ppc/xive: Introduce a XivePresenter interface

ppc/xive: Introduce a XivePresenter interface

When the XIVE IVRE sub-engine (XiveRouter) looks for a Notification
Virtual Target (NVT) to notify, it broadcasts a message on the
PowerBUS to find an XIVE IVPE sub-engine (Presenter) with the NVT
dispatched on one of its HW threads, and then forwards the
notification if any response was received.

The current XIVE presenter model is sufficient for the pseries machine
because it has a single interrupt controller device, but the PowerNV
machine can have multiple chips each having its own interrupt
controller. In this case, the XIVE presenter model is too simple and
the CAM line matching should scan all chips of the system.

To start fixing this issue, we first extend the XIVE Router model with
a new XivePresenter QOM interface representing the XIVE IVPE
sub-engine. This interface exposes a 'match_nvt' handler which the
sPAPR and PowerNV XIVE Router models will need to implement to perform
the CAM line matching.

Signed-off-by: Cédric Le Goater <[email protected]>
Reviewed-by: Greg Kurz <[email protected]>
Signed-off-by: Cédric Le Goater <[email protected]>
Message-Id: <20191125065820[email protected]>
Signed-off-by: David Gibson <[email protected]>