Updating check for Hyper-V

[PatrickLang]

This is an updated check to tell if a hypervisor (including Hyper-V) is running on Windows. Virtualbox uses this check to avoid crashing (See #9258).

This fix covers a few more corner cases than the previous one in #9456:

• Allow virtualbox to run if Hyper-V is installed, but currently disabled. If you want to switch a machine between using Virtualbox and Hyper-V, you can do it with another boot entry - Link
• Works on Windows Server & Windows 10. Windows Server uses Get-WindowsFeature to check for install, while Get-WindowsOptionalFeature is used on Windows 10 ¯\(ツ)/¯
• There are two other features that use the hypervisor, so it's possible to have it loaded but Microsoft-HyperV-All isn't installed: Windows-Defender-ApplicationGuard, and DeviceGuard which is controlled through group policy

[PatrickLang]

Oops sorry about that. Need to read up on Ruby unit testing. I think the commit I added should fix it.

My manual test on a win10 laptop with Hyper-V enabled works as expected

>vagrant up --provider=virtualbox
The provider 'virtualbox' that was requested to back the machine
'default' is reporting that it isn't usable on this system. The
reason is shown below:

Hyper-V and VirtualBox cannot be used together and will result in a
system crash. Vagrant will now exit. Please disable Hyper-V if you wish
to use VirtualBox.

[briancain]

@PatrickLang - Thanks for the update! A couple of questions...

Is there a better check for seeing if Hyper-V is "installed" but disabled? Also do you have an example of how to get to that state in windows 10? Every bit of documentation I see says that it's either enabled or disabled, but I see no language around it being installed but "off". I ask because this command:

$(Get-ComputerInfo).HypervisorPresent

Won't work for this because it returns true if you're running vagrant on Windows inside of a virtual machine. :(

We will however need some sort of check to ensure that this is only checked against windows 10 (maybe windows 8 works?), because these commands fail and do not exist on older systems like windows 7.

[briancain]

Edit on this: I just tried this on windows 7. We will be fine without a OS check, as the Powershell.execute_cmd function returns nil if a command fails (i.e. doesn't exist).

[PatrickLang]

Here's the corner cases I can think of:

Windows 7 - check should always fail. Hyper-V not present, and check for it isn't there
Windows 8 / Windows Server 2012 - check should work. If Hyper-V is present, the check should do the right thing.

One false positive would be:
Windows 8+ or Windows Server 2012+ running under VMWare, KVM or Xen. Those will also return Hypervisor present. If Virtualbox works nested under those hypervisors, then we should switch to a per-hypervisor check which will be much more difficult. You'd have to look at what devices are present to guess what hypervisor you're under and of course hypervisors can lie :/

[briancain]

So yesterday I did some tests. We should be good without a "check" for which OS we're on, because if the powershell command fails, its helper function in Vagrant will just return nil so we won't have to worry about an uncaught exception for a command that doesn't exist on Windows 7. The original check will just be false, and we should be good to continue on using the virtualbox provider.

Finally that being said, I'm still pretty confident that the check in place is enough to determine if Hyper-V is running...but I might be missing something.

$(Get-WindowsOptionalFeature -FeatureName Microsoft-Hyper-V-All -Online).State

This returns either Enabled or Disabled. I'm assuming if it's Enabled, Hyper-V is running, and therefore Vagrant needs to bail out before it brings up a virtual machine in virtualbox and blue screens the machine. Are you saying this is not the case? (i.e. the command returns Disabled, but some how it's running?)

Thanks!

[Quix0r]

Conflicts found, can you please fix them? Is still crashing with version 2.1.1 (docker installed, vagrant up gives BSOD).

[briancain]

Hi there, this check was improved via a997a27 which includes the ability to check on Windows Sever. I'm going to close this pull request now. Thanks!

[Quix0r]

Nice work.

[ghost]

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