netdev - RE: Question about flow table offload in mlx5e

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Date:   Thu, 21 Nov 2019 07:42:46 +0000
From:   Paul Blakey <paulb@...lanox.com>
To:     wenxu <wenxu@...oud.cn>
CC:     "pablo@...filter.org" <pablo@...filter.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Mark Bloch <markb@...lanox.com>
Subject: RE: Question about flow table offload in mlx5e

Hi,

The original design was the block setup to use TC_SETUP_FT type, and the tc event type to be case TC_SETUP_CLSFLOWER.
We will post a patch to change that. I would advise to wait till we fix that 😊
I'm not sure how you get to this function mlx5e_rep_setup_ft_cb() if it the nf_flow_table_offload ndo_setup_tc event was TC_SETUP_BLOCK, and not TC_SETUP_FT.

In our driver en_rep.c we have:
>-------switch (type) {
>-------case TC_SETUP_BLOCK:
>------->-------return flow_block_cb_setup_simple(type_data,
>------->------->------->------->------->-------  &mlx5e_rep_block_tc_cb_list,
>------->------->------->------->------->-------  mlx5e_rep_setup_tc_cb,
>------->------->------->------->------->-------  priv, priv, true);
>-------case TC_SETUP_FT:
>------->-------return flow_block_cb_setup_simple(type_data,
>------->------->------->------->------->-------  &mlx5e_rep_block_ft_cb_list,
>------->------->------->------->------->-------  mlx5e_rep_setup_ft_cb,
>------->------->------->------->------->-------  priv, priv, true);
>-------default:
>------->-------return -EOPNOTSUPP;
>-------}

In nf_flow_table_offload.c:
>-------bo.binder_type>-= FLOW_BLOCK_BINDER_TYPE_CLSACT_INGRESS;
>-------bo.extack>------= &extack;
>-------INIT_LIST_HEAD(&bo.cb_list);

>-------err = dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_BLOCK, &bo);
>-------if (err < 0)
>------->-------return err;

>-------return nf_flow_table_block_setup(flowtable, &bo, cmd);
}
EXPORT_SYMBOL_GPL(nf_flow_table_offload_setup);


So unless you changed that as well, you should have gotten to mlx5e_rep_setup_tc_cb and not mlx5e_rep_setup_tc_ft.

Regarding the encap action, there should be no difference on which chain the rule is on.


> -----Original Message-----
> From: wenxu <wenxu@...oud.cn>
> Sent: Thursday, November 21, 2019 9:30 AM
> To: Paul Blakey <paulb@...lanox.com>
> Cc: pablo@...filter.org; netdev@...r.kernel.org; Mark Bloch
> <markb@...lanox.com>
> Subject: Question about flow table offload in mlx5e
> 
> Hi  paul,
> 
> The flow table offload in the mlx5e is based on TC_SETUP_FT.
> 
> 
> It is almost the same as TC_SETUP_BLOCK.
> 
> It just set MLX5_TC_FLAG(FT_OFFLOAD) flags and change
> cls_flower.common.chain_index = FDB_FT_CHAIN;
> 
> In following codes line 1380 and 1392
> 
> 1368 static int mlx5e_rep_setup_ft_cb(enum tc_setup_type type, void
> *type_data,
> 1369                                  void *cb_priv)
> 1370 {
> 1371         struct flow_cls_offload *f = type_data;
> 1372         struct flow_cls_offload cls_flower;
> 1373         struct mlx5e_priv *priv = cb_priv;
> 1374         struct mlx5_eswitch *esw;
> 1375         unsigned long flags;
> 1376         int err;
> 1377
> 1378         flags = MLX5_TC_FLAG(INGRESS) |
> 1379                 MLX5_TC_FLAG(ESW_OFFLOAD) |
> 1380                 MLX5_TC_FLAG(FT_OFFLOAD);
> 1381         esw = priv->mdev->priv.eswitch;
> 1382
> 1383         switch (type) {
> 1384         case TC_SETUP_CLSFLOWER:
> 1385                 if (!mlx5_eswitch_prios_supported(esw) || f-
> >common.chain_index)
> 1386                         return -EOPNOTSUPP;
> 1387
> 1388                 /* Re-use tc offload path by moving the ft flow to the
> 1389                  * reserved ft chain.
> 1390                  */
> 1391                 memcpy(&cls_flower, f, sizeof(*f));
> 1392                cls_flower.common.chain_index = FDB_FT_CHAIN;
> 1393                 err = mlx5e_rep_setup_tc_cls_flower(priv, &cls_flower, flags);
> 1394                 memcpy(&f->stats, &cls_flower.stats, sizeof(f->stats));
> 
> 
> I want to add tunnel offload support in the flow table, I  add some patches in
> nf_flow_table_offload.
> 
> Also add the indr setup support in the mlx driver. And Now I can  flow table
> offload with decap.
> 
> 
> But I meet a problem with the encap.  The encap rule can be added in
> hardware  successfully But it can't be offloaded.
> 
> But I think the rule I added is correct.  If I mask the line 1392. The rule also can
> be add success and can be offloaded.
> 
> So there are some limit for encap operation for FT_OFFLOAD in
> FDB_FT_CHAIN?
> 
> 
> BR
> 
> wenxu
>