From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54534) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aWfzH-0007Q7-FT for qemu-devel@nongnu.org; Fri, 19 Feb 2016 03:00:28 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aWfzF-0001wk-RH for qemu-devel@nongnu.org; Fri, 19 Feb 2016 03:00:27 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39645) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aWfzF-0001wg-Lm for qemu-devel@nongnu.org; Fri, 19 Feb 2016 03:00:25 -0500 Date: Fri, 19 Feb 2016 10:00:21 +0200 From: "Michael S. Tsirkin" Message-ID: <1455868726-26350-6-git-send-email-mst@redhat.com> References: <1455868726-26350-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1455868726-26350-1-git-send-email-mst@redhat.com> Subject: [Qemu-devel] [PULL 05/13] vhost: simplify vhost_needs_vring_endian() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Laurent Vivier , Peter Maydell , Cornelia Huck , Greg Kurz From: Greg Kurz After the call to virtio_vdev_has_feature(), we only care for legacy devices, so we don't need the extra check in virtio_is_big_endian(). Also the device_endian field is always set (VIRTIO_DEVICE_ENDIAN_UNKNOWN may only happen on a virtio_load() path that cannot lead here), so we don't need the assert() either. This open codes the device_endian checking in vhost_needs_vring_endian(). It also adds a comment to explain the logic, as recent reviews showed the cross-endian tweaks aren't that obvious. Signed-off-by: Greg Kurz Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Reviewed-by: Laurent Vivier Reviewed-by: Cornelia Huck --- hw/virtio/vhost.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index bb17177..9f8ac38 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c @@ -749,6 +749,11 @@ static void vhost_log_stop(MemoryListener *listener, /* FIXME: implement */ } +/* The vhost driver natively knows how to handle the vrings of non + * cross-endian legacy devices and modern devices. Only legacy devices + * exposed to a bi-endian guest may require the vhost driver to use a + * specific endianness. + */ static inline bool vhost_needs_vring_endian(VirtIODevice *vdev) { if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) { @@ -756,9 +761,9 @@ static inline bool vhost_needs_vring_endian(VirtIODevice *vdev) } #ifdef TARGET_IS_BIENDIAN #ifdef HOST_WORDS_BIGENDIAN - return !virtio_is_big_endian(vdev); + return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_LITTLE; #else - return virtio_is_big_endian(vdev); + return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_BIG; #endif #else return false; -- MST