i40e: document drivers use of ntuple filters

Add documentation describing the drivers use of ethtool ntuple filters,
including the limitations that it has due to hardware, as well as how it
reads and parses the user-def data block.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
This commit is contained in:
Jacob Keller 2017-02-06 14:38:52 -08:00 committed by Jeff Kirsher
parent f223c8752a
commit 55877012d5
1 changed files with 72 additions and 0 deletions

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@ -63,6 +63,78 @@ Additional Configurations
The latest release of ethtool can be found from
https://www.kernel.org/pub/software/network/ethtool
Flow Director n-ntuple traffic filters (FDir)
---------------------------------------------
The driver utilizes the ethtool interface for configuring ntuple filters,
via "ethtool -N <device> <filter>".
The sctp4, ip4, udp4, and tcp4 flow types are supported with the standard
fields including src-ip, dst-ip, src-port and dst-port. The driver only
supports fully enabling or fully masking the fields, so use of the mask
fields for partial matches is not supported.
Additionally, the driver supports using the action to specify filters for a
Virtual Function. You can specify the action as a 64bit value, where the
lower 32 bits represents the queue number, while the next 8 bits represent
which VF. Note that 0 is the PF, so the VF identifier is offset by 1. For
example:
... action 0x800000002 ...
Would indicate to direct traffic for Virtual Function 7 (8 minus 1) on queue
2 of that VF.
The driver also supports using the user-defined field to specify 2 bytes of
arbitrary data to match within the packet payload in addition to the regular
fields. The data is specified in the lower 32bits of the user-def field in
the following way:
+----------------------------+---------------------------+
| 31 28 24 20 16 | 15 12 8 4 0|
+----------------------------+---------------------------+
| offset into packet payload | 2 bytes of flexible data |
+----------------------------+---------------------------+
As an example,
... user-def 0x4FFFF ....
means to match the value 0xFFFF 4 bytes into the packet payload. Note that
the offset is based on the beginning of the payload, and not the beginning
of the packet. Thus
flow-type tcp4 ... user-def 0x8BEAF ....
would match TCP/IPv4 packets which have the value 0xBEAF 8bytes into the
TCP/IPv4 payload.
For ICMP, the hardware parses the ICMP header as 4 bytes of header and 4
bytes of payload, so if you want to match an ICMP frames payload you may need
to add 4 to the offset in order to match the data.
Furthermore, the offset can only be up to a value of 64, as the hardware
will only read up to 64 bytes of data from the payload. It must also be even
as the flexible data is 2 bytes long and must be aligned to byte 0 of the
packet payload.
When programming filters, the hardware is limited to using a single input
set for each flow type. This means that it is an error to program two
different filters with the same type that don't match on the same fields.
Thus the second of the following two commands will fail:
ethtool -N <device> flow-type tcp4 src-ip 192.168.0.7 action 5
ethtool -N <device> flow-type tcp4 dst-ip 192.168.15.18 action 1
This is because the first filter will be accepted and reprogram the input
set for TCPv4 filters, but the second filter will be unable to reprogram the
input set until all the conflicting TCPv4 filters are first removed.
Note that the user-defined flexible offset is also considered part of the
input set and cannot be programmed separately for multiple filters of the
same type. However, the flexible data is not part of the input set and
multiple filters may use the same offset but match against different data.
Data Center Bridging (DCB)
--------------------------
DCB configuration is not currently supported.