Re: port-amd64/49150: xrstor is privileged in Xen

[David Laight <david%l8s.co.uk@localhost>]

The following reply was made to PR port-amd64/49150; it has been noted by GNATS.

From: David Laight <david%l8s.co.uk@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: port-amd64/49150: xrstor is privileged in Xen
Date: Thu, 11 Sep 2014 21:26:43 +0100

 On Mon, Aug 25, 2014 at 05:25:00AM +0000, 
jnemeth%CornerstoneService.ca@localhost wrote:
 > >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.
 
 ISTR this is in 'fpu' setup deecting avx??
 
 IIRC the kernel only calls xrstor instruction if one of the other
 registers says it is available.
 So xen is failing to lie....
 
 Possibly the instruction needs a 'trap detect' added and to disable avx
 if it faults.
 
        David
 
 -- 
 David Laight: david%l8s.co.uk@localhost