[ovs-dev] [PATCH V2 05/14] netdev-offload-dpdk: Implement HW miss packet recover for vport

[Eli Britstein]

On 2/23/2021 3:10 PM, Sriharsha Basavapatna wrote:
> On Wed, Feb 10, 2021 at 8:57 PM Eli Britstein <elibr at nvidia.com> wrote:
>> A miss in virtual port offloads means the flow with tnl_pop was
>> offloaded, but not the following one. Recover the state and continue
>> with SW processing.
> Relates to my comment on Patch-1; please explain what is meant by
> recovering the packet state.
See my response there.
>
>> Signed-off-by: Eli Britstein <elibr at nvidia.com>
>> Reviewed-by: Gaetan Rivet <gaetanr at nvidia.com>
>> ---
>>   lib/netdev-offload-dpdk.c | 95 +++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 95 insertions(+)
>>
>> diff --git a/lib/netdev-offload-dpdk.c b/lib/netdev-offload-dpdk.c
>> index 8cc90d0f1..21aa26b42 100644
>> --- a/lib/netdev-offload-dpdk.c
>> +++ b/lib/netdev-offload-dpdk.c
>> @@ -1610,6 +1610,100 @@ netdev_offload_dpdk_flow_dump_destroy(struct netdev_flow_dump *dump)
>>       return 0;
>>   }
>>
>> +static struct netdev *
>> +get_vport_netdev(const char *dpif_type,
>> +                 struct rte_flow_tunnel *tunnel,
>> +                 odp_port_t *odp_port)
>> +{
>> +    const struct netdev_tunnel_config *tnl_cfg;
>> +    struct netdev_flow_dump **netdev_dumps;
>> +    struct netdev *vport = NULL;
>> +    bool found = false;
>> +    int num_ports = 0;
>> +    int err;
>> +    int i;
>> +
>> +    netdev_dumps = netdev_ports_flow_dump_create(dpif_type, &num_ports, false);
> This relates to my comment in Patch-3; flow_dump_create() in this
> context is very confusing since we are not really dumping flows. We
> might as well walk the list of ports/netdevs looking for a specific
> netdev, just like other netdev_ports_*() routines in netdev-offload.c;
> may be add a new function in netdev-offload.c:
As in the response there. I used an existing API, not introducing new ones.
>
> netdev_ports_get_tunnel_vport(dpif_type, tunnel_type, tp_dst):    /*
> example: tunnel_type == "vxlan", tp_dst = 4789 */
>
> HMAP_FOR_EACH (data, portno_node, &port_to_netdev) {
>      if (netdev_get_dpif_type(data->netdev) == dpif_type &&
>          netdev_get_type(data->netdev) == tunnel_type) {
>              tnl_cfg = netdev_get_tunnel_config(data->netdev);
>               if (tnl_cfg && tnl_cfg->dst_port == tp_dst) {
>               ....
>               ....
>              }
>      }
>
>> +    for (i = 0; i < num_ports; i++) {
>> +        if (!found && tunnel->type == RTE_FLOW_ITEM_TYPE_VXLAN &&
>> +            !strcmp(netdev_get_type(netdev_dumps[i]->netdev), "vxlan")) {
>> +            tnl_cfg = netdev_get_tunnel_config(netdev_dumps[i]->netdev);
>> +            if (tnl_cfg && tnl_cfg->dst_port == tunnel->tp_dst) {
>> +                found = true;
>> +                vport = netdev_dumps[i]->netdev;
>> +                netdev_ref(vport);
>> +                *odp_port = netdev_dumps[i]->port;
>> +            }
>> +        }
>> +        err = netdev_flow_dump_destroy(netdev_dumps[i]);
>> +        if (err != 0 && err != EOPNOTSUPP) {
>> +            VLOG_ERR("failed dumping netdev: %s", ovs_strerror(err));
>> +        }
>> +    }
>> +    return vport;
>> +}
>> +
>> +static int
>> +netdev_offload_dpdk_hw_miss_packet_recover(struct netdev *netdev,
>> +                                           struct dp_packet *packet)
>> +{
>> +    struct rte_flow_restore_info rte_restore_info;
>> +    struct rte_flow_tunnel *rte_tnl;
>> +    struct rte_flow_error error;
>> +    struct netdev *vport_netdev;
>> +    struct pkt_metadata *md;
>> +    struct flow_tnl *md_tnl;
>> +    odp_port_t vport_odp;
>> +
>> +    if (netdev_dpdk_rte_flow_get_restore_info(netdev, packet,
>> +                                              &rte_restore_info, &error)) {
>> +        /* This function is called for every packet, and in most cases there
>> +         * will be no restore info from the HW, thus error is expected.
> Right now this API (get_restore_info) is needed only in the case of
> tunnel offloads; is there some way we could avoid calling this for
> every packet (e.g non-offloaded, non-tunnel-offloaded packets) ?
No other way I can think of. Suggestions?
> What is expected from the PMD using the given 'packet' argument ? This
> is not clear from the API description in rte_flow.h.

