[PATCH V7 07/12] migration: preserve suspended for snapshot
Restoring a snapshot can break a suspended guest. Snapshots suffer from
the same suspended-state issues that affect live migration, plus they must
handle an additional problematic scenario, which is that a running vm must
remain running if it loads a suspended snapshot.
To save, the existing vm_stop call now completely stops the suspended
state. Finish with vm_resume to leave the vm in the state it had prior
to the save, correctly restoring the suspended state.
To load, if the snapshot is not suspended, then vm_stop + vm_resume
correctly handles all states, and leaves the vm in the state it had prior
to the load. However, if the snapshot is suspended, restoration is
trickier. First, call vm_resume to restore the state to suspended so the
current state matches the saved state. Then, if the pre-load state is
running, call wakeup to resume running.
Prior to these changes, the vm_stop to RUN_STATE_SAVE_VM and
RUN_STATE_RESTORE_VM did not change runstate if the current state was
suspended, but now it does, so allow these transitions.
Signed-off-by: Steve Sistare
Reviewed-by: Peter Xu
---
include/migration/snapshot.h | 7 +++
migration/migration-hmp-cmds.c | 8 +---
migration/savevm.c | 23 +--
system/runstate.c | 5 +
system/vl.c| 2 ++
5 files changed, 32 insertions(+), 13 deletions(-)
diff --git a/include/migration/snapshot.h b/include/migration/snapshot.h
index e72083b..9e4dcaa 100644
--- a/include/migration/snapshot.h
+++ b/include/migration/snapshot.h
@@ -16,6 +16,7 @@
#define QEMU_MIGRATION_SNAPSHOT_H
#include "qapi/qapi-builtin-types.h"
+#include "qapi/qapi-types-run-state.h"
/**
* save_snapshot: Save an internal snapshot.
@@ -61,4 +62,10 @@ bool delete_snapshot(const char *name,
bool has_devices, strList *devices,
Error **errp);
+/**
+ * load_snapshot_resume: Restore runstate after loading snapshot.
+ * @state: state to restore
+ */
+void load_snapshot_resume(RunState state);
+
#endif
diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
index 86ae832..c8d70bc 100644
--- a/migration/migration-hmp-cmds.c
+++ b/migration/migration-hmp-cmds.c
@@ -399,15 +399,17 @@ void hmp_info_migrate_parameters(Monitor *mon, const
QDict *qdict)
void hmp_loadvm(Monitor *mon, const QDict *qdict)
{
-int saved_vm_running = runstate_is_running();
+RunState saved_state = runstate_get();
+
const char *name = qdict_get_str(qdict, "name");
Error *err = NULL;
vm_stop(RUN_STATE_RESTORE_VM);
-if (load_snapshot(name, NULL, false, NULL, ) && saved_vm_running) {
-vm_start();
+if (load_snapshot(name, NULL, false, NULL, )) {
+load_snapshot_resume(saved_state);
}
+
hmp_handle_error(mon, err);
}
diff --git a/migration/savevm.c b/migration/savevm.c
index eec5503..26866f0 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -3046,7 +3046,7 @@ bool save_snapshot(const char *name, bool overwrite,
const char *vmstate,
QEMUSnapshotInfo sn1, *sn =
int ret = -1, ret2;
QEMUFile *f;
-int saved_vm_running;
+RunState saved_state = runstate_get();
uint64_t vm_state_size;
g_autoptr(GDateTime) now = g_date_time_new_now_local();
AioContext *aio_context;
@@ -3094,8 +3094,6 @@ bool save_snapshot(const char *name, bool overwrite,
const char *vmstate,
}
aio_context = bdrv_get_aio_context(bs);
-saved_vm_running = runstate_is_running();
-
global_state_store();
vm_stop(RUN_STATE_SAVE_VM);
@@ -3163,9 +3161,7 @@ bool save_snapshot(const char *name, bool overwrite,
const char *vmstate,
bdrv_drain_all_end();
-if (saved_vm_running) {
-vm_start();
-}
+vm_resume(saved_state);
return ret == 0;
}
@@ -3339,6 +3335,14 @@ err_drain:
return false;
}
+void load_snapshot_resume(RunState state)
+{
+vm_resume(state);
+if (state == RUN_STATE_RUNNING && runstate_get() == RUN_STATE_SUSPENDED) {
+qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, _abort);
+}
+}
+
bool delete_snapshot(const char *name, bool has_devices,
strList *devices, Error **errp)
{
@@ -3403,16 +3407,15 @@ static void snapshot_load_job_bh(void *opaque)
{
Job *job = opaque;
SnapshotJob *s = container_of(job, SnapshotJob, common);
-int orig_vm_running;
+RunState orig_state = runstate_get();
job_progress_set_remaining(>common, 1);
-orig_vm_running = runstate_is_running();
vm_stop(RUN_STATE_RESTORE_VM);
s->ret = load_snapshot(s->tag, s->vmstate, true, s->devices, s->errp);
-if (s->ret && orig_vm_running) {
-vm_start();
+if (s->ret) {
+load_snapshot_resume(orig_state);
}
job_progress_update(>common, 1);
diff --git a/system/runstate.c b/system/runstate.c
index e2fa204..ca9eb54 100644
--- a/system/runstate.c
+++ b/system/runstate.c
@@
[PATCH V7 07/12] migration: preserve suspended for snapshot
Restoring a snapshot can break a suspended guest. Snapshots suffer from
the same suspended-state issues that affect live migration, plus they must
handle an additional problematic scenario, which is that a running vm must
remain running if it loads a suspended snapshot.
