Paolo Bonzini writes:
> QEMU objects usually have their pointer shared with the "outside
> world" very early in their lifetime, for example when they create their
> MemoryRegions. Because at this point it is not valid anymore to
> create a &mut reference to the device, individual parts of the
QEMU objects usually have their pointer shared with the "outside
world" very early in their lifetime, for example when they create their
MemoryRegions. Because at this point it is not valid anymore to
create a &mut reference to the device, individual parts of the
device struct must be made mutable
