Re: [Xen-devel] Notes on stubdoms and latency on ARM

[Dario Faggioli <dario.faggioli@xxxxxxxxxx>]

On Wed, 2017-05-31 at 10:09 +0100, George Dunlap wrote:
> On 30/05/17 18:29, Stefano Stabellini wrote:
> > On Fri, 26 May 2017, Volodymyr Babchuk wrote:
> > > On other hand, EL0 app (as I see them) does not need such events.
> > > Basically, you just call function `handle_mmio()` right in the
> > > app.
> > > So, apps can live without interrupts and they still be able to
> > > handle
> > > request.
> > 
> > That's true.
> 
> Well if they're in a separate security zone, that's not going to
> work.
> You have to have a defined interface between things and sanitize
> inputs
> between them.  
>
Exactly, I was about to ask almost the same thing.

In fact, if you are "not" in Xen, as in, you are (and want to be there
by design) in an entity that is scheduled by Xen, and runs at a
different privilege level than Xen code, how come you can just call
random hypervisor functions?

Or am I still missing something (of either ARM in general, or of these
Apps in particular)?

Regards,
Dario
-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
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Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)

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