Running a script in VM (from hypervisor)

guardian1 · 06-03-2012, 05:53 AM

Hi guys,

I was wondering whether it is possible to execute a script or a process in a virtual machine from a hypervisor such as Xen.

My thinking is along these lines - a particular event is triggered - the hypervisor (configured to look for this sort of thing) catches this event (through VM introspection, for example), and then wishes to execute something in response to this event.

Is there anything which might allow a developer to implement something like this?

r0h1t · 06-04-2012, 10:31 PM

Sorry I dont have a concrete solution for you but I read about this in a book.
Try checking this out : http://wiki.xen.org/wiki/Hypercall

EDIT:
Or maybe a 'cheaper' way to do it is for the host to automatically SSH into the guest VMs and execute a script? Just my 2 cents

guardian1 · 06-05-2012, 05:09 AM

r0h1t, thanks for your response. the hypercall you mention is actually in the opposite direction to what i was thinking of, since the calls to the processor of course have to pass through the hypervisor as a matter of course.

I would like to send a command direct to the operating system of a virtual machine, from the hypervisor, if possible.

pan64 · 06-05-2012, 05:43 AM

ssh should work anyway. have you tried?

guardian1 · 06-05-2012, 05:59 AM

I think you are correct that SSH would work, but the work I am trying to do is intended to rely on utilising the abilities of a hypervisor (which SSH is not using).

jefro · 06-05-2012, 02:45 PM

I wish I knew more about xen. Just kind of talking out loud here.

My thinking is that you want (Domain0) to watch for an event where I'd be more inclined to let the base OS do that. Then any means to access a system would do. This may also be affected on the exact hardware. I'd think a fully supported hardware install would be perfect for using the host to monitor.

I did find this kind of useful. http://cosi.clarkson.edu/docs/instal..._Xen_Class.pdf