[Qemu-devel] Question regarding a special case VM communication

[Qemu-devel] Question regarding a special case VM communication

[Jidong Xiao]

Hello, All,

I am facing this special case of VM communication.

I have a Linux host machine, on which two Qemu/KVM virtual machines
are launched. Let's say they are VM1 and VM2, and their corresponding
processes on the host are Qemu1 and Qemu2. Inside VM2, I need nested
virtualization, i.e., A qemu process is started inside VM2, let's say
it's Qemu3, and a virtual machine VM3 is created accordingly.

What I want to achieve is: communication between Qemu1 and Qemu3. For
example, if I need to migrate VM1 from Qemu1 to Qemu3, how do I
achieve that? One naïve solution is just go through the TCP stack,
however, since they are in the same host machine, is there any fast or
efficient way to implement it? I.e., Something similar to Unix domain
socket. I know Unix domain socket is not applicable to case like this,
but I am just looking for something similar to that. Does anyone have
any suggestions, ideas? Thanks.

-Jidong

Re: [Qemu-devel] Question regarding a special case VM communication

[Stefan Hajnoczi]

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On Wed, Mar 02, 2016 at 08:55:26PM -0700, Jidong Xiao wrote:
> I have a Linux host machine, on which two Qemu/KVM virtual machines
> are launched. Let's say they are VM1 and VM2, and their corresponding
> processes on the host are Qemu1 and Qemu2. Inside VM2, I need nested
> virtualization, i.e., A qemu process is started inside VM2, let's say
> it's Qemu3, and a virtual machine VM3 is created accordingly.
> 
> What I want to achieve is: communication between Qemu1 and Qemu3. For
> example, if I need to migrate VM1 from Qemu1 to Qemu3, how do I
> achieve that? One naïve solution is just go through the TCP stack,
> however, since they are in the same host machine, is there any fast or
> efficient way to implement it? I.e., Something similar to Unix domain
> socket. I know Unix domain socket is not applicable to case like this,
> but I am just looking for something similar to that. Does anyone have
> any suggestions, ideas? Thanks.

Use TCP/IP.  The nested virtualization and migration aspect makes this
non-trivial unless you choose a network protocol that supports routing.

Stefan

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