Win10 VM won't change CPU

[Taleya]

I'm playing around with updating a machine to win 11, and changed the CPU from KVM to QEMU 64. That had no luck unfortunately, so I'm tweaking to x86-64-v2 AES, but no matter what I do now it's still only reading in the OS as running QEMU virtual CPU version 2.5
Anyone encountered this issue? I've powered the host down via PVE, even gone as far as rebooting the entire PVE but absolutely no joy. Won't even recognise cycling back to KVM64.

Does win10 hard lock the CPU? This was a clone of an existing win10 VM, but the CPU was changed to QEMU before first boot.

 

[smueller@TK]

Hi @Taleya,
If you have set it to x86-64-v2-AES in PVE then QEMU Virtual CPU version 2.5+ will be shown in Windows

If you want the VM to see the CPU Type of our host set the CPU in PVE to host

CPU in PVE: x86-64-v2-AES
In Windows:


CPU in PVE: Default (kvm64)
In Windows:


CPU in PVE: host
In Windows:


Best practice for Windows is to set the CPU to x86-64-v2-AES

Hope this answered your question.

 

[Taleya]

Hi Gabriel,

the windows VM is set to x86-64-v2-AES - forgive me, I'm having some difficulty parsing your phrasing, but it sounds like you're saying I need to actually reset the CPU under pve? I didn't realise such a thing was possible - I can't find the option under the PVE itself, where would this be located?

 

[kosnar]

Hi Taleya,

For setting the CPU type on a VM, please follow these steps:

• Click on the desired VM and navigate to Hardware.
• Double-click on Processor.
• In the Type field, select either "x86-64-v2-AES" or "host" as suggested before.

R.

 

[Taleya]

Hi Taleya,

For setting the CPU type on a VM, please follow these steps:

• Click on the desired VM and navigate to Hardware.
• Double-click on Processor.
• In the Type field, select either "x86-64-v2-AES" or "host" as suggested before.

R.

Perhaps I was unclear.

This has been done. These changes are not reflecting in the OS.

 

[kosnar]

Perhaps I was unclear.

This has been done. These changes are not reflecting in the OS.

When you change from "qemu64" to "x86-64-v2-AES" or similar the name of CPU is not changing. When you change it to "host" then you see the name of real used CPU. The name is also changing when you use named type of CPU like "skylake".

Every time you change type of CPU is necessary full power cycle (Power off and then Power on) to apply this changes.

R.

 

[Taleya]

When you change from "qemu64" to "x86-64-v2-AES" or similar the name of CPU is not changing. When you change it to "host" then you see the name of real used CPU. The name is also changing when you use named type of CPU like "skylake".

Every time you change type of CPU is necessary full power cycle (Power off and then Power on) to apply this changes.

R.

This has also been done.

[...] changed the CPU from KVM to QEMU 64. [then changed] to x86-64-v2 AES, but no matter what I do now it's still only reading in the OS as running QEMU virtual CPU version 2.5
[...] I've powered the host down via PVE, even gone as far as rebooting the entire PVE but absolutely no joy.

 

[kosnar]

Different CPU types like KVM64, QEMU64, and x86-64-v2-AES has actually same label in VM. The change is set of instructions reported to the virtual machine. So the key difference lies in which instructions (for example, AES, AVX, or SSE) are presented to the VM.

To change the CPU label, you can use a named model such as "Skylake-server" or "host". The "host" option provides maximum performance, but it has limitations on High Availability (HA) migration since it requires the exact same host CPU type on the target server. Additionally, all CPU types starting with "Skylake-server" will present the same label to the VM.

We use the x86-64-v2-AES model, as it offers a good balance between performance and HA migration capability.