PING: RFR: 8250598: Hyper-V is detected in spite of running on host OS
Yasumasa Suenaga
suenaga at oss.nttdata.com
Tue Aug 25 14:50:25 UTC 2020
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.
>
>
>
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