Implementing a simple TAP PMD to dpdk-vhost structure

[David Marchand]

On Wed, Sep 6, 2023 at 9:53 AM Nicolson Ken (ニコルソン ケン)
<ken.nicolson at jp.panasonic.com> wrote:
> > Alternatively, did you consider using testpmd with the vhost pmd instead ?
>
> I've tried that before, but as far as I can see from net/vhost/rte_eth_host.c it uses rte_vost_enqueue/dequeue_burst() to basically act as a loopback for the Guest OS. I use:
>
> $ sudo dpdk-testpmd -l 0-3 -n 4 --vdev 'net_tap0' --vdev 'net_vhost1,iface=/tmp/sock0,client=1' -- -i
>
> But if I feed data in using "tcpreplay -I dtap0 ...", "show port stats all" shows everything going into the TAP but nothing is forward to vhost.

Well, pinging from a dtap0 netdev in the host to a virtio-net netdev
in a guest works me.

testpmd> set verbose 3
Change verbose level from 0 to 3
testpmd> start
io packet forwarding - ports=2 - cores=1 - streams=2 - NUMA support
enabled, MP allocation mode: native
Logical Core 1 (socket 1) forwards packets on 2 streams:
  RX P=0/Q=0 (socket 0) -> TX P=1/Q=0 (socket 0) peer=02:00:00:00:00:01
  RX P=1/Q=0 (socket 0) -> TX P=0/Q=0 (socket 0) peer=02:00:00:00:00:00

port 0/queue 0: received 16 packets
  src=26:9B:E2:29:7E:C6 - dst=33:33:00:00:00:16 - pool=mb_pool_0 -
type=0x86dd - length=90 - nb_segs=1 - hw ptype: L2_ETHER L3_IPV6_EXT
- sw ptype: L2_ETHER L3_IPV6_EXT  - l2_len=14 - l3_len=48 - Receive
queue=0x0
  ol_flags: RTE_MBUF_F_RX_L4_CKSUM_UNKNOWN
RTE_MBUF_F_RX_IP_CKSUM_UNKNOWN RTE_MBUF_F_RX_OUTER_L4_CKSUM_UNKNOWN
  src=26:9B:E2:29:7E:C6 - dst=33:33:00:00:00:16 - pool=mb_pool_0 -
type=0x86dd - length=90 - nb_segs=1 - hw ptype: L2_ETHER L3_IPV6_EXT
- sw ptype: L2_ETHER L3_IPV6_EXT  - l2_len=14 - l3_len=48 - Receive
queue=0x0
  ol_flags: RTE_MBUF_F_RX_L4_CKSUM_UNKNOWN
RTE_MBUF_F_RX_IP_CKSUM_UNKNOWN RTE_MBUF_F_RX_OUTER_L4_CKSUM_UNKNOWN
  src=26:9B:E2:29:7E:C6 - dst=33:33:FF:29:7E:C6 - pool=mb_pool_0 -
type=0x86dd - length=86 - nb_segs=1 - hw ptype: L2_ETHER L3_IPV6  - sw
ptype: L2_ETHER L3_IPV6  - l2_len=14 - l3_len=40 - Receive queue=0x0
  ol_flags: RTE_MBUF_F_RX_L4_CKSUM_UNKNOWN
RTE_MBUF_F_RX_IP_CKSUM_UNKNOWN RTE_MBUF_F_RX_OUTER_L4_CKSUM_UNKNOWN


Are you seeing the vhost port getting initialised in testpmd output?
How are you sure that nothing is forwarded?


-- 
David Marchand