PCI Passthrough of USB suddenly doesn't work after chassis change

[jcarrut2]

Hello, I recently migrated from TrueNAS CORE to TrueNAS Scale 22.02.0. I had a VM running Home Assistant OS that was successfully migrated, but I had to re-passthrough the USB Zigbee dongle (Conbee II) plugged into one of the motherboard USB ports using Scale's PCI method which I was able to do successfully. I have operated this way with no issue for the past month, until yesterday when I changed my chassis from a tower chassis to a rack-mount. When I turned to server on again, everything came up as expected, except for the VM, which was supposed to autostart. I tried starting the VM manually but it gave me a "failed to start, no PCI detected" error. The USB controller was the only PCI device I had passed through to the VM, so I tried deleting the PCI device from the devices list and starting the VM. This time the VM came back normally, save for the lack of the USB dongle obviously. When I then tried to add the PCI device back to the devices list for the VM, the list of possible devices was unpopulated, whereas when I initially added the PCI device a month ago the list was fully populated with all PCI addresses. I tried spinning up a brand new VM and adding a PCI device to it, but again the PCI device list was unpopulated. Finally I checked my BIOS to make sure VT-D was still enabled (it was) and checked the output of:

Code:

dmesg | grep -e DMAR -e IOMMU
[    0.036879] DMAR: IOMMU enabled
[    1.828228] AMD-Vi: AMD IOMMUv2 functionality not available on this system - This is not a bug.

That seemed like the expected output indicating everything was ready for virtualization and passthrough so at this point I'm at a bit of a loss as to why I lost PCI passthrough when all I did was swap server chassis. Maybe someone out there can offer a suggestion on other things I can try to recover passthrough support?

Thank you!

Show : See My freeNAS system

OS Version:TrueNAS-SCALE-22.02.0
Product:System Product Name
Model:Intel(R) Xeon(R) CPU E5-2697 v2 @ 2.70GHz
Mobo: Asus Rampage IV Black Edition
Memory:47 GiB

 

[jcarrut2]

I solved the problem. As it turns out, it seems disconnecting the motherboard from the power supply to facilitate the chassis swap reset several settings in the BIOS. The Intel Virtualization Technology option remained enabled, which I initially misinterpreted as the VT-D option. It was not. When I checked the BIOS again more thoroughly, I noticed a separate VT-D option buried in System Configuration options which had apparently returned to 'Disabled' during the hardware transfer. When I re-enabled this option and started TrueNAS, PCI passthrough capabilities returned to normal.

Mea Culpa. Just goes to show I need to be more thorough with my checks before posting.

 

[jgreco]

You need to check and probably replace your CMOS battery. Typically a CR2032.