virtio: assert 32 bit features in transports

At this point, no transports set any of the high 32 feature bits.
Since transports generally can't (yet) cope with such bits, add BUG_ON
checks to make sure they are not set by mistake.

Based on rproc patch by Rusty.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/misc/mic/card/mic_virtio.c b/drivers/misc/mic/card/mic_virtio.c
index f5e756132bdb..d027d299602f 100644
--- a/drivers/misc/mic/card/mic_virtio.c
+++ b/drivers/misc/mic/card/mic_virtio.c
@@ -96,6 +96,9 @@ static void mic_finalize_features(struct virtio_device *vdev)
         /* Give virtio_ring a chance to accept features. */
         vring_transport_features(vdev);
 
+        /* Make sure we don't have any features > 32 bits! */
+        BUG_ON((u32)vdev->features != vdev->features);
+
         memset_io(out_features, 0, feature_len);
         bits = min_t(unsigned, feature_len,
                 sizeof(vdev->features)) * 8;