[Qemu-devel] [PATCH 1/1] s390x: create a compat s390 phb for <=2.10

[Cornelia Huck <cohuck@redhat.com>]

d32bd032d8 ("s390x/ccw: create s390 phb conditionally") made
creating the s390 phb dependant on the zpci facility. This broke
migration from pre-cpu model machines which was fixed with
8ad9087c4a ("s390x/ccw: create s390 phb for compat reasons as well").
However, that is not enough: Migration from 2.10 with -cpu z13
breaks as well.

Let's create a phb for all pre-2.11 compat machines to fix this.
We leave the zpci facility off to avoid a guest-visible change
with cpu models on.

Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Fixes: d32bd032d8 ("s390x/ccw: create s390 phb conditionally")
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
---
 hw/s390x/s390-virtio-ccw.c         | 8 +++++++-
 include/hw/s390x/s390-virtio-ccw.h | 1 +
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index 1bcb7000ab..981f1c4336 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -247,6 +247,8 @@ 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;
@@ -266,7 +268,7 @@ 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()->phb_compat) {
         DeviceState *dev = qdev_create(NULL, TYPE_S390_PCI_HOST_BRIDGE);
         object_property_add_child(qdev_get_machine(),
                                   TYPE_S390_PCI_HOST_BRIDGE,
@@ -407,6 +409,7 @@ 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->phb_compat = false;
     mc->init = ccw_init;
     mc->reset = s390_machine_reset;
     mc->hot_add_cpu = s390_hot_add_cpu;
@@ -716,6 +719,9 @@ static void ccw_machine_2_10_instance_options(MachineState *machine)
 
 static void ccw_machine_2_10_class_options(MachineClass *mc)
 {
+    S390CcwMachineClass *s390mc = S390_MACHINE_CLASS(mc);
+
+    s390mc->phb_compat = pci_available;
     ccw_machine_2_11_class_options(mc);
     SET_MACHINE_COMPAT(mc, CCW_COMPAT_2_10);
 }
diff --git a/include/hw/s390x/s390-virtio-ccw.h b/include/hw/s390x/s390-virtio-ccw.h
index a9a90c2022..fb717afe92 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 phb_compat;
 } S390CcwMachineClass;
 
 /* runtime-instrumentation allowed by the machine */
-- 
2.13.5