| Message ID | 20140624175126.17522.85549.stgit@bahia.local |
|---|---|
| State | New |
| Headers | show |
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 <mst@redhat.com> > Signed-off-by: Greg Kurz <gkurz@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;
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;
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 <mst@redhat.com> Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> --- hw/net/vhost_net.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)