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[ovs-dev,v3,0/5] tc: Fixes for tunnel offloading.

Message ID 20220814144603.2058894-1-i.maximets@ovn.org
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Series tc: Fixes for tunnel offloading. | expand

Message

Ilya Maximets Aug. 14, 2022, 2:45 p.m. UTC 
This is started from the issue with broken ERSPAN tunnel
reported by Eelco, but turned out a much wider problem with
ignoring different tunnel keys and flags while constructing
TC flower.  Some of that can be fixed, some can't be fixed
due to lack of support from kernel.  Strictly speaking, we
should have prohibit silent ignoring of everything including
DONT_FRAGMENT and CSUM tunnel flags, but that will break the
tunnel offloading entirely.  So, partially keeping incorrect
behaviour for now, fixing the most broken bits.

To have a more or less viable solution, TC in kernel should add
support for TUNNEL_DONT_FRAGMENT in set tunnel key action
(also, TUNNEL_OAM support would be nice).  And we also need
support to match on them, i.e. support for:

  TCA_FLOWER_KEY_ENC_DONT_FRAGMENT
  TCA_FLOWER_KEY_ENC_NO_CSUM
  TCA_FLOWER_KEY_ENC_OAM

And corresponding _MASK keys as well.
Maybe TCA_FLOWER_KEY_ENC_TUN_FLAGS instead?

With that OVS will have to probe the kernel for support and
use them or fail the offload.

I didn't test these patches with real HW.  Only checked
system tests from check-offloads and normal check-kernel
hacked with offlaods enabled.


Version 3:
  - Added 'Reviewed-by' from Roi on patches 2, 3 and 5.
  - Fixed incorect read from the OVS_TUNNEL_KEY_ATTR_CSUM
    flag attribute.  [Paul]
  - Re-worked setting/clearing FLOW_TNL_F_UDPIF flag along
    with the metadata.present.len, because flower always
    has an exact match on the length and the metadata is
    always in UDPIF format. [Roi]

Version 2:
  - Added clear of tunnel masks on 'else' condition, since
    some bits can still be there even if the tunnel matching
    is not needed.
  - Instead of adding support for masked match on tp_dst,
    it just handled explicitly with exact match to avoid
    inability of offload on mlx5 NICs.
  - Added patch to fix mask of the tunnel metadata length.
  - 'Masks vs keys' fix stripped into a separate patch.
  - New patch added to handle tp_src that was kind of consumed
    by tc_flower structure but was never actually passed
    to/from TC.

Ilya Maximets (5):
  netdev-offload-tc: Fix the mask for tunnel metadata length.
  netdev-offload-tc: Explicitly handle mask for the tunnel destination
    port.
  netdev-offload-tc: Use masks instead of keys while parsing tunnel
    attributes.
  netdev-offload-tc: Fix ignoring unknown tunnel keys.
  netdev-offload-tc: Add missing handling of the tunnel source port.

 lib/dpif-netlink.c      |  14 +---
 lib/netdev-offload-tc.c | 139 +++++++++++++++++++++++++++++++++-------
 lib/netdev-offload.h    |   3 -
 lib/tc.c                |  43 +++++++++++--
 4 files changed, 153 insertions(+), 46 deletions(-)