE_BOOL_NO:
- detail = VIR_DOMAIN_EVENT_SHUTDOWN_HOST;
- break;
+ case VIR_TRISTATE_BOOL_NO:
+ detail = VIR_DOMAIN_EVENT_SHUTDOWN_HOST;
+ break;
- case VIR_TRISTATE_BOOL_ABSENT:
- case VIR_TRISTATE_BOOL_LAST:
- default:
- detail = VIR_DOMAIN_EVENT_SHUTDOWN_FINISHED;
- break;
- }
+ case VIR_TRISTATE_BOOL_ABSENT:
+ case VIR_TRISTATE_BOOL_LAST:
+ default:
+ detail = VIR_DOMAIN_EVENT_SHUTDOWN_FINISHED;
+ break;
+ }
- event = virDomainEventLifecycleNewFromObj(vm,
- VIR_DOMAIN_EVENT_SHUTDOWN,
- detail);
+ event = virDomainEventLifecycleNewFromObj(vm,
+ VIR_DOMAIN_EVENT_SHUTDOWN,
+ detail);
- if (virDomainObjSave(vm, driver->xmlopt, cfg->stateDir) < 0) {
- VIR_WARN("Unable to save status on vm %s after state change",
- vm->def->name);
+ if (virDomainObjSave(vm, driver->xmlopt, cfg->stateDir) < 0) {
+ VIR_WARN("Unable to save status on vm %s after state change",
+ vm->def->name);
+ }
+ } else {
+ priv->pausedShutdown = true;
}
if (priv->agent)
@@ -651,7 +659,10 @@ qemuProcessHandleStop(qemuMonitorPtr mon G_GNUC_UNUSED,
reason = priv->pausedReason;
priv->pausedReason = VIR_DOMAIN_PAUSED_UNKNOWN;
- if (virDomainObjGetState(vm, NULL) == VIR_DOMAIN_RUNNING) {
+ /* In case of fake reboot qemu paused state is transient so don't
+ * reveal it in domain state nor sent events */
+ if (virDomainObjGetState(vm, NULL) == VIR_DOMAIN_RUNNING &&
+ !priv->pausedShutdown) {
if (priv->job.asyncJob == QEMU_ASYNC_JOB_MIGRATION_OUT) {
if (priv->job.current->status == QEMU_DOMAIN_JOB_STATUS_POSTCOPY)
reason = VIR_DOMAIN_PAUSED_POSTCOPY;
--
2.23.0
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