vl: Add an -action option specifying response to guest events

Several command line options currently in use are meant to modify
the behavior of QEMU in response to certain guest events like:
-no-reboot, -no-shutdown, -watchdog-action.

These can be grouped into a single option of the form:

-action event=action

Which can be used to specify the existing options above in the
following format:

-action reboot=none|shutdown
-action shutdown=poweroff|pause
-action watchdog=reset|shutdown|poweroff|pause|debug|none|inject-nmi

This is done in preparation for adding yet another option of this
type, which modifies the QEMU behavior when a guest panic occurs.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Message-Id: <1607705564-26264-2-git-send-email-alejandro.j.jimenez@oracle.com>
[Use QemuOpts help support, invoke QMP command. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

qemu-options.hx

@@ -3894,6 +3894,28 @@ SRST
     changes to the disk image.
 ERST
 
+DEF("action", HAS_ARG, QEMU_OPTION_action,
+    "-action reboot=none|shutdown\n"
+    "                   action when guest reboots [default=none]\n"
+    "-action shutdown=poweroff|pause\n"
+    "                   action when guest shuts down [default=poweroff]\n"
+    "-action watchdog=reset|shutdown|poweroff|inject-nmi|pause|debug|none\n"
+    "                   action when watchdog fires [default=reset]\n",
+    QEMU_ARCH_ALL)
+SRST
+``-action event=action``
+    The action parameter serves to modify QEMU's default behavior when
+    certain guest events occur. It provides a generic method for specifying the
+    same behaviors that are modified by the ``-no-reboot`` and ``-no-shutdown``
+    parameters.
+
+    Examples:
+
+    ``-action reboot=shutdown,shutdown=pause``
+    ``-watchdog i6300esb -action watchdog=pause``
+
+ERST
+
 DEF("loadvm", HAS_ARG, QEMU_OPTION_loadvm, \
     "-loadvm [tag|id]\n" \
     "                start right away with a saved state (loadvm in monitor)\n",

softmmu/vl.c

@@ -30,6 +30,7 @@
 #include "hw/boards.h"
 #include "hw/qdev-properties.h"
 #include "qapi/error.h"
+#include "qapi/qmp/qdict.h"
 #include "qemu-version.h"
 #include "qemu/cutils.h"
 #include "qemu/help_option.h"
@@ -477,6 +478,25 @@ static QemuOptsList qemu_fw_cfg_opts = {
     },
 };
 
+static QemuOptsList qemu_action_opts = {
+    .name = "action",
+    .merge_lists = true,
+    .head = QTAILQ_HEAD_INITIALIZER(qemu_action_opts.head),
+    .desc = {
+        {
+            .name = "shutdown",
+            .type = QEMU_OPT_STRING,
+        },{
+            .name = "reboot",
+            .type = QEMU_OPT_STRING,
+        },{
+            .name = "watchdog",
+            .type = QEMU_OPT_STRING,
+        },
+        { /* end of list */ }
+    },
+};
+
 /**
  * Get machine options
  *
@@ -2298,6 +2318,26 @@ static void qemu_process_sugar_options(void)
     }
 }
 
+/* -action processing */
+
+/*
+ * Process all the -action parameters parsed from cmdline.
+ */
+static int process_runstate_actions(void *opaque, QemuOpts *opts, Error **errp)
+{
+    Error *local_err = NULL;
+    QDict *qdict = qemu_opts_to_qdict(opts, NULL);
+    QObject *ret = NULL;
+    qmp_marshal_set_action(qdict, &ret, &local_err);
+    qobject_unref(ret);
+    qobject_unref(qdict);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return 1;
+    }
+    return 0;
+}
+
 static void qemu_process_early_options(void)
 {
 #ifdef CONFIG_SECCOMP
@@ -2310,6 +2350,11 @@ static void qemu_process_early_options(void)
     qemu_opts_foreach(qemu_find_opts("name"),
                       parse_name, NULL, &error_fatal);
 
+    if (qemu_opts_foreach(qemu_find_opts("action"),
+                          process_runstate_actions, NULL, &error_fatal)) {
+        exit(1);
+    }
+
 #ifndef _WIN32
     qemu_opts_foreach(qemu_find_opts("add-fd"),
                       parse_add_fd, NULL, &error_fatal);
@@ -2560,6 +2605,7 @@ void qemu_init(int argc, char **argv, char **envp)
     qemu_add_opts(&qemu_icount_opts);
     qemu_add_opts(&qemu_semihosting_config_opts);
     qemu_add_opts(&qemu_fw_cfg_opts);
+    qemu_add_opts(&qemu_action_opts);
     module_call_init(MODULE_INIT_OPTS);
 
     error_init(argv[0]);
@@ -3010,6 +3056,12 @@ void qemu_init(int argc, char **argv, char **envp)
                 }
                 watchdog = optarg;
                 break;
+            case QEMU_OPTION_action:
+                olist = qemu_find_opts("action");
+                if (!qemu_opts_parse_noisily(olist, optarg, false)) {
+                     exit(1);
+                }
+                break;
             case QEMU_OPTION_watchdog_action:
                 if (select_watchdog_action(optarg) == -1) {
                     error_report("unknown -watchdog-action parameter");
@@ -3155,10 +3207,12 @@ void qemu_init(int argc, char **argv, char **envp)
                 qemu_opts_parse_noisily(olist, "hpet=off", false);
                 break;
             case QEMU_OPTION_no_reboot:
-                reboot_action = REBOOT_ACTION_SHUTDOWN;
+                olist = qemu_find_opts("action");
+                qemu_opts_parse_noisily(olist, "reboot=shutdown", false);
                 break;
             case QEMU_OPTION_no_shutdown:
-                shutdown_action = SHUTDOWN_ACTION_PAUSE;
+                olist = qemu_find_opts("action");
+                qemu_opts_parse_noisily(olist, "shutdown=pause", false);
                 break;
             case QEMU_OPTION_show_cursor:
                 warn_report("The -show-cursor option is deprecated. Please "