pseries: Don't expose PCIe extended config space on older machine types

bb998645 "spapr_pci: Advertise access to PCIe extended config space"
allowed guests to access the extended config space of PCI Express devices
via the PAPR interfaces, even though the paravirtualized bus mostly acts
like plain PCI.

However, that patch enabled access unconditionally, including for existing
machine types, which is an unwise change in behaviour.  This patch limits
the change to pseries-2.9 (and later) machine types.
Suggested-by: NAndrea Bolognani <abologna@redhat.com>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr.c

@@ -3163,8 +3163,13 @@ DEFINE_SPAPR_MACHINE(2_9, "2.9", true);
 /*
  * pseries-2.8
  */
-#define SPAPR_COMPAT_2_8                            \
-    HW_COMPAT_2_8
+#define SPAPR_COMPAT_2_8                                        \
+    HW_COMPAT_2_8                                               \
+    {                                                           \
+        .driver   = TYPE_SPAPR_PCI_HOST_BRIDGE,                 \
+        .property = "pcie-extended-configuration-space",        \
+        .value    = "off",                                      \
+    },
 
 static void spapr_machine_2_8_instance_options(MachineState *machine)
 {

hw/ppc/spapr_pci.c

@@ -1321,7 +1321,7 @@ static int spapr_populate_pci_child_dt(PCIDevice *dev, void *fdt, int offset,
     _FDT(fdt_setprop(fdt, offset, "assigned-addresses",
                      (uint8_t *)rp.assigned, rp.assigned_len));
 
-    if (pci_is_express(dev)) {
+    if (sphb->pcie_ecs && pci_is_express(dev)) {
         _FDT(fdt_setprop_cell(fdt, offset, "ibm,pci-config-space-type", 0x1));
     }
 
@@ -1858,6 +1858,8 @@ static Property spapr_phb_properties[] = {
     DEFINE_PROP_UINT32("numa_node", sPAPRPHBState, numa_node, -1),
     DEFINE_PROP_BOOL("pre-2.8-migration", sPAPRPHBState,
                      pre_2_8_migration, false),
+    DEFINE_PROP_BOOL("pcie-extended-configuration-space", sPAPRPHBState,
+                     pcie_ecs, true),
     DEFINE_PROP_END_OF_LIST(),
 };
 

include/hw/pci-host/spapr.h

@@ -80,6 +80,8 @@ struct sPAPRPHBState {
 
     uint32_t numa_node;
 
+    bool pcie_ecs; /* Allow access to PCIe extended config space? */
+
     /* Fields for migration compatibility hacks */
     bool pre_2_8_migration;
     uint32_t mig_liobn;