[Lguest] Communication between host and guest

Earlence Fernandes earlenceferns at gmail.com
Wed May 29 08:30:53 EST 2013


I found some test code in tools/virtio and drivers/vhost/test.c
I guess this is what I wanted.

-Earlence


On Tue, May 28, 2013 at 5:59 PM, Earlence Fernandes <earlenceferns at gmail.com
> wrote:

> Yes. using vring is the best plan.
>
> My need is as follows: in the host kernel, I have a module that kicks off
> a kthread which basically services requests from other places in the
> kernel. This kthread should in turn make requests to the guest virtio
> driver. The guest virtio driver will service the request and hypercall back
> to the host indicating completion of the request.
>
> To understand how to implement this I started looking at the
> virtio_balloon driver (since it uses the stats_vq to wait for host
> requests). This is the guest side of the connection. However, I'm clueless
> as to how to setup the host side of the communication. I saw some code in
> lguest.c (the launcher), but that seems to be all userspace helpers. can
> somebody help me understand how to write the host-side of the communication
> in a kernel module?
>
> -Earlence
>
>
> On Mon, May 27, 2013 at 9:34 PM, Rusty Russell <rusty at rustcorp.com.au>wrote:
>
>> Earlence Fernandes <earlenceferns at gmail.com> writes:
>>
>> > Yep. I was grepping thru the sources.
>> >
>> > I think the best way would be to create a virtio device coupled with a
>> > hypercall to return data (which is typically one value).
>> >
>> > Of course, I was thinking, what if I simply did a write() to lguest_fd
>> and
>> > pull that in the read loop in the guest...
>>
>> That's going to be less efficient than just using a virtio ring
>> with a writable part in the descriptor for the reply (this is what
>> virtio-blk does for a write, for example).
>>
>> Cheers,
>> Rusty.
>>
>
>
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