Xen 4.18.5 PV dbregs fail

[Manuel Bouyer <bouyer@xxxxxxxxxxxxxxx>]

Hello,
since I updated to Xen 4.18.5 (from 4.18.4), NetBSD's dbregs-related tests
are failing. Only for PV; PVH and HVM guests are fine. They are
failing for both 32bits and 64bits guests.

I tracked it down to dr6 being 0xffff0ff0 after the trace trap, when at
last one of the lower bits should be 1 (I think it's bit 0, from the code).

I looked at the commit log between 4.18.4 and 4.18.5 but didn't see
anything obvious.

Any idea ?

-- 
Manuel Bouyer <bouyer@xxxxxxxxxxxxxxx>
     NetBSD: 26 ans d'experience feront toujours la difference
--