[Qemu-devel] [PATCH 6/7] Monitor: Don't allow cont on bad VM state

[Luiz Capitulino <lcapitulino@redhat.com>]

We have two states where issuing cont before system_reset can be
catastrophic: QSTATE_SHUTDOWN (when -no-shutdown is used) and
QSTATE_INTERROR (which only happen with kvm).

This commit fixes that by making system_reset mandatory before
issuing cont in those states.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
---
 cpus.c    |    4 ++++
 monitor.c |    8 ++++++++
 qerror.c  |    4 ++++
 qerror.h  |    3 +++
 sysemu.h  |    2 +-
 vl.c      |    1 +
 6 files changed, 21 insertions(+), 1 deletions(-)

diff --git a/cpus.c b/cpus.c
index 65ea503..a61e658 100644
--- a/cpus.c
+++ b/cpus.c
@@ -125,6 +125,10 @@ static void do_vm_stop(QemuState state)
         pause_all_vcpus();
         qemu_state_set(state);
         vm_state_notify(0, state);
+        if (state == QSTATE_INTERROR || state == QSTATE_SHUTDOWN) {
+            /* system_reset is required by 'cont' */
+            system_reset_required = 1;
+        }
         qemu_aio_flush();
         bdrv_flush_all();
         monitor_protocol_event(QEVENT_STOP, NULL);
diff --git a/monitor.c b/monitor.c
index 3fa2cf7..f1cb5af 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1312,7 +1312,14 @@ static int do_cont(Monitor *mon, const QDict *qdict, QObject **ret_data)
     if (qemu_state_get() == QSTATE_INMIGRATE) {
         qerror_report(QERR_MIGRATION_EXPECTED);
         return -1;
+    } else if (qemu_state_get() == QSTATE_INTERROR ||
+               qemu_state_get() == QSTATE_SHUTDOWN) {
+        if (system_reset_required) {
+            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) {
@@ -2014,6 +2021,7 @@ static int do_system_reset(Monitor *mon, const QDict *qdict,
                            QObject **ret_data)
 {
     qemu_system_reset_request();
+    system_reset_required = 0;
     return 0;
 }
 
diff --git a/qerror.c b/qerror.c
index 69c1bc9..0dd65a1 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/sysemu.h b/sysemu.h
index 46079ab..12a3f6a 100644
--- a/sysemu.h
+++ b/sysemu.h
@@ -30,7 +30,7 @@ typedef enum {
 } QemuState;
 
 extern const char *bios_name;
-
+extern int system_reset_required;
 extern const char *qemu_name;
 extern uint8_t qemu_uuid[];
 int qemu_uuid_parse(const char *str, uint8_t *uuid);
diff --git a/vl.c b/vl.c
index 65cf4a5..7fad355 100644
--- a/vl.c
+++ b/vl.c
@@ -183,6 +183,7 @@ int mem_prealloc = 0; /* force preallocation of physical target memory */
 #endif
 int nb_nics;
 NICInfo nd_table[MAX_NICS];
+int system_reset_required = 0;
 int autostart;
 static int rtc_utc = 1;
 static int rtc_date_offset = -1; /* -1 means no change */
-- 
1.7.6.396.ge0613