Xen 
 
Home About Xen.org Xen Xen Summit Wiki Mailing List Bug Tracker Xen Downloads
 
   
 

xen-devel

RE: [Xen-devel] Live migration leaves page tables read-only?

To: "John Byrne" <john.l.byrne@xxxxxx>, <ian.pratt@xxxxxxxxxxxx>
Subject: RE: [Xen-devel] Live migration leaves page tables read-only?
From: "Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>
Date: Fri, 1 Dec 2006 01:13:01 -0000
Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Thu, 30 Nov 2006 17:13:42 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <456CD0A5.1060701@xxxxxx> <456CD2DC.2020201@xxxxxx> <8A87A9A84C201449A0C56B728ACF491E01FA12@xxxxxxxxxxxxxxxxxxxxxxxxxxx> <456CF5F9.7070009@xxxxxx> <456F6AF5.2090005@xxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AccU2HnzVNI8kNo/T1KhA6jvR0RwIwADQQ0A
Thread-topic: [Xen-devel] Live migration leaves page tables read-only?
> >> What happens if you use non-live relo?
> >
> > I thought I had tested that way back at the beginning without seeing
the
> > problem, but I must not have, because I just retested it to be sure
and
> > it died the same way. (Now I am truly confused and I need to go back
and
> > re-examine some of my earlier experiments.)
> >
> 
> After redoing some of my tests and understanding more about how Xen
> handles page tables, I started looking at ptwr_do_page_fault() and put
> debugging code into it. (On Xen 3.0.3 x86-64.)  The fixup is failing
in
> x86_emulate_memop(). Building a debug version of Xen provided some
> additional information (the final line is from my debugging, after the
> ":" is domid, addr, pte, pte flags, type_info, page owner, domain):

You say you can repro the problem using non-live relo. In that case, you
should also be able to repro it using save/restore, which has almost
identical code paths.

Please try and isolate whether the crash happens on save or restore, and
further whether a given saved images crashes every time in the same way
when you try and restore it (mfns will be different, but pfns may be the
same).

 
Ian


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel