Bug 1914414

Disclaimer
----------

I know this NIC model is not part of the list of officialy supported models but it used to work fine with OCP 4.4 and/or 4.5.

Description of problem
----------------------

Trying to enable SRIOV for device Intel Corporation Ethernet Connection X722 (rev 09) (PCI ID 8086:37cc) fails with the following error:

> W0108 17:33:29.166332    5288 utils.go:70] DiscoverSriovDevices(): unable to parse device driver for device 0000:08:00.0 -> class: 'Network controller' vendor: 'Intel Corporation' product: 'Ethernet Connection X722' "error getting driver info for device 0000:08:00.0 readlink /sys/bus/pci/devices/0000:08:00.0/driver: no such file or directory"

Version-Release number of selected component
--------------------------------------------

> OCP: 4.7.0-fc.0
> RHCOS: 47.83.202012171901-0
> SR-IOV Network Operator: 4.6.0-202012160125.p0

Steps to Reproduce
------------------

1. Deploy an OCP BM IPI cluster.

2. Deploy the NFD operator to get nodes labeled as sriov capable:

> feature.node.kubernetes.io/network-sriov.capable: "true"
> feature.node.kubernetes.io/pci-10df.present: "true"
> feature.node.kubernetes.io/pci-10df.sriov.capable: "true"
> feature.node.kubernetes.io/pci-8086.present: "true"
> feature.node.kubernetes.io/pci-8086.sriov.capable: "true"

3. Deploy the SRIOV operator.

> NAME                                           DISPLAY                   VERSION                 REPLACES   PHASE
> sriov-network-operator.4.6.0-202012160125.p0   SR-IOV Network Operator   4.6.0-202012160125.p0              Succeeded

4. Disable sriov operator-webhook as described in OCP documentation:

> oc patch sriovoperatorconfig default \
>   --namespace='openshift-sriov-network-operator' \
>   --type='merge' \
>   --patch='{"spec":{"enableOperatorWebhook":false}}'

5. Create a SriovNetworkNodePolicy:

> ---
> kind: SriovNetworkNodePolicy
> apiVersion: sriovnetwork.openshift.io/v1
> metadata:
>   name: sriov-network-policy
>   namespace: openshift-sriov-network-operator
> spec:
>   resourceName: sriov_nics
>   nodeSelector:
>     feature.node.kubernetes.io/network-sriov.capable: "true"
>   nicSelector:
>     pfNames:
>       - ens2f0
>   deviceType: vfio-pci
>   numVfs: 16

Actual results
--------------

Nodes reboot several times during SRIOV configuration but no VFs are created for ens2f0 NIC.

An error is logged by the sriov-network-config-daemon DaemonSet:

> W0108 17:33:29.166332    5288 utils.go:70] DiscoverSriovDevices(): unable to parse device driver for device 0000:08:00.0 -> class: 'Network controller' vendor: 'Intel Corporation' product: 'Ethernet Connection X722' "error getting driver info for device 0000:08:00.0 readlink /sys/bus/pci/devices/0000:08:00.0/driver: no such file or directory"

Expected results
----------------

16 VFs should be created for ens2f0 NIC.

Additional info
---------------

No driver file is actually present in /sys/bus/pci/devices/0000:08:00.0/:

> sudo ls -l /sys/bus/pci/devices/0000:08:00.0/
> 
> [snip]
> 
> -r--r--r--. 1 root root     4096 Jan  8 16:51 device
> -r--r--r--. 1 root root     4096 Jan  8 18:05 dma_mask_bits
> -rw-r--r--. 1 root root     4096 Jan  8 18:05 driver_override
> -rw-r--r--. 1 root root     4096 Jan  8 18:05 enable
> lrwxrwxrwx. 1 root root        0 Jan  8 16:53 firmware_node -> ../../../../../LNXSYSTM:00/LNXSYBUS:00/PNP0A08:01/device:f3/device:f5/device:fc/device:fd
> lrwxrwxrwx. 1 root root        0 Jan  8 16:53 iommu -> ../../../../../virtual/iommu/dmar4
> lrwxrwxrwx. 1 root root        0 Jan  8 16:53 iommu_group -> ../../../../../../kernel/iommu_groups/25
> 
> [snip]
> 
> -rw-r--r--. 1 root root     4096 Jan  8 18:05 sriov_drivers_autoprobe
> -rw-r--r--. 1 root root     4096 Jan  8 16:53 sriov_numvfs
> -r--r--r--. 1 root root     4096 Jan  8 18:05 sriov_offset
> -r--r--r--. 1 root root     4096 Jan  8 18:05 sriov_stride
> -r--r--r--. 1 root root     4096 Jan  8 16:53 sriov_totalvfs
> -r--r--r--. 1 root root     4096 Jan  8 18:05 sriov_vf_device
> 
> [snip]
> 

Looking at the code we can see the following function call:

> DiscoverSriovDevices()
> └─ https://github.com/openshift/sriov-network-operator/blob/release-4.7/pkg/utils/utils.go#L45-L119
>    └─ GetDriverName()
>       └─ https://github.com/openshift/sriov-network-operator/blob/release-4.7/vendor/github.com/intel/sriov-network-device-plugin/pkg/utils/utils.go#L343-L351

This code does not appear to have changed for some time so it might be due to a change outside of sriov operator (RHCOS kernel?).