[PVE-User] Problem running any VM with more then 1 Core ( PVE 4.x)

[Eugen Mayer]

Hello,

having an issue with proxmox 4.x running any VM with more then 1 core.

Hardware:
 - Intel(R) Xeon(R) CPU E3-1275 v5 @ 3.60GHz
 - 64GB ram
 - HW raid SSD

PVE 4.x just got installed freshly, just 1 other VM on that box ( 1core opnsense ) and nothing else, so fairly idle and nothing really to be worry about.

I tried boot rancheros 1.0.1 and grml 2014.11 ( both 64bit ), both have the same pattern, when i boot them first, it works, when i reboot them using the cli
 - grub shows up ( if present as menu )
 - selecting anything leads to a stalled VM which i only can stop using qm kill <>

Using 1 core only, everything works just fine 2-4 broke, did not try more. It does not matter if i boot an iso or e.g an installed version of rancheros, reboot stalls every single time.

I have never seen grml not boot up on anything yet, pretty sure that is a general issue.

Logs / Details:
 - dmsg just shows nothing during that happening
 - pve-manager                     4.4-13
 - kernel: 4.9.0-0.bpo.2-amd64 #1 SMP Debian 4.9.18-1~bpo8+1
 - debian 8.8 fully upgraded
 - nothing runs on the host except shorewall

Can i provide anything else? Any clues?

Thanks!

Eugen