Re: setting flow spec rules under vswitch configuration

On 09/10/2012 18:48, Ben Hutchings wrote:

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

quoted

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.

quoted

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struct ethtool_rx_ntuple_flow_spec is obsolete; struct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,

Thanks for setting the sketch of a plan here... so if we go little bit into details, we can safely move 20 bytes from the hadata[60] field into the beginning of struct ethtool_flow_ext, which will still allow old
user space to work with newer kernels. As for newer uses space that would like to set mac addresses within
ethtool_flow_ext, how are they supposed to identify if the kernel supports this extension (of the extension...)? this might be newbee question, I didn't made many ethtool patches so far.

Also on a related note, what does the 64bit data field of ethtool_flow_ext used for?

Or.