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>

2 files changed, 6 insertions, 0 deletions

diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index c63d0efa947b..aec1daee9ada 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -159,6 +159,9 @@ static void vm_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);
+
         writel(0, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES_SEL);
         writel(vdev->features, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES);
 }
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 7e0efa7fc384..dd6df979862b 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -119,6 +119,9 @@ static void vp_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);
+
         /* We only support 32 feature bits. */
         iowrite32(vdev->features, vp_dev->ioaddr + VIRTIO_PCI_GUEST_FEATURES);
 }