[PATCH V1 26/32] monitor: save/restore QMP negotiation status

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

From: Mark Kanda <mark.kanda@oracle.com>

Save and restore QMP compatibility negotiation status across cprsave and
cprload.

Signed-off-by: Mark Kanda <mark.kanda@oracle.com>
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 include/sysemu/sysemu.h |  1 +
 migration/savevm.c      |  1 +
 monitor/qmp.c           | 42 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 44 insertions(+)

diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index 3e7bfee..c5b2f24 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -30,6 +30,7 @@ void load_cpr_snapshot(const char *file, Error **errp);
 void save_chardev_fds(void);
 void save_vnc_fds(void);
 void load_vnc_fds(void);
+void save_qmp_negotiation_status(void);
 
 extern int autostart;
 
diff --git a/migration/savevm.c b/migration/savevm.c
index 35fafb7..225eaa6 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2770,6 +2770,7 @@ void save_cpr_snapshot(const char *file, const char *mode, Error **errp)
         save_chardev_fds();
         save_vnc_fds();
         walkenv(FD_PREFIX, preserve_fd, 0);
+        save_qmp_negotiation_status();
         qemu_system_exec_request();
         putenv((char *)"QEMU_START_FREEZE=");
     }
diff --git a/monitor/qmp.c b/monitor/qmp.c
index d433cea..9944ce5 100644
--- a/monitor/qmp.c
+++ b/monitor/qmp.c
@@ -33,6 +33,8 @@
 #include "qapi/qmp/qlist.h"
 #include "qapi/qmp/qstring.h"
 #include "trace.h"
+#include "qemu/env.h"
+#include "sysemu/sysemu.h"
 
 struct QMPRequest {
     /* Owner of the request */
@@ -398,6 +400,21 @@ static void monitor_qmp_setup_handlers_bh(void *opaque)
     monitor_list_append(&mon->common);
 }
 
+static void setenv_qmp(const char *name, bool val)
+{
+    setenv_bool(name, val);
+}
+
+static bool getenv_qmp(const char *name)
+{
+    bool ret = getenv_bool(name);
+    if (ret != -1) {
+        unsetenv_bool(name);
+        return ret;
+    }
+    return false;
+}
+
 void monitor_init_qmp(Chardev *chr, bool pretty, Error **errp)
 {
     MonitorQMP *mon = g_new0(MonitorQMP, 1);
@@ -438,4 +455,29 @@ void monitor_init_qmp(Chardev *chr, bool pretty, Error **errp)
                                  NULL, &mon->common, NULL, true);
         monitor_list_append(&mon->common);
     }
+
+    /*
+     * If a chr->label qmp env var is true, this is a restored qmp
+     * connection with capabilities negotiated.
+     */
+    if (getenv_qmp(chr->label) == true) {
+        mon->commands = &qmp_commands;
+    }
+}
+
+void save_qmp_negotiation_status(void)
+{
+    Monitor *mon;
+    MonitorQMP *qmp_mon;
+
+    QTAILQ_FOREACH(mon, &mon_list, entry) {
+        if (!monitor_is_qmp(mon)) {
+            continue;
+        }
+
+        qmp_mon = container_of(mon, MonitorQMP, common);
+        if (qmp_mon->commands == &qmp_commands) {
+            setenv_qmp(mon->chr.chr->label, true);
+        }
+    }
 }
-- 
1.8.3.1