i40e: stop disabling VFs due to PF error responses

i40e: stop disabling VFs due to PF error responses

BugLink: https://bugs.launchpad.net/bugs/1966056
[ Upstream commit 5710ab79166504013f7c0ae6a57e7d2fd26e5c43 ]

The i40e_vc_send_msg_to_vf_ex (and its wrapper i40e_vc_send_msg_to_vf)
function has logic to detect "failure" responses sent to the VF. If a VF
is sent more than I40E_DEFAULT_NUM_INVALID_MSGS_ALLOWED, then the VF is
marked as disabled. In either case, a dev_info message is printed
stating that a VF opcode failed.

This logic originates from the early implementation of VF support in
commit 5c3c48ac6bf5 ("i40e: implement virtual device interface").

That commit did not go far enough. The "logic" for this behavior seems
to be that error responses somehow indicate a malicious VF. This is not
really true. The PF might be sending an error for any number of reasons
such as lacking resources, an unsupported operation, etc. This does not
indicate a malicious VF. We already have a separate robust malicious VF
detection which relies on hardware logic to detect and prevent a variety
of behaviors.

There is no justification for this behavior in the original
implementation. In fact, a later commit 18b7af57d9c1 ("i40e: Lower some
message levels") reduced the opcode failure message from a dev_err to a
dev_info. In addition, recent commit 01cbf50877e6 ("i40e: Fix to not
show opcode msg on unsuccessful VF MAC change") changed the logic to
allow quieting it for expected failures.

That commit prevented this logic from kicking in for specific
circumstances. This change did not go far enough. The behavior is not
documented nor is it part of any requirement for our products. Other
operating systems such as the FreeBSD implementation of our driver do
not include this logic.

It is clear this check does not make sense, and causes problems which
led to ugly workarounds.

Fix this by just removing the entire logic and the need for the
i40e_vc_send_msg_to_vf_ex function.

Fixes: 01cbf50877e6 ("i40e: Fix to not show opcode msg on unsuccessful VF MAC change")
Fixes: 5c3c48ac6bf5 ("i40e: implement virtual device interface")
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>