Nested deployement: Are parameters title confusing or is it just me?

[greegthegeek]

Hi Communities,

Running ESXi 6.5, I was digging on 2 CPU parameters for my VMs:

1. Hardware virtualization: Expose Hardware assisted Virtualization to the guest OS
2. CPU/MMU Virtualization: Automatic/Hard CPU & Soft MMU/Soft CPU & Hard MMU/Both hard

I understood that we have two level/generations of native virtualized instructions here:

1. Hardware virtualization: use VT-X (or AMD-V) for my guest
2. CPU/MMU Virtualization: Use Intel EPT (or AMD-V Nested paging) for my guest

But, what is not clear is why we are mixing CPU in CPU/MMU Virtulization? the choice of "Hardware CPU (& {soft, hard} memory)" is about to use VT-X right? So if I choose Hardware CPU in 2) and not checking "Hardware virtualization" in 1), it's confusing right?

Furthermore, I have an esxi running on a Xeon(R) Gold 6126 (yeah), that have VT-X/EPT... And I can not choose Hardware MMU and CPU on parameter 2), even if I checked 1) !

Please enlight me community!

Thanks & have a nice day!

Greg

[greegthegeek]

Hi here,

I went further in my reflexion: Can we consider that enable assisted virtualization in a on/off button and CPU/MMU virtualization is more like the policy to apply?

[greegthegeek · Accepted solution]

As I digged this question on a another medium (great thanks to NathanosBlightcaller (Amin Masoudifard)​):

You understood MMU hardware assisted will avoid the use of guest shadow tables, and roughly, the result is to reduce latency to access to page tables.

But what about the CPU? Why can we activate CPU hardware virtualization here ("CPU/MMU virtualization: Hardware CPU, software MMU") and also on the other parameters ("Hardware virtualization: Expose hardware assisted virutalization to the guest os")?

What are the differences between the two CPU features? Because when you red documentation for "CPU/MMU virtualization: Hardware CPU, software MMU" and "Hardware virtualization: Expose hardware assisted virutalization to the guest os" they are talking together about using VT-X.

Here is the answers:

- Do your VM are 64 bits are need to make nested virtualization? Check Expose hardware assisted virutalization to the guest os

     => this is for Guest optimization

- Do you have VT-X/AMD-V instructions? To optimize VMWare VMM mechanisms, select CPU Hardware.

     => this is for Host optimization

- Do you have Intel EPT/AMD NPT instructions? To optimize VMWare VMM mechanisms, select MMU Hardware.

     => this is for Host optimization

Here is complete thread with Amine: Re: CPU/MMU configuration

Have a nice day!

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