Microcode patch warning

Products

• VMware Desktop Hypervisor
• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• The vmware.log file of the VMware ESXi virtual machine displays a message entitled CPU microcode update available that says:
  
  CPU microcode update available. The guest OS tried to update the microcode from patch level XX (YYh) to patch level ZZ (TTh), but VMware ESX does not allow microcode patches to be applied from within a virtual machine. Microcode patches are used to correct CPU errata. If you are not experiencing any problems with your CPU, you can ignore this microcode patch. Otherwise, you may be able to obtain a BIOS/firmware update which includes this microcode patch from your system vendor, or your host OS may provide a facility for loading microcode patches obtained directly from the Intel web site.
  
  
• VMware Fusion displays a message entitled CPU microcode update available that says:
  
  The guest OS tried to update the microcode from patch level XX to patch level YY, but VMware Fusion does not allow microcode patches to be applied from within a virtual machine.
  
  
• VMware Player displays a message entitled CPU microcode update available that says:
  
  The guest OS tried to update the microcode from patch level XX to patch level YY, but VMware Player does not allow microcode patches to be applied from within a virtual machine.
  
  
• VMware Workstation displays a message entitled CPU microcode update available that says:
  
  The guest OS tried to update the microcode from patch level XX to patch level YY, but VMware Workstation does not allow microcode patches to be applied from within a virtual machine.

Environment

VMware Player 4.x (Windows)
VMware Workstation 8.x (Linux)
VMware vSphere ESXi 5.1
VMware Player 4.x (Linux)
VMware vSphere ESXi 5.0
VMware Workstation 8.x (Windows)
VMware vSphere ESXi 5.5
VMware Fusion 4.x

Resolution

Microcode patches are provided by CPU vendors to correct CPU errata. These errata generally affect a very small number of users, so unless your system is mission-critical or you are already experiencing problems, you can likely continue without this microcode patch.

Typically, system vendors provide microcode patches as part of their BIOS/firmware updates. You may be able to obtain a BIOS/firmware update from your system vendor that contains this microcode patch.

Microsoft also provides microcode patches in their Windows updates. If you are running Microsoft Windows on your host, you may be able to obtain a Windows update that contains this microcode patch.

Linux provides a facility for loading microcode patches at boot. If you are running Linux on your host, see the man page for microcode_ctl(8). This facility requires a microcode data file, which you can download from Intel.

If you come across this issue in an ESXi/ESX virtual machine, contact your server hardware vendor to update your BIOS firmware.

To download the microcode data file from Intel:

1. Go to http://downloadcenter.intel.com/default.aspx.
2. Choose Processors from the Select a product family list.
3. Choose your CPU's product line and product name from the Select a Product Line and Select a product name lists. Click Find.
4. Choose an operating system as appropriate for your Linux distribution, then choose Firmware from the Download Type list.
5. Choose the most recent Linux Processor Microcode Data File for download.