On Sun, Aug 01, 2010 at 12:14:40PM +0300, Avi Kivity wrote: > 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. We can fix that, or make it smarter. Look for io instruction at rip/rip-2 and use rip accordingly for instance. > > >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). > IIRC it was always this way in emulator. I'd rather fix userspace than break emulator. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
