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

[Baesken, Matthias]

Hi Yasumasa, I put your patch into our internal  nightly  build/test  queue . 


>   - Hyper-V is detected on Windows in spite of running on host OS

So it is in your case a host that  runs  Hyper-V guests.  And the host  reports too  "HyperV virtualization detected" .
Do I get you  right ?
Maybe we should be more specific in this case (however I did not see much problem so far with the  current output ).

>   - Call CPUID with other than EAX = 40000000h (it is not described in the spec [1])

I think we had  some virtualizations that needed checking  CPUID with other than EAX = 40000000h  for detection, 
 But might be these were old or buggy versions , cannot find much details about it atm .

>   - Does not check CPUID hypervisor present bit [1]

Yes, this could/should indeed be added  ( we even did this in our internal JVM a while ago).

>   - Does not support x86 (32bit) platform

This is true , it was not added because   I think 32bit support has not much importance any more in current jdk .
However in case the new version does  support 32bit too, it is for sure a good thing!

Best regards, Matthias



-----Original Message-----
From: Yasumasa Suenaga <suenaga at oss.nttdata.com> 
Sent: Montag, 27. Juli 2020 06:25
To: hotspot-runtime-dev at openjdk.java.net; Baesken, Matthias <matthias.baesken at sap.com>
Cc: David Holmes <david.holmes at oracle.com>
Subject: RFR: 8250598: Hyper-V is detected in spite of running on host OS

Hi all,

Please review this change:

   JBS: https://bugs.openjdk.java.net/browse/JDK-8250598
   webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-8250598/webrev.00/

When I got hs_err log on Windows, I saw "HyperV virtualization detected" in it in spite of running on host OS.

Hypervisor detector has been introduced in JDK-8219241, but it has some problems as below:

   - Hyper-V is detected on Windows in spite of running on host OS
   - Call CPUID with other than EAX = 40000000h (it is not described in the spec [1])
   - Does not check CPUID hypervisor present bit [1]
   - Does not support x86 (32bit) platform

I've tested this change on submit repo, and have checked output from VM.info jcmd on following environment:

   - Windows x64 (host)
   - Windows x64 (Hyper-V guest)
   - Fedora32 x64 (Hyper-V guest)
   - 32 bit JDK on Fedora32 x64 (Hyper-V guest)


Thanks,

Yasumasa


[1] https://kb.vmware.com/s/article/1009458