Hypervisor detector for Windows

[David Holmes]

Hi Yasumasa,

My recollection from reviewing this was that it was all based on vendor 
strings. Best to ask Matthias (cc'd) if you need more details.

Cheers,
David

On 25/07/2020 3:51 pm, Yasumasa Suenaga wrote:
> Hi all,
> 
> When I got hs_err log on Windows, I saw "HyperV virtualization detected" 
> in it in spite of running on host OS.
> 
> I tried to file it to JBS and to fix it, but I have some questions for 
> this.
> (This feature has been introduced in JDK-8219241)
> 
> 
>    - According to [1] (it is mentioned in the source code), we need to 
> check bit 31 in ECX when CPUID is called with EAX = 1h. Why it would not 
> do so?
> 
>    - Why would VM_Version::check_virtualizations() call CPUID with 
> 40000000h to 4000FF00h? 40000000h should be used if we want to get 
> vendor ID.
> 
>    - Why VM_Version::check_virt_cpuid() is separated for GNU C (GAS) and 
> MacroAssembler? I guess we can use MacroAssembler for x86 / x86_64.
> 
>    - In case of Hyper-V, host OS is treated as root partition [2], so we 
> cannot use this CPUID solution for Hyper-V. I guess we need to check it 
> with other solutions like [3].
> 
> 
> Thanks,
> 
> Yasumasa
> 
> 
> [1] https://kb.vmware.com/s/article/1009458
> [2] 
> https://docs.microsoft.com/virtualization/hyper-v-on-windows/reference/hyper-v-architecture 
> 
> [3] 
> https://stackoverflow.com/questions/10544498/detect-the-virtualization-layer-from-a-guest-instancevm-vpc-or-hyper-v-in-c 
>