[fedora-virt] Nested KVM help

[Cole Robinson]

On 08/19/2013 12:43 PM, James Slagle wrote:
> Hi,
> 
> When I try to use nested KVM with Fedora 19, I'm experiencing a hang of the L1
> vm.  I eventually have to do a "Force Off" from virt-manager on L0 since the L1
> vm is completely unresponsive.
> 
> Both my L0 and L1 are F19, x86_64.  L2 doesn't really seem to matter as I can't
> even get the guest to start before L1 completely locks up.  Even just
> attempting to define a L2 guest that uses kvm virtualization locks up L1
> completely.
> 
> Here are some more details.
> 
> On L0 (i've rebooted L0 after enabling the nested parameter):
> [root at dublin ~]# uname -a
> Linux dublin 3.10.7-200.fc19.x86_64 #1 SMP Thu Aug 15 23:19:45 UTC 2013 x86_64
> x86_64 x86_64 GNU/Linux
> [root at dublin ~]# cat /sys/module/kvm_intel/parameters/nested 
> Y
> [root at dublin ~]# rpm -q libvirt
> libvirt-1.0.5.5-1.fc19.x86_64
> [root at dublin ~]# lsmod | grep kvm
> kvm_intel             138528  3 
> kvm                   422809  1 kvm_intel
> 
> cpu section of libvirt xml for L1 vm:
>   <cpu mode='custom' match='exact'>
>     <model fallback='allow'>Nehalem</model>
>     <feature policy='require' name='vmx'/>
>   </cpu>
> 
> 
> On L1:
> [root at localhost jslagle]# uname -a
> Linux localhost.localdomain 3.10.7-200.fc19.x86_64 #1 SMP Thu Aug 15 23:19:45
> UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
> [root at localhost jslagle]# rpm -q libvirt
> libvirt-1.0.5.5-1.fc19.x86_64
> [root at localhost jslagle]# lsmod | grep kvm
> kvm_intel             138528  0 
> kvm                   422809  1 kvm_intel
> 
> 
> I've looked in dmesg output, /var/log/messages, and libvirt logs on both L0 and
> L1 and can't see any errors.
> 
> Any ideas on how to debug this further?
> Let me know if should file a bugzilla, I wasn't sure I had enough to go on to
> go ahead and do that yet.
> 

Unfortunately doesn't sound like there is much to go on, maybe the kvm
maintainers can give some hints. Please file a bug against the kernel and CC me.

Thanks,
Cole