qmp hmp: Make system_wakeup check wake-up support and run state

The qmp/hmp command 'system_wakeup' is simply a direct call to
'qemu_system_wakeup_request' from vl.c. This function verifies if
runstate is SUSPENDED and if the wake up reason is valid before
proceeding. However, no error or warning is thrown if any of those
pre-requirements isn't met. There is no way for the caller to
differentiate between a successful wakeup or an error state caused
when trying to wake up a guest that wasn't suspended.

This means that system_wakeup is silently failing, which can be
considered a bug. Adding error handling isn't an API break in this
case - applications that didn't check the result will remain broken,
the ones that check it will have a chance to deal with it.

Adding to that, the commit before previous created a new QMP API called
query-current-machine, with a new flag called wakeup-suspend-support,
that indicates if the guest has the capability of waking up from suspended
state. Although such guest will never reach SUSPENDED state and erroring
it out in this scenario would suffice, it is more informative for the user
to differentiate between a failure because the guest isn't suspended versus
a failure because the guest does not have support for wake up at all.

All this considered, this patch changes qmp_system_wakeup to check if
the guest is capable of waking up from suspend, and if it is suspended.
After this patch, this is the output of system_wakeup in a guest that
does not have wake-up from suspend support (ppc64):

(qemu) system_wakeup
wake-up from suspend is not supported by this guest
(qemu)

And this is the output of system_wakeup in a x86 guest that has the
support but isn't suspended:

(qemu) system_wakeup
Unable to wake up: guest is not in suspended state
(qemu)

Reported-by: Balamuruhan S <bala24@linux.vnet.ibm.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20181205194701.17836-4-danielhb413@gmail.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Acked-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

diff --git a/hmp.c b/hmp.c
index 43ae9ec61a0c55194987751ded3a001603358eb4..80aa5ab504be41b2252c5b6d89c53835a66e9f6d 100644 (file)
--- a/hmp.c
+++ b/hmp.c
@@ -1220,7 +1220,10 @@ void hmp_cont(Monitor *mon, const QDict *qdict)
 
 void hmp_system_wakeup(Monitor *mon, const QDict *qdict)
 {
-    qmp_system_wakeup(NULL);
+    Error *err = NULL;
+
+    qmp_system_wakeup(&err);
+    hmp_handle_error(mon, &err);
 }
 
 void hmp_nmi(Monitor *mon, const QDict *qdict)

diff --git a/hw/acpi/core.c b/hw/acpi/core.c
index 52e18d781038913c7917d61140b357380ce9f999..d6f07096915b4addca47a20437230553de3a8dae 100644 (file)
--- a/hw/acpi/core.c
+++ b/hw/acpi/core.c
@@ -514,7 +514,8 @@ static uint32_t acpi_pm_tmr_get(ACPIREGS *ar)
 static void acpi_pm_tmr_timer(void *opaque)
 {
     ACPIREGS *ar = opaque;
-    qemu_system_wakeup_request(QEMU_WAKEUP_REASON_PMTIMER);
+
+    qemu_system_wakeup_request(QEMU_WAKEUP_REASON_PMTIMER, NULL);
     ar->tmr.update_sci(ar);
 }
 

diff --git a/hw/char/serial.c b/hw/char/serial.c
index 02463e338821807d150b4fdbc32c90c0618f7d29..7c42a2abfc18328cf0f45ffbf6bd402661917fbb 100644 (file)
--- a/hw/char/serial.c
+++ b/hw/char/serial.c
@@ -611,7 +611,7 @@ static void serial_receive1(void *opaque, const uint8_t *buf, int size)
     SerialState *s = opaque;
 
     if (s->wakeup) {
-        qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
+        qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, NULL);
     }
     if(s->fcr & UART_FCR_FE) {
         int i;

diff --git a/hw/input/ps2.c b/hw/input/ps2.c
index eb33ee9b6f0d294e8f165e1550dca8366707ba5c..d3161f1e7c392216014e8ac59fafb55b8f569213 100644 (file)
--- a/hw/input/ps2.c
+++ b/hw/input/ps2.c
@@ -255,7 +255,7 @@ static void ps2_put_keycode(void *opaque, int keycode)
     PS2KbdState *s = opaque;
 
     trace_ps2_put_keycode(opaque, keycode);
-    qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
+    qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, NULL);
 
     if (s->translate) {
         if (keycode == 0xf0) {
@@ -285,7 +285,7 @@ static void ps2_keyboard_event(DeviceState *dev, QemuConsole *src,
         return;
     }
 
-    qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
+    qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, NULL);
     assert(evt->type == INPUT_EVENT_KIND_KEY);
     qcode = qemu_input_key_value_to_qcode(key->key);
 
