From 371df9f5e0f175a1d8f2e9f2e86cf65f952b1c56 Mon Sep 17 00:00:00 2001 From: Greg Kurz Date: Tue, 24 Jun 2014 19:55:03 +0200 Subject: [PATCH] vhost-net: disable when cross-endian 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 be impacted. Suggested-by: Michael S. Tsirkin Signed-off-by: Greg Kurz Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- 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 7ac7c21bdb..f87c79824b 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;