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

[Yasumasa Suenaga]

Hi Matthias,

Thanks for reviewing and testing this change!

On 2020/08/25 20:22, Baesken, Matthias wrote:
> Hello,
>       the latest webrev  looks good to me .
> I tested additionally  on  VMWare / Xen / KVM  and  the detection worked nicely .
> 
> You might want to rephrase this comment  (it sounds a little strange to me)
> 
> http://cr.openjdk.java.net/~ysuenaga/JDK-8250598/webrev.02/src/hotspot/cpu/x86/vm_version_x86.cpp.frames.html
> 
> 1821   // In case of Xen, it might be appear until 0x40010000.

Ok, I will set following comment here:

   "Xen cpuid leaves can be found 0x100 aligned boundary starting from 0x40000000 until 0x40010000."


> Don't  need to see another webrev for this .

I will push the change tomorrow.


Thanks,

Yasumasa


> Best regards, Matthias
> 
> 
> 
>> On 2020/08/18 23:39, Doerr, Martin wrote:
>>> Hi Yasumasa,
>>>
>>> thanks a lot for measuring and improving the overhead. This version looks much better.
>>>
>>> I still wonder what the reason was for using a stub. There was probably a reason, but I don't remember.
>>
>> It might be called in many times, so I made change would generate stub in first.
>>
>> VM_Version::check_virtualizations() would call CPUID 256 times (0x40000000 to 0x40010000 step 0x100),
>> and also I changed it is used to call CPUID with EAX = 0x40000007 in Hyper-V.
>>
>>
>>> Hopefully, Matthias can find time for another review when he's back next week.
>>
>> Yeah, I want to commit this change after his review.
> 
> 
>