[PATCH V6 2/4 resend] nmi: make cpu-index argument optional

[Lai Jiangshan <laijs@cn.fujitsu.com>]

When the argument "cpu-index" is not given,
then "nmi" command will inject NMI on all CPUs.

This simulate the nmi button on physical machine.

Note: it will allow non-argument "nmi" command and
      change the human monitor behavior.

Thanks to Markus Armbruster for correcting the logic
detecting "cpu-index" is given or not.

Signed-off-by:  Lai Jiangshan <laijs@cn.fujitsu.com>
---
diff --git a/hmp-commands.hx b/hmp-commands.hx
index e43ac7c..ec1a4db 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -721,9 +721,10 @@ ETEXI
 #if defined(TARGET_I386)
     {
         .name       = "nmi",
-        .args_type  = "cpu-index:i",
-        .params     = "cpu",
-        .help       = "inject an NMI on the given CPU",
+        .args_type  = "cpu-index:i?",
+        .params     = "[cpu]",
+        .help       = "Inject an NMI on all CPUs if no argument is given, "
+                      "otherwise inject it on the specified CPU",
         .mhandler.cmd = do_inject_nmi,
     },
 #endif
diff --git a/monitor.c b/monitor.c
index a916771..387b020 100644
--- a/monitor.c
+++ b/monitor.c
@@ -2545,8 +2545,15 @@ static void do_wav_capture(Monitor *mon, const QDict *qdict)
 static void do_inject_nmi(Monitor *mon, const QDict *qdict)
 {
     CPUState *env;
-    int cpu_index = qdict_get_int(qdict, "cpu-index");
+    int cpu_index;
 
+    if (!qdict_haskey(qdict, "cpu-index")) {
+        for (env = first_cpu; env != NULL; env = env->next_cpu)
+            cpu_interrupt(env, CPU_INTERRUPT_NMI);
+        return;
+    }
+
+    cpu_index = qdict_get_int(qdict, "cpu-index");
     for (env = first_cpu; env != NULL; env = env->next_cpu)
         if (env->cpu_index == cpu_index) {
             if (kvm_enabled())