CPU option “IOMMU: Expose IOMMU to the guest OS”

[carlbinns]

I'm running ESXi 5.5.0 and 6.7 and this option doesn't appear for me in the web GUI, is there something I must do to have the option available? I have VT-d enabled in the server BIOS.

[arshad21dvmw]

Have you enabled hardware-assisted virtualization to the guest OS? 

Both Hardware-assisted virtualization and PCI-Passthrough cannot be enabled simultaneously 

[carlbinns]

Please see attached screenshot of my VM's CPU settings. The “IOMMU: Expose IOMMU to the guest OS” option isn't even present.

[arshad21dvmw]

What is your VM , the so and version 

[bluefirestorm]

The vmx entry is for "Expose IOMMU to the guest OS" checked/enable

vvtd.enable = "TRUE"

But I think this IOMMU setting is only effective for virtual hardware 14 or newer so it will not work with ESXi 5.5.

[carlbinns]

Hi,

The VM OS is Oracle Linux 7.8.

What I'm struggling to understand is why the “IOMMU: Expose IOMMU to the guest OS” option is not listed in any of the documentation (6.0, 6.5, 6.7 or 7.0 "vSphere Virtual Machine Administration" documents).

[bluefirestorm]

As far as I know this feature (expose IOMMU to guest OS) is to be used for virtualisation based security (VBS) in Windows VMs, so I wouldn't know what you can use this feature for with an Oracle Linux 7.8 VM.

It is not listed for ESXi 6.0, ESXi 6.5 documents because the expose IOMMU to guest feature and VBS inside Windows VMs was introduced with ESXi 6.7, Workstation Pro 14.x and Fusion 10.x; which is why virtual hardware version 14 is needed. In Workstation/Fusion, once VBS is enabled is on the guest VM settings, the virtualised IOMMU will also be enabled.