Win7 64bit guest, works with kvm64 cpu mode, crashes physical host with "host" cpu mode

[UrkoM]

Hello,
We created a VM for Windows 7 64bit. We didn't notice that we had the VM in kvm64 default mode until everything was fully installed and running. (We usually use "host" mode, because 3 of our nodes have the same specifications.)
Now, if I shut down the Windows 7 guest, and configure it to use "host" cpu mode, the whole physical server crashes, with NMI watchdog errors, when the VM starts.

Proxmox VE 4.3
CPU: Intel(R) Xeon(R) CPU E3-1230 v3 @ 3.30GHz (1 Socket)
Kernel Version: Linux 4.4.19-1-pve #1 SMP Wed Sep 14 14:33:50 CEST 2016
Host RAM: 16Gb

Has anyone had this problem? Can I actually switch Windows 7 to Host cpu with this Xeon CPU?

 

[spirit]

Its akways better to chose a defined cpu type because they define supported qemu cpu flags. You ll have same perf than host type with choosing the right cpu model (with better stability)

 

[UrkoM]

I'll give that a go. I think Sandy Bridge is the best fit for my hosts. I have one node that seems to be only Nehalem, so...

I have found several places where they talk about using some commands to figure out the best common cpu flags for the processors in your cluster, but they require virsh commands, which I can't find in Proxmox.
Do you have any tips for this?
Thanks for your help!

 

[spirit]

I'll give that a go. I think Sandy Bridge is the best fit for my hosts. I have one node that seems to be only Nehalem, so...

I have found several places where they talk about using some commands to figure out the best common cpu flags for the processors in your cluster, but they require virsh commands, which I can't find in Proxmox.
Do you have any tips for this?
Thanks for your help!

If you use specific cpumodel (or host), you'll be able to live migrate only on host which support this model cpu flags.
So, you need to choose lowest model if you want to live migration.
(default kvm64 model has the lowest cpu flags, and works between amd && intel for example).

So, in your case, you can choose nehalem if you want to live migration between all hosts.
If you don't care about live migration, you can choose sandybridge.

(note that the vm will not start if cpu flags are not supported, so you can do tests like this)