softmmu: Don't use 'singlestep' global in QMP and HMP commands

The HMP 'singlestep' command, the QMP 'query-status' command and the
HMP 'info status' command (which is just wrapping the QMP command
implementation) look at the 'singlestep' global variable. Make them
access the new TCG accelerator 'one-insn-per-tb' property instead.

This leaves the HMP and QMP command/field names and output strings
unchanged; we will clean that up later.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20230417164041.684562-3-peter.maydell@linaro.org

softmmu/runstate-hmp-cmds.c

@@ -20,6 +20,7 @@
 #include "qapi/error.h"
 #include "qapi/qapi-commands-run-state.h"
 #include "qapi/qmp/qdict.h"
+#include "qemu/accel.h"
 
 void hmp_info_status(Monitor *mon, const QDict *qdict)
 {
@@ -43,13 +44,26 @@ void hmp_info_status(Monitor *mon, const QDict *qdict)
 void hmp_singlestep(Monitor *mon, const QDict *qdict)
 {
     const char *option = qdict_get_try_str(qdict, "option");
+    AccelState *accel = current_accel();
+    bool newval;
+
+    if (!object_property_find(OBJECT(accel), "one-insn-per-tb")) {
+        monitor_printf(mon,
+                       "This accelerator does not support setting one-insn-per-tb\n");
+        return;
+    }
+
     if (!option || !strcmp(option, "on")) {
-        singlestep = 1;
+        newval = true;
     } else if (!strcmp(option, "off")) {
-        singlestep = 0;
+        newval = false;
     } else {
         monitor_printf(mon, "unexpected option %s\n", option);
+        return;
     }
+    /* If the property exists then setting it can never fail */
+    object_property_set_bool(OBJECT(accel), "one-insn-per-tb",
+                             newval, &error_abort);
 }
 
 void hmp_watchdog_action(Monitor *mon, const QDict *qdict)

softmmu/runstate.c

@@ -40,6 +40,7 @@
 #include "qapi/error.h"
 #include "qapi/qapi-commands-run-state.h"
 #include "qapi/qapi-events-run-state.h"
+#include "qemu/accel.h"
 #include "qemu/error-report.h"
 #include "qemu/job.h"
 #include "qemu/log.h"
@@ -234,9 +235,16 @@ bool runstate_needs_reset(void)
 StatusInfo *qmp_query_status(Error **errp)
 {
     StatusInfo *info = g_malloc0(sizeof(*info));
+    AccelState *accel = current_accel();
 
+    /*
+     * We ignore errors, which will happen if the accelerator
+     * is not TCG. "singlestep" is meaningless for other accelerators,
+     * so we will set the StatusInfo field to false for those.
+     */
+    info->singlestep = object_property_get_bool(OBJECT(accel),
+                                                "one-insn-per-tb", NULL);
     info->running = runstate_is_running();
-    info->singlestep = singlestep;
     info->status = current_run_state;
 
     return info;