To save, the existing vm_stop call now completely stops the suspended
state. Finish with vm_resume to leave the vm in the state it had prior
to the save, correctly restoring the suspended state.
To load, if the snapshot is not suspended, then vm_stop + vm_resume
correctly handles all states, and leaves the vm in the state it had prior
to the load. However, if the snapshot is suspended, restoration is
trickier. First, call vm_resume to restore the state to suspended so the
current state matches the saved state. Then, if the pre-load state is
running, call wakeup to resume running.
Prior to these changes, the vm_stop to RUN_STATE_SAVE_VM and
RUN_STATE_RESTORE_VM did not change runstate if the current state was
suspended, but now it does, so allow these transitions.
Signed-off-by: Steve Sistare
Reviewed-by: Peter Xu
---
include/migration/snapshot.h | 7 +++
migration/migration-hmp-cmds.c | 8 +---
migration/savevm.c | 23 +--
system/runstate.c | 5 +
system/vl.c| 2 ++
5 files changed, 32 insertions(+), 13 deletions(-)
diff --git a/include/migration/snapshot.h b/include/migration/snapshot.h
index e72083b..9e4dcaa 100644
--- a/include/migration/snapshot.h
+++ b/include/migration/snapshot.h
@@ -16,6 +16,7 @@
#define QEMU_MIGRATION_SNAPSHOT_H
#include "qapi/qapi-builtin-types.h"
+#include "qapi/qapi-types-run-state.h"
/**
* save_snapshot: Save an internal snapshot.
@@ -61,4 +62,10 @@ bool delete_snapshot(const char *name,
bool has_devices, strList *devices,
Error **errp);
+/**
+ * load_snapshot_resume: Restore runstate after loading snapshot.
+ * @state: state to restore
+ */
+void load_snapshot_resume(RunState state);
+
#endif
diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
index 86ae832..c8d70bc 100644
--- a/migration/migration-hmp-cmds.c
+++ b/migration/migration-hmp-cmds.c
@@ -399,15 +399,17 @@ void hmp_info_migrate_parameters(Monitor *mon, const
QDict *qdict)
void hmp_loadvm(Monitor *mon, const QDict *qdict)
{
-int saved_vm_running = runstate_is_running();
+RunState saved_state = runstate_get();
+
const char *name = qdict_get_str(qdict, "name");
Error *err = NULL;
vm_stop(RUN_STATE_RESTORE_VM);
-if (load_snapshot(name, NULL, false, NULL, ) && saved_vm_running) {
-vm_start();
+if (load_snapshot(name, NULL, false, NULL, )) {
+load_snapshot_resume(saved_state);
}
+
hmp_handle_error(mon, err);
}
diff --git a/migration/savevm.c b/migration/savevm.c
index eec5503..26866f0 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -3046,7 +3046,7 @@ bool save_snapshot(const char *name, bool overwrite,
const char *vmstate,
QEMUSnapshotInfo sn1, *sn =
int ret = -1, ret2;
QEMUFile *f;
-int saved_vm_running;
+RunState saved_state = runstate_get();
uint64_t vm_state_size;
g_autoptr(GDateTime) now = g_date_time_new_now_local();
AioContext *aio_context;
@@ -3094,8 +3094,6 @@ bool save_snapshot(const char *name, bool overwrite,
const char *vmstate,
}
aio_context = bdrv_get_aio_context(bs);
-saved_vm_running = runstate_is_running();
-
global_state_store();
vm_stop(RUN_STATE_SAVE_VM);
@@ -3163,9 +3161,7 @@ bool save_snapshot(const char *name, bool overwrite,
const char *vmstate,
bdrv_drain_all_end();
-if (saved_vm_running) {
-vm_start();
-}
+vm_resume(saved_state);
return ret == 0;
}
@@ -3339,6 +3335,14 @@ err_drain:
return false;
}
+void load_snapshot_resume(RunState state)
+{
+vm_resume(state);
+if (state == RUN_STATE_RUNNING && runstate_get() == RUN_STATE_SUSPENDED) {
+qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, _abort);
+}
+}
+
bool delete_snapshot(const char *name, bool has_devices,
strList *devices, Error **errp)
{
@@ -3403,16 +3407,15 @@ static void snapshot_load_job_bh(void *opaque)
{
Job *job = opaque;
SnapshotJob *s = container_of(job, SnapshotJob, common);
-int orig_vm_running;
+RunState orig_state = runstate_get();
job_progress_set_remaining(>common, 1);
-orig_vm_running = runstate_is_running();
vm_stop(RUN_STATE_RESTORE_VM);
s->ret = load_snapshot(s->tag, s->vmstate, true, s->devices, s->errp);
-if (s->ret && orig_vm_running) {
-vm_start();
+if (s->ret) {
+load_snapshot_resume(orig_state);
}
job_progress_update(>common, 1);
diff --git a/system/runstate.c b/system/runstate.c
index e2fa204..ca9eb54 100644
--- a/system/runstate.c
+++ b/system/runstate.c
@@
