[ovs-dev] [PATCH v8 5/5] datapath: add layer 3 support to ovs_packet_cmd_execute()

[Jesse Gross]

On Mon, Nov 17, 2014 at 1:50 PM, Lori Jakab <lojakab at cisco.com> wrote:
> On 11/17/14 8:03 PM, Jesse Gross wrote:
>> On Mon, Nov 17, 2014 at 9:24 AM, Lorand Jakab <lojakab at cisco.com> wrote:
>>> diff --git a/datapath/flow_netlink.c b/datapath/flow_netlink.c
>>> index 54510c8..8ca3469 100644
>>> --- a/datapath/flow_netlink.c
>>> +++ b/datapath/flow_netlink.c
>>> @@ -692,6 +692,18 @@ static int metadata_from_nlattrs(struct
>>> sw_flow_match *match,  u64 *attrs,
>>>                  else
>>>                          SW_FLOW_KEY_PUT(match, phy.is_layer3, true,
>>> is_mask);
>>>          }
>>> +       /* Layer 3 packets from user space have the EtherType as metadata
>>> */
>>> +       if (*attrs & (1ULL << OVS_KEY_ATTR_ETHERTYPE)) {
>>
>> Is this correct? I thought that EtherType wasn't serialized in this
>> case - in other places we extract this from the IP/IPv6 attribute
>> directly.
>
>
> For "ovs_flow" Netlink messages we can do that, but not for "ovs_packet"
> messages, which only have packet metadata, not the full flow key.  Packet
> metadata didn't include EtherType until now, but I unless we use the nibble
> from the IP version, we need to add it for layer 3 packets only.

Hmm, I see. I think that diverging the Netlink encoding for flow
installation vs. metadata is probably not a good idea over the long
term. If I remember correctly, I believe the reason for only encoding
part of the flow key for metadata was to reduce serialization cost.
Jarno is thinking about combining the packet execution with flow
installation, which would might make this a moot point. If that's the
case, then we can probably solve this issue by just using the full
flow key.