[PPA] VT is not used with libvirt 0.7.5

[Id2ndR]

When starting a VM with the virtual manager, VT is not used and the VM is slow.

System : Ubuntu 9.10
Hardware : CPU Intel with VT
Software : libvirt from dnjl's Virtualization PPA

I can see it because it's possible to remove kvm_intel module while the VM is running.
The trouble appears with last update (1 mounth before it was running normally).

The command line runned by libvirt seams correct :
/usr/bin/kvm -S -M pc-0.11 -enable-kvm -m 384 -smp 2 -name obm23-lenny -uuid f25941b5-8a0b-086a-888e-fe8570f0487d -monitor unix:/var/lib/libvirt/qemu/obm23-lenny.monitor,server,nowait -boot c -drive if=ide,media=cdrom,index=2 -drive file=/home/fabiena/kvm/libvirt-image/obm23-lenny.qcow2,if=virtio,index=0,boot=on,format=qcow2 -net nic,macaddr=52:54:00:4a:73:fb,vlan=0,model=e1000,name=e1000.0 -net tap,fd=48,vlan=0,name=tap.0 -serial pty -parallel none -usb -vnc 127.0.0.1:0 -k fr -vga cirrus -soundhw es1370

The VM run with this command use VT :
sudo /usr/bin/kvm -M pc-0.11 -enable-kvm -m 384 -smp 2 -name obm23-lenny -uuid f25941b5-8a0b-086a-888e-fe8570f0487d -boot c -drive file=/home/fabiena/kvm/libvirt-image/obm23-lenny.qcow2,if=virtio,index=0,boot=on,format=qcow2 -net nic,macaddr=52:54:00:4a:73:fb,vlan=0,model=e1000,name=e1000.0 -net tap,fd=48,vlan=0,name=tap.0

With this last case the network is not operational but the aim is to test the use of VT.
I think this can be related with the "-S" option that is used by libvirt.

[Daniel Baumann (dnjl)]

This -S switch is not the problem - libvirt will manage the running qemu/kvm instances, and this is used for this.

What kernel are you running? The newer libvirt requires a kernel with some more enabled cgroups parameters.
Ubuntu's kernel has enabled this since 2.6.32-5.6. So please try this with a current Lucid kernel (https://launchpad.net/ubuntu/lucid/+source/linux).
Also, you will find such kernels in my kernel ppa (https://launchpad.net/~dnjl/+archive/kernel) - the lxc-flavours are the right ones.

[Id2ndR (id2ndr)]

I just installed the lucid's kernel.

I've got the following traceback when trying to launch a VM :

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/engine.py", line 588, in run_domain
    vm.startup()
  File "/usr/share/virt-manager/virtManager/domain.py", line 150, in startup
    self._backend.create()
  File "/usr/lib/python2.6/dist-packages/libvirt.py", line 300, in create
    if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self)
libvirtError: internal error unable to start guest: open /dev/kvm: Permission denied
Could not initialize KVM, will disable KVM support
qemu: could not open disk image /home/fabiena/kvm/libvirt-image/obm23-lenny.qcow2

Then I changed permissions of /dev/kvm from
crw-rw----+ 1 root kvm 10
to
crw-rw----+ 1 root libvirtd 10

and I got the following error :
Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/engine.py", line 588, in run_domain
    vm.startup()
  File "/usr/share/virt-manager/virtManager/domain.py", line 150, in startup
    self._backend.create()
  File "/usr/lib/python2.6/dist-packages/libvirt.py", line 300, in create
    if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self)
libvirtError: internal error unable to start guest: qemu: could not open disk image /home/fabiena/kvm/libvirt-image/obm23-lenny.qcow2

$ ls -l /home/fabiena/kvm/libvirt-image/obm23-lenny.qcow2-rw-r--r-- 1 root root 1009516544 2010-01-05 18:01 /home/fabiena/kvm/libvirt-image/obm23-lenny.qcow2

The owner and group of this file have been changed (by libvirt ?) when I tried to run the VM.

Then I tried this :
$ sudo /etc/init.d/libvirt-bin restart

And now I can run the VM and it uses VT !

Thanks for your information !

----

So it seems that there are 2 troubles :
- the group of /dev/kvm : I have to check how this group is set (maybe it's one of my script)
- the restart of libvirt-bin daemon : does everyone have to do this or is it a trouble of my environment ?

[Daniel Baumann (dnjl)]

libvirt 0.7.5 wil run qemu/kvm hypervisor as user libvirt-qemu group libvirtd.
so add user libvirt-qemu to group kvm to make qemu use of kvm. The same vor kqemu.
In next release libvirt >=0.7.5-2ubuntu0~dnjl1) this is automatically done in postinst.

Thanks!

[Thierry Carrez (ttx)]

Not a bug in Ubuntu's libvirt package

[Id2ndR (id2ndr)]

I changed the group bug it still doesn't use kvm.

$ groups libvirt-qemu
libvirt-qemu : libvirtd kvm

As strange as it can be, when I run the kvm same command as user libvirt-qemu it appears that kvm is used (I can't remove the module), but not when using virt-manager.
I checked euid et ruid of the process without founding any solution, and I have no idea for an explanation.

[Id2ndR (id2ndr)]

I just update the packages that added libvirt-qemu to kqemu too but doesn't solve the trouble. I still have to change the permissions of /dev/kvm. Am I the only one that encountered this trouble ?