Re: setting flow spec rules under vswitch configuration

On Tue, 2012-10-09 at 11:37 +0200, Or Gerlitz wrote:

Hi Ben,

Looking on kernel ethtool flow steering APIs in the context of a device
which is used as the uplink of a virtual switch, the admin should be able
to provide flow specification and action (e.g drop) that relates to traffic
coming from a specific port of the switch e.g that relates to a certain 
VM,etc.

For that end, we need to be able to specify both the L3/L4 attributes of
the flow and an L2 spec, that is the L2 spec containing the destination MAC
can't be assumed as the one of that device.

Specifically, in struct ethtool_rx_ntuple_flow_spec, I think we should 
let the
to provide an ethhdr even when L3/L4 spec is given, make sense?

Yes, but the ethertype looks redundant - the inner type is implied by
the L3 flow type and the outer type for a VLAN-encapsulated packet
should be matched against ethtool_flow_ext::vlan_etype.  Might be better
to avoid confusion by just specifying the L2 addresses.

if yes, how
would you like to see this change, add a union entry that contains both, 
or in
another way?

struct ethtool_rx_ntuple_flow_spec is obsolete; struct
ethtool_rx_flow_spec is what we have to consider.  That effectively has:

	union ethtool_flow_union {
		struct ethtool_tcpip4_spec		tcp_ip4_spec;
		struct ethtool_tcpip4_spec		udp_ip4_spec;
		struct ethtool_tcpip4_spec		sctp_ip4_spec;
		struct ethtool_ah_espip4_spec		ah_ip4_spec;
		struct ethtool_ah_espip4_spec		esp_ip4_spec;
		struct ethtool_usrip4_spec		usr_ip4_spec;
		struct ethhdr				ether_spec;
		/* above are up to 16 bytes long */
		__u8					hdata[60];
	} h_u;
	struct ethtool_flow_ext {
		__be16	vlan_etype;
		__be16	vlan_tci;
		__be32	data[2];
	} h_ext;
	union ethtool_flow_union m_u;
	struct ethtool_flow_ext m_ext;

So ethtool_flow_union::hdata currently provides 44 bytes of padding
between the per-protocol flow specs and ethtool_flow_ext, which can be
reallocated to the *beginning* of ethtool_flow_ext.  At some point we'll
presumably want to add IPv6 flow specs, which will use up 24 bytes of
that padding at the front.  So we can potentially extend
ethtool_flow_ext by up to 20 bytes.

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.