Date:	Thu, 4 Sep 2014 14:46:00 +0200
From:	Jiri Pirko <jiri@...nulli.us>
To:	John Fastabend <john.fastabend@...il.com>
Cc:	netdev@...r.kernel.org, davem@...emloft.net, nhorman@...driver.com,
	andy@...yhouse.net, tgraf@...g.ch, dborkman@...hat.com,
	ogerlitz@...lanox.com, jesse@...ira.com, pshelar@...ira.com,
	azhou@...ira.com, ben@...adent.org.uk, stephen@...workplumber.org,
	jeffrey.t.kirsher@...el.com, vyasevic@...hat.com,
	xiyou.wangcong@...il.com, john.r.fastabend@...el.com,
	edumazet@...gle.com, jhs@...atatu.com, sfeldma@...ulusnetworks.com,
	f.fainelli@...il.com, roopa@...ulusnetworks.com,
	linville@...driver.com, dev@...nvswitch.org, jasowang@...hat.com,
	ebiederm@...ssion.com, nicolas.dichtel@...nd.com,
	ryazanov.s.a@...il.com, buytenh@...tstofly.org,
	aviadr@...lanox.com, nbd@...nwrt.org, alexei.starovoitov@...il.com,
	Neil.Jerram@...aswitch.com, ronye@...lanox.com
Subject: Re: [patch net-next 03/13] net: introduce generic switch devices
 support

Wed, Sep 03, 2014 at 05:46:23PM CEST, john.fastabend@...il.com wrote:
>On 09/03/2014 02:24 AM, Jiri Pirko wrote:
>>The goal of this is to provide a possibility to suport various switch
>>chips. Drivers should implement relevant ndos to do so. Now there is a
>>couple of ndos defines:
>>- for getting physical switch id is in place.
>>- for work with flows.
>>
>>Note that user can use random port netdevice to access the switch.
>>
>>Signed-off-by: Jiri Pirko <jiri@...nulli.us>
>>---
>
>
>[...]
>
>>  struct netpoll_info;
>>@@ -997,6 +999,24 @@ typedef u16 (*select_queue_fallback_t)(struct net_device *dev,
>>   *	Callback to use for xmit over the accelerated station. This
>>   *	is used in place of ndo_start_xmit on accelerated net
>>   *	devices.
>>+ *
>>+ * int (*ndo_swdev_get_id)(struct net_device *dev,
>>+ *			   struct netdev_phys_item_id *psid);
>>+ *	Called to get an ID of the switch chip this port is part of.
>>+ *	If driver implements this, it indicates that it represents a port
>>+ *	of a switch chip.
>>+ *
>>+ * int (*ndo_swdev_flow_insert)(struct net_device *dev,
>>+ *				const struct sw_flow *flow);
>>+ *	Called to insert a flow into switch device. If driver does
>>+ *	not implement this, it is assumed that the hw does not have
>>+ *	a capability to work with flows.
>>+ *
>>+ * int (*ndo_swdev_flow_remove)(struct net_device *dev,
>>+ *				const struct sw_flow *flow);
>>+ *	Called to remove a flow from switch device. If driver does
>>+ *	not implement this, it is assumed that the hw does not have
>>+ *	a capability to work with flows.
>>   */
>>  struct net_device_ops {
>>  	int			(*ndo_init)(struct net_device *dev);
>>@@ -1146,6 +1166,14 @@ struct net_device_ops {
>>  							struct net_device *dev,
>>  							void *priv);
>>  	int			(*ndo_get_lock_subclass)(struct net_device *dev);
>>+#ifdef CONFIG_NET_SWITCHDEV
>>+	int			(*ndo_swdev_get_id)(struct net_device *dev,
>>+						    struct netdev_phys_item_id *psid);
>>+	int			(*ndo_swdev_flow_insert)(struct net_device *dev,
>>+							 const struct sw_flow *flow);
>>+	int			(*ndo_swdev_flow_remove)(struct net_device *dev,
>>+							 const struct sw_flow *flow);
>
>Not really a critique of your patch but I'll need to extend this
>with a ndo_swdev_flow_dump() to get the fields. Without this if
>your user space side ever restarts, gets out of sync there is no
>way to get back in sync.

Sure. I do not say that the api is complete (If anything ever is...)
Feel free to add dump ndo. In fact we can take care of it and implement
in rocker driver.


>
>Also with hardware that has multiple flow tables we need to indicate
>the table to insert the flow into. One concrete reason to do this
>is to create atomic updates of multiple ACLs. The idea is to create
>a new ACL table build the table up and then link it in. This can be
>added when its needed my opensource drivers don't support this yet
>either but maybe adding multiple tables to rocker switch will help
>flush this out.

Ok. Lets leave this for future follow-ups.

>
>Finally we need some way to drive capabilities out of the swdev.
>Even rocker switch needs this to indicate it doesn't support matching
>on all the sw_flow fields. Without this its not clear to me how to
>manage the device from user space. I tried writing user space daemon
>for the simpler flow director interface and the try and see model
>breaks quickly.

Hmm. I was under impression that a simple fact that the flow insertion
fails with error is enough. But thining of it more. I believe that a set
of features makes sense. I will think about it and add it into the next
patchset version.

>
>>+#endif
>>  };
>>
>>  /**
>>diff --git a/include/net/sw_flow.h b/include/net/sw_flow.h
>>index 21724f1..3af7758 100644
>>--- a/include/net/sw_flow.h
>>+++ b/include/net/sw_flow.h
>>@@ -81,7 +81,21 @@ struct sw_flow_mask {
>>  	struct sw_flow_key key;
>>  };
>>
>>+enum sw_flow_action_type {
>>+	SW_FLOW_ACTION_TYPE_OUTPUT,
>>+	SW_FLOW_ACTION_TYPE_VLAN_PUSH,
>>+	SW_FLOW_ACTION_TYPE_VLAN_POP,
>>+};
>>+
>
>OK my previous comment about having another patch to create
>generic actions seems to be resolved here. I'm not sure how
>important it is but if we abstract the flow types away from
>OVS is there any reason not to reuse and relabel the action
>types as well? I guess we can't break userspace API but maybe
>a 1:1 mapping would be better?
>
>>  struct sw_flow_action {
>>+	enum sw_flow_action_type type;
>>+	union {
>>+		u32 out_port_ifindex;
>>+		struct {
>>+			__be16 vlan_proto;
>>+			u16 vlan_tci;
>>+		} vlan;
>>+	};
>>  };
>
>[...]
>
>I think my comments could be addressed with additional patches
>if you want. I could help but it will be another week or so
>before I have some time. The biggest issue IMO is the lack of
>capabilities queries.

Np. I will handle these (probably not before I return from vacation (Sep
15)).

Thanks!

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