We use transport revisions in virtio-ccw for introducing new commands
etc.; revision 1 denotes operating according to the standard. Legacy
devices do not understand the command to set a revision; for those, we
presume to operate at revision 0.
Add a parameter min_revision to be able to actively restrict use of
old transport revisions. In particular, setting a minimum revision
of 1 makes our driver act as a non-transitional driver.
With the default min_revision of 0, we continue to act as a
transitional driver.
Signed-off-by: Cornelia Huck <cohuck@xxxxxxxxxx>
---
drivers/s390/virtio/virtio_ccw.c | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)
diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index 54e686dca6de..0d3971dbc109 100644
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c
@@ -34,6 +34,16 @@
#include <asm/isc.h>
#include <asm/airq.h>
+/*
+ * Provide a knob to turn off support for older revisions. This is useful
+ * if we want to act as a non-transitional virtio device driver: requiring
+ * a minimum revision of 1 turns off support for legacy devices.
+ */
+static int min_revision;
+
+module_param(min_revision, int, 0444);
+MODULE_PARM_DESC(min_revision, "minimum transport revision to accept");
+
/*
* virtio related functions
*/
@@ -1271,7 +1281,10 @@ static int virtio_ccw_set_transport_rev(struct virtio_ccw_device *vcdev)
else
vcdev->revision--;
}
- } while (ret == -EOPNOTSUPP);
+ } while (vcdev->revision >= min_revision && ret == -EOPNOTSUPP);
+
+ if (ret == -EOPNOTSUPP && vcdev->revision < min_revision)
+ ret = -EINVAL;
ccw_device_dma_free(vcdev->cdev, ccw, sizeof(*ccw));
ccw_device_dma_free(vcdev->cdev, rev, sizeof(*rev));
@@ -1315,8 +1328,12 @@ static int virtio_ccw_online(struct ccw_device *cdev)
vcdev->vdev.id.device = cdev->id.cu_model;
ret = virtio_ccw_set_transport_rev(vcdev);
- if (ret)
+ if (ret) {
+ dev_warn(&cdev->dev,
+ "Could not set a supported transport revision: %d\n",
+ ret);
goto out_free;
+ }
ret = register_virtio_device(&vcdev->vdev);
if (ret) {
--
2.26.2
