Reconfiguration of virtual machines with PCI passthrough device fails when CPU Hot Add is enabled

Products

• VMware vSphere ESXi

Issue/Introduction

When reconfiguring a virtual machine, it might fail with the following error: 

"Invalid virtual machine configuration. Virtual NUMA cannot be configured when CPU hotadd is enabled"

This might happen under the following conditions:

• The VMware vSphere ESXi version is 8.0 
• The virtual machine hardware version is 20
• The virtual machine motherboard layout is set to ACPI
• CPU Hot Add is enabled
• At least on PCI passthrough device is configured (DirectPath I/O, SR-IOV, vGPU)
• One power cycle has been completed since configuration 

This issue can be encountered even if the virtual machine is not crossing physical NUMA boundaries and only has one vNUMA node.

Environment

• VMware vSphere ESXi 8.0.2
• VMware vSphere ESXi 8.0.0

Cause

Due to the configuration of PCI passthrough and an ACPI motherboard layout, this makes the VM appear NUMA enabled and as such, invalid for use with CPU Hot Add.

Resolution

This issue is resolved in VMware vSphere ESXi 8.0 U1 (build number 21495797).

Workaround:

Disable CPU Hot Add before attempting any other reconfigurations.

Additional Information

vNUMA is disabled if vCPU hotplug is enabled