Re: [Qemu-devel] E5-2620v2 - emulation stop error

Radim Krčmář
2015-04-01T11:49:30Z

2015-03-31 21:23+0300, Andrey Korolyov:
> On Tue, Mar 31, 2015 at 9:04 PM, Bandan Das <bsd@redhat.com> wrote:
> > Bandan Das <bsd@redhat.com> writes:
> >> Andrey Korolyov <andrey@xdel.ru> writes:
> >> ...
> >>> http://xdel.ru/downloads/kvm-e5v2-issue/another-tracepoint-fail-with-apicv.dat.gz
> >>>
> >>> Something a bit more interesting, but the mess is happening just
> >>> *after* NMI firing.
> >>
> >> What happens if NMI is turned off on the host ?
> >
> > Sorry, I meant the watchdog..
>
> Thanks, everything goes well (as it probably should go there):
> http://xdel.ru/downloads/kvm-e5v2-issue/apicv-enabled-nmi-disabled.dat.gz

Nice revelation!

KVM doesn't expect host's NMIs to look like this so it doesn't pass them
to the host. What was the watchdog that casually sent NMIs?
(It worked after "nmi_watchdog=0" on the host?)

(Guest's NMI should have a different result as well. NMI_EXCEPTION is
an expected exit reason for guest's hard exceptions, they are then
differentiated by intr_info and nothing hinted that this was a NMI.)