selftests: forwarding: Make tc-police pass on debug kernels

The test configures a policer with a rate of 80Mbps and expects to
measure a rate close to it. This is a too high rate for debug kernels,
causing the test to fail [1].

Fix by reducing the rate to 10Mbps.

[1]
# ./tc_police.sh
TEST: police on rx [FAIL]
Expected rate 76.2Mbps, got 29.6Mbps, which is -61% off. Required accuracy is +-10%.
TEST: police on tx [FAIL]
Expected rate 76.2Mbps, got 30.4Mbps, which is -60% off. Required accuracy is +-10%.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Link: https://lore.kernel.org/r/20240304095612.462900-4-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/sched: act_police: more accurate MTU policing

in current Linux, MTU policing does not take into account that packets at
the TC ingress have the L2 header pulled. Thus, the same TC police action
(with the same value of tcfp_mtu) behaves differently for ingress/egress.
In addition, the full GSO size is compared to tcfp_mtu: as a consequence,
the policer drops GSO packets even when individual segments have the L2 +
L3 + L4 + payload length below the configured valued of tcfp_mtu.

Improve the accuracy of MTU policing as follows:
- account for mac_len for non-GSO packets at TC ingress.
- compare MTU threshold with the segmented size for GSO packets.
Also, add a kselftest that verifies the correct behavior.

Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests: forwarding: Add tc-police tests for packets per second

Test tc-police action for packets per second.
The test is mainly in scenarios Rx policing and Tx policing.
The test passes with veth pairs ports.

Signed-off-by: Baowen Zheng <baowen.zheng@corigine.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests: forwarding: Add tc-police tests

Test tc-police action in various scenarios such as Rx policing, Tx
policing, shared policer and police piped to mirred. The test passes
with both veth pairs and loopbacked ports.

# ./tc_police.sh
TEST: police on rx [ OK ]
TEST: police on tx [ OK ]
TEST: police with shared policer - rx [ OK ]
TEST: police with shared policer - tx [ OK ]
TEST: police rx and mirror [ OK ]
TEST: police tx and mirror [ OK ]

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>