From patchwork Fri Feb 19 08:00:21 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Michael S. Tsirkin" X-Patchwork-Id: 8357341 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id BF32CC0553 for ; Fri, 19 Feb 2016 08:03:25 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 2DC3B203F3 for ; Fri, 19 Feb 2016 08:03:25 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 67C06203EC for ; Fri, 19 Feb 2016 08:03:24 +0000 (UTC) Received: from localhost ([::1]:49577 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aWg27-0004mY-Rb for patchwork-qemu-devel@patchwork.kernel.org; Fri, 19 Feb 2016 03:03:23 -0500 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 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (Postfix) with ESMTPS id 154587AE88; Fri, 19 Feb 2016 08:00:25 +0000 (UTC) Received: from redhat.com (vpn1-5-108.ams2.redhat.com [10.36.5.108]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id u1J80MqW011726; Fri, 19 Feb 2016 03:00:23 -0500 Date: Fri, 19 Feb 2016 10:00:21 +0200 From: "Michael S. Tsirkin" To: qemu-devel@nongnu.org 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-Disposition: inline In-Reply-To: <1455868726-26350-1-git-send-email-mst@redhat.com> X-Mutt-Fcc: =sent X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: Laurent Vivier , Peter Maydell , Cornelia Huck , Greg Kurz Subject: [Qemu-devel] [PULL 05/13] vhost: simplify vhost_needs_vring_endian() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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;