On Tue, Jun 24, 2014 at 07:55:03PM +0200, Greg Kurz wrote:
> 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.
s/will/will be/
>
> Suggested-by: Michael S. Tsirkin <m...@redhat.com>
> Signed-off-by: Greg Kurz <gk...@linux.vnet.ibm.com>
> ---
> 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;
