Re: [Qemu-devel] [PATCH 1/1] qmp: process system-reset event in paused state

["Denis V. Lunev" <den@openvz.org>]

On 12/16/2015 03:02 PM, Paolo Bonzini wrote:
>
> On 16/12/2015 10:50, Peter Krempa wrote:
>> We check that the state is "paused" and continue the vCPUs only in
>> that case. The panic devices will move the VM to 'crashed' state.
>> The code that is issuing 'system_reset' does not modify the state
>> in any way.
> Ok, thanks.
>
>> I'd say NACK here. This will break the possibility to reset a
>> system while the vCPUs are paused. The problem should be fixed in
>> libvirt.
> It is indeed a QEMU bug, and it was introduced in commit df39076 ("vl:
> allow "cont" from panicked state", 2013-11-04).
>
> Until that commit, a system_reset in panicked state would change the
> status to paused.  The commit changed that as a side effect of
> removing VM_STATE_GUEST_PANICKED from runstate_needs_reset; see the
> call to runstate_needs_reset in main_loop_should_exit.
>
> IMO, after a reset, main_loop_should_exit should actually transition
> to VM_STATE_PRELAUNCH (*not* RUN_STATE_PAUSED) for *all* states except
> RUN_STATE_INMIGRATE, RUN_STATE_SAVE_VM (which I think cannot happen
> there) and (of course) RUN_STATE_RUNNING.  Some changes will be required
> to the transition table as well.
>
> This will fix similar bugs for other runstates as well, though most of
> them probably cannot be triggered from libvirt.
>
> Thanks,
>
> Paolo
ok. Thank you for this input. I'll analyse this and come with
corrected patch :)

Den