@@ -748,7 +748,7 @@ static void ps2_mouse_sync(DeviceState *dev)
     }
 
     if (s->mouse_buttons) {
-        qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
+        qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, NULL);
     }
     if (!(s->mouse_status & MOUSE_STATUS_REMOTE)) {
         /* if not remote, send event. Multiple events are sent if

diff --git a/hw/timer/mc146818rtc.c b/hw/timer/mc146818rtc.c
index e4e4de8b8ab58da0d32d56ea56389a0455a7cda0..69483152c3966202026f623aed9a6eaababf57ed 100644 (file)
--- a/hw/timer/mc146818rtc.c
+++ b/hw/timer/mc146818rtc.c
@@ -455,7 +455,7 @@ static void rtc_update_timer(void *opaque)
     if (qemu_clock_get_ns(rtc_clock) >= s->next_alarm_time) {
         irqs |= REG_C_AF;
         if (s->cmos_data[RTC_REG_B] & REG_B_AIE) {
-            qemu_system_wakeup_request(QEMU_WAKEUP_REASON_RTC);
+            qemu_system_wakeup_request(QEMU_WAKEUP_REASON_RTC, NULL);
         }
     }
 

diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index d9cabb34bdfe78d506b218b25e7385df892d2b32..c8efdeb376c5edea022094ca65d05d8c88c1e01f 100644 (file)
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -54,7 +54,8 @@ void qemu_exit_preconfig_request(void);
 void qemu_system_reset_request(ShutdownCause reason);
 void qemu_system_suspend_request(void);
 void qemu_register_suspend_notifier(Notifier *notifier);
-void qemu_system_wakeup_request(WakeupReason reason);
+bool qemu_wakeup_suspend_enabled(void);
+void qemu_system_wakeup_request(WakeupReason reason, Error **errp);
 void qemu_system_wakeup_enable(WakeupReason reason, bool enabled);
 void qemu_register_wakeup_notifier(Notifier *notifier);
 void qemu_register_wakeup_support(void);

diff --git a/migration/migration.c b/migration/migration.c
index 49ffb9997a3de3d67be6cb07071e4387726d95ca..ffc4d9e556f8774b5e3972ff59cc8a66145f951a 100644 (file)
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2408,7 +2408,7 @@ static int postcopy_start(MigrationState *ms)
     qemu_mutex_lock_iothread();
     trace_postcopy_start_set_run();
 
-    qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
+    qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, NULL);
     global_state_store();
     ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
     if (ret < 0) {
@@ -2612,7 +2612,7 @@ static void migration_completion(MigrationState *s)
     if (s->state == MIGRATION_STATUS_ACTIVE) {
         qemu_mutex_lock_iothread();
         s->downtime_start = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
-        qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
+        qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, NULL);
         s->vm_was_running = runstate_is_running();
         ret = global_state_store();
 

diff --git a/qapi/misc.json b/qapi/misc.json
index c4696ef150008c2555389ad4fe1b546cbcc70b24..24d20a880a15ec43938646eb0f93c58480f030a0 100644 (file)
--- a/qapi/misc.json
+++ b/qapi/misc.json
@@ -1239,12 +1239,18 @@
 ##
 # @system_wakeup:
 #
-# Wakeup guest from suspend.  Does nothing in case the guest isn't suspended.
+# Wake up guest from suspend. If the guest has wake-up from suspend
+# support enabled (wakeup-suspend-support flag from
+# query-current-machine), wake-up guest from suspend if the guest is
+# in SUSPENDED state. Return an error otherwise.
 #
 # Since:  1.1
 #
 # Returns:  nothing.
 #
+# Note: prior to 4.0, this command does nothing in case the guest
+# isn't suspended.
+#
 # Example:
 #
 # -> { "execute": "system_wakeup" }

diff --git a/qmp.c b/qmp.c
index 82298f6cb089107899be800c2755a30f157a3eef..4c819dd8cfdd23234874fae3d457f4d4e7fac1e7 100644 (file)
--- a/qmp.c
+++ b/qmp.c
@@ -183,7 +183,13 @@ void qmp_cont(Error **errp)
 
 void qmp_system_wakeup(Error **errp)
 {
-    qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
+    if (!qemu_wakeup_suspend_enabled()) {
+        error_setg(errp,
+                   "wake-up from suspend is not supported by this guest");
+        return;
+    }
+
+    qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, errp);
 }
 
 ObjectPropertyInfoList *qmp_qom_list(const char *path, Error **errp)

diff --git a/vl.c b/vl.c
index 2bd869580fbf0d5d07467943bb4f6d80b45a1f2f..9dbba36ad3ec2f95935bf4685320aa5b1551734c 100644 (file)
--- a/vl.c
+++ b/vl.c
@@ -1752,11 +1752,13 @@ void qemu_register_suspend_notifier(Notifier *notifier)
     notifier_list_add(&suspend_notifiers, notifier);
 }
 
-void qemu_system_wakeup_request(WakeupReason reason)
+void qemu_system_wakeup_request(WakeupReason reason, Error **errp)
 {
     trace_system_wakeup_request(reason);
 
     if (!runstate_check(RUN_STATE_SUSPENDED)) {
+        error_setg(errp,
+                   "Unable to wake up: guest is not in suspended state");
         return;
     }
     if (!(wakeup_reason_mask & (1 << reason))) {
@@ -1786,7 +1788,7 @@ void qemu_register_wakeup_support(void)
     wakeup_suspend_enabled = true;
 }
 
-static bool qemu_wakeup_suspend_enabled(void)
+bool qemu_wakeup_suspend_enabled(void)
 {
     return wakeup_suspend_enabled;
 }