Re: [Qemu-devel] [PATCH V6 02/10] net/filter-mirror.c: Make filter mirror support vnet support.

[Jason Wang <jasowang@redhat.com>]

On 2017年06月14日 16:04, Zhang Chen wrote:
>
>
> On 06/13/2017 05:14 PM, Jason Wang wrote:
>>
>>
>> On 2017年06月12日 17:27, Zhang Chen wrote:
>>>>
>>>>> +        if (nf->direction == NET_FILTER_DIRECTION_RX ||
>>>>> +            nf->direction == NET_FILTER_DIRECTION_ALL) {
>>>>> +            vnet_hdr_len = nf->netdev->vnet_hdr_len;
>>>>
>>>> This can only work if e.g virtio-net set its own vnet_hdr_len. But 
>>>> looks like it use guest_hdr_len instead.
>>>
>>> I see in hw/net/virtio-net.c use the 
>>> "qemu_set_vnet_hdr_len(nc->peer, n->guest_hdr_len);" to
>>> set the nf->netdev->vnet_hdr_len, any case not include here? 
>>
>> You mean:
>>
>>         if (peer_has_vnet_hdr(n) &&
>>             qemu_has_vnet_hdr_len(nc->peer, n->guest_hdr_len)) {
>>             qemu_set_vnet_hdr_len(nc->peer, n->guest_hdr_len);
>>             n->host_hdr_len = n->guest_hdr_len;
>>         }
>>
>> ?
>>
>> From the code, it only set peer's vnet header when peer supports 
>> vnet_hdr up to n->guest_hdr_len. If peer can't, virtio-net will strip 
>> the header.
>
> So, We should get the n->guest_hdr_len in another way? like set a new 
> parameter in NetClientState?
> Any suggestion about it?
>
> Thanks
> Zhang Chen

Rethink about this, a question is do we really care guest vnet header 
len? During guest transmission, when packet reaches netfilter. The 
vnet_header should have been stripped to netdev->vnet_hdr_len.

I still think use nf->netdev->vnet_hdr_len is sufficient.

Thanks

>
>>
>> Thanks
>>
>>
>>
>