Re: Inter VM Communication

[Brian Jackson <iggy@theiggy.com>]

On Tuesday 24 March 2009 15:41:43 Cam Macdonell wrote:
> Avi Kivity wrote:
> > Kumar, Venkat wrote:
> >> Just like how Xen has Xenbus, Emulated Platform-PCI device and Events
> >> for Inter VM communication, Does KVM has any mechanism for Inter VM
> >> communication? How to share a page between two virtual machines
> >> running on KVM?
> >
> > If you just want to share a page (or a bunch of memory), write a qemu
> > PCI device model that exposes that page through a BAR.  The guests can
> > then map the BAR and access the page.
> >
> > To share the page, use normal Linux memory sharing, such as shared
> > memory segments or mapped files (possibly on /dev/shm).
>
> I've actually created a patch (and corresponding device driver) that
> works this way based on Avi's suggestion of this approach before.  I'm
> willing to release it of course, but it's in pretty rough form being my
> first Qemu/KVM PCI device.  Avi (or anyone else), would you mind having
> a quick look first before I release it to the list?

I agree with Avi on just going ahead and sending it. I'd like to take a look 
too.

>
> FYI, I'm using this for my PhD research.
>
> > Note that sharing will break as soon as one of the guests is migrated
> > away.
> >
> > To send events you can utilize pci interrupts.
>
> I haven't implemented PCI interrupts yet, but would appreciate some
> pointers on how to go about this.
>
> Thanks,
> Cam
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