Hypervisor detection from within a Linux VM

Hypervisor detection from within a Linux VM

[Chetan Loke]

Hello,


Requirement:
I have the need to support my apps(running on a Linux VM) on different
*nix hypervisors(ESX/Xen etc). I need to know on which hypervisor my
app is running. I read the CPUID usage thread -
http://thread.gmane.org/gmane.comp.emulators.kvm.devel/22643 but to be
honest in the end I looked at
http://lxr.linux.no/#linux+v2.6.34/arch/x86/kernel/cpu/vmware.c#L88
The vmware_platform() detection code is straight forward.

Current-hack:
As a quick hack we just grep lspci for VMware's pci-ids.

Solution:
I can write a bare minimal driver, check the cpu-id as VMware's
balloon driver does and then emit a proc/sysfs node. The setup
packages and the apps can then check for this node-string.I'm
currently working on ESX and I am hoping that this thin-driver will
work.

Question:
Q1)Is it possible to get this functionality as part of the stock
kernel or is that a bad idea? I suspect there could be other
users/apps who would need to know what *nix hypervisor(or a
non-virtualized environment) they are
running on?
Q2)If this is not the right approach then can someone please suggest
another approach?

Regards
Chetan Loke

Re: Hypervisor detection from within a Linux VM

[Anthony Liguori]

On 06/29/2010 04:25 PM, Chetan Loke wrote:
> Hello,
>
>
> Requirement:
> I have the need to support my apps(running on a Linux VM) on different
> *nix hypervisors(ESX/Xen etc). I need to know on which hypervisor my
> app is running. I read the CPUID usage thread -
> http://thread.gmane.org/gmane.comp.emulators.kvm.devel/22643 but to be
> honest in the end I looked at
> http://lxr.linux.no/#linux+v2.6.34/arch/x86/kernel/cpu/vmware.c#L88
> The vmware_platform() detection code is straight forward.
>
> Current-hack:
> As a quick hack we just grep lspci for VMware's pci-ids.
>
> Solution:
> I can write a bare minimal driver, check the cpu-id as VMware's
> balloon driver does and then emit a proc/sysfs node. The setup
> packages and the apps can then check for this node-string.I'm
> currently working on ESX and I am hoping that this thin-driver will
> work.
>    

It can be done entirely in userspace.  Take a look at virt-what:

http://people.redhat.com/~rjones/virt-what/

> Question:
> Q1)Is it possible to get this functionality as part of the stock
> kernel or is that a bad idea? I suspect there could be other
> users/apps who would need to know what *nix hypervisor(or a
> non-virtualized environment) they are
> running on?
> Q2)If this is not the right approach then can someone please suggest
> another approach?
>    

It might be reasonable to list the hypervisor signature as a field in 
/proc/cpuinfo.  There's also a /sys/hypervisor where such information 
could go.

Regards,

Anthony Liguori

> Regards
> Chetan Loke
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>    

Re: Hypervisor detection from within a Linux VM

[Chetan Loke]

On Tue, Jun 29, 2010 at 5:44 PM, Anthony Liguori <anthony@codemonkey.ws> wrote:
> On 06/29/2010 04:25 PM, Chetan Loke wrote:
> It can be done entirely in userspace.  Take a look at virt-what:
>
> http://people.redhat.com/~rjones/virt-what/
>

Just posted a patch for virt-what.in which can be used as a wrapper
script. I will be using that for now.

>> Question:
>> Q1)Is it possible to get this functionality as part of the stock
>> kernel or is that a bad idea? I suspect there could be other
>> users/apps who would need to know what *nix hypervisor(or a
>> non-virtualized environment) they are
>> running on?
>
> It might be reasonable to list the hypervisor signature as a field in
> /proc/cpuinfo.  There's also a /sys/hypervisor where such information could
> go.
>

I like the idea of spitting out a signature under /proc/cpuinfo
primarily because everyone is familiar with that node.

> Regards,
> Anthony Liguori

Regards
Chetan Loke