Re: [Qemu-discuss] Windows-10 virtualization and nested virtualization

[Jeff Forbes]

I was responding to Bandan Das' comment about Hyper-v NOT running when
the hypervisor flag is present. What I observed was just the opposite. 
With "-cpu host,+vmx" Hyper-V will try to start the VM and then report
that a component required by Hyper-V failed to start. The end result is
the same; however, with the kernel and qemu-kvm in Fedora-22 the VMBus
device does not start. Now with the the latest kernel and qemu-kvm,
VMBus starts, but the same error is given. Progress from all of the
hard work of the KVM developers. I am afraid that helping in this area
is beyond my current abilities, so I must defer to you and your colleag
ues.

Paolo,
Since you are the most likely person to know, is Hyper-V nested
virtualization likely to work with KVM in the near term? 

Jeff


On Wed, 2016-04-06 at 18:11 +0200, Paolo Bonzini wrote:
> 
> On 06/04/2016 17:27, Jeff Forbes wrote:
> > When I use "-cpu host,+VMX,-hypervisor", Hyper-V gives this error
> > when trying to start a VM: Virtual Machine could not be started
> > because the hypervisor is not running.
> > 
> > So with the latest kernel and qemu-kvm, the hypervisor flag is
> > needed.
> 
> That is not what the error means.  The error means that Hyper-V has
> failed to start.
> 
> Paolo
> 
> > 
> > On Mon, 2016-04-04 at 17:35 -0400, Bandan Das wrote:
> > > Jeff Forbes <address@hidden <mailto:
> > > address@hidden>> writes:
> > > 
> > > > We have a Windows-10 application which uses a virtual as part
> > > > of the
> > > > process. I am trying to get the application to work in a
> > > > virtual
> > > > environment, which of course will require nested
> > > > virtualization.
> > > > Using a libvirt xml description for a RHEL virtual where nested
> > > > virtualization works, I installed windows-10, Hyper-v and the
> > > > application software under the latest updates of Fedora 22.
> > > > Windows-10 works great; however, VMBus device required for
> > > > Hyper-V to
> > > > work would not start and was flagged in the Device Manager.
> > > > Trying to
> > > > start a virtual resulted in the error that a component required
> > > > by
> > > > Hyper-V failed to start. I then ported the VM to VMWare
> > > > Workstation
> > > > 12 and in this environment t he VMBus device starts and nested
> > > > virtuals start as expected. These results indicated that the VM
> > > > was
> > > > working correctly and the problem was likely with the QEMU-KVM
> > > > hypervisor. Reading recent messages on the KVM and QEMU mail
> > > > lists
> > > > indicated that there were many KVM updates made to the 4.6.0
> > > > -rc1
> > > > kernel, so I download, compiled and installed this kernel. I
> > > > also
> > > > cloned the latest version of qemu. When I run my Windows-10 VM
> > > > in
> > > > this environment with the latest updates. the VMBus device
> > > > starts and
> > > > there are not warnings in the Device Manager; however, the
> > > > nested VMs
> > > > do not start and the same error about a component required by
> > > > Hyper-V
> > > > failed to start. Do I need to turn something on to get this to
> > > > work
> > > > or is the Hyper-V support still under development? 
> > > 
> > > 
> > > I am not sure if anyone has been successful with running Hyper-V
> > > nested.
> > > The first obstacle I remember is Hyper-V refusing to run when it
> > > finds
> > > the "hypervisor" flag in guest cpu. If you are past that step, 
> > >  maybe
> > > the vmbus dependency is something else.
> > > 
> > > > Please advise. Best, Jeff-- To unsubscribe from this list: send
> > > > the
> > > > line "unsubscribe kvm" in the body of a message to
> > > > address@hidden <mailto:address@hidden>
> > > > More
> > > > majordomo info at http://vger.kernel.org/majordomo-info.html