I have Qemu VMs running FreeBSD, Windows and Linux, and I can send them a hardware NMI via the Qemu monitor.
qm monitor 100
Entering Qemu Monitor for VM 100 - type 'help' for help
qm> help nmi
nmi -- inject an NMI
When inkecting the NMI to a Windows VM, I get the message is saving a crash dump, and this reboot the VM.
On Linux I get the message
[26731.911302] Uhhuh. NMI received for unknown reason 31 on CPU 0.
[26731.911303] Do you have a strange power saving mode enabled?
[26731.911304] Dazed and confused, but trying to continue
How to get the kernel to print a stack trace on the console instead of only this message ?
I would need this to debug VMs hanging because of very slow IO.