[PATCH V1 05/32] savevm: QMP command for cprload

[Steve Sistare <steven.sistare@oracle.com>]

Provide the cprload QMP command.  The VM is created from the file produced
by the cprsave command.  Guest RAM is restored in-place from the shared
memory backend file, and guest block devices are used as is.  The contents
of such devices must not be modified between the cprsave and cprload
operations.  If the VM was running at cprsave time, then VM execution
resumes.

Syntax:
  {'command':'cprload', 'data':{'file':'str'}}

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Signed-off-by: Maran Wilson <maran.wilson@oracle.com>
---
 include/sysemu/sysemu.h |  2 ++
 migration/savevm.c      | 34 ++++++++++++++++++++++++++++++++++
 monitor/qmp-cmds.c      |  5 +++++
 qapi/migration.json     | 11 +++++++++++
 softmmu/vl.c            | 15 ++++++++++++++-
 5 files changed, 66 insertions(+), 1 deletion(-)

diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index 6fe86e6..5360da5 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -25,6 +25,7 @@ void qemu_add_machine_init_done_notifier(Notifier *notify);
 void qemu_remove_machine_init_done_notifier(Notifier *notify);
 
 void save_cpr_snapshot(const char *file, const char *mode, Error **errp);
+void load_cpr_snapshot(const char *file, Error **errp);
 
 extern int autostart;
 
@@ -53,6 +54,7 @@ extern uint8_t *boot_splash_filedata;
 extern bool enable_mlock;
 extern bool enable_cpu_pm;
 extern QEMUClockType rtc_clock;
+extern int start_on_wake;
 
 #define MAX_OPTION_ROMS 16
 typedef struct QEMUOptionRom {
diff --git a/migration/savevm.c b/migration/savevm.c
index ff1a46e..1509173 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2948,6 +2948,40 @@ void qmp_xen_load_devices_state(const char *filename, Error **errp)
     migration_incoming_state_destroy();
 }
 
+void load_cpr_snapshot(const char *file, Error **errp)
+{
+    QEMUFile *f;
+    int ret;
+    RunState state;
+
+    if (runstate_is_running()) {
+        error_setg(errp, "cprload called for a running VM");
+        return;
+    }
+
+    f = qf_file_open(file, O_RDONLY, 0, errp);
+    if (!f) {
+        return;
+    }
+
+    ret = qemu_loadvm_state(f, VMS_REBOOT);
+    qemu_fclose(f);
+    if (ret < 0) {
+        error_setg(errp, "Error %d while loading VM state", ret);
+        return;
+    }
+
+    state = global_state_get_runstate();
+    if (state == RUN_STATE_RUNNING) {
+        vm_start();
+    } else {
+        runstate_set(state);
+        if (runstate_check(RUN_STATE_SUSPENDED)) {
+            start_on_wake = 1;
+        }
+    }
+}
+
 int load_snapshot(const char *name, Error **errp)
 {
     BlockDriverState *bs, *bs_vm_state;
diff --git a/monitor/qmp-cmds.c b/monitor/qmp-cmds.c
index 9ec7b88..81e6feb 100644
--- a/monitor/qmp-cmds.c
+++ b/monitor/qmp-cmds.c
@@ -167,6 +167,11 @@ void qmp_cprsave(const char *file, const char *mode, Error **errp)
     save_cpr_snapshot(file, mode, errp);
 }
 
+void qmp_cprload(const char *file, Error **errp)
+{
+    load_cpr_snapshot(file, errp);
+}
+
 void qmp_system_wakeup(Error **errp)
 {
     if (!qemu_wakeup_suspend_enabled()) {
diff --git a/qapi/migration.json b/qapi/migration.json
index b61df1d..ce4d32b 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -1635,3 +1635,14 @@
 ##
 { 'command': 'cprsave', 'data': { 'file': 'str', 'mode': 'str' } }
 
+##
+# @cprload:
+#
+# Start virtual machine from checkpoint file that was created earlier using
+# the cprsave command.
+#
+# @file: name of checkpoint file
+#
+# Since 5.0
+##
+{ 'command': 'cprload', 'data': { 'file': 'str' } }
diff --git a/softmmu/vl.c b/softmmu/vl.c
index 660537a..8478778 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -137,6 +137,7 @@ static time_t rtc_ref_start_datetime;
 static int rtc_realtime_clock_offset; /* used only with QEMU_CLOCK_REALTIME */
 static int rtc_host_datetime_offset = -1; /* valid & used only with
                                              RTC_BASE_DATETIME */
+int start_on_wake;
 QEMUClockType rtc_clock;
 int vga_interface_type = VGA_NONE;
 static DisplayOptions dpy;
@@ -602,6 +603,8 @@ static const RunStateTransition runstate_transitions_def[] = {
     { RUN_STATE_PRELAUNCH, RUN_STATE_RUNNING },
     { RUN_STATE_PRELAUNCH, RUN_STATE_FINISH_MIGRATE },
     { RUN_STATE_PRELAUNCH, RUN_STATE_INMIGRATE },
+    { RUN_STATE_PRELAUNCH, RUN_STATE_SUSPENDED },
+    { RUN_STATE_PRELAUNCH, RUN_STATE_PAUSED },
 
     { RUN_STATE_FINISH_MIGRATE, RUN_STATE_RUNNING },
     { RUN_STATE_FINISH_MIGRATE, RUN_STATE_PAUSED },
@@ -1519,7 +1522,17 @@ void qemu_system_wakeup_request(WakeupReason reason, Error **errp)
     if (!(wakeup_reason_mask & (1 << reason))) {
         return;
     }
-    runstate_set(RUN_STATE_RUNNING);
+
+    /*
+     * Must call vm_start if it has never been called, to invoke the state
+     * change callbacks for the first time.
+     */
+    if (start_on_wake) {
+        start_on_wake = 0;
+        vm_start();
+    } else {
+        runstate_set(RUN_STATE_RUNNING);
+    }
     wakeup_reason = reason;
     qemu_notify_event();
 }
-- 
1.8.3.1