[PATCH v5 02/22] KVM: arm/arm64: Add GICV3 pending table save API documentation

[Dr. David Alan Gilbert]

* Peter Maydell (peter.maydell at linaro.org) wrote:
> On 26 April 2017 at 09:26, Auger Eric <eric.auger at redhat.com> wrote:
> > On 25/04/2017 12:43, Peter Maydell wrote:
> >> When does the -EFAULT return happen? (if the guest points GITS_BASER<n>
> >> etc at invalid memory, presumably?)
> >
> > Yes that's correct, when GICR_PENDBASER contains a bad GPA.
> >
> >>  How does the QEMU migration code
> >> handle this case? Failing migration because the guest has done something
> >> silly doesn't seem too palatable, but trying to avoid that could be
> >> more effort than an obscure corner case really merits.
> >
> > The kvm_device_access will cause an abort() as for other errors returned
> > by kvm_device_ioctl().
> 
> That's pretty nasty. Guests shouldn't be able to provoke QEMU
> into abort()ing, ideally. We don't necessarily have to produce
> a successful migration, but we should at least fail it cleanly.

Yes, no abort()'s during migration due to guest behaviour.
They always end up coming back around to being filed as migration
bugs and people worry why they've got cores.

Ideally log a message into stderr to say that the guest state
is inconsistent so that when someone comes to debug it then they
can see it's obvious.

Dave

> thanks
> -- PMM
--
Dr. David Alan Gilbert / dgilbert at redhat.com / Manchester, UK