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

[Marcel Apfelbaum]

On 29/11/2017 15:12, David Gibson wrote:
> 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.

OK

Reviewed-by: Marcel Apfelbaum <address@hidden>

Thanks,
Marcel

> > Thanks,
> > Marcel
> >
> > > Signed-off-by: David Gibson <address@hidden>
> > > ---
> > >    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,