virtio: add feature checking helpers

Add a helper function for checking whether a bit is set in the guest
features for a vdev as well as one that works on a feature bit set.

Convert code that open-coded this: It cleans up the code and makes it
easier to extend the guest feature bits.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index 85e72d6fd9..d95f8b6d50 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -231,6 +231,17 @@ static inline void virtio_clear_feature(uint32_t *features, unsigned int fbit)
     *features &= ~(1 << fbit);
 }
 
+static inline bool __virtio_has_feature(uint32_t features, unsigned int fbit)
+{
+    assert(fbit < 32);
+    return !!(features & (1 << fbit));
+}
+
+static inline bool virtio_has_feature(VirtIODevice *vdev, unsigned int fbit)
+{
+    return __virtio_has_feature(vdev->guest_features, fbit);
+}
+
 static inline bool virtio_is_big_endian(VirtIODevice *vdev)
 {
     assert(vdev->device_endian != VIRTIO_DEVICE_ENDIAN_UNKNOWN);