Re: [PATCH net-next] selftests: drv-net: hw: reset HDS mode after netkit devmem tests

[Simon Horman <horms@kernel.org>]

On Tue, Aug 04, 2026 at 08:10:40AM -0700, Jakub Kicinski wrote:
> HDS mode has confusing semantics. On GET kernel reports
> effective mode. On SET kernel expects explicit config.
> Effective mode on GET means that we know the current
> state, but we don't know if it's a driver default
> or user setting. This matter because driver default
> can change automatically when e.g. XDP is attached.
> Explicit user setting must not be lost.
> 
> With that in mind, we can't restore the HDS setting
> like we restore other NIC config. We should always
> reset to default ("unknown").
> 
> This fixes an issue with tests running after the devmem
> test not being able to attach XDP, e.g.
> 
>    Exception|   File "./xdp_metadata.py", line 105, in test_xdp_rss_hash
>    [...]
>    Exception| net.lib.py.utils.CmdExitFailure: Command failed
>    Exception| CMD: ip link set dev ens9np0 xdpdrv pinned /sys/fs/bpf/xdp_metadata_test/xdp_rss_hash
>    Exception|   EXIT: 2
>    Exception|   STDERR: Error: unable to install XDP to device using tcp-data-split.
>    not ok 1 xdp_metadata.test_xdp_rss_hash.tcp
> 
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Reviewed-by: Simon Horman <horms@kernel.org>