Re: [Qemu-devel] [Qemu-ppc] [PATCH v2] spapr-rtas: add ibm, get-vpd RTAS interface

["Maxiwell S. Garcia" <maxiwell@linux.ibm.com>]

On Tue, Feb 26, 2019 at 02:21:03PM +1100, David Gibson wrote:
> On Mon, Feb 25, 2019 at 08:20:09PM -0300, Murilo Opsfelder Araujo wrote:
> > Hi, Maxiwell.
> > 
> > On Mon, Feb 25, 2019 at 01:23:25PM -0300, Maxiwell S. Garcia wrote:
> > > This adds a handler for ibm,get-vpd RTAS calls, allowing pseries
> > > guest to collect host information. It is disabled by default to
> > > avoid unwanted information leakage. To enable it, use:
> > > ‘-M pseries,vpd-export=on’
> > 
> > The patch for setting host-serial and host-model already landed Gibson's
> > ppc-for-4.0 branch:
> > 
> >   commit 9e584f45868f6945c1282c938278038cba0e4af2
> >   Author: Prasad J Pandit <pjp@fedoraproject.org>
> >   Date:   Mon Feb 18 23:43:49 2019 +0530
> > 
> >       ppc: add host-serial and host-model machine attributes (CVE-2019-8934)
> > 
> > 
> > QEMU should only return host-serial and host-model from the host if the
> > following combination of parameters are provided:
> > 
> >   -M host-serial=passthrough,host-model=passthrough,vpd-export=on
> > 
> > If host-serial or host-model are set with a user-string, ibm,get-vpd should
> > honor these values and return them, not exposing host information by accident.
> > 
> > I'm not even sure if we need vpd-export=<bool> setting. Its logic could be
> > derived from the presence of host-serial=passthrough and host-model=passthrough
> > options.
> > 
> > What do you think?
> 
> That's an excellent point - I hadn't thought through the fact that
> this is the same information exposed by those properties.  I do indeed
> think that exposing the same information set in those properties - and
> thereby avoiding the new machine option - would be a better plan.
> 

I saw that the patch was applied. So I will work in another patch
to use these properties and remove the export-vpd option.

Another thing that I thought the fact that 'host-serial' and 'host-model'
nodes in Device Tree are not in accordance with LoPAPR document. What
you think in use only get-vpd to get these information and remove
nodes from device tree?

> -- 
> David Gibson			| I'll have my music baroque, and my code
> david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
> 				| _way_ _around_!
> http://www.ozlabs.org/~dgibson