Nowadays, we use qemu_mutex_lock_iothread()/qemu_mutex_unlock_iothread() to protect the race to access the emulated dev launched by vcpu threads & iothread.
But this lock is too big. We can break it down. These patches separate the CPUArchState's protection from the other devices, so we can have a per-cpu lock for each CPUArchState, not the big lock any longer.
