system/cpus: Add cpu_pause() function

This factors the CPU pause function from pause_all_vcpus() into a
new cpu_pause() function, similarly to cpu_resume(). cpu_resume()
is moved to keep it next to cpu_pause().

Cc: Philippe Mathieu-Daudé <philmd@linaro.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Message-ID: <20240712120247.477133-17-npiggin@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

include/hw/core/cpu.h

@@ -984,6 +984,14 @@ void cpu_reset_interrupt(CPUState *cpu, int mask);
  */
 void cpu_exit(CPUState *cpu);
 
+/**
+ * cpu_pause:
+ * @cpu: The CPU to pause.
+ *
+ * Pauses CPU, i.e. puts CPU into stopped state.
+ */
+void cpu_pause(CPUState *cpu);
+
 /**
  * cpu_resume:
  * @cpu: The CPU to resume.

system/cpus.c

@@ -568,6 +568,22 @@ void cpu_thread_signal_destroyed(CPUState *cpu)
     qemu_cond_signal(&qemu_cpu_cond);
 }
 
+void cpu_pause(CPUState *cpu)
+{
+    if (qemu_cpu_is_self(cpu)) {
+        qemu_cpu_stop(cpu, true);
+    } else {
+        cpu->stop = true;
+        qemu_cpu_kick(cpu);
+    }
+}
+
+void cpu_resume(CPUState *cpu)
+{
+    cpu->stop = false;
+    cpu->stopped = false;
+    qemu_cpu_kick(cpu);
+}
 
 static bool all_vcpus_paused(void)
 {
@@ -588,12 +604,7 @@ void pause_all_vcpus(void)
 
     qemu_clock_enable(QEMU_CLOCK_VIRTUAL, false);
     CPU_FOREACH(cpu) {
-        if (qemu_cpu_is_self(cpu)) {
-            qemu_cpu_stop(cpu, true);
-        } else {
-            cpu->stop = true;
-            qemu_cpu_kick(cpu);
-        }
+        cpu_pause(cpu);
     }
 
     /* We need to drop the replay_lock so any vCPU threads woken up
@@ -613,13 +624,6 @@ void pause_all_vcpus(void)
     bql_lock();
 }
 
-void cpu_resume(CPUState *cpu)
-{
-    cpu->stop = false;
-    cpu->stopped = false;
-    qemu_cpu_kick(cpu);
-}
-
 void resume_all_vcpus(void)
 {
     CPUState *cpu;