Aidan Finn, IT Pro

Microsoft released a hotfix to deal with an issue where AVX instructions do not work in a virtual machine on a Windows Server 2008 R2-based computer that has an AMD CPU which supports the AVX feature.

Consider the following scenario:

• An AMD CPU that supports the Advanced Vector Extensions (AVX) feature is installed in a computer that is running Windows Server 2008 R2.
  Note AMD introduces support for the AVX feature in Bulldozer-based multicore processors.
• You install the Hyper-V server role on the computer.
• You create a virtual machine on the computer, and then you start the virtual machine.

In this scenario, AVX instructions do not work as expected on the virtual machine.  This issue occurs because the CPUID maximum function limit is not updated to reflect the support for the AVX feature on AMD processors.

A supported hotfix is available from Microsoft.

Copyright Warning

This blog post is the property of Aidan Finn (@joe_elway / http://www.aidanfinn.com) and may not be reused in any manner without prior consent of Aidan Finn. You may quote one paragraph from this blog post if you link to the original blog post.

Related posts:

1. KB2711774 – AltGr Key Does Not Work In Red Hat Linux virtual VM On A W2008R2 Hyper-V
2. KB2752183 – Cannot Migrate A W2008 R2 Hyper-V VM From Non-Bulldozer Host To Bulldozer Host
3. KB2710487 – Error 1359 & Cluster Service Stops In W2008 or W2008 R2 Failover Cluster