Re: Re: WARNING in x86_emulate_insn

[Lan, Tianyu]

On 12/8/2017 5:27 PM, Wanpeng Li wrote:
> 2017-12-08 16:28 GMT+08:00 Tianyu Lan <lantianyu1986@xxxxxxxxx>:
> > Hi Jim&Wanpeng:
> >           Thanks for your help.
> >
> > 2017-12-08 5:25 GMT+08:00 Jim Mattson <jmattson@xxxxxxxxxx>:
> > > Try disabling the module parameter, "unrestricted_guest." Make sure
> > > that the module parameter, "emulate_invalid_guest_state" is enabled.
> > > This combination allows userspace to feed invalid guest state into the
> > > in-kernel emulator.
> >
> > Yes, you are right. I need to disable unrestricted_guest to reproduce the issue.
>
> I can observe ctxt->exception.vector == 0xff which triggers Dmitry's
> report. Do you figure out the reason?

Yes, this is caused by that emulation callback returns error code while
not emulate exception and not set exception vector.
ctxt->exception.vector is default to be 0xff in emulate instruction code
path.