Re: [Qemu-devel] [for-2.12 4/7] pci: Simplify pci_bus_is_root()

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, Nov 29, 2017 at 12:45:28PM +0200, Marcel Apfelbaum wrote:
> On 29/11/2017 10:46, David Gibson wrote:
> > pci_bus_is_root() currently relies on a method in the PCIBusClass.
> > But it's always known if a PCI bus is a root bus when we create it, so
> > using a dynamic method is overkill.
> > 
> > This replaces it with an IS_ROOT bit in a new flags field, which is set on
> > root buses and otherwise clear.  As a bonus this removes the special
> > is_root logic from pci_expander_bridge, since it already creates its bus
> > as a root bus.
> > 
> 
> I agree it makes the code simpler, I am not sure about
> the enum. Why not make it a boolean field and when will need
> more flags just convert it to an enum (or not)?

Well, I have some patches I'm working on (rather slowly) which add a
second flag.

> 
> Thanks,
> Marcel
> 
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> >   hw/pci-bridge/pci_expander_bridge.c |  6 ------
> >   hw/pci/pci.c                        | 14 ++------------
> >   include/hw/pci/pci.h                | 12 +++++++++++-
> >   3 files changed, 13 insertions(+), 19 deletions(-)
> > 
> > diff --git a/hw/pci-bridge/pci_expander_bridge.c b/hw/pci-bridge/pci_expander_bridge.c
> > index 5652cf06e9..11dfa9258e 100644
> > --- a/hw/pci-bridge/pci_expander_bridge.c
> > +++ b/hw/pci-bridge/pci_expander_bridge.c
> > @@ -65,11 +65,6 @@ static int pxb_bus_num(PCIBus *bus)
> >       return pxb->bus_nr;
> >   }
> > -static bool pxb_is_root(PCIBus *bus)
> > -{
> > -    return true; /* by definition */
> > -}
> > -
> >   static uint16_t pxb_bus_numa_node(PCIBus *bus)
> >   {
> >       PXBDev *pxb = convert_to_pxb(bus->parent_dev);
> > @@ -82,7 +77,6 @@ static void pxb_bus_class_init(ObjectClass *class, void *data)
> >       PCIBusClass *pbc = PCI_BUS_CLASS(class);
> >       pbc->bus_num = pxb_bus_num;
> > -    pbc->is_root = pxb_is_root;
> >       pbc->numa_node = pxb_bus_numa_node;
> >   }
> > diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> > index 6e11dc2fec..5fab7f23b3 100644
> > --- a/hw/pci/pci.c
> > +++ b/hw/pci/pci.c
> > @@ -126,14 +126,9 @@ static void pci_bus_unrealize(BusState *qbus, Error **errp)
> >       vmstate_unregister(NULL, &vmstate_pcibus, bus);
> >   }
> > -static bool pcibus_is_root(PCIBus *bus)
> > -{
> > -    return !bus->parent_dev;
> > -}
> > -
> >   static int pcibus_num(PCIBus *bus)
> >   {
> > -    if (pcibus_is_root(bus)) {
> > +    if (pci_bus_is_root(bus)) {
> >           return 0; /* pci host bridge */
> >       }
> >       return bus->parent_dev->config[PCI_SECONDARY_BUS];
> > @@ -156,7 +151,6 @@ static void pci_bus_class_init(ObjectClass *klass, void *data)
> >       k->unrealize = pci_bus_unrealize;
> >       k->reset = pcibus_reset;
> > -    pbc->is_root = pcibus_is_root;
> >       pbc->bus_num = pcibus_num;
> >       pbc->numa_node = pcibus_numa_node;
> >   }
> > @@ -385,6 +379,7 @@ static void pci_root_bus_init(PCIBus *bus, DeviceState *parent,
> >       bus->slot_reserved_mask = 0x0;
> >       bus->address_space_mem = address_space_mem;
> >       bus->address_space_io = address_space_io;
> > +    bus->flags |= PCI_BUS_IS_ROOT;
> >       /* host bridge */
> >       QLIST_INIT(&bus->child);
> > @@ -397,11 +392,6 @@ bool pci_bus_is_express(PCIBus *bus)
> >       return object_dynamic_cast(OBJECT(bus), TYPE_PCIE_BUS);
> >   }
> > -bool pci_bus_is_root(PCIBus *bus)
> > -{
> > -    return PCI_BUS_GET_CLASS(bus)->is_root(bus);
> > -}
> > -
> >   void pci_root_bus_new_inplace(PCIBus *bus, size_t bus_size, DeviceState *parent,
> >                                 const char *name,
> >                                 MemoryRegion *address_space_mem,
> > diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
> > index 77d92a3dc4..cbb3386207 100644
> > --- a/include/hw/pci/pci.h
> > +++ b/include/hw/pci/pci.h
> > @@ -404,6 +404,11 @@ typedef AddressSpace *(*PCIIOMMUFunc)(PCIBus *, void *, int);
> >   #define PCI_BUS_GET_CLASS(obj) OBJECT_GET_CLASS(PCIBusClass, (obj), TYPE_PCI_BUS)
> >   #define TYPE_PCIE_BUS "PCIE"
> > +enum PCIBusFlags {
> > +    /* This bus is the root of a PCI domain */
> > +    PCI_BUS_IS_ROOT                                         = 0x0001,
> > +};
> > +
> >   typedef struct PCIBusClass {
> >       /*< private >*/
> >       BusClass parent_class;
> > @@ -416,6 +421,7 @@ typedef struct PCIBusClass {
> >   struct PCIBus {
> >       BusState qbus;
> > +    enum PCIBusFlags flags;
> >       PCIIOMMUFunc iommu_fn;
> >       void *iommu_opaque;
> >       uint8_t devfn_min;
> > @@ -440,8 +446,12 @@ struct PCIBus {
> >       Notifier machine_done;
> >   };
> > +static inline bool pci_bus_is_root(PCIBus *bus)
> > +{
> > +    return !!(bus->flags & PCI_BUS_IS_ROOT);
> > +}
> > +
> >   bool pci_bus_is_express(PCIBus *bus);
> > -bool pci_bus_is_root(PCIBus *bus);
> >   void pci_root_bus_new_inplace(PCIBus *bus, size_t bus_size, DeviceState *parent,
> >                                 const char *name,
> >                                 MemoryRegion *address_space_mem,
> > 
> 

-- 
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

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