net: selftest: add test for netdev netlink queue-get API

Add a selftest for netdev generic netlink. For now there is only a
single test that exercises the `queue-get` API.

The test works with netdevsim by default or with a real device by
setting NETIF.

Add a timeout param to cmd() since ethtool -L can take a long time on
real devices.

Signed-off-by: David Wei <dw@davidwei.uk>
Link: https://lore.kernel.org/r/20240507163228.2066817-3-dw@davidwei.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

selftests: net: exercise page pool reporting via netlink

Add a Python test for the basic ops.

# ./net/nl_netdev.py
KTAP version 1
1..3
ok 1 nl_netdev.empty_check
ok 2 nl_netdev.lo_check
ok 3 nl_netdev.page_pool_check
# Totals: pass:3 fail:0 xfail:0 xpass:0 skip:0 error:0

Reviewed-by: Petr Machata <petrm@nvidia.com>
Link: https://lore.kernel.org/r/20240412141436.828666-7-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

selftests: net: support use of NetdevSimDev under "with" in python

Using "with" on an entire driver test env is supported already,
but it's also useful to use "with" on an individual nsim.

Reviewed-by: Petr Machata <petrm@nvidia.com>
Link: https://lore.kernel.org/r/20240412141436.828666-6-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

selftests: net: reuse common code in bpf_offload

net/lib/py/nsim.py already contains the most useful parts
of the netdevsim wrapper classes. Reuse them.

Acked-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20240409031549.3531084-5-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

selftests: drivers: add scaffolding for Netlink tests in Python

Add drivers/net as a target for mixed-use tests.
The setup is expected to work similarly to the forwarding tests.
Since we only need one interface (unlike forwarding tests)
read the target device name from NETIF. If not present we'll
try to run the test against netdevsim.

Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>