Redirect cpu_interrupt to callback handler

This allows to override the interrupt handling of QEMU in system mode.
KVM will make use of it to set a specialized handler.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/cpu-all.h b/cpu-all.h
index 0bae6df..88126ea 100644
--- a/cpu-all.h
+++ b/cpu-all.h
@@ -799,7 +799,19 @@
 #define CPU_INTERRUPT_SIPI   0x800 /* SIPI pending. */
 #define CPU_INTERRUPT_MCE    0x1000 /* (x86 only) MCE pending. */
 
-void cpu_interrupt(CPUState *s, int mask);
+#ifndef CONFIG_USER_ONLY
+typedef void (*CPUInterruptHandler)(CPUState *, int);
+
+extern CPUInterruptHandler cpu_interrupt_handler;
+
+static inline void cpu_interrupt(CPUState *s, int mask)
+{
+    cpu_interrupt_handler(s, mask);
+}
+#else /* USER_ONLY */
+void cpu_interrupt(CPUState *env, int mask);
+#endif /* USER_ONLY */
+
 void cpu_reset_interrupt(CPUState *env, int mask);
 
 void cpu_exit(CPUState *s);