Virtualization - Jan 2022 -

On Wed, Dec 29, 2021 at 5:31 PM Wu Zongyong
<wuzongyong at linux.alibaba.com> wrote:
>
> linux-kernel at vger.kernel.org
> Bcc:
> Subject: Should we call vdpa_config_ops->get_vq_num_{max,min} with a
>  virtqueue index?
> Reply-To: Wu Zongyong <wuzongyong at linux.alibaba.com>
>
> Hi jason,
>
> AFAIK, a virtio device may have multiple virtqueues of diffrent sizes.
> It is okay for modern devices with the vdpa_config_ops->get_vq_num_max
> implementation with a static number currently since modern devices can
> reset the queue size. But for legacy-virtio based devices, we cannot
> allocate correct sizes for these virtqueues since it is not supported to
> negotiate the queue size with harware.
>
> So as the title said, I wonder is it neccessary to add a new parameter
> `index` to vdpa_config_ops->get_vq_num_{max,min} to help us get the size
> of a dedicated virtqueue.
I've posted something like this in the past here:

https://lore.kernel.org/lkml/CACycT3tMd750PQ0mgqCjHnxM4RmMcx2+Eo=2RBs2E2W3qPJang
at mail.gmail.com/
>
> Or we can introduce a new callback like get_config_vq_num?
>
> What do you think?
If you wish, you can carry on my work. We can start by reusing the
current ops, if it doesn't work, we can use new.

Thanks
>
> Thanks
>
>
>
>
>
>

On Wed, Jan 5, 2022 at 2:05 PM Jason Wang <jasowang at redhat.com>
wrote:
>
> On Wed, Dec 29, 2021 at 5:31 PM Wu Zongyong
> <wuzongyong at linux.alibaba.com> wrote:
> >
> > linux-kernel at vger.kernel.org
> > Bcc:
> > Subject: Should we call vdpa_config_ops->get_vq_num_{max,min} with
a
> >  virtqueue index?
> > Reply-To: Wu Zongyong <wuzongyong at linux.alibaba.com>
> >
> > Hi jason,
> >
> > AFAIK, a virtio device may have multiple virtqueues of diffrent sizes.
> > It is okay for modern devices with the
vdpa_config_ops->get_vq_num_max
> > implementation with a static number currently since modern devices can
> > reset the queue size. But for legacy-virtio based devices, we cannot
> > allocate correct sizes for these virtqueues since it is not supported
to
> > negotiate the queue size with harware.
> >
> > So as the title said, I wonder is it neccessary to add a new parameter
> > `index` to vdpa_config_ops->get_vq_num_{max,min} to help us get the
size
> > of a dedicated virtqueue.
>
> I've posted something like this in the past here:
>
>
https://lore.kernel.org/lkml/CACycT3tMd750PQ0mgqCjHnxM4RmMcx2+Eo=2RBs2E2W3qPJang
at mail.gmail.com/
>
> >
> > Or we can introduce a new callback like get_config_vq_num?
> >
> > What do you think?
>
> If you wish, you can carry on my work. We can start by reusing the
> current ops, if it doesn't work, we can use new.
Just to clarify, I meant, we probably need to introduce a new uAPI on
top of the above version.

Thanks
>
> Thanks
>
> >
> > Thanks
> >
> >
> >
> >
> >
> >