Re: [PATCH] libxl: arm: Allow grant mappings for backends running on Dom0

[Juergen Gross <jgross@xxxxxxxx>]

On 08.05.23 06:09, Viresh Kumar wrote:
> On 05-05-23, 16:11, Oleksandr Tyshchenko wrote:
> > I was going to propose an idea, but I have just realized that you already
> > voiced it here [1] ))
> > So what you proposed there sounds reasonable to me.
> >
> > I will just rephrase it according to my understanding:
> >
> > We probably need to consider transforming your "forced_grant" to something
> > three-state, for example
> > "grant_usage" (or "use_grant" as you suggested) which could be "default
> > behaviour" or "always disabled", or "always enabled".
> >
> > With "grant_usage=default" we will get exact what we have at the moment
> > (only create iommu nodes if backend-domid != 0)
> > With "grant_usage=disabled" we will force grants to be always disabled
> > (don't create iommu nodes irrespective of the domain)
> > With "grant_usage=enabled" we will force grants to be always enabled
> > (always create iommu nodes irrespective of the domain)
> I was wondering if "grant_usage=default" can be interpreted by the
> absence of the grant_usage parameter. So just grant_usage=1 or 0,
> which would mean enabled or disabled and if grant_usage isn't passed,
> we would switch back to default.
I don't think this is a good idea. I think you'd need the 3rd state already
in the interface between xl and libxl.


Juergen

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