Re: Inter VM Communication

[Cam Macdonell <cam@cs.ualberta.ca>]

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?

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