Re: [Xen-devel][Xense-devel][PATCH][XSM][1/4] Xen Security Modules Patch

[Stefan Berger <stefanb@xxxxxxxxxx>]

xen-devel-bounces@xxxxxxxxxxxxxxxxxxx wrote on 03/09/2007
03:04:56 PM:

> On Fri, 2007-03-09 at 12:51 -0500, Stefan Berger wrote:
> > 
> > xen-devel-bounces@xxxxxxxxxxxxxxxxxxx wrote on 03/09/2007 11:55:11
AM:
> > 
> > > On Fri, 2007-03-09 at 09:43 +0000, Keir Fraser wrote:
> > > > On 8/3/07 19:58, "George S. Coker, II" <gscoker@xxxxxxxxxxxxxx>
> > wrote:
> > > > 
> > > 
> > > > > To achieve a very light-weight
> > > > > domain, one would like to remove as much functionality
from that
> > domain
> > > > > as possible, to include the interrupt handler.
 Instead, there
> > would
> > > > > exist a light-weight domain interrupt handler
domain that is
> > responsible
> > > > > for this functionality.  These interrupts
would manifest as
> > interdomain
> > > > > channels; however, the ipi mechanism remains unless
a hook
> > exists to
> > > > > block this code path.  Likewise, the light-weight
domains
> > wouldn't be
> > > > > able to close their channels arbitrarily, and
require a check on
> > close
> > > > > as well.
> > > > 
> > > > I think this sounds like a microkernel-style 'interrupt
server'?
> > Why would
> > > > you want that? And if you did have it, why would you
care about
> > the clients
> > > > of this server closing their ends of interdomain event
channels?
> > > > 
> > > Fair enough.  I'll remove the close check, although
we will still
> > need a
> > > hook in the close code path for cleanup.
> > >  
> > 
> > There's also a mediation in evtchn_init() [.evtchn_init]. evtchn_init
> > () is called from one since place only and that is domain_create(),
> > which in turn is behind the xsm_createdomain() mediation call
> > [.createdomain]. I suppose it would be enough to guard the creation
of
> > a domain by the xsm_createdomain() hook only, no? 
> > 
> In light of the other comments, you are correct.

Why is there mediation in evtchn_reset [.evtchn_reset]?
It looks like the code tries to only close an event channel if necessary.
I suppose that once you have been allowed to open an event channel you
should be able to reset (close) it. 

   Stefan

> 
> >    Stefan 
> > 
> > 
> > > >  -- Keir
> > > 
> > > 
> > > _______________________________________________
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> > > http://lists.xensource.com/xen-devel
> 
> 
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