Re: [PATCH v2 for 4.5] xen/arm: Add support for GICv3 for domU

[Ian Campbell <Ian.Campbell@citrix.com>]

On Wed, 2014-11-05 at 11:02 +0000, Stefano Stabellini wrote:
> On Wed, 5 Nov 2014, Ian Campbell wrote:
> > On Wed, 2014-11-05 at 10:31 +0000, Stefano Stabellini wrote:
> > > On Wed, 5 Nov 2014, Ian Campbell wrote:
> > > > > +         * hardware GIC. Only the value XEN_DOMCTL_CONFIG_GIC_DEFAULT
> > > > > +         * is allowed. The DOMCTL will return the actual version of the
> > > > > +         * GIC.
> > > > > +         */
> > > > > +        if ( domctl->u.configuredomain.gic_version != XEN_DOMCTL_CONFIG_GIC_DEFAULT )
> > > > > +            return -EOPNOTSUPP;
> > > > 
> > > > EOPNOTSUPP doesn't seem quite right. EPARM  or EINVAL perhaps?
> > > > 
> > > > I'm also tempted to suggest that we should accept gic_version == the hw
> > > > value, i.e. by moping the switch below up and including
> > > >         && domctl->u.configuredomain.gic_version != gic_version
> > > > in the condition.
> > > 
> > > I suggested to use -EOPNOTSUPP because one day we want to be able to use
> > > this hypercall to choose a specific gic_version for the guest domain,
> > > including gicv2 on gicv3 hardware for example.
> > 
> > Why is EOPNOTSUPP an appropriate error code for that though?
> 
> Because at the moment we don't support this use case? If we did we would
> be OK with the user passing gic_version = 2 for example.

Ah, I suggested separately in the review we should just accept the g/w
version.

Ian.