VirtualBox 6.0 and Hyper-V

[floogy]

I'm wondering if Oracle still is working on a solution without rebooting (Using the Hyper-V) that not slow down the paravirtualized VT-x/AMD-v Access in virtualbox. Also, when I see the Turtle, but using Hyper-V paravirtualizing is that machine slow as coming with no acceleration or only with a bit decreased performance because of the still buggy implementation of the use of Hyper-V in virtualbox?

I would appreciate a solution, which toggle without reboot. Though I'm not sure if that is technically possible at all.

I used Hyper-V last Weekend the first time and run virtualbox already for a very long time. Yesterday I installed 6.1.14 and today I realized the issue.

Edit: Okay, didn't noticed that this thread is that long before posting this message. How are the test builds like 6.1.15 behave in this regard?

I found these interesting links:
https://windowsserver.uservoice.com/for ... nested-vir
https://github.com/microsoft/WSL/issues ... -638409782
https://unclassified.software/de/apps/hypervswitch
https://github.com/ygoe/HyperVSwitch

[scottgus1]

toggle without reboot. Though I'm not sure if that is technically possible at all.

No, it is not, due to the type of hypervisor Hyper-V is, Type 1, which runs before the host OS starts. Virtualbox is Type 2, which runs after the host OS starts. So toggling Hyper-V requires rebooting the host OS.

Microsoft is working on and changing Hyper-V, so Microsoft's target is moving. As anyone who has done target practice, hitting a stationary target is hard enough. Hitting a moving one?

See viewtopic.php?f=6&t=90853&start=285#p483829

[floogy]

I thought they are trying to use Hyper-V, which is accessing the CPU VT-x/AMD-v Extension, and pass it eventually through to virtual box via API. Maybe that link which votes for nesting extensions to Hyper-V is such an approach. I don't know exactly, though, had to look deeper into this.

[scottgus1]

The devs are working on trying to get Virtualbox to run while Hyper-V is enabled. It's getting better, but it's just not there yet.

[Guyver]

I have it working with Solaris 11.4 as the guest under V-Box (test build 6.1.97r) under Win10 2004 Hyper-V.

[thegioidotapgym]

Why can't VirtualBox or VMware run with Hyper-V enabled on Windows 10?

[scottgus1]

Hyper-V is a type-1 hypervisor, meaning it touches the bare metal PC first, then the control OS and other OS's ride on top.

Virtualbox and some VMware offerings are type-2 hypervisors, meaning they ride on an OS that has already started the bare metal PC. SO they can only use what the OS allows them to use.

If Hyper-V is running it takes "virtualization technology" capabilities of the PC (VT-X,AMD-V/SVM) so other programs, like Virtualbox, can't use them. Virtualbox is attempting to use the Hyper-V engine on Hyper-V-enabled Windows PC's, but it's still a work in progress, and for now it is easier to tell folks who have trouble running Virtualbox to turn off Hyper-V to get running Virtualbox.

The Virtualbox test builds have the latest attempts to get working Virtualbox on enabled Hyper-V.

[Arny1]

Looks like the recent commits have really fixed something.
...
I used 6.1.15 r140351 to run Ubuntu 20.04 in Windows 10 to compile OpenWrt. It finally worked (unlike a few weeks ago).

Incited by your post, I now tried again with Virtualbox test version 6.1.15 r 140899.

I can confirm that VirtualBox seems to work now with Hyper-V:
My Knoppix ISO-ms5sum checksum test consistently returns the correct checksum now.

Checksum processing time:
83 / 56 secs on first/second test run with Hyper-V
42 / 25 secs on first/second test run without Hyper-V

So a 50% performance hit in this test.
Anyway, this is still better than getting a corrupt system.

[chli]

Cross-posting from : github . com/MicrosoftDocs/WSL/issues/798
Opened a ticket at : virtualbox . org/ticket/19987

Hyper-V and VirtualBox 6.1.16 Windows Home x64 2004 still causing issues here.

I can start my debian "sid" VM (Linux Kernel 5.9.0.1-amd64) when I type in a Windows admin console:

bcdedit /set hypervisorlaunchtype off

and then reboot.

But if I enable it (needed for WSL2) with:

bcdedit /set hypervisorlaunchtype auto

and then reboot, my VM doesn't boot anymore but there are still things happening in the Linux Kernel before it hangs. (I left it overnight last time and nothing happened after that last message).

Attached are the Kernel logs, the one that didn't boot has extra "console=ttyS0 console=tty0 ignore_loglevel" as parameters so I can capture the Kernel log in a virtual serial port through VirtualBox.

Hyper-V off:

kernel-boot-hyperv-off.txt

Kernel Boots with Hyper-V OFF

(40.41 KiB) Downloaded 4 times

Hyper-V on:

kernel-hang-hyperv-on.txt

Kernel Hangs with Hyper-V ON

(9.33 KiB) Downloaded 7 times

[fth0]

In the HyperV-off case, VirtualBox intercepts the Linux kernel setting the LOCK bit in the IA32_FEATURE_CONTROL MSR. In the HyperV-on case, the log messages stop right before that.