LHC@home

I just upgraded to 25.04 and there was an issue with VirtualBox:

VBoxManage: error: VirtualBox can't enable the AMD-V extension. Please disable the KVM kernel extension, recompile your kernel and reboot (VERR_SVM_IN_USE)

there was a fix here:

https://superuser.com/questions/1845776/virtualbox-cant-operate-in-vmx-mode

Thanks. I found another page with the

sudo modprobe -r kvm_amd

but it had a different file to modify and a different line to add for a permanent fix. I shall try the one from that link.

Really the kernel developers and the VBox people should get together to sort this out so users don't need to do this.

Have you tried "module_blacklist" in your kernel parameters?

Have you tried "module_blacklist" in your kernel parameters?

I have done that now. Thanks. I haven't tried a reboot to check it yet. I wonder if it would be worth putting out a push notification on BOINC aimed at Linux users as I can see quite a few work units there are at least one or two failures because of VBox not starting just on work units where I have had tasks from. I know my way around a terminal to some extent but there will be a lot out there who don't.

Ubuntu 24.04 HWE recently upgraded to Linux kernel 6.14, and started experiencing similar issues.

This is caused by a change in behavior starting with Linux kernel 6.12 on when KVM initiates the processor's virtualization support. Older kernels initialized virtualization extensions on use -- kernel 6.12 and onward initialize them when the KVM modules are loaded (even if the KVM modules then sit idle and are never actually used).

I didn't want to solve this by blacklisting the KVM modules (as is the common solution if you do a web search), so I reverted to the previous initialization behavior with the following "modprobe" conf file:

# /etc/modprobe.d/virtualbox-no-kvm.conf
#
# In kernel 6.12, KVM initializes virtualization on module loading by default.
# This prevents VirtualBox VMs from starting.
#
# In order to avoid this, either add "kvm.enable_virt_at_load=0" parameter
# into kernel command line or unload corresponding kvm_XXX module.

options kvm enable_virt_at_load=0

The change should take effect on unloading/reloading the KVM kernel modules, or by rebooting (my testing was with the latter).

To verify that things are working properly:

# All commands tested with VirtualBox 7.1.12, but should work with earlier versions

# Create a simple VM. This will always succeed unless your VirtualBox install is broken.
VBoxManage createvm --name "TestVM" --ostype "Linux_64" --register

# Start the VM.
#
# If VirtualBox is working, the VM should start successfully (or fail with an error about
# no bootable media, which is a success for our purposes).
#
# If your CPU doesn't have working hardware virtualization support, or KVM has
# initialized your CPU's hardware virtualization, this will fail with an error about
# your CPU's virtualization extensions being unavailable.
VBoxManage startvm "TestVM" --type headless

# Stop the VM (if it started successfully)
VBoxManage controlvm "TestVM" poweroff

# Clean up the VM
VBoxManage unregistervm "TestVM" --delete