Re: [Qemu-devel] [PATCH v2 00/38] Delay destruction of memory regions to instance_finalize

[Paolo Bonzini]

Il 17/09/2013 17:59, Michael S. Tsirkin ha scritto:
> Yes but just not freeing it is unlikely to be enough.
> We need to make sure data structures are consistent.
> So this really needs to be done carefully, device by device.

Of course.  I checked SCSI already and it's sane.

>>>> - del_vm_change_state_handler
>>
>> Same here: user can stop/cont between exit and finalize, for example
>> because the I/O failed.
> 
> Device that is not guest visible is very unlikely to
> care about whether guest is running.

Most devices do not care at all whether the guest is running. :)  If
they do, they usually just use vm_clock.

But retrying failed I/O uses qemu_add_vm_change_set_handler, and that
has to be done even after the device is not guest visible anymore.

BTW, qemu_del_nic is another one that I forgot to mention.  You could
have MMIO that triggers a transmit while the device is going down, for
example.

Paolo