Re: [PATCH 1/2] KVM: x86 emulator: don't update vcpu state if instruction is restarted.

Avi Kivity
2010-08-01T09:14:42Z

On 08/01/2010 12:01 PM, Gleb Natapov wrote:
>>>
>>> It uses rip _during_ pio. And pio emulation changes rip
>>> only at the end of emulation.
>> But non-emulated pio does a skip_emulated_instruction() immediately
>> (or so the code in kvm-tpr-opt.c assumes:
>>
> Indeed, this is bug in non-emulated pio.

But userspace depends on this bug.

> But the patch does not change
> rip behaviour for emulated pio. vcpu->arch.emulate_ctxt.eip is updated
> only at the end of emulation.

That will lead to failures if the emulator is used for the kvm-tpr-opt
pio (which may happen with big real mode).

--
error compiling committee.c: too many arguments to function