0017788: nested virtualization: Win10 Guest with hypervisor features hits boot loop in 8.2, but not in 8.1 - CentOS Bug Tracker

ID	Project	Category	View Status	Date Submitted	Last Update

0017788	CentOS-8	qemu-kvm	public	2020-10-09 07:18	2020-10-09 07:18

Reporter	amather	Assigned To
Priority	normal	Severity	major	Reproducibility	always
Status	new	Resolution	open
Product Version	8.2.2004

Summary	0017788: nested virtualization: Win10 Guest with hypervisor features hits boot loop in 8.2, but not in 8.1
Description	With the current qemu-kvm package in 8.2, I'm unable to boot a Win10 Pro VM with hypervisor enabled - Windows will boot loop and finally hit Automatic Repair. This works though if I downgrade the qemu-kvm package to the version shipped with 8.1. Not working: qemu-kvm-2.12.0-99 (CentOS 8.2 / AppStream) Working: qemu-kvm-2.12.0-88 (CentOS 8.1 / AppStream)
Steps To Reproduce	- install CentOS 8.2 - create windows VM (in my case: UEFI, no secureboot, host-passthrough in libvirt config) - install hypervisor features within windows - reboot VM To allow windows VM to boot, disable hypervisor feature, e.g.: <feature policy='disable' name='hypervisor'/> This allows the VM to boot, but no nested virtualization is working.
Additional Information	I've tried to windbg the VM, but as I'm not skilled in this area the only thing I can report is that I hit a lot of Access Violation exceptions, multiple of which happened within OslArchHypervisorSetup. I've also tried several different qemu configs (enable secureboot, try different CPU features, etc.) but to no avail. The only thing that worked was to downgrade the qemu-kvm package. Also, I'm not the only one to experience this, as I got the clue from serverfault: https://serverfault.com/questions/1036113/l0-kvm-and-win10-l1-nested-virtualization-not-working-windows-boot-loop I have no access to RHEL, but it's possible the problem exists there as well.
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Date Modified	Username	Field	Change
2020-10-09 07:18	amather	New Issue