[Bug 261746] hn(4): Communication stops when enabling SR-IOV secondary mlx5en(4) interface (640FLR-SFP28) on Windows Server 2022

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=261746

--- Comment #5 from Michael <michael.adm@gmail.com> ---
  Firstly, I did a little investigation to find out what kind of commit cuts
the connection when using the SR-IOV technology and mlx5en VF. This is commit
e059c120b4223fd5ec3af9def21c0519f439fe57.
  With the GENERIC kernel and the previous commit
a8e715d21b963251e449187c98292fff77dc7576, everything works as it should -
SR-IOV VF works for both ConnectX-3 mlx4en and ConnectX-4 mlx5en.

root@frw05v5:/usr/src # git checkout e059c120b4223fd5ec3af9def21c0519f439fe57
Previous HEAD position was a8e715d21b9 mlx5en: Add race protection for SQ remap
HEAD is now at e059c120b42 mlx5en: Create and destroy all flow tables and rules
when the network interface attaches and detaches.

  After the e059c120b42 checkout, the mlx5en VF network connection breaks.

> How do you verify that the second interface stopped working?
    The working state is checked in an elementary way: Ping from the VM IP
address outside the VM (in the same subnet, of course) and ping from outside
the VM IP of the network interface of our VM we need.

> If only the second SRIOV nic (Mellanox CX-4) causes problem, what happen if 
you just enable this nic, not enable the first one (Mellanox CX-3)? Does the
second interface work in this case?
    I cited the use of the first network interface as an example to illustrate
that the SR-IOV VF technology is operational on the hypervisor. And no, even
with only one ConnectX-4 mlx5en network interface, this behavior is as
described at the beginning.

> How do you enable and disable the SRIOV interfaces?
    Hyper-V Manager -> right click on the VM -> Options -> Network adapter ->
Hardware acceleration -> "checkbox" Enable SR-IOV

Secondly.

FreeBSD-12.3-STABLE-amd64-20220203-r371543-disc1.iso - no changes were made
(installing the system out of the box) - Everything is OK - SR-IOV VF works for
both ConnectX-3 mlx4en and ConnectX-4 mlx5en.

FreeBSD-13.0-STABLE-amd64-20220203-40b816bd4f0-249223-disc1.iso - no changes
were made (installing the system out of the box) - Everything is OK - SR-IOV VF
works for both ConnectX-3 mlx4en and ConnectX-4 mlx5en.

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