[Qemu-devel] [PATCH 1/2] pci: Simplify pci_bus_is_root()

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

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.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
---
 hw/pci-bridge/pci_expander_bridge.c |  6 ------
 hw/pci/pci.c                        | 14 ++------------
 hw/virtio/virtio-pci.c              |  1 +
 include/hw/pci/pci.h                |  1 -
 include/hw/pci/pci_bus.h            | 11 +++++++++++
 5 files changed, 14 insertions(+), 19 deletions(-)

diff --git a/hw/pci-bridge/pci_expander_bridge.c b/hw/pci-bridge/pci_expander_bridge.c
index e62de4218f..ca66bc721a 100644
--- a/hw/pci-bridge/pci_expander_bridge.c
+++ b/hw/pci-bridge/pci_expander_bridge.c
@@ -66,11 +66,6 @@ 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);
@@ -83,7 +78,6 @@ 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 c9fc2fbe19..f6d8b337db 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -129,14 +129,9 @@ 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];
@@ -159,7 +154,6 @@ 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;
 }
@@ -379,6 +373,7 @@ 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);
@@ -396,11 +391,6 @@ 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/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index e978bfe760..a3e43ebe31 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -20,6 +20,7 @@
 #include "standard-headers/linux/virtio_pci.h"
 #include "hw/virtio/virtio.h"
 #include "hw/pci/pci.h"
+#include "hw/pci/pci_bus.h"
 #include "qapi/error.h"
 #include "qemu/error-report.h"
 #include "hw/pci/msi.h"
diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
index d87f5f93e9..1273deb740 100644
--- a/include/hw/pci/pci.h
+++ b/include/hw/pci/pci.h
@@ -395,7 +395,6 @@ typedef PCIINTxRoute (*pci_route_irq_fn)(void *opaque, int pin);
 #define TYPE_PCIE_BUS "PCIE"
 
 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,
diff --git a/include/hw/pci/pci_bus.h b/include/hw/pci/pci_bus.h
index dfb75752cb..3a4d599da3 100644
--- a/include/hw/pci/pci_bus.h
+++ b/include/hw/pci/pci_bus.h
@@ -20,8 +20,14 @@ typedef struct PCIBusClass {
     uint16_t (*numa_node)(PCIBus *bus);
 } PCIBusClass;
 
+enum PCIBusFlags {
+    /* This bus is the root of a PCI domain */
+    PCI_BUS_IS_ROOT                                         = 0x0001,
+};
+
 struct PCIBus {
     BusState qbus;
+    enum PCIBusFlags flags;
     PCIIOMMUFunc iommu_fn;
     void *iommu_opaque;
     uint8_t devfn_min;
@@ -46,4 +52,9 @@ struct PCIBus {
     Notifier machine_done;
 };
 
+static inline bool pci_bus_is_root(PCIBus *bus)
+{
+    return !!(bus->flags & PCI_BUS_IS_ROOT);
+}
+
 #endif /* QEMU_PCI_BUS_H */
-- 
2.20.1