qom: Add cpu_exec_enter and cpu_exec_exit hooks

In preparation for removing a bunch of ifdefs from cpu_exec.

Cc: Andreas Färber <afaerber@suse.de>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 1410626734-3804-2-git-send-email-rth@twiddle.net
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

cpu-exec.c

@@ -317,10 +317,7 @@ volatile sig_atomic_t exit_request;
 int cpu_exec(CPUArchState *env)
 {
     CPUState *cpu = ENV_GET_CPU(env);
-#if !(defined(CONFIG_USER_ONLY) && \
-      (defined(TARGET_M68K) || defined(TARGET_PPC) || defined(TARGET_S390X)))
     CPUClass *cc = CPU_GET_CLASS(cpu);
-#endif
 #ifdef TARGET_I386
     X86CPU *x86_cpu = X86_CPU(cpu);
 #endif
@@ -382,9 +379,8 @@ int cpu_exec(CPUArchState *env)
 #elif defined(TARGET_XTENSA)
 #elif defined(TARGET_TRICORE)
     /* XXXXX */
-#else
-#error unsupported target CPU
 #endif
+    cc->cpu_exec_enter(cpu);
     cpu->exception_index = -1;
 
     /* Calculate difference between guest clock and host clock.
@@ -856,9 +852,8 @@ int cpu_exec(CPUArchState *env)
 #elif defined(TARGET_S390X)
 #elif defined(TARGET_XTENSA)
     /* XXXXX */
-#else
-#error unsupported target CPU
 #endif
+    cc->cpu_exec_exit(cpu);
 
     /* fail safe : never use current_cpu outside cpu_exec() */
     current_cpu = NULL;

include/qom/cpu.h

@@ -99,6 +99,8 @@ struct TranslationBlock;
  * @vmsd: State description for migration.
  * @gdb_num_core_regs: Number of core registers accessible to GDB.
  * @gdb_core_xml_file: File name for core registers GDB XML description.
+ * @cpu_exec_enter: Callback for cpu_exec preparation.
+ * @cpu_exec_exit: Callback for cpu_exec cleanup.
  *
  * Represents a CPU family or model.
  */
@@ -149,6 +151,9 @@ typedef struct CPUClass {
     const struct VMStateDescription *vmsd;
     int gdb_num_core_regs;
     const char *gdb_core_xml_file;
+
+    void (*cpu_exec_enter)(CPUState *cpu);
+    void (*cpu_exec_exit)(CPUState *cpu);
 } CPUClass;
 
 #ifdef HOST_WORDS_BIGENDIAN

qom/cpu.c

@@ -202,7 +202,7 @@ static bool cpu_common_virtio_is_big_endian(CPUState *cpu)
     return target_words_bigendian();
 }
 
-static void cpu_common_debug_excp_handler(CPUState *cpu)
+static void cpu_common_noop(CPUState *cpu)
 {
 }
 
@@ -344,7 +344,9 @@ static void cpu_class_init(ObjectClass *klass, void *data)
     k->gdb_read_register = cpu_common_gdb_read_register;
     k->gdb_write_register = cpu_common_gdb_write_register;
     k->virtio_is_big_endian = cpu_common_virtio_is_big_endian;
-    k->debug_excp_handler = cpu_common_debug_excp_handler;
+    k->debug_excp_handler = cpu_common_noop;
+    k->cpu_exec_enter = cpu_common_noop;
+    k->cpu_exec_exit = cpu_common_noop;
     dc->realize = cpu_common_realizefn;
     /*
      * Reason: CPUs still need special care by board code: wiring up