Hi devs!
XEN devs:
As per short discussion with ktemkin earlier in January in #xen:
"ktemkin Jan 10, 2016 16:21:50
This test patch did appear to make the system work, though:
https://gist.github.com/ktemkin/0e81b93654ae800a5609ktemkin Jan 10, 2016 16:24:55
Only real difference I see between that and the upstream behavior (besides limiting things to dom0 so things weren't accidentally passed through) is the call to disable_pmr on line 117 before aborting."
Makes total sense to my early understanding, since it seems that it is said that vt-d engine gets disabled, but disable_pmr(iommu) function is not called to enforce.