[PATCH RFC 1/2] virtio/s390: add parameter for minimum revision
From: Cornelia Huck <cohuck@redhat.com>
Date: 2021-03-04 13:29:56
Also in:
kvm, linux-s390
Subsystem:
s390 architecture, the rest, virtio drivers for s390 · Maintainers:
Heiko Carstens, Vasily Gorbik, Alexander Gordeev, Linus Torvalds, Cornelia Huck, Halil Pasic, Eric Farman
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@redhat.com> --- 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
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