You cannot start virtual machines on a computer that is running Windows Server 2008 R2 and on which a CPU is installed that supports the AVX feature

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft website:

http://support.microsoft.com/contactus/?ws=supportNote The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Workaround for Windows Server 2008 R2

To work around this issue, you can force compatible CPU flags by setting a WMI property. This property is inaccessible from any user interface (UI). However, this property is documented on the Microsoft Software Developer Network (MSDN) website. You may have to perform this workaround for all virtual machines that are created. The change is persistent after the computer restarts. However, there are two known issues when you perform this workaround. Also, see the following sample Windows PowerShell script.

• The workaround also sets compatibility for other CPU features such as Cache line size. Therefore, the virtual machines cannot use the full capabilities of the CPU.

• The workaround is required to be run every time that a new virtual machine is created.

The following is a sample Windows PowerShell script. LimitProcFeatures.ps1:

$VirtualMachines = gwmi -namespace "root\virtualization" Msvm_ComputerSystem
$VMManagementService = Get-WmiObject -Namespace "root\virtualization" -Class Msvm_VirtualSystemManagementService

foreach ($vm in $VirtualMachines)
{
$vmName = $vm.Name
$vmElementName = $vm.ElementName
if(!$vm.Caption.Contains("Hosting Computer System"))
{
Write-Output "Limiting $vmElementName CPU features"
$VMProcessors = (gwmi -namespace "root\virtualization" Msvm_ProcessorSettingData) | where { $_.InstanceID -match "Microsoft:$vmName.*" }
$VMProcessors | foreach { $_.LimitProcessorFeatures = $true}
$retValue = $VMProcessors | foreach {$VMManagementService.ModifyVirtualSystemResources($vm.__PATH, $_.GetText([System.Management.TextFormat]::WmiDtd20) )}
if(!$retValue.ReturnValue)
{
Write-Output "Success";
}
}
}

Additional file information