Re: [Qemu-devel] [PATCH] ppc/pnv: Add model for Power8 PHB3 PCIe Host bridge

[Andrea Bolognani <abologna@redhat.com>]

On Wed, 2018-06-27 at 18:41 +1000, Benjamin Herrenschmidt wrote:
> On Wed, 2018-06-27 at 09:46 +0200, Cédric Le Goater wrote:
> > So the "IBM PHB3 PCIE Root Port" is already user createable.
> > 
> > I can take a look at user createable PHB3s. I think this is OK from a model
> > perspective. The object is rather standalone, it needs the machine for 
> > the XICS fabric and a couple of ids, phb id and chip id. These can come
> > from the command line.
> > 
> > We want at least one PHB3 per socket/chip though. 
> 
> We don't want the user to specify the SCOM addresses though (for the
> MMIO windows we should get skiboot to assign them).
> 
> If the user gets to specify a thing it would be which of the 3 or 4 HW
> PHBs of the chip it is, the SCOM addresses gets deduced.

For pSeries guests libvirt will either automatically create, or
allow users to configure manually, PHBs with something like

  <controller type='pci' index='1' model='pci-root'>
    <target index='1'/>
  </controller>

which is ultimately converted to

  -device spapr-pci-host-bridge,index=1,id=pci.1

Ideally the interface for PowerNV guests can be made to be similar
if not identical at the libvirt level, without having to add too
many hacks... It would certainly help a lot if the QEMU interface
for PowerNV PHBs didn't stray too far from the above.

-- 
Andrea Bolognani / Red Hat / Virtualization