[PATCH v3 2/6] virtio_ccw: legacy: don't negotiate rev 1/features

Michael S. Tsirkin
2014-12-08T13:05:54Z

Legacy balloon device doesn't pretend to support revision 1 or 64 bit
features.

But just in case someone implements a broken one that does, let's not
even try to drive legacy only devices using revision 1, and let's not
give them a chance to say they support VIRTIO_F_VERSION_1 by not reading
high feature bits.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
drivers/s390/kvm/virtio_ccw.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
index 4a3e6e5..c792b5f 100644
--- a/drivers/s390/kvm/virtio_ccw.c
+++ b/drivers/s390/kvm/virtio_ccw.c
@@ -733,6 +733,9 @@ static u64 virtio_ccw_get_features(struct virtio_device *vdev)

rc = le32_to_cpu(features->features);

+ if (vcdev->revision == 0)
+ goto out_free;
+
/* Read second half of the feature bits from the host. */
features->index = 1;
ccw->cmd_code = CCW_CMD_READ_FEAT;
@@ -775,6 +778,9 @@ static void virtio_ccw_finalize_features(struct virtio_device *vdev)
ccw->cda = (__u32)(unsigned long)features;
ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_WRITE_FEAT);

+ if (vcdev->revision == 0)
+ goto out_free;
+
features->index = 1;
features->features = cpu_to_le32(vdev->features >> 32);
/* Write the second half of the feature bits to the host. */
@@ -1182,9 +1188,13 @@ static int virtio_ccw_online(struct ccw_device *cdev)
vcdev->vdev.id.vendor = cdev->id.cu_type;
vcdev->vdev.id.device = cdev->id.cu_model;

- ret = virtio_ccw_set_transport_rev(vcdev);
- if (ret)
- goto out_free;
+ if (virtio_device_is_legacy_only(vcdev->vdev.id)) {
+ vcdev->revision = 0;
+ } else {
+ ret = virtio_ccw_set_transport_rev(vcdev);
+ if (ret)
+ goto out_free;
+ }

ret = register_virtio_device(&vcdev->vdev);
if (ret) {
--
MST