In this article, you will learn about how to disable side-channel mitigations on VMware Workstation. Recent version of VMware Workstation 17.x “Install Workstation Pro 17: Fix failed to initialise library for mounting and unmounting virtual disks“. The Virtual Machines have side channel mitigations enabled on Windows hosts. See this article on how to install VMware Workstation Pro 17. Please see Downgrade VMware Workstation: Fix the Processor does not support xsave on VMware Workstation.
You may want to see How to install Windows Server 2022 on VMware Workstation, and All Group Policies (GPO) available to configure Microsoft Edge settings.
What are the consequences of Consequences?
The settings come with some performance issues as shown in the image below. To improve performance, we must disable side-channel mitigations.
According to VMware, the root cause of the performance degradation is most likely due to mitigations for side channel attacks such as Spectre and Meltdown.
Side channel attacks allow unauthorized read access by malicious processes or virtual machines to the contents of protected kernel or host memory. CPU vendors have introduced several features to protect data against this class of attacks such as indirect branch prediction barriers, single thread indirect branch predictor mode, indirect branch restricted speculation mode and L1 data cache flushing.
While these features are effective at preventing side-channel attacks. They can cause noticeable performance degradation in some cases as stated above.
See the workaround for a zero-day vulnerability on Microsoft Exchange Server, and how to Enable Exploit Protection feature on Windows using the Windows Security App, Microsoft Endpoint Configuration Manager, and Group Policy.
Solution: Disable side channel mitigation
Launch VMware Workstation. Ensure the Virtual Machine are Shut Down and click on Edit Virtual Machine settings.
Navigate to the VM > Settings > Options > Advanced. Check “Disable Side Channel Mitigations for Hyper-V enabled hosts”.
The Side channel on VMware Workstation is disabled
When this is done, the error will no longer appear.
Alternatively, you could add the following line to .vmx file. This is the same as disabling it by GUI above.
ulm.disableMitigations = "TRUE"
I hope you found this article useful on “How to disable side-channel mitigations on VMware Workstation”. Please feel free to leave a comment below.
