[libvirt] Making panic great again

[Ed Swierk]

On Fri, Apr 28, 2017 at 1:46 AM, Daniel P. Berrange <berrange at redhat.com> wrote:
> With the watchdog we have a much wider set of actions that we can
> instruct QEMU to do:
>
>     'reset' — default, forcefully reset the guest
>     'shutdown' — gracefully shutdown the guest (not recommended)
>     'poweroff' — forcefully power off the guest
>     'pause' — pause the guest
>     'none' — do nothing
>     'dump' — automatically dump the guest Since 0.8.7
>     'inject-nmi' — inject a non-maskable interrupt into the guest Since 1.2.17
>
> IMHO, we need an RFE against QEMU to allow pvpanic to have the same kind
> of configurability as watchdog. So instead of QEMU blindly pausing the
> guest, it can be told 'none' at which point libvirt can emit the event
> and the admin can decide what further action they wish to take, if any.

I agree the panic device should support the same actions as the watchdog does.

All of them could be implemented without changing QEMU, though. For
example libvirt could implement the 'none' action by resuming the
guest. That means the guest still gets paused briefly, but I'd view
fixing this as more of a performance optimization than a prerequisite
for supporting the full set of actions.

--Ed