Re: [PATCH 2/2] x86: Bail out on unemulated instructions

[Gleb Natapov <gleb@redhat.com>]

On Sun, Aug 15, 2010 at 03:43:15PM +0300, Mohammed Gamal wrote:
> 2010/8/15 Gleb Natapov <gleb@redhat.com>:
> > On Sun, Aug 15, 2010 at 03:40:00PM +0300, Mohammed Gamal wrote:
> >> On Sun, Aug 15, 2010 at 10:32 AM, Gleb Natapov <gleb@redhat.com> wrote:
> >> > On Sat, Aug 14, 2010 at 06:51:34PM +0300, Mohammed Gamal wrote:
> >> >> If emulation fails due to the instruction being unemulated. Return immediately
> >> >> instead of restarting the instruction and infinitely trying to execute it.
> >> >>
> >> > This is already handled correctly as far as I can see. Sometimes
> >> > instruction should be retried and reexecute_instruction() checks
> >> > for that case. If instruction emulation fails in big real mode
> >> > re-executing instruction will be useless though, so what should be done
> >> > is to make reexecute_instruction() return false if vcpu is in big real
> >> > mode and cpu relies on emulation to handle it.
> >> We don't have a separate mode for big real mode. The emulation modes
> >> we have are real and vm86
> >>
> > That doesn't makes the patch right. So we will have to figure something
> > out.
> True. Can we do it for real mode in general (i.e. X86EMUL_MODE_REAL)?
If we flush all shadow pages when moving from paged mode to non paged
checking for X86EMUL_MODE_REAL sounds enough to me, but Avi knows better.
Or we can add is_big_real_mode() callback to x86_ops and implement it in
vmx accordingly.

--
			Gleb.