[net-next,mlxsw,v4,00/18] mlxsw: Introduce algorithmic TCAM support

Message

Ido Schimmel July 24, 2018, 2:29 p.m. UTC

The Spectrum-2 ASIC uses an algorithmic TCAM (A-TCAM) where multiple
exact matches lookups are performed instead of a single lookup as with
standard circuit TCAM (C-TCAM) memory. This allows for higher scale and
reduced power consumption.

The lookups are performed by masking a packet using different masks
(e.g., {dst_ip/24, ethtype}) defined for the region and looking for an
exact match. Eventually, the rule with the highest priority will be
picked.

Since the number of masks per-region is limited, the ASIC includes a
C-TCAM that can be used as a spill area for rules that do not fit into
the A-TCAM.

The driver currently uses a C-TCAM only mode which is similar to
Spectrum-1. However, this mode severely limits both the number of
supported ACL rules and the performance of the ACL lookup.

This patch set introduces initial support for the A-TCAM mode where the
C-TCAM is only used for rule spillage.

The first five patches add the registers and ASIC resources needed in
order to make use of the A-TCAM.

Next three patches are the "meat" and add the eRP core which is used to
manage the masks used by each ACL region. The individual commit messages
are lengthy and aim to thoroughly explain the subject.

The next seven patches perform small adjustments in the code and the
related data structures and are meant to prepare the code base to the
introduction of the A-TCAM in the last two patches.

Last patch adds a selftests that verifies different scenarios, which are
documented in the test itself.

Various A-TCAM optimization will be the focus of follow-up patch sets:

* Pruning - Used to reduce the number of lookups. Each rule will include
  a prune vector that indicates which masks should not be considered for
  further lookups as they cannot result in a higher priority match

* Bloom filter - Used to reduce the number of lookups. Before performing
  a lookup with a given mask the ASIC will consult a bloom filter
  (managed by the driver) that indicates whether a match might exist using
  the considered mask

* Masks aggregation - Used to increase scale and reduce lookups. Masks
  that only differ by up to eight consecutive bits (delta bits) can be
  aggregated into a single mask. The delta bits then become a part of the
  rule's key. For example, dst_ip/16 and dst_ip/17 can be represented as
  dst_ip/16 with a delta bit of one. Rules using the aggregated mask then
  specify whether the 17-th bit should be masked or not and its value

v4:
* In patch 12, directly return in mlxsw_sp_acl_atcam_region_init()
  instead of returning 'err'

v3:
* Add forgotten error checking in mlxsw_sp_acl_atcam_region_init()
* Remove redundant blank line
* Insert rules into C-TCAM from A-TCAM code instead of Spectrum-2 code
* Introduce 'achunk' that encapsulates 'cchunk' (like we already do
  with 'aentry' and 'aregion')
* Spill to C-TCAM from A-TCAM code instead of Spectrum-2 code, that only
  calls mlxsw_sp_acl_atcam_entry_add()
* Fix print in ctcam_one_atcam_mask_test()

v2:
* Fix typo in patch 6
* Implement mlxsw_sp_acl_erp_no_mask_destroy() as WARN_ON(1)
* Do not cast to 'void *'
* Do not break lines at 80 chars where cure is worse than the disease
* Extend mlxsw_afk_encode() instead of creating a new function in patch
  10
* Move C-TCAM region init to be part of A-TCAM region init in patch 12

Ido Schimmel (18):
  mlxsw: reg: Prepare PERERP register for A-TCAM usage
  mlxsw: reg: Add Policy-Engine TCAM Entry Register Version 3
  mlxsw: reg: Add Policy-Engine eRP Table Register
  mlxsw: resources: Add Spectrum-2 maximum large key ID resource
  mlxsw: resources: Add Spectrum-2 eRP resources
  mlxsw: spectrum_acl: Implement common eRP core
  mlxsw: spectrum_acl: Enable C-TCAM only mode in eRP core
  mlxsw: spectrum_acl: Add support for C-TCAM eRPs
  mlxsw: spectrum_acl: Extend Spectrum-2 region struct
  mlxsw: spectrum_acl: Allow encoding a partial key
  mlxsw: spectrum_acl: Add A-TCAM initialization
  mlxsw: spectrum_acl: Encapsulate C-TCAM region in A-TCAM region
  mlxsw: spectrum_acl: Make global TCAM resources available to regions
  mlxsw: spectrum_acl: Add A-TCAM region initialization
  mlxsw: spectrum_acl: Pass C-TCAM region and entry to insert function
  mlxsw: spectrum_acl: Add A-TCAM rule insertion and deletion
  mlxsw: spectrum_acl: Start using A-TCAM
  selftests: mlxsw: Add TC flower test for Spectrum-2

 drivers/net/ethernet/mellanox/mlxsw/Kconfig   |    1 +
 drivers/net/ethernet/mellanox/mlxsw/Makefile  |    2 +-
 .../mellanox/mlxsw/core_acl_flex_keys.c       |   10 +-
 .../mellanox/mlxsw/core_acl_flex_keys.h       |    2 +-
 drivers/net/ethernet/mellanox/mlxsw/reg.h     |  301 ++++-
 .../net/ethernet/mellanox/mlxsw/resources.h   |   14 +
 .../net/ethernet/mellanox/mlxsw/spectrum.h    |    1 +
 .../mellanox/mlxsw/spectrum1_acl_tcam.c       |   24 +-
 .../mellanox/mlxsw/spectrum2_acl_tcam.c       |   82 +-
 .../mellanox/mlxsw/spectrum_acl_atcam.c       |  509 ++++++-
 .../mellanox/mlxsw/spectrum_acl_ctcam.c       |   40 +-
 .../mellanox/mlxsw/spectrum_acl_erp.c         | 1199 +++++++++++++++++
 .../mellanox/mlxsw/spectrum_acl_tcam.c        |    2 +-
 .../mellanox/mlxsw/spectrum_acl_tcam.h        |  117 +-
 .../drivers/net/mlxsw/spectrum-2/tc_flower.sh |  366 +++++
 15 files changed, 2601 insertions(+), 69 deletions(-)
 create mode 100644 drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_erp.c
 create mode 100755 tools/testing/selftests/drivers/net/mlxsw/spectrum-2/tc_flower.sh