Re: [Xen-devel] [PATCH 2/7] ioreq: add internal ioreq initialization support

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Roger Pau Monne <roger.pau@xxxxxxxxxx>
> Sent: 22 August 2019 08:24
> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Jan Beulich <jbeulich@xxxxxxxx>; Andrew 
> Cooper
> <Andrew.Cooper3@xxxxxxxxxx>; Wei Liu <wl@xxxxxxx>
> Subject: Re: [PATCH 2/7] ioreq: add internal ioreq initialization support
> 
> On Wed, Aug 21, 2019 at 06:24:17PM +0200, Paul Durrant wrote:
> > > -----Original Message-----
> > > From: Roger Pau Monne <roger.pau@xxxxxxxxxx>
> > > Sent: 21 August 2019 15:59
> > > To: xen-devel@xxxxxxxxxxxxxxxxxxxx
> > > Cc: Roger Pau Monne <roger.pau@xxxxxxxxxx>; Jan Beulich 
> > > <jbeulich@xxxxxxxx>; Andrew Cooper
> > > <Andrew.Cooper3@xxxxxxxxxx>; Wei Liu <wl@xxxxxxx>; Paul Durrant 
> > > <Paul.Durrant@xxxxxxxxxx>
> > > Subject: [PATCH 2/7] ioreq: add internal ioreq initialization support
> > >
> > > Add support for internal ioreq servers to initialization and
> > > deinitialization routines, prevent some functions from being executed
> > > against internal ioreq servers and add guards to only allow internal
> > > callers to modify internal ioreq servers. External callers (ie: from
> > > hypercalls) are only allowed to deal with external ioreq servers.
> >
> > It's kind of ugly to have the extra 'internal' argument passed to anything 
> > other than the create
> function so I wonder whether it would be neater to encode it in the ioreq 
> server id. I.e. we have
> distinct id ranges for internal and external servers. What do you think?
> 
> That would be fine, I guess I could use the most significant bit in
> the id to signal whether the server is internal or external, and
> reject dmop calls that target internal servers based on the provided
> id. Does that sound sensible?
> 

Yes, that's basically what I was thinking initially although, as you observe, 
in the thread for patch #3 having two smaller consecutive ranges would be more 
convenient.

  Paul

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