Re: [Xen-devel] [PATCH v3 01/62] Revert "xen/arm: vgic-v2: Drop cbase from arch_domain"

[Shannon Zhao <shannon.zhao@xxxxxxxxxx>]

On 2015/11/18 19:41, Julien Grall wrote:
> Hi Shannon,
>
> On 18/11/15 02:28, Shannon Zhao wrote:
>
> > On 2015/11/17 21:57, Julien Grall wrote:
> > > On 17/11/15 12:32, Shannon Zhao wrote:
> > > > > Hi Julien,
> > > > >
> > > > > On 2015/11/17 19:27, Julien Grall wrote:
> > > > > > > Hi Shannon,
> > > > > > >
> > > > > > > Why do you want to revert this patch?
> > > > > Because d->arch.vgic.cbase will be used by creating Dom0 MADT table
> > > > > later. See [PATCH v3 43/62].
> > > > > +            gicc.base_address = d->arch.vgic.cbase;
> > > > >
> > > > > My previous way is get this from ACPI table but someone suggest get it
> > > > > from struct domain and I think this way is better too since it uses the
> > > > > value after being parsed.
> > > It's pointless to store the value in arch_domain for something that it's
> > > only use during building...
> > >
> > > We have struct kernel_info which store any information related to the
> > > DOM0 during the building.
> > Yeah, that would be better if it could use kernel_info. But the problem
> > is that kernel_info is firstly used in construct_dom0(), while it needs
> > to store the cbase in domain_create() which is called before
> > construct_dom0(). And if we pass kernel_info as parameter to
> > domain_create(), this would introduce more changes to common codes.
> >
> > Do you have any better idea to handle this?
> Yes, introducing callback to create the ACPI table in the GIC driver.
> See what we did for make_hwdom_dt_node.
>
> We are trying to make the domain_build domain as agnostic as possible
> from the GIC version. However in patch #43, you implement specific
> version in the domain builder.
>
> It will also not scale very well when we will introduce GICv2m and ITS.
>
> The version of the GIC (ACPI_MADT_GIC_*) could be introduced in the
> vgic_ops.
>
> The re-distributor could be moved in gic-v3.c and the generic interrupt
> controller in gic-v2.c.
>
> Note it's a mandatory to emulate the same version as the hardware for
> the virtual GIC.
So it doesn't support vGICv2 on GICv3 hardware for Xen?

Thanks,
--
Shannon

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