On Wed, 25 Oct 2023 09:25:07 +0100, Oliver Upton <oliver.upton@xxxxxxxxx> wrote: > > On Wed, Oct 25, 2023 at 09:04:58AM +0100, Marc Zyngier wrote: > > [...] > > > While I totally agree that this *debug* statement should go, we should > > also replace it with something else. > > > > Because when you're trying to debug a guest (or even KVM itself), > > seeing this message is a sure indication that the guest is performing > > an access outside of memory. The fact that KVM tries to handle it as > > MMIO is just an implementation artefact. > > > > So I'd very much welcome a replacement tracepoint giving a bit more > > information, such as guest PC, IPA being accessed, load or store. With > > that, everybody wins. > > Aren't we already covered by the kvm_guest_fault tracepoint? Userspace > can filter events on ESR to get the faults it cares about. I'm not > against adding another tracepoint, but in my experience kvm_guest_fault > has been rather useful for debugging any type of guest fault. That tracepoint is one of the most triggered, and sifting through this is a painful experience. If we go down that road, adding a bit of extra documentation (pointed to from the KVM_RUN entry) and an example filter script would be most useful. Thanks, M. -- Without deviation from the norm, progress is not possible.
