Linux Virtualization - Dec 2016 - [PATCH net 7/9] virtio-net: forbid XDP when VIRTIO_NET_F_GUEST_UFO is support

On 16-12-23 06:37 AM, Jason Wang wrote:
> When VIRTIO_NET_F_GUEST_UFO is negotiated, host could still send UFO
> packet that exceeds a single page which could not be handled
> correctly by XDP. So this patch forbids setting XDP when GUEST_UFO is
> supported. While at it, forbid XDP for ECN (which comes only from GRO)
> too to prevent user from misconfiguration.
> 
> Cc: John Fastabend <john.r.fastabend at intel.com>
> Signed-off-by: Jason Wang <jasowang at redhat.com>
> ---
>  drivers/net/virtio_net.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 77ae358..c1f66d8 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1684,7 +1684,9 @@ static int virtnet_xdp_set(struct net_device *dev,
struct bpf_prog *prog)
>  	int i, err;
>  
>  	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
> -	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6)) {
> +	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6) ||
> +	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_ECN) ||
> +	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_UFO)) {
>  		netdev_warn(dev, "can't set XDP while host is implementing LRO,
disable LRO first\n");
>  		return -EOPNOTSUPP;
>  	}
> 
Acked-by: John Fastabend <john.r.fastabend at intel.com>

On 16-12-23 08:02 AM, John Fastabend wrote:
> On 16-12-23 06:37 AM, Jason Wang wrote:
>> When VIRTIO_NET_F_GUEST_UFO is negotiated, host could still send UFO
>> packet that exceeds a single page which could not be handled
>> correctly by XDP. So this patch forbids setting XDP when GUEST_UFO is
>> supported. While at it, forbid XDP for ECN (which comes only from GRO)
>> too to prevent user from misconfiguration.
>>
Is sending packets greater than single page though normal in this case?
I don't have any need to support big packet mode other than MST asked
for it. And I wasn't seeing this in my tests. MTU is capped at 4k - hdr
when XDP is enabled.

.John
>> Cc: John Fastabend <john.r.fastabend at intel.com>
>> Signed-off-by: Jason Wang <jasowang at redhat.com>
>> ---
>>  drivers/net/virtio_net.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index 77ae358..c1f66d8 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -1684,7 +1684,9 @@ static int virtnet_xdp_set(struct net_device
*dev, struct bpf_prog *prog)
>>  	int i, err;
>>  
>>  	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
>> -	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6)) {
>> +	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6) ||
>> +	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_ECN) ||
>> +	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_UFO)) {
>>  		netdev_warn(dev, "can't set XDP while host is implementing
LRO, disable LRO first\n");
>>  		return -EOPNOTSUPP;
>>  	}
>>
> 
> Acked-by: John Fastabend <john.r.fastabend at intel.com>
>

On 2016?12?24? 00:10, John Fastabend wrote:
> On 16-12-23 08:02 AM, John Fastabend wrote:
>> On 16-12-23 06:37 AM, Jason Wang wrote:
>>> When VIRTIO_NET_F_GUEST_UFO is negotiated, host could still send
UFO
>>> packet that exceeds a single page which could not be handled
>>> correctly by XDP. So this patch forbids setting XDP when GUEST_UFO
is
>>> supported. While at it, forbid XDP for ECN (which comes only from
GRO)
>>> too to prevent user from misconfiguration.
>>>
> Is sending packets greater than single page though normal in this case?
Yes, when NETIF_F_UFO was enabled for tap, it won't segment UFO packet 
and will send it directly to guest. (This could be reproduced with 
UDP_STREAM between two guests or host to guest).

Thanks
> I don't have any need to support big packet mode other than MST asked
> for it. And I wasn't seeing this in my tests. MTU is capped at 4k - hdr
> when XDP is enabled.
>
> .John
>
>>> Cc: John Fastabend <john.r.fastabend at intel.com>
>>> Signed-off-by: Jason Wang <jasowang at redhat.com>
>>> ---
>>>   drivers/net/virtio_net.c | 4 +++-
>>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>>> index 77ae358..c1f66d8 100644
>>> --- a/drivers/net/virtio_net.c
>>> +++ b/drivers/net/virtio_net.c
>>> @@ -1684,7 +1684,9 @@ static int virtnet_xdp_set(struct net_device
*dev, struct bpf_prog *prog)
>>>   	int i, err;
>>>   
>>>   	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
>>> -	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6)) {
>>> +	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6) ||
>>> +	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_ECN) ||
>>> +	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_UFO)) {
>>>   		netdev_warn(dev, "can't set XDP while host is
implementing LRO, disable LRO first\n");
>>>   		return -EOPNOTSUPP;
>>>   	}
>>>
>> Acked-by: John Fastabend <john.r.fastabend at intel.com>
>>