[RFCv2 8/9] pseries: Advertise HPT resizing support via CAS

[Paul Mackerras]

On Fri, Jan 29, 2016 at 04:24:02PM +1100, David Gibson wrote:
> The hypervisor needs to know a guest is capable of using the HPT resizing
> PAPR extension in order to make full advantage of it for memory hotplug.
> 
> If the hypervisor knows the guest is HPT resize aware, it can size the
> initial HPT based on the initial guest RAM size, relying on the guest to
> resize the HPT when more memory is hot-added.  Without this, the hypervisor
> must size the HPT for the maximum possible guest RAM, which can lead to
> a huge waste of space if the guest never actually expends to that maximum
> size.
> 
> This patch advertises the guest's support for HPT resizing via the
> ibm,client-architecture-support OF interface.  Obviously, the actual
> encoding in the CAS vector is tentative until the extension is officially
> incorporated into PAPR.  For now we use bit 0 of (previously unused) byte 8
> of option vector 5.
> 
> Signed-off-by: David Gibson <david at gibson.dropbear.id.au>

Reviewed-by: Paul Mackerras <paulus at samba.org>