PVE 4.0 Beta2 + qemu + acpi

Paolo from qemu team think that it could be a (physical) cpu bug.
Is your bios and cpu microcode updated to last version ?

My server where I can hit the bug is not updated since 2010.

I using the latest BIOS but the server is still quite old. What server version do you have?
 
Here we go

Code:
root@pve:~# grep -r . /sys/module/kvm*/parameters
/sys/module/kvm_intel/parameters/ept:Y
/sys/module/kvm_intel/parameters/pml:N
/sys/module/kvm_intel/parameters/vpid:Y
/sys/module/kvm_intel/parameters/enable_shadow_vmcs:N
/sys/module/kvm_intel/parameters/eptad:N
/sys/module/kvm_intel/parameters/flexpriority:Y
/sys/module/kvm_intel/parameters/ple_window_grow:2
/sys/module/kvm_intel/parameters/ple_window_shrink:0
/sys/module/kvm_intel/parameters/ple_window_max:1073741823
/sys/module/kvm_intel/parameters/fasteoi:Y
/sys/module/kvm_intel/parameters/enable_apicv:N
[COLOR=#ff0000][B]/sys/module/kvm_intel/parameters/unrestricted_guest:Y[/B][/COLOR]
/sys/module/kvm_intel/parameters/emulate_invalid_guest_state:Y
/sys/module/kvm_intel/parameters/nested:N
/sys/module/kvm_intel/parameters/vmm_exclusive:Y
/sys/module/kvm_intel/parameters/ple_window:4096
/sys/module/kvm_intel/parameters/ple_gap:128
/sys/module/kvm/parameters/tsc_tolerance_ppm:250
/sys/module/kvm/parameters/halt_poll_ns:0
/sys/module/kvm/parameters/min_timer_period_us:500
/sys/module/kvm/parameters/kvmclock_periodic_sync:Y
/sys/module/kvm/parameters/ignore_msrs:N
/sys/module/kvm/parameters/allow_unsafe_assigned_interrupts:N
/sys/module/kvm/parameters/lapic_timer_advance_ns:0