On 01/26/18 11:46, Andy Lutomirski wrote:
>
> Under QEMU TCG, gs stays equal to 1. On native or KVM, on Skylake, it
> changes to 0.
>
> On KVM or native, I do not observe do_debug getting called with %gs ==
> 1. On TCG, I do. I don't think that's precisely the problem that's
> causing the test to fail, since the test doesn't use TF or ptrace, but
> I wouldn't be shocked if it's related.
>
> hpa, any insight?
>
> (NB: if you want to play with this as I've described it, you may need
> to make invalid_selector() in ptrace.c always return false. The
> current implementation is too strict and causes problems.)
>
Looking at it. I want to grok this in the general context of fsgsbase
as well, of course.
-hpa
