[libvirt-users] CPU Mode= Host passthrough

[Michael Beham]

Hi,

I´m doing some research on Nested Virtualization with KVM and Xen. My 
cpu on bare-metal system is a Opteron_G4 --> (AMD Opteron 4280).
qemu-version 1.0; libvirt 0.9.12

For nesting KVM in KVM I´m adding the <cpu mode='host-passthrough'/> 
command to the XML-File of the VM on Layer 0. So I´m able to install KVM 
in KVM and create nested guests at Layer 2.

L2 --> Nested VM
L1 --> KVM / XEN
L0 --> KVM

If i try the same with installing Xen in the VM on Layer 1 Xen don´t 
boot and I get following error:

Panic on CPU 0:
GENERAL PROTECTION FAULT
[error_code=0000]

If I remove <cpu mode='host-passthrough'/> command from the VM´s XML Xen 
boot is successful and Nesting Xen in KVM works!
May this problem depends on the following problem --> 
https://bugzilla.redhat.com/show_bug.cgi?id=804224