Re: [Qemu-devel] [RFC 2/7] pci: Change pci_bus_init() 'parent' parameter to PCIHostState

[Eduardo Habkost]

On Tue, Apr 18, 2017 at 01:51:02PM +1000, David Gibson wrote:
> On Mon, Apr 17, 2017 at 06:59:11PM -0300, Eduardo Habkost wrote:
> > pci_bus_init() already requires 'parent' to be a PCI_HOST_BRIDGE object,
> > so change the parameter type to reflect that.
> > 
> > Cc: "Michael S. Tsirkin" <address@hidden>
> > Cc: Marcel Apfelbaum <address@hidden>
> > Signed-off-by: Eduardo Habkost <address@hidden>
> 
> Reviewed-by: David Gibson <address@hidden>
> 
> I had to do some looking to convince myself this wouldn't break P2P
> bridges.
> 
> I wonder if we should rename pci_bus_init() / pci_bus_new() to make it
> clearer that they're about creating a whole new PCI domain, and not
> for a new bus within an existing domain.

Good point. The current naming is confusing. I only knew the
change was safe because pci_bus_new() would crash if 'parent'
wasn't a PCI_HOST_BRIDGE. But I took some time to find the other
places where PCI buses could be created, and I'm not sure yet if
I found all of them.

Is there any other code that creates TYPE_PCI_BUS objects, except
for the ones touched by this series and pci_bridge_initfn()?

> 
> > ---
> >  hw/pci/pci.c | 10 ++++++----
> >  1 file changed, 6 insertions(+), 4 deletions(-)
> > 
> > diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> > index 25118fb91d..d9535c0bdc 100644
> > --- a/hw/pci/pci.c
> > +++ b/hw/pci/pci.c
> > @@ -362,7 +362,7 @@ const char *pci_root_bus_path(PCIDevice *dev)
> >      return rootbus->qbus.name;
> >  }
> >  
> > -static void pci_bus_init(PCIBus *bus, DeviceState *parent,
> > +static void pci_bus_init(PCIBus *bus, PCIHostState *phb,
> >                           MemoryRegion *address_space_mem,
> >                           MemoryRegion *address_space_io,
> >                           uint8_t devfn_min)
> > @@ -375,7 +375,7 @@ static void pci_bus_init(PCIBus *bus, DeviceState 
> > *parent,
> >      /* host bridge */
> >      QLIST_INIT(&bus->child);
> >  
> > -    pci_host_bus_register(PCI_HOST_BRIDGE(host));
> > +    pci_host_bus_register(phb);
> >  }
> >  
> >  bool pci_bus_is_express(PCIBus *bus)
> > @@ -394,8 +394,9 @@ void pci_bus_new_inplace(PCIBus *bus, size_t bus_size, 
> > DeviceState *parent,
> >                           MemoryRegion *address_space_io,
> >                           uint8_t devfn_min, const char *typename)
> >  {
> > +    PCIHostState *phb = PCI_HOST_BRIDGE(parent);
> >      qbus_create_inplace(bus, bus_size, typename, parent, name);
> > -    pci_bus_init(bus, parent, address_space_mem, address_space_io, 
> > devfn_min);
> > +    pci_bus_init(bus, phb, address_space_mem, address_space_io, devfn_min);
> >  }
> >  
> >  PCIBus *pci_bus_new(DeviceState *parent, const char *name,
> > @@ -403,10 +404,11 @@ PCIBus *pci_bus_new(DeviceState *parent, const char 
> > *name,
> >                      MemoryRegion *address_space_io,
> >                      uint8_t devfn_min, const char *typename)
> >  {
> > +    PCIHostState *phb = PCI_HOST_BRIDGE(parent);
> >      PCIBus *bus;
> >  
> >      bus = PCI_BUS(qbus_create(typename, parent, name));
> > -    pci_bus_init(bus, parent, address_space_mem, address_space_io, 
> > devfn_min);
> > +    pci_bus_init(bus, phb, address_space_mem, address_space_io, devfn_min);
> >      return bus;
> >  }
> >  
> 
> -- 
> David Gibson                  | I'll have my music baroque, and my code
> david AT gibson.dropbear.id.au        | minimalist, thank you.  NOT _the_ 
> _other_
>                               | _way_ _around_!
> http://www.ozlabs.org/~dgibson



-- 
Eduardo