s390x/css: provide introspection for virtual subchannel and device busid

Expose the busids of the virtual I/O subchannel and the virtual CCW
device to ease debugging. This is needed because:
1. subchannel id are assigned dynamically, and cannot be set from
   outside.
2. device busid could possibly be auto generated.

An example of using HMP to retrieve the property values of a
virtio-balloon-ccw device looks like:

[root@localhost ~]# lscss -d 0.0.0004
Device   Subchan.  DevType CU Type Use  PIM PAM POM  CHPIDs
----------------------------------------------------------------------
0.0.0004 0.0.0003  0000/00 3832/05 yes  80  80  ff   00000000 00000000

(qemu) info qtree
... ...
      dev: virtio-balloon-ccw, id "balloon0"
        devno = "<unset>"
        ioeventfd = true
        max_revision = 2 (0x2)
        dev_id = "fe.0.0004"
        subch_id = "fe.0.0003"
... ...

After migration, if we have the same device that shows up on a
different subchannel, we must re-fill the subch_id of the ccw
device with the new schid, or the subch_id will have an old wrong
schid value. So this also re-fills the subch_id after migration.

While we are at it, also neaten the related error handling a bit.

Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/hw/s390x/ccw-device.c b/hw/s390x/ccw-device.c
index 28ea20440e..8fe3cf49ef 100644
--- a/hw/s390x/ccw-device.c
+++ b/hw/s390x/ccw-device.c
@@ -11,11 +11,50 @@
 #include "qemu/osdep.h"
 #include "ccw-device.h"
 
+static void ccw_device_refill_ids(CcwDevice *dev)
+{
+    SubchDev *sch = dev->sch;
+
+    assert(sch);
+
+    dev->dev_id.cssid = sch->cssid;
+    dev->dev_id.ssid = sch->ssid;
+    dev->dev_id.devid = sch->devno;
+    dev->dev_id.valid = true;
+
+    dev->subch_id.cssid = sch->cssid;
+    dev->subch_id.ssid = sch->ssid;
+    dev->subch_id.devid = sch->schid;
+    dev->subch_id.valid = true;
+}
+
+static void ccw_device_realize(CcwDevice *dev, Error **errp)
+{
+    ccw_device_refill_ids(dev);
+}
+
+static Property ccw_device_properties[] = {
+    DEFINE_PROP_CSS_DEV_ID_RO("dev_id", CcwDevice, dev_id),
+    DEFINE_PROP_CSS_DEV_ID_RO("subch_id", CcwDevice, subch_id),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void ccw_device_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    CCWDeviceClass *k = CCW_DEVICE_CLASS(klass);
+
+    k->realize = ccw_device_realize;
+    k->refill_ids = ccw_device_refill_ids;
+    dc->props = ccw_device_properties;
+}
+
 static const TypeInfo ccw_device_info = {
     .name = TYPE_CCW_DEVICE,
     .parent = TYPE_DEVICE,
     .instance_size = sizeof(CcwDevice),
     .class_size = sizeof(CCWDeviceClass),
+    .class_init = ccw_device_class_init,
     .abstract = true,
 };