Hi,
On Monday, May 13, 2024 7:53:40 PM GMT+5:30 Eugenio Perez Martin wrote:
> [...]
> > I have started working on implementing packed virtqueue support in
> > vhost-shadow-virtqueue.c. The changes I have made so far are very
> > minimal. I have one confusion as well.
> >
> > In "vhost_svq_add()" [1], a structure of type "VhostShadowVirtqueue"
> > is being used. My initial idea was to create a whole new structure (eg:
> > VhostShadowVirtqueuePacked). But I realized that "VhostShadowVirtqueue"
> > is being used in a lot of other places such as in "struct vhost_vdpa" [2]
> > (in "vhost-vdpa.h"). So maybe this isn't a good idea.
> >
> > The problem is that "VhostShadowVirtqueue" has a member of type "struct
> > vring" [3] which represents a split virtqueue [4]. My idea now is to
> > instead wrap this member in a union so that the struct would look
> > something like this.
> >
> > struct VhostShadowVirtqueue {
> > union {
> > struct vring vring;
> > struct packed_vring vring;
> > }
> > ...
> > }
> >
> > I am not entirely sure if this is a good idea. It is similar to what's
> > been done in linux's "drivers/virtio/virtio_ring.c" ("struct
> > vring_virtqueue" [5]).
> >
> > I thought I would ask this first before continuing further.
>
> That's right, this second option makes perfect sense.
>
> VhostShadowVirtqueue should abstract both split and packed. You'll see
> that some members are reused, while others are only used in one
> version so they are placed after a union. They should follow the same
> pattern, although it is not a problem if we need to divert a little
> bit from the kernel's code.
>
Understood, thank you for the reply.
Thanks,
Sahil
