[Qemu-devel] [PULL 2/4] virtio-ccw/migration: Migrate config vector for virtio devices

[Christian Borntraeger]

From: "Jason J. Herne" <address@hidden>

virtio_ccw_{save|load}_config are missing code to save and restore a vdev's
config_vector value. This causes some virtio devices to become disabled
following a migration.

This patch fixes a bug whereby the qmp/hmp balloon command (virsh setmem)
silently fails to update the guest's available memory because the device was not
properly migrated.

This will break compatibility, but vmstate_s390_cpu was bumped from
version 2 to version 4 between v2.3.0 and v2.4.0 without a compat
handler. Furthermore, there is no production environment yet so
migration is fenced anyway between any relevant version of 2.3 and 2.4.

Signed-off-by: Jason J. Herne <address@hidden>
Message-Id: <address@hidden>
Reviewed-by: Michael S. Tsirkin <address@hidden>
Signed-off-by: Christian Borntraeger <address@hidden>
---
 hw/s390x/virtio-ccw.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index ab629fe..ab5fc7f 100644
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -1311,6 +1311,7 @@ static void virtio_ccw_save_config(DeviceState *d, 
QEMUFile *f)
 {
     VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d);
     SubchDev *s = dev->sch;
+    VirtIODevice *vdev = virtio_ccw_get_vdev(s);
 
     subch_device_save(s, f);
     if (dev->indicators != NULL) {
@@ -1334,6 +1335,7 @@ static void virtio_ccw_save_config(DeviceState *d, 
QEMUFile *f)
         qemu_put_be32(f, 0);
         qemu_put_be64(f, 0UL);
     }
+    qemu_put_be16(f, vdev->config_vector);
     qemu_put_be64(f, dev->routes.adapter.ind_offset);
     qemu_put_byte(f, dev->thinint_isc);
 }
@@ -1342,6 +1344,7 @@ static int virtio_ccw_load_config(DeviceState *d, 
QEMUFile *f)
 {
     VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d);
     SubchDev *s = dev->sch;
+    VirtIODevice *vdev = virtio_ccw_get_vdev(s);
     int len;
 
     s->driver_data = dev;
@@ -1367,6 +1370,7 @@ static int virtio_ccw_load_config(DeviceState *d, 
QEMUFile *f)
         qemu_get_be64(f);
         dev->summary_indicator = NULL;
     }
+    qemu_get_be16s(f, &vdev->config_vector);
     dev->routes.adapter.ind_offset = qemu_get_be64(f);
     dev->thinint_isc = qemu_get_byte(f);
     if (s->thinint_active) {
-- 
2.3.0