accel: Introduce cpu_exec_reset_hold()

Introduce cpu_exec_reset_hold() which call an accelerator
specific AccelOpsClass::cpu_reset_hold() handler.

Define a stub on TCG user emulation, because CPU reset is
irrelevant there.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Anton Johansson <anjo@rev.ng>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230918104153.24433-3-philmd@linaro.org>

accel/tcg/user-exec-stub.c

@@ -14,6 +14,10 @@ void qemu_init_vcpu(CPUState *cpu)
 {
 }
 
+void cpu_exec_reset_hold(CPUState *cpu)
+{
+}
+
 /* User mode emulation does not support record/replay yet.  */
 
 bool replay_exception(void)

hw/core/cpu-common.c

@@ -137,6 +137,7 @@ static void cpu_common_reset_hold(Object *obj)
     cpu->crash_occurred = false;
     cpu->cflags_next_tb = -1;
 
+    cpu_exec_reset_hold(cpu);
     if (tcg_enabled()) {
         tcg_flush_jmp_cache(cpu);
         tcg_flush_softmmu_tlb(cpu);

include/hw/core/cpu.h

@@ -1153,6 +1153,7 @@ void cpu_class_init_props(DeviceClass *dc);
 void cpu_exec_initfn(CPUState *cpu);
 void cpu_exec_realizefn(CPUState *cpu, Error **errp);
 void cpu_exec_unrealizefn(CPUState *cpu);
+void cpu_exec_reset_hold(CPUState *cpu);
 
 /**
  * target_words_bigendian:

include/sysemu/accel-ops.h

@@ -30,6 +30,7 @@ struct AccelOpsClass {
     void (*ops_init)(AccelOpsClass *ops);
 
     bool (*cpus_are_resettable)(void);
+    void (*cpu_reset_hold)(CPUState *cpu);
 
     void (*create_vcpu_thread)(CPUState *cpu); /* MANDATORY NON-NULL */
     void (*kick_vcpu_thread)(CPUState *cpu);

system/cpus.c

@@ -201,6 +201,13 @@ bool cpus_are_resettable(void)
     return true;
 }
 
+void cpu_exec_reset_hold(CPUState *cpu)
+{
+    if (cpus_accel->cpu_reset_hold) {
+        cpus_accel->cpu_reset_hold(cpu);
+    }
+}
+
 int64_t cpus_get_virtual_clock(void)
 {
     /*