[Lguest] Communication between host and guest

[Rusty Russell]

Earlence Fernandes <earlenceferns at gmail.com> writes:
> So I've spent some time studying the sources to the balloon driver and the
> "vringh" implementation.
> My understanding is that I will write a driver similar to the balloon in
> terms of communication. That is, my driver
> will initialize a virtqueue for incoming requests. It will initialize the
> vq's using scatterlist init functions (as in the balloon driver).
>
> Then my "device" in the host kernel will use the same functions as vringh
> (or use vringh functions themselves?) to send
> and receive data from the driver in the guest.
>
> I don't understand how the vringh functions will get pointers to the
> descriptors initialized in the guest?
> Coz, for example, I guess I will have to use
> int vringh_init_kern(struct vringh *vrh, u32 features,
>      unsigned int num, bool weak_barriers,
>      struct vring_desc *desc,
>      struct vring_avail *avail,
>      struct vring_used *used);
>
> as an init function in my host "device". I think that these pointers are to
> guest virtqueues, so how ill this function be called correctly?

(You'll actually use the vringh_*_user functions, BTW).

You will have to add an ioctl for the Launcher to tell your code where
the virtio queue rings are.

Cheers,
Rusty.