virtualbox.org

Sorry to bother guys.
I'm using VirtualBox on a Windows 11 host and holding a Win7 and an Ubuntu guest. Everything went well until the host Win 11 updated itself. After the update I couldn't start the Ubuntu VM and got the error 'End kernel panic - not syncing: attempted to kill the idle task''. Also I couldn't boot from original installation live CD and got the same error. And the Win 11 update included the "KB5013943" which was mentioned in Pagafantas' post posted on May 13th. I attached my Ubuntu guest logs below, hoping to provide more useful info.

I also upgraded VirtualBox, trying to solve the above issue. After upgrading the VBox main program, extension package and guest additions in Win7 from 6.1.28 to 6.1.34, I found the Win7 guest started freezing from time to time, especially during start up process. It stuck at the logo page for about 10 min every time I launch the VM. After getting to the desktop, the UI always stops responding(cannot move the mouse or type anything, and the animation on the screen stops as well) and resumes several seconds later. Sometimes the Win7 guest promoted "Video Adapter Driver Not Responding and is Successfully Restored". I tried to reinstall the Guest Additions in Win7 guest, check & uncheck the 3D acceleration options, change the video adapter controller type and enlarge the vRAM in VM configurations, rollback to the previous snapshot, boot from installation CD but that didn't help. When I booted from installation CD, all I got is a black screen after the loading file page. I also attached the logs from Win7 guest below. Hope to get some help.

Thank you!

Hyper-v is enabled.

00:00:10.831706 HM: HMR3Init: Attempting fall back to NEM: VT-x is not available
00:00:11.112723 NEM: info: Found optional import WinHvPlatform.dll!WHvQueryGpaRangeDirtyBitmap.
00:00:11.112778 NEM: WHvCapabilityCodeHypervisorPresent is TRUE, so this might work...

See HMR3Init: Attempting fall back to NEM (Hyper-V is active).

mpack wrote:Hyper-v is enabled.
..........

Thank you so much mpack! I followed the instruction in your reply and disabled hyper-v on the host completely (In fact I know VirtualBox will not work well with hyper-v so I checked the functions in control panel to make sure the hyper-v function was not checked before I installed VirtualBox, but obviously it was not enough). The icon in the status bar of VM changed from turtle to the V icon. Now the Win7 guest has a much better performance and doesn't freeze any more. And I tried Ubuntu, everything went well and kernel panic error disappeared. Maybe the Win 11 patch KB5013943 only affects the VMs failing to use VT-x or AMD-V.

One more question. I noticed that even if the VT-x/AMD-V is available for my VMs now, the enable nested VT-x/AMD-V option is still disabled on the processor tab in the configuration. Althought I won't virtualize another OS in the guest, I just wonder why it is disabled by VirtualBox. Does it need the support from guest OS and Win7 doesn't meet the requirement?

Thank you!

LXH wrote: One more question. I noticed that even if the VT-x/AMD-V is available for my VMs now, the enable nested VT-x/AMD-V option is still disabled on the processor tab in the configuration.

Either :-
o The VM was still active at the time - most settings can only be changed when the VM is completely shut down, i.e. not running or suspended.
o VirtualBox doesn't properly recognize your CPU. If this is the case then you may need to raise a BugTracker ticket.

LXH wrote:I noticed that even if the VT-x/AMD-V is available for my VMs now, the enable nested VT-x/AMD-V option is still disabled on the processor tab in the configuration. Althought I won't virtualize another OS in the guest, I just wonder why it is disabled by VirtualBox. Does it need the support from guest OS and Win7 doesn't meet the requirement?

No, but your host CPU doesn't support the Intel vPro features. For the technical details, see Nested VT-x and VMCS Shadowing.

Thank you for your reply mpack and fth0!

fth0 wrote:No, but your host CPU doesn't support the Intel vPro features. For the technical details, see Nested VT-x and VMCS Shadowing.

I spent some time studying the link mentioned in the reply. I think that's the reason why the option of nested virtualization is disabled in VirtualBox. I'm using Intel Core i5-10210U CPU and it's definitely not one of the high-end types. And I checked the VT-x section in the logs of VM and it did show no support for VMCS Shadowing on my CPU.
Also I found the method to enable this option via VboxManage command line, but it may not be a good idea to force it according to the content in link.

Thank you again for your help. The optimized performance of the VMs after enabling VT-x did change my opinion towards VirtualBox. I really appreciate that.