Re: [PATCH] VMX: Invalid guest state detection enhancements and bug fixes

[Gleb Natapov <gleb@redhat.com>]

On Tue, May 11, 2010 at 01:53:51PM +0300, Mohammed Gamal wrote:
> >>                if (err != EMULATE_DONE) {
> >> +                       kvm_report_emulation_failure(vcpu, "invalid guest
> >> state handler");
> >>                        vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> >>                        vcpu->run->internal.suberror =
> >> KVM_INTERNAL_ERROR_EMULATION;
> >>                        vcpu->run->internal.ndata = 0;
> >>
> >
> > Uneeded, userspace can report it.
> 
> Userspace does report the address at which a VM fails, it doesn't for
> instance show the contents of RIP which is necessary for knowing which
> instruction failed, this is at least needed for testing purposes. IIRC
> I've seen some trace_kvm_failed_insn() functions somewhere. But I
> don't know how to use tracing utilities so I'd be delighted if someone
> could point me to some relevant documentation or something.
Userspace can be extended to print instruction at RIP on emulation
failure. Furthermore userspace can even disassemble it for you. IIRC
kvm_report_emulation_failure() was once removed from here and I've
actually sent patch to remove kvm_report_emulation_failure() at all.

--
			Gleb.