Re: [PATCH v2] target/i386: seg_helper: Correct segement selector nullification in the RET/IRET helper

[Bin Meng]

Hi Paolo,

On Fri, Nov 13, 2020 at 6:39 PM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 13/11/20 11:23, Bin Meng wrote:
> >> It would be nicer if the commit message explained how
> >> the guest can notice the difference.
> >
> > The commit message says "Per the SDM" :) The actual failure case
> > involves a special code sequence that is exposed in VxWorks guest
> > testing. Linux does not expose this however.
>
> I see.  Is there any chance you could write a testcase for
> kvm-unit-tests?  Or just explain how to write such a test, and then I
> can write it myself; it's not clear to me how the guest can observe the
> base and limit of a non-present segment.

I am not familiar with kvm-unit-test. The original issue cannot be
reproduced with a KVM enabled QEMU as the codes-in-flaw is in the
emulation path.

Regards,
Bin