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vhost-net: disable when cross-endian

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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 <mst@redhat.com>
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Greg Kurz 2014-06-24 19:55:03 +02:00 committed by Michael S. Tsirkin
parent 7826c2b2a4
commit 371df9f5e0
1 changed files with 19 additions and 0 deletions
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19
hw/net/vhost_net.c
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@ -275,6 +275,19 @@ static void vhost_net_stop_one(struct vhost_net *net,
vhost_dev_disable_notifiers(&net->dev, dev); 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 vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
int total_queues) int total_queues)
{ {
@ -283,6 +296,12 @@ int vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus); VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
int r, i = 0; 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) { if (!k->set_guest_notifiers) {
error_report("binding does not support guest notifiers"); error_report("binding does not support guest notifiers");
r = -ENOSYS; r = -ENOSYS;