[SOLVED] Windows VM is in a boot loop after updating to Kernel 7.0.x

[BenediktS]

After the upgrade to PVE 9.2 and Kernel 7.0.14-6 a "Windows 11 25H2" machine is in a boot loop.
I am unable to get windows to start in "SecureBoot" or to tell me any error. There isn't even a BSOD.

If i go back to Kernel 6.17.13-19 the machine boots again.
It's a UEFI Boot VM.

No error messages in the logs of proxmox node.
Ans also there are no signs of the failed boots in the windows log.
So the error raises before the windows logs starts.

qm config 122
agent: 1
balloon: 0
bios: ovmf
boot: order=scsi0;ide0
cores: 8
cpu: host
efidisk0: ALL_DISKS:base-111-disk-0/vm-122-disk-0,efitype=4m,pre-enrolled-keys=1,size=528K
hostpci0: 0000:05:00.0,pcie=1
ide0: none,media=cdrom
machine: pc-q35-11.0+pve1
memory: 16000
meta: creation-qemu=6.1.1,ctime=1645116980
name: vsx-Blender4
net0: virtio=AA:17:10:64:CF:0A,bridge=vmbr0,firewall=1
numa: 0
ostype: win10
parent: autodaily260727220748
scsi0: ALL_DISKS:base-111-disk-1/vm-122-disk-1,cache=writeback,discard=on,iothread=1,size=256G
scsihw: virtio-scsi-single
smbios1: uuid=23f7d83a-dcb0-4941-a40a-a79fba6696b8
sockets: 1
tags: win11
tpmstate0: ALL_DISKS:base-111-disk-2/vm-122-disk-2,size=4M,version=v2.0
vmgenid: 90635c97-e239-444c-812d-54be81ddd33f

The error also exists if we disable the pci passthrough.
Also we tried many different machine types, SCSI IOs, etc.

 

[BenediktS]

I just saw the line "ostype: win10" .

When we change that to "ostype: win11", the machine gets to the win11 loading screen and hangs then with 100% CPU 100% RAM usage.
On a second boot the machine started fine.

If we go back to "ostype: win10" the machine is in a boot loop again.


So changing this option changes the boot behavior in Kernel 7.0.x from not booting to booting.
The setting is there on "win10" because we updated the machine in place, but did not chage this setting under options.
After changing the setting from "win10" to "win11" the first boot hangs, and after that the boots went fine.