[Qemu-ppc] [RFC PATCH qemu] spapr_pci: Create PCI-express root bus by default

[Alexey Kardashevskiy]

At the moment sPAPR PHB creates a root buf of TYPE_PCI_BUS type.
This means that vfio-pci devices attached to it (and this is
a default behaviour) hide PCIe extended capabilities as
the bus does not pass a pci_bus_is_express(pdev->bus) check.

This changes adds a default PCI bus type property to sPAPR PHB
and uses TYPE_PCIE_BUS if none passed; older machines get TYPE_PCI_BUS
for backward compatibility as a bus type is used in the bus name
so the root bus name becomes "pcie.0" instead of "pci.0".

Signed-off-by: Alexey Kardashevskiy <address@hidden>
---

What can possibly go wrong with such change of a name?
>From devices prospective, I cannot see any.

libvirt might get upset as "pci.0" will not be available,
will it make sense to create pcie.0 as a root bus and always
add a PCIe->PCI bridge and name its bus "pci.0"?

Or create root bus from TYPE_PCIE_BUS and force name to "pci.0"?
pci_register_bus() can do this.


---
 hw/ppc/spapr.c              | 5 +++++
 hw/ppc/spapr_pci.c          | 5 ++++-
 include/hw/pci-host/spapr.h | 1 +
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 0b3820b..a268511 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2541,6 +2541,11 @@ DEFINE_SPAPR_MACHINE(2_8, "2.8", true);
         .driver   = TYPE_SPAPR_PCI_HOST_BRIDGE,     \
         .property = "mem64_win_size",               \
         .value    = "0",                            \
+    },                                              \
+    {                                               \
+        .driver   = TYPE_SPAPR_PCI_HOST_BRIDGE,     \
+        .property = "root_bus_type",                \
+        .value    = TYPE_PCI_BUS,                   \
     },
 
 static void phb_placement_2_7(sPAPRMachineState *spapr, uint32_t index,
diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 7cde30e..2fa1f22 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -1434,7 +1434,9 @@ static void spapr_phb_realize(DeviceState *dev, Error 
**errp)
     bus = pci_register_bus(dev, NULL,
                            pci_spapr_set_irq, pci_spapr_map_irq, sphb,
                            &sphb->memspace, &sphb->iospace,
-                           PCI_DEVFN(0, 0), PCI_NUM_PINS, TYPE_PCI_BUS);
+                           PCI_DEVFN(0, 0), PCI_NUM_PINS,
+                           sphb->root_bus_type ? sphb->root_bus_type :
+                           TYPE_PCIE_BUS);
     phb->bus = bus;
     qbus_set_hotplug_handler(BUS(phb->bus), DEVICE(sphb), NULL);
 
@@ -1590,6 +1592,7 @@ static Property spapr_phb_properties[] = {
     DEFINE_PROP_UINT64("pgsz", sPAPRPHBState, page_size_mask,
                        (1ULL << 12) | (1ULL << 16)),
     DEFINE_PROP_UINT32("numa_node", sPAPRPHBState, numa_node, -1),
+    DEFINE_PROP_STRING("root_bus_type", sPAPRPHBState, root_bus_type),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/include/hw/pci-host/spapr.h b/include/hw/pci-host/spapr.h
index b92c1b5..a4ee873 100644
--- a/include/hw/pci-host/spapr.h
+++ b/include/hw/pci-host/spapr.h
@@ -79,6 +79,7 @@ struct sPAPRPHBState {
     uint64_t dma64_win_addr;
 
     uint32_t numa_node;
+    char *root_bus_type;
 };
 
 #define SPAPR_PCI_MEM_WIN_BUS_OFFSET 0x80000000ULL
-- 
2.5.0.rc3