On 11/01/2016 17:13, Greg Kurz wrote: > Indeed vhost doesn't need to ask for vring endian fixing if the device is > virtio 1.0, since it is already handled by the in-kernel vhost driver. This > patch simply consolidates the logic into the existing helper. > > Signed-off-by: Greg Kurz <gk...@linux.vnet.ibm.com> > Reviewed-by: Cornelia Huck <cornelia.h...@de.ibm.com> > --- > hw/virtio/vhost.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c > index 2e1e792d599e..aef750df22ad 100644 > --- a/hw/virtio/vhost.c > +++ b/hw/virtio/vhost.c > @@ -750,6 +750,9 @@ static void vhost_log_stop(MemoryListener *listener, > > static inline bool vhost_needs_vring_endian(VirtIODevice *vdev) > { > + if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) { > + return false; > + } > #ifdef TARGET_IS_BIENDIAN > #ifdef HOST_WORDS_BIGENDIAN > return !virtio_is_big_endian(vdev);
I'm wondering if in term of performance you can remove the call of virtio_vdev_has_feature() as it is done in virtio_is_big_endian(). > @@ -811,8 +814,7 @@ static int vhost_virtqueue_start(struct vhost_dev *dev, > return -errno; > } > > - if (!virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1) && > - vhost_needs_vring_endian(vdev)) { > + if (vhost_needs_vring_endian(vdev)) { > r = vhost_virtqueue_set_vring_endian_legacy(dev, > > virtio_is_big_endian(vdev), > vhost_vq_index); > @@ -908,8 +910,7 @@ static void vhost_virtqueue_stop(struct vhost_dev *dev, > /* In the cross-endian case, we need to reset the vring endianness to > * native as legacy devices expect so by default. > */ > - if (!virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1) && > - vhost_needs_vring_endian(vdev)) { > + if (vhost_needs_vring_endian(vdev)) { > r = vhost_virtqueue_set_vring_endian_legacy(dev, > > !virtio_is_big_endian(vdev), > vhost_vq_index); > >