Forum Discussion

Copper Contributor

Jul 28, 2022

Solved

Installing Hyper-V on Windows Server 2022 reduces host system CPU to 1 core 1 thread

Bit of an odd situation, I've installed Windows Server 2022 (desktop experience) on a server, installed MegaStorage MSM and the relevant drivers from Supermicro and any Windows updates. When I instal...

Hyper-V

Windows Server

SanderNewVM
Aug 09, 2022
Got it! My colleague searched and searched for it. And found a workaround!
Ok, the workaround is nasty and shows a problem in how HyperV 2022 in somewhere in the latest Windows Updates communicates with the BIOS and CPU.
In the BIOS, go to Advanced -> CPU Configuration -> Advanced Power Management Configuration -> "ENERGY_PERF_BIAS_CFG mode". Edit this option.

You will find six options;
* Extreme Performance (does not work)
* Maximum Performance (does not work)
* Performance (works)
* Balanced Performance (works)
* Balanced Power (works)
* Power (works)

See following screenshot as example:

Select one of the working templates and you will get the CPU cores back.

But why?! It looks like there is something wrong with the exposure of the CPU C-states. In this particular situation is looks like it have to do something with CPU masks and with HyperV not accepting/recognizing them:
"Extended Auto-HALT State C1E"

Sander.

Dave Patrick

MVP

Jul 28, 2022

The vendor will be your best resource for problem with the hardware.

https://www.supermicro.com/en/contact

Intfk

Copper Contributor

Jul 29, 2022

I'm not sure I follow the logic, it works fine with Server 2019, why would a hardware problem manifest itself in that way? But yes, I have contacted the supplier. They were unaware of the problem and didn't have any suggestions beyond contacting Microsoft, as they are of the opinion that it is a software problem.

Funnily enough, they linked me to my own discussion thread on serverfault.

Dave Patrick
MVP
Jul 29, 2022
That's pretty poor support from the vendor. Might try asking in a forum geared towards supermicro hardware otherwise you can also start a case here with product support.

Services Hub (microsoft.com)

bug fixes are always free of charge.
- SanderNewVM
  Copper Contributor
  Aug 09, 2022
  Hi,
  we have the same behavior with one of two servers in a HyperV Failovercluster.
  
  Host1 and Host2 shows all cores/cpu's in Device Manager, but Host1 only runs on one core and one CPU. Also visible in TaskManager.
  
  Reinstalled, new BIOS, reset BIOS, latest updates. Supermicro distributor is trying to help, but no clue...
  No difference in hardware and (software) versions.
  
  Sander.
  - SanderNewVM
    Copper Contributor
    Aug 09, 2022
    Got it! My colleague searched and searched for it. And found a workaround!
    Ok, the workaround is nasty and shows a problem in how HyperV 2022 in somewhere in the latest Windows Updates communicates with the BIOS and CPU.
    In the BIOS, go to Advanced -> CPU Configuration -> Advanced Power Management Configuration -> "ENERGY_PERF_BIAS_CFG mode". Edit this option.
    
    You will find six options;
    * Extreme Performance (does not work)
    * Maximum Performance (does not work)
    * Performance (works)
    * Balanced Performance (works)
    * Balanced Power (works)
    * Power (works)
    
    See following screenshot as example:
    
    Select one of the working templates and you will get the CPU cores back.
    
    But why?! It looks like there is something wrong with the exposure of the CPU C-states. In this particular situation is looks like it have to do something with CPU masks and with HyperV not accepting/recognizing them:
    "Extended Auto-HALT State C1E"
    
    Sander.