virtio: Add transport feature handling stub for virtio_ring.

To prepare for virtio_ring transport feature bits, hook in a call in
all the users to manipulate them.  This currently just clears all the
bits, since it doesn't understand any features.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c
index 5953510e7d5f..79954bd6bfa5 100644
--- a/drivers/s390/kvm/kvm_virtio.c
+++ b/drivers/s390/kvm/kvm_virtio.c
@@ -95,6 +95,9 @@ static void kvm_finalize_features(struct virtio_device *vdev)
         /* Second half of bitmap is features we accept. */
         u8 *out_features = kvm_vq_features(desc) + desc->feature_len;
 
+        /* Give virtio_ring a chance to accept features. */
+        vring_transport_features(vdev);
+
         memset(out_features, 0, desc->feature_len);
         bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
         for (i = 0; i < bits; i++) {