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I've setup nested virtualization on a virtual machine and could successfully run Windows guest on it. I used the google example which uses Debian from here

The problem is once I shut down the instance and come later to try it does seem like nested virtualization is disabled. I am testing the following command:

grep -cw vmx /proc/cpuinfo

Which normally returns a non-zero value when nested virtualization is enabled, but now returns zero.

Could it be a problem with nested virtualisation ?

Michael Hampton
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Japheth Odonya
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    I was able to reproduce this simply by stopping and restarting the instance. – Michael Hampton Mar 07 '18 at 04:27
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    I reproduced it as well, I have misread your question before and provided an answer not completely related. – GalloCedrone Mar 07 '18 at 10:46
  • What could be the problem? I asked Google guys from their support and they say that one needs to ensure that they are using Haswell or later cpu and be in a region that supports haswell or later plus check that the used the correct license (I dont know how to verify the license once I use it in creating an image). I tried even using Skylake cpu but the instance doesnt start with nested virtualization enabled. There could be something wrong with the instances – Japheth Odonya Mar 07 '18 at 14:23
  • I believe it is a bug, I updated the answer, it should not be anyhow related to your configuration. @Michael – GalloCedrone Mar 07 '18 at 16:12

1 Answers1

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UPDATE: the bug has been solved.

I tested the behaviour and it is quite weird:

  • if you reboot the instance it is not a problem, the nested virtualisation keeps working.

  • if you stop the instance and restart it the nested virtualisation is no longer working and grep -cw vmx /proc/cpuinfo return 0 as you noticed since.

Since I believe it is not the expected behaviour and it is a bug I raised an public bug in the google issuetracker, you can follow the updated and get updates through the following link:

I advise you to star the public issue in order to get mail notifications.

Disclaimer: I work for Google Cloud Platform Support.

GalloCedrone
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