s390-virtio: clear {used,avail}_event_idx on reset as well

The old s390-virtio transport clears the vring used/avail indices in
the shared area on reset. When we enabled event_idx for virtio-blk, we
noticed that this is not enough: We also need to clear the published
used/avail event indices, or reboot will fail.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>

hw/s390x/s390-virtio-bus.c

@@ -77,10 +77,18 @@ void s390_virtio_reset_idx(VirtIOS390Device *dev)
             VIRTIO_VRING_AVAIL_IDX_OFFS;
         address_space_stw(&address_space_memory, idx_addr, 0,
                           MEMTXATTRS_UNSPECIFIED, NULL);
+        idx_addr = virtio_queue_get_avail_addr(dev->vdev, i) +
+            virtio_queue_get_avail_size(dev->vdev, i);
+        address_space_stw(&address_space_memory, idx_addr, 0,
+                          MEMTXATTRS_UNSPECIFIED, NULL);
         idx_addr = virtio_queue_get_used_addr(dev->vdev, i) +
             VIRTIO_VRING_USED_IDX_OFFS;
         address_space_stw(&address_space_memory, idx_addr, 0,
                           MEMTXATTRS_UNSPECIFIED, NULL);
+        idx_addr = virtio_queue_get_used_addr(dev->vdev, i) +
+            virtio_queue_get_used_size(dev->vdev, i);
+        address_space_stw(&address_space_memory, idx_addr, 0,
+                          MEMTXATTRS_UNSPECIFIED, NULL);
     }
 }