From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34549) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WzUwC-0005Pi-3L for qemu-devel@nongnu.org; Tue, 24 Jun 2014 13:55:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WzUw2-0000FZ-DH for qemu-devel@nongnu.org; Tue, 24 Jun 2014 13:55:20 -0400 Received: from e06smtp10.uk.ibm.com ([195.75.94.106]:53544) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WzUw2-0000Er-56 for qemu-devel@nongnu.org; Tue, 24 Jun 2014 13:55:10 -0400 Received: from /spool/local by e06smtp10.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 24 Jun 2014 18:55:08 +0100 Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by d06dlp03.portsmouth.uk.ibm.com (Postfix) with ESMTP id 4A62F1B08040 for ; Tue, 24 Jun 2014 18:55:38 +0100 (BST) Received: from d06av08.portsmouth.uk.ibm.com (d06av08.portsmouth.uk.ibm.com [9.149.37.249]) by b06cxnps4076.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s5OHt6tB35455164 for ; Tue, 24 Jun 2014 17:55:06 GMT Received: from d06av08.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av08.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s5OHt5rS004508 for ; Tue, 24 Jun 2014 11:55:06 -0600 From: Greg Kurz Date: Tue, 24 Jun 2014 19:55:03 +0200 Message-ID: <20140624175126.17522.85549.stgit@bahia.local> In-Reply-To: <20140624151955.17522.62537.stgit@bahia.local> References: <20140624151955.17522.62537.stgit@bahia.local> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] [PATCH v9 22/22] vhost-net: disable when cross-endian List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , Peter Maydell , Stefan Hajnoczi , Juan Quintela , Rusty Russell , Alexander Graf , "Michael S. Tsirkin" , aneesh.kumar@linux.vnet.ibm.com, Anthony Liguori , Amit Shah , Paolo Bonzini , Andreas =?utf-8?q?F=C3=A4rber?= As of today, vhost assumes guest and host have the same endianness. This is definitely not compatible with modern PPC64 and ARM that can change endianness at runtime. Let's disable vhost-net and print an error message when we detect such a case: qemu-system-ppc64: vhost-net does not support cross-endian qemu-system-ppc64: unable to start vhost net: 38: falling back on userspace virtio This way users can continue to run VMs without changing their setup and have a chance to know that performance will impacted. Suggested-by: Michael S. Tsirkin Signed-off-by: Greg Kurz --- hw/net/vhost_net.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c index 7ac7c21..f87c798 100644 --- a/hw/net/vhost_net.c +++ b/hw/net/vhost_net.c @@ -275,6 +275,19 @@ static void vhost_net_stop_one(struct vhost_net *net, vhost_dev_disable_notifiers(&net->dev, dev); } +static bool vhost_net_device_endian_ok(VirtIODevice *vdev) +{ +#ifdef TARGET_IS_BIENDIAN +#ifdef HOST_WORDS_BIGENDIAN + return virtio_is_big_endian(vdev); +#else + return !virtio_is_big_endian(vdev); +#endif +#else + return true; +#endif +} + int vhost_net_start(VirtIODevice *dev, NetClientState *ncs, int total_queues) { @@ -283,6 +296,12 @@ int vhost_net_start(VirtIODevice *dev, NetClientState *ncs, VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus); int r, i = 0; + if (!vhost_net_device_endian_ok(dev)) { + error_report("vhost-net does not support cross-endian"); + r = -ENOSYS; + goto err; + } + if (!k->set_guest_notifiers) { error_report("binding does not support guest notifiers"); r = -ENOSYS;