RFR: 8250598: Hyper-V is detected in spite of running on host OS

Yasumasa Suenaga suenaga at oss.nttdata.com
Mon Jul 27 08:53:25 UTC 2020

On 2020/07/27 17:42, Florian Weimer wrote:
> * Yasumasa Suenaga:
>> The current code reports Hyper-V even if it is running on native OS
>> (root partition - not a guest OS).  In root partition, bit 31 is
>> always 1 and Hyper-V is always reported (CPUID always returns
>> "Microsoft Hv")
>> To avoid this problem, the new code would check with WMI whether it is
>> running on Virtual Machine or not.
> But isn't it correct to say that the OS is running under virtualization
> in this case?  It is running on a hypervisor, and not bare metal, after
> all.

You are right in technically, but I think hypervisor detector is expected it would report the process is running on guest OS or not like Dom0 and DomU in Xen. I think it might be useful information from customers for troubleshooting.

At least, hs_err log which was generated in Windows was confused me why it reports Hyper-V when I haven't been installed Windows as a guest.



> The KVM model, where you can run on the virtualization host itself
> (pretty much like bare metal), is somewhat unusual and not even
> supported directly by all CPU architectures.  Not all hypervisors use
> this model.
> Thanks,
> Florian

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