port-amd64/49150: xrstor is privileged in Xen

[jnemeth%CornerstoneService.ca@localhost]

>Number:         49150
>Category:       port-amd64
>Synopsis:       xrstor instruction is privileged in Xen
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    port-amd64-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Aug 25 05:25:00 +0000 2014
>Originator:     John Nemeth
>Release:        NetBSD 7.0 BETA and -current of same time frame
>Organization:
NetBSD
>Environment:
>Description:
        The xrstor instruction is privileged in Xen and the use of
it leads to a panic, "fatal privileged instruction fault in supervisor
mode".
>How-To-Repeat:
        Attempt to boot a NetBSD 7 BETA domu kernel and watch it go
boom at mountroot time.
>Fix: