nftables offload doesn't seem to work

[Patrick McLean <chutzpah@gentoo.org>]

Hi,

I am trying to test the nftables offload support, as describe in
https://lwn.net/Articles/810663/

When I try to load the rules, or check a rules file, nft errors out, it
appears that it does not understand "flags offload;":

# nft --check --file test.nft
test.nft:6:51-55: Error: syntax error, unexpected flags
                type filter hook ingress device if0 priority 0; flags offload;

Here is the contents of the file I am trying to load:

table netdev filter_test {
    chain ingress {
        type filter hook ingress device eth0 priority 0; flags offload;

        192.168.0.10 tcp dport 22 drop
    }
}

I am using the 5.4.22 kernel with nftables 0.9.3, the hardware is mlx5:

# ethtool --driver eth0
driver: mlx5_core
version: 5.0-0
firmware-version: 16.23.1020 (MT_0000000012)
expansion-rom-version:
bus-info: 0000:61:00.0
supports-statistics: yes
supports-test: yes
supports-eeprom-access: no
supports-register-dump: no
supports-priv-flags: yes

lspci reports it as:
61:00.0 Ethernet controller: Mellanox Technologies MT27800 Family [ConnectX-5]