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-rw-r--r--drivers/s390/virtio/virtio_ccw.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index c188e4f20ca3..97e51c34e6cf 100644
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c
@@ -971,6 +971,10 @@ static void virtio_ccw_set_status(struct virtio_device *vdev, u8 status)
ccw->flags = 0;
ccw->count = sizeof(status);
ccw->cda = (__u32)(unsigned long)&vcdev->dma_area->status;
+ /* We use ssch for setting the status which is a serializing
+ * instruction that guarantees the memory writes have
+ * completed before ssch.
+ */
ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_WRITE_STATUS);
/* Write failed? We assume status is unchanged. */
if (ret)