[Bug 1892132] Re: Failure to get the correct UpLink Representor

[Launchpad Bug Tracker]

** Merge proposal linked:
   https://code.launchpad.net/~fnordahl/ubuntu/+source/python-os-vif/+git/python-os-vif/+merge/408212

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https://bugs.launchpad.net/bugs/1892132

Title:
  Failure to get the correct UpLink Representor

Status in os-vif:
  Fix Released
Status in os-vif victoria series:
  Fix Committed
Status in libvirt package in Ubuntu:
  Fix Released
Status in python-os-vif package in Ubuntu:
  Fix Released
Status in libvirt source package in Focal:
  Fix Committed
Status in python-os-vif source package in Focal:
  In Progress
Status in libvirt source package in Groovy:
  Won't Fix
Status in python-os-vif source package in Groovy:
  Won't Fix
Status in libvirt source package in Hirsute:
  Fix Committed
Status in python-os-vif source package in Hirsute:
  Fix Released
Status in libvirt source package in Impish:
  Fix Released
Status in python-os-vif source package in Impish:
  Fix Released

Bug description:
  [Impact] 
  An update to the mlx5_core driver [1] which will be made available to users of stable releases both through HWE kernels and DKMS packages provided by NVIDIA/Mellanox [2] makes some assumptions about sysfs layout made by OS-VIF and Libvirt apparent.

  To allow users with this hardware to continue to enjoy their existing
  systems with the most recent drivers updates are required to os-vif
  and libvirt.

  Without this update these systems will stop functioning when upgrading
  to the new mlx5_core driver.

  [Test Plan]
  Note: Hardware making use of the mlx5_core driver with support for HWOL is required to test these changes.

  1. Deploy OpenStack on machines with HWOL enabled using kernel without [1]
  2. Create an instance using an HWOL port
  3. Confirm the instance can start and that it has connectivity
  4. Upgrade to kernel with [1] and re-confirm

  [Regression Potential]
  For OS-VIF the changes are made to code paths used exclusively by consumers of this type of hardware and HWOL enabled. They are also made in a backward compatible way so that it works both with the old and new driver.

  For Libvirt the change is made in such a way that it will behave as
  before when used to look up hardware that populates net/phys_port_id.
  When used with hardware that do not populate net/phys_port_id but use
  net_phys_port_name instead, which is typical for the hardware in
  question, the new behavior is used.

  [Original Bug Description]
  Due to new kernel patch here [1], the PF and VF representors are linked to their parent PCI device.

  Old Structure:
  The structure of VF's PCI Address/physfn/net contains only the PF of that VF

  $ ls /sys/bus/pci/devices/<vf-pci-addre>/physfn/net/
  enp2s0f0

  $ ls -l /sys/class/net
  ...
  lrwxrwxrwx 1 root root 0 Aug 17 11:11 enp2s0f0_0 -> ../../devices/virtual/net/enp2s0f0_0
  lrwxrwxrwx 1 root root 0 Aug 17 11:11 enp2s0f0_1 -> ../../devices/virtual/net/enp2s0f0_1
  lrwxrwxrwx 1 root root 0 Aug 17 11:11 enp2s0f0_2 -> ../../devices/virtual/net/enp2s0f0_2
  lrwxrwxrwx 1 root root 0 Aug 17 11:11 enp2s0f0_3 -> ../../devices/virtual/net/enp2s0f0_3
  ...

  New Structure:
  The structure of VF's PCI Address/physfn/net contains the PF of that VF and the VF representors

  $ ls /sys/bus/pci/devices/<vf-pci-addre>/physfn/net/
  enp3s0f0  enp3s0f0_0  enp3s0f0_1  enp3s0f0_2  enp3s0f0_3

  $ ls -l /sys/class/net
  ...
  lrwxrwxrwx. 1 root root    0 Aug 17 08:43 enp3s0f0_0 -> ../../devices/pci0000:00/0000:00:02.0/0000:03:00.0/net/enp3s0f0_0
  lrwxrwxrwx. 1 root root    0 Aug 17 08:43 enp3s0f0_1 -> ../../devices/pci0000:00/0000:00:02.0/0000:03:00.0/net/enp3s0f0_1
  lrwxrwxrwx. 1 root root    0 Aug 17 08:43 enp3s0f0_2 -> ../../devices/pci0000:00/0000:00:02.0/0000:03:00.0/net/enp3s0f0_2
  lrwxrwxrwx. 1 root root    0 Aug 17 08:43 enp3s0f0_3 -> ../../devices/pci0000:00/0000:00:02.0/0000:03:00.0/net/enp3s0f0_3
  ...

  [1] https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=123f0f53dd64b67e34142485fe866a8a581f12f1
  [2] https://www.mellanox.com/products/infiniband-drivers/linux/mlnx_ofed

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