selftests: mlxsw: vxlan_flooding_ipv6: Prevent flooding of unwanted packets

The test verifies that packets are correctly flooded by the bridge and
the VXLAN device by matching on the encapsulated packets at the other
end. However, if packets other than those generated by the test also
ingress the bridge (e.g., MLD packets), they will be flooded as well and
interfere with the expected count.

Make the test more robust by making sure that only the packets generated
by the test can ingress the bridge. Drop all the rest using tc filters
on the egress of 'br0' and 'h1'.

In the software data path, the problem can be solved by matching on the
inner destination MAC or dropping unwanted packets at the egress of the
VXLAN device, but this is not currently supported by mlxsw.

Fixes: d01724dd2a66 ("selftests: mlxsw: spectrum-2: Add a test for VxLAN flooding with IPv6")
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Amit Cohen <amcohen@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests: mlxsw: spectrum-2: Add a test for VxLAN flooding with IPv6

The device stores flood records in a singly linked list where each
record stores up to X IP addresses of remote VTEPs.

The number of records is changed according to ASIC type and address
family.

Add a test which is similar to the existing IPv4 test to check IPv6.
The test is dedicated for Spectrum-2 and above, which support up to four
IPv6 addresses in one record.

The test verifies that packets are correctly flooded in various cases such
as deletion of a record in the middle of the list.

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>