[EXT] Re: [dpdk-dev] [PATCH 22.02 2/2] net/cnxk: add devargs for configuring SDP channel mask

[Ferruh Yigit]

On 1/11/2022 2:29 PM, Satheesh Paul wrote:
> Hi,
> 
> Please find reply inline.
> 
> Thanks,
> Satheesh.
> 
> -----Original Message-----
> From: Ferruh Yigit <ferruh.yigit at intel.com>
> Sent: 11 January 2022 05:26 PM
> To: Satheesh Paul <psatheesh at marvell.com>; Nithin Kumar Dabilpuram <ndabilpuram at marvell.com>; Kiran Kumar Kokkilagadda <kirankumark at marvell.com>; Sunil Kumar Kori <skori at marvell.com>; Satha Koteswara Rao Kottidi <skoteshwar at marvell.com>
> Cc: dev at dpdk.org; Ori Kam <orika at nvidia.com>; Andrew Rybchenko <andrew.rybchenko at oktetlabs.ru>
> Subject: [EXT] Re: [dpdk-dev] [PATCH 22.02 2/2] net/cnxk: add devargs for configuring SDP channel mask
> 
> External Email
> 
> ----------------------------------------------------------------------
> On 11/9/2021 9:42 AM, psatheesh at marvell.com wrote:
>> From: Satheesh Paul <psatheesh at marvell.com>
>>
>> This patch adds support to configure channel mask which will be used
>> by rte flow when adding flow rules on SDP interfaces.
>>
> 
>> Hi Satheesh,
> 
>> + Ori & Andrew.
> 
>> What 'SDP' stands for?
> It stands for "System DMA Packet Interface". This is when the system acts as PCIe endpoint. For instance, an x86 machine can act as a host having an Octeon TX* board plugged through this PCIe interface and packets are transferred through this PCIe interface.
> 
>> And can this new devarg be provided with flow rule? Why it needs to be a new devarg?
> SDP and its channel related info are specific to the hardware and rte flow api cannot be extended to support them. Hence, it is added as a new devarg.
> 
>> Can you please give a sample of the rte flow API that will be used?
> This channel mask will be used by the rte_flow_create() api. It is actually transparent at rte_flow_create() invocation itself. That is, at the time of rte_flow_create() invocation, user does not give any additional information. But internally, the driver's flow creation api takes the SDP channel/mask value supplied at the startup and applies it. Basically, in Octeon tx*, the interfaces have a "channel identifier" number. The rules in packet classification hardware are configured to match the channel number. With this change, we are relaxing the exact match and are allowing a range for this SDP interface.
> 

Got it. I am still not quite clear what SDP is, but from below document
my understanding was user need to provide these channel & mask while
creating a flow rule, but according above description that is not the case,
but this is internal to the driver, so I am OK to proceed.

Thanks for clarification.

> Thanks,
> ferruh
> 
> 
>> Signed-off-by: Satheesh Paul <psatheesh at marvell.com>
>> ---
>>    doc/guides/nics/cnxk.rst               | 21 ++++++++++++++
>>    drivers/net/cnxk/cnxk_ethdev_devargs.c | 40 ++++++++++++++++++++++++--
>>    2 files changed, 59 insertions(+), 2 deletions(-)
>>
>> diff --git a/doc/guides/nics/cnxk.rst b/doc/guides/nics/cnxk.rst index
>> 837ffc02b4..470e01b811 100644
>> --- a/doc/guides/nics/cnxk.rst
>> +++ b/doc/guides/nics/cnxk.rst
>> @@ -276,6 +276,27 @@ Runtime Config Options
>>       set with this custom mask, inbound encrypted traffic from all ports with
>>       matching channel number pattern will be directed to the inline IPSec device.
>>    
>> +- ``SDP device channel and mask`` (default ``none``)
>> +   Set channel and channel mask configuration for the SDP device. This
>> +   will be used when creating flow rules on the SDP device.
>> +
>> +   By default, for rules created on the SDP device, the RTE Flow API sets the
>> +   channel number and mask to cover the entire SDP channel range in the channel
>> +   field of the MCAM entry. This behaviour can be modified using the
>> +   ``sdp_channel_mask`` ``devargs`` parameter.
>> +
>> +   For example::
>> +
>> +      -a 0002:1d:00.0,sdp_channel_mask=0x700/0xf00
>> +
>> +   With the above configuration, RTE Flow rules API will set the channel
>> +   and channel mask as 0x700 and 0xF00 in the MCAM entries of the  flow rules
>> +   created on the SDP device. This option needs to be used when more than one
>> +   SDP interface is in use and RTE Flow rules created need to distinguish
>> +   between traffic from each SDP interface. The channel and mask combination
>> +   specified should match all the channels(or rings) configured on the SDP
>> +   interface.
>> +
>>    .. note::
>>    
> 
> <...>