From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44122) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aImkl-0002vY-FV for qemu-devel@nongnu.org; Mon, 11 Jan 2016 19:24:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aImki-0005bj-Aa for qemu-devel@nongnu.org; Mon, 11 Jan 2016 19:24:03 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35177) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aImki-0005ba-4q for qemu-devel@nongnu.org; Mon, 11 Jan 2016 19:24:00 -0500 References: <20160111161156.17428.20668.stgit@bahia.huguette.org> <20160111161306.17428.37423.stgit@bahia.huguette.org> From: Laurent Vivier Message-ID: <5694479C.9070808@redhat.com> Date: Tue, 12 Jan 2016 01:23:56 +0100 MIME-Version: 1.0 In-Reply-To: <20160111161306.17428.37423.stgit@bahia.huguette.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 4/5] vhost: move virtio 1.0 check to cross-endian helper List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Greg Kurz , "Michael S. Tsirkin" Cc: qemu-devel@nongnu.org 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 > Reviewed-by: Cornelia Huck > --- > 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); > >