Possible PSOD when ENS is configured with overlay and VM sends overlay packet with offloading enabled

Products

• VMware vSphere ESXi

Issue/Introduction

There is a possibility of ESX hypervisor PSODing when the following conditions are met:

1. ENS is configured with overlay
2. VM sends overlay packet with offloading enabled
3. vmxnet3 v7 driver 1.7.0.0-k

Symptoms:

PSOD with @BlueScreen: ASSERT bora/vmkernel/net/ens/ens_mbuf.h:304

Environment

VMware vSphere ESXi 7.0.0

Cause

There is a double encap issue that happens when the above 3 conditions are met which is not handled leading to a PSOD.

Resolution

Recommend to follow the workaround for now until the resolution is confirmed

Workaround:

Disable hardware offload on the vnic (in the VM).

For Linux VMs follow steps in:
Enable or Disable TSO on a Linux Virtual Machine

For Windows VMs follow steps in:
Enable or Disable TSO on a Windows Virtual Machine

Additional Information

Impact/Risks:
This can cause issues in a production environment.