W11 VM - Change / Update processor type


Well-Known Member
Aug 1, 2017
Oregon, USA
PVE 8.0.4 hosting a W11vm that working just fine on a x86-64-v2-AES processor type.
However, I would like to change the processor type to host or at least x86-64 v4 for the improved instruction set.
Just changing the processor causes the W11 VM to bluescreen or not even boot.

Has anyone done this after the W11 VM is setup?
I suspect there needs to be changes to UEFI and TP stuff, but this is where I'm fuzzy.
Any guidance or link to someone who's done this would be great.

Here's my config for the VM.
agent: 1
bios: ovmf
boot: order=ide0;ide2
cores: 16
cpu: x86-64-v2-AES
efidisk0: local-lvm:vm-106-disk-0,efitype=4m,pre-enrolled-keys=1,size=4M
ide0: BigStor:vm-106-disk-0,cache=writeback,discard=on,size=201252M
ide2: local:iso/virtio-win-0.1.229.iso,media=cdrom,size=522284K
machine: pc-q35-8.0
memory: 32768
meta: creation-qemu=8.0.2,ctime=1691000625
name: W11-1
net0: e1000=52:B2:18:FF:2D:72,bridge=vmbr0,firewall=1
numa: 0
ostype: win11
scsihw: virtio-scsi-single
smbios1: uuid=cde2f3de-3c94-469c-84f0-8c2b5faf8f48
sockets: 1
tpmstate0: local-lvm:vm-106-disk-1,size=4M,version=v2.0
vga: memory=512
vmgenid: 56b46dcb-9549-429d-a58c-7a9ce82bb00c
Windows is notoriously sensitive to (virtual) hardware changes. Best to install it with the desired configuration from the start.
It was imaged from a real machine, so I'm stuck trying to make it work per the image.

I'm willing to futz with it, but just need to know where to start.
I've never had trouble changing cpu masks.

what cpu does your host have?
40 x Intel(R) Xeon(R) CPU E5-2660 v3 @ 2.60GHz (2 Sockets)

If I change the CPU or the display type it will not boot. Console won't even connect.
Last edited:
Haswell-IBRS fails to boot - host missing bit 4&11
Haswell-noTSX-IBRS boots.
KVM64 boots as well. (Seems to have better performance)

KVM64 seems to have better performance; but this is purely subjective, to actually measured. Either option definitely performed better than x89-64-v2-AES.

Now I need to figure out why I can't get the SPICE display not working. (new thread)

Any clues as to which processor selection "should" perform better?
all the fake CPUs have similar performance but lack instruction set extensions. kvm64 should be one of the oldest/slowest.

I have 4 options:


I would just use Haswell, that is what your physical processor is.

What was the processor of the original computer that the VM was imaged from?
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Haswell-EP is what you have in your host. Use Haswell-noTSX-IBRS for now, and see if there is any unknown hardware in device manager, or how Windows identifies the VM CPU.
imo, you're in nested virt because of Win11 enable by default their VBS (Virtualization Based Security) / HVCI Hypervisor-Enforced Code Integrity HVCI, which enable hyperv.
Disable it then change cpu to host.
Last edited:
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