The PMD is expected to use any data on the packet in order to provide 
the HW info.

mlx5 PMD uses mark to do it, but each PMD is free to use whatever 
implementation suitable for its HW.

If the description is not clear enough, I suggest you comment/fix in 
DPDK ML.

> Is the PMD supposed to parse this packet and return success only if it
> is an encapsulated packet ? Are there any other additional conditions
> like the packet should be marked (i.e., the PMD should validate
> rte_mbuf->hash.fdir fields etc) ? If it is a marked packet, does OVS
> set the mark action or should the PMD implicitly add a mark action,
> while offloading flow F1 ? If the PMD implicitly adds a mark action,
> won't it conflict with mark-ids managed by OVS ?

Again, it is the PMD decision. In mlx5, there is a devarg to enable 
tunnel offload APIs. In this mode, the PMD uses internal marks, and deny 
the user to use his own MARK actions, so no conflict.

OVS partial offload doesn't work in this mode.

>
>> +         */
>> +        (void) error;
>> +        return -1;
>> +    }
>> +
>> +    rte_tnl = &rte_restore_info.tunnel;
>> +    if (rte_restore_info.flags & RTE_FLOW_RESTORE_INFO_TUNNEL) {
>> +        vport_netdev = get_vport_netdev(netdev->dpif_type, rte_tnl,
>> +                                        &vport_odp);
>> +        md = &packet->md;
>> +        if (rte_restore_info.flags & RTE_FLOW_RESTORE_INFO_ENCAPSULATED) {
>> +            if (!vport_netdev || !vport_netdev->netdev_class ||
>> +                !vport_netdev->netdev_class->pop_header) {
>> +                VLOG_ERR("vport nedtdev=%s with no pop_header method",
>> +                         netdev_get_name(vport_netdev));
>> +                return -1;
>> +            }
>> +            vport_netdev->netdev_class->pop_header(packet);
>> +            netdev_close(vport_netdev);
>> +         } else {
> The else condition handles the case when the packet is tunneled, but
> it is not encapsulated ? It is not clear how/when this could happen ?
Again, this is the PMD decision. OVS should handle.
> Thanks,
> -Harsha
>
>> +             md_tnl = &md->tunnel;
>> +             if (rte_tnl->is_ipv6) {
>> +                 memcpy(&md_tnl->ipv6_src, &rte_tnl->ipv6.src_addr,
>> +                        sizeof md_tnl->ipv6_src);
>> +                 memcpy(&md_tnl->ipv6_dst, &rte_tnl->ipv6.dst_addr,
>> +                        sizeof md_tnl->ipv6_dst);
>> +             } else {
>> +                 md_tnl->ip_src = rte_tnl->ipv4.src_addr;
>> +                 md_tnl->ip_dst = rte_tnl->ipv4.dst_addr;
>> +             }
>> +             md_tnl->tun_id = htonll(rte_tnl->tun_id);
>> +             md_tnl->flags = rte_tnl->tun_flags;
>> +             md_tnl->ip_tos = rte_tnl->tos;
>> +             md_tnl->ip_ttl = rte_tnl->ttl;
>> +             md_tnl->tp_src = rte_tnl->tp_src;
>> +         }
>> +         if (vport_netdev) {
>> +             md->in_port.odp_port = vport_odp;
>> +         }
>> +    }
>> +    dp_packet_reset_offload(packet);
>> +
>> +    return 0;
>> +}
>> +
>>   const struct netdev_flow_api netdev_offload_dpdk = {
>>       .type = "dpdk_flow_api",
>>       .flow_put = netdev_offload_dpdk_flow_put,
>> @@ -1619,4 +1713,5 @@ const struct netdev_flow_api netdev_offload_dpdk = {
>>       .flow_flush = netdev_offload_dpdk_flow_flush,
>>       .flow_dump_create = netdev_offload_dpdk_flow_dump_create,
>>       .flow_dump_destroy = netdev_offload_dpdk_flow_dump_destroy,
>> +    .hw_miss_packet_recover = netdev_offload_dpdk_hw_miss_packet_recover,
>>   };
>> --
>> 2.28.0.546.g385c171
>>