[Qemu-devel] [PATCH 7/9] Monitor/QMP: Don't allow cont on bad VM state

[Luiz Capitulino <lcapitulino@redhat.com>]

We have two states where issuing cont before system_reset can
cause problems: RSTATE_SHUTDOWN (when -no-shutdown is used) and
RSTATE_PANICKED (which only happens with kvm).

This commit fixes that by doing the following when state is
RSTATE_SHUTDOWN or RSTATE_PANICKED:

 1. returning an error to the user/client if cont is issued
 2. automatically transition to RSTATE_PAUSED during system_reset

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
---
 monitor.c |    5 +++++
 qerror.c  |    4 ++++
 qerror.h  |    3 +++
 vl.c      |    4 ++++
 4 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/monitor.c b/monitor.c
index 10cab1d..6e5bb56 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1314,7 +1314,12 @@ static int do_cont(Monitor *mon, const QDict *qdict, QObject **ret_data)
     if (runstate_check(RSTATE_IN_MIGRATE)) {
         qerror_report(QERR_MIGRATION_EXPECTED);
         return -1;
+    } else if (runstate_check(RSTATE_PANICKED) ||
+               runstate_check(RSTATE_SHUTDOWN)) {
+        qerror_report(QERR_RESET_REQUIRED);
+        return -1;
     }
+
     bdrv_iterate(encrypted_bdrv_it, &context);
     /* only resume the vm if all keys are set and valid */
     if (!context.err) {
diff --git a/qerror.c b/qerror.c
index 3d64b80..c591a54 100644
--- a/qerror.c
+++ b/qerror.c
@@ -194,6 +194,10 @@ static const QErrorStringTable qerror_table[] = {
         .desc      = "QMP input object member '%(member)' is unexpected",
     },
     {
+        .error_fmt = QERR_RESET_REQUIRED,
+        .desc      = "Resetting the Virtual Machine is required",
+    },
+    {
         .error_fmt = QERR_SET_PASSWD_FAILED,
         .desc      = "Could not set password",
     },
diff --git a/qerror.h b/qerror.h
index 8058456..d407001 100644
--- a/qerror.h
+++ b/qerror.h
@@ -163,6 +163,9 @@ QError *qobject_to_qerror(const QObject *obj);
 #define QERR_QMP_EXTRA_MEMBER \
     "{ 'class': 'QMPExtraInputObjectMember', 'data': { 'member': %s } }"
 
+#define QERR_RESET_REQUIRED \
+    "{ 'class': 'ResetRequired', 'data': {} }"
+
 #define QERR_SET_PASSWD_FAILED \
     "{ 'class': 'SetPasswdFailed', 'data': {} }"
 
diff --git a/vl.c b/vl.c
index b1f3352..917c348 100644
--- a/vl.c
+++ b/vl.c
@@ -1650,6 +1650,10 @@ static void main_loop(void)
             cpu_synchronize_all_states();
             qemu_system_reset(VMRESET_REPORT);
             resume_all_vcpus();
+            if (runstate_check(RSTATE_PANICKED) ||
+                runstate_check(RSTATE_SHUTDOWN)) {
+                runstate_set(RSTATE_PAUSED);
+            }
         }
         if (qemu_powerdown_requested()) {
             monitor_protocol_event(QEVENT_POWERDOWN, NULL);
-- 
1.7.7.rc0.72.g4b5ea