Enabling 'unrestricted guest' VMX feature on Azure Dv3 instance

Question

Enabling 'unrestricted guest' VMX feature on Azure Dv3 instance

Bogdan-Cosmin Chifor 0

I am attempting to use an Azure Dv3 instance for nested virtualization (running a crosvm that uses kvm on Ubuntu 22), but I need the 'unrestricted guest' VMX feature in addition to the available VMX in the CPU flags. Does anyone know if it's possible to enable this feature? Thanks in advance! Bogdan Chifor.

Anonymous

2024-02-07T17:58:34.0433333+00:00

@Bogdan-Cosmin Chifor
Checking this and it seems that “VMX Unrestricted Guest” feature is inherent to the architecture of certain Intel processors. It is not something that needs to be explicitly enabled or disabled by the user. Can you clarify the error you are facing?
Mikko Koivisto 0 Reputation points

2024-02-08T06:46:47.8633333+00:00
More details on issue can be found on this crosvm-dev post

In short, it seems that we are not able to launch Cuttlefish android emulator on Azure because of missing unrestricted guest feature. Fixing that would need either crosvm changes or host with unrestricted guest enabled.
On GCP host I can see these flags:

vmx flags : vnmi preemption_timer invvpid ept_x_only ept_ad flexpriority tsc_offset vtpr mtf vapic ept vpid unrestricted_guest vapic_reg vid shadow_vmcd

On Azure host the post above mentions these flags:

vmx flags : vnmi invvpid tsc_offset vtpr ept vpid
Bogdan-Cosmin Chifor 0 Reputation points

2024-02-09T20:48:13.14+00:00

Hello, Yes, I could use these as alternatives. Will validate my scenario ASAP. Thank you for the answer.

1 answer

Your answer

Anonymous

2024-02-07T17:58:34.0433333+00:00

@Bogdan-Cosmin Chifor
Checking this and it seems that “VMX Unrestricted Guest” feature is inherent to the architecture of certain Intel processors. It is not something that needs to be explicitly enabled or disabled by the user. Can you clarify the error you are facing?
Mikko Koivisto 0 Reputation points

2024-02-08T06:46:47.8633333+00:00

More details on issue can be found on this crosvm-dev post

In short, it seems that we are not able to launch Cuttlefish android emulator on Azure because of missing unrestricted guest feature. Fixing that would need either crosvm changes or host with unrestricted guest enabled.
On GCP host I can see these flags:

vmx flags : vnmi preemption_timer invvpid ept_x_only ept_ad flexpriority tsc_offset vtpr mtf vapic ept vpid unrestricted_guest vapic_reg vid shadow_vmcd

On Azure host the post above mentions these flags:

vmx flags : vnmi invvpid tsc_offset vtpr ept vpid
Bogdan-Cosmin Chifor 0 Reputation points

2024-02-09T20:48:13.14+00:00

Hello, Yes, I could use these as alternatives. Will validate my scenario ASAP. Thank you for the answer.

Answer 1

@Bogdan-Cosmin Chifor
I checked dv4 and dv5 and both have the unrestricted_guest flag when checking the CPU. Please switch to these VM types and let me know if still need assistance.

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Enabling 'unrestricted guest' VMX feature on Azure Dv3 instance

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