[Qemu-devel] [PATCH RFC 1/1] s390x/ccw: create s390 phb for compat reasons as well

[Cornelia Huck <cohuck@redhat.com>]

d32bd032d8 ("s390x/ccw: create s390 phb conditionally") made
registering the s390 pci host bridge conditional on presense
of the zpci facility bit. Sadly, that breaks migration from
some old machines.

Create the s390 phb if we need it for compat reasons, even if
we don't provide the zpci facility.

Fixes: d32bd032d8 ("s390x/ccw: create s390 phb conditionally")
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
---
 hw/s390x/s390-virtio-ccw.c         | 6 +++++-
 include/hw/s390x/s390-virtio-ccw.h | 1 +
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index 0471407187..7e3148eb4a 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -269,6 +269,8 @@ static void s390_create_virtio_net(BusState *bus, const char *name)
     }
 }
 
+static S390CcwMachineClass *get_machine_class(void);
+
 static void ccw_init(MachineState *machine)
 {
     int ret;
@@ -288,7 +290,7 @@ static void ccw_init(MachineState *machine)
                       machine->initrd_filename, "s390-ccw.img",
                       "s390-netboot.img", true);
 
-    if (s390_has_feat(S390_FEAT_ZPCI)) {
+    if (s390_has_feat(S390_FEAT_ZPCI) || get_machine_class()->pci_compat) {
         DeviceState *dev = qdev_create(NULL, TYPE_S390_PCI_HOST_BRIDGE);
         object_property_add_child(qdev_get_machine(),
                                   TYPE_S390_PCI_HOST_BRIDGE,
@@ -429,6 +431,7 @@ static void ccw_machine_class_init(ObjectClass *oc, void *data)
     s390mc->cpu_model_allowed = true;
     s390mc->css_migration_enabled = true;
     s390mc->gs_allowed = true;
+    s390mc->pci_compat = false;
     mc->init = ccw_init;
     mc->reset = s390_machine_reset;
     mc->hot_add_cpu = s390_hot_add_cpu;
@@ -784,6 +787,7 @@ static void ccw_machine_2_7_class_options(MachineClass *mc)
     S390CcwMachineClass *s390mc = S390_MACHINE_CLASS(mc);
 
     s390mc->cpu_model_allowed = false;
+    s390mc->pci_compat = pci_available;
     ccw_machine_2_8_class_options(mc);
     SET_MACHINE_COMPAT(mc, CCW_COMPAT_2_7);
 }
diff --git a/include/hw/s390x/s390-virtio-ccw.h b/include/hw/s390x/s390-virtio-ccw.h
index a9a90c2022..9978c89e90 100644
--- a/include/hw/s390x/s390-virtio-ccw.h
+++ b/include/hw/s390x/s390-virtio-ccw.h
@@ -41,6 +41,7 @@ typedef struct S390CcwMachineClass {
     bool cpu_model_allowed;
     bool css_migration_enabled;
     bool gs_allowed;
+    bool pci_compat;
 } S390CcwMachineClass;
 
 /* runtime-instrumentation allowed by the machine */
-- 
2.13.5