On Tue, Oct 25, 2022 at 01:46:43PM +0800, Jason Wang wrote:
> On Tue, Oct 25, 2022 at 1:36 PM Michael S. Tsirkin <m...@redhat.com> wrote:
> >
> > On Tue, Oct 25, 2022 at 10:26:35AM +0800, Jason Wang wrote:
> > > On Mon, Oct 24, 2022 at 10:05 PM Michael S. Tsirkin <m...@redhat.com>
> > > wrote:
> > > >
> > > > On Mon, Oct 24, 2022 at 04:00:37PM +0200, Eugenio Perez Martin wrote:
> > > > > > > It's generally a waste that we don't use endian-ness annotations
> > > > > > > the way linux does.
> > > > > >
> > > > > > Yes, it's worth doing something similar sometime.
> > > > > >
> > > > >
> > > > > Maybe we could wrap them in some struct like virtio_le16 or virtio_16,
> > > > > avoiding at least integer direct assignment? Wrappers like
> > > > > cpu_to_virtio16 could return these structs and I think all compilers
> > > > > should emit the same code as direct assignment.
> > > > >
> > > > > Thanks!
> > > > >
> > > >
> > > > This will break bitwise operations such as | and &.
> > > > Generally Linux has solved the problem and I don't think
> > > > we should go look for another solution.
> > >
> > > Yes, but it should not block this series (we can do that in the future
> > > if we had bandwidth).
> > >
> > > Thanks
> >
> > Sorry I don't get what you are saying. Which series?
>
> I meant this series.
>
> > Making LE tags structs is not going to fly, this is why sparse
> > implements the __bitwise__ tag and in fact this is where the name comes
> > from - bitwise operations need to work.
>
> Yes but do we want to add sparse checks in this series only for shadow
> virtqueue code?
>
> Thanks
No, I think a concerted effort to add endian-ness tagging is more
appropriate. Has nothing to do with shadow vq.
> >
> >
> >
> > > >
> > > >
> > > > >
> > > > >
> > > > > > Thanks
> > > > > >
> > > > > > >
> > > > > > >
> > > > > > > > > Thanks
> > > > > > > > >
> > > > > > > > > > + } else {
> > > > > > > > > > + svq->vring.avail->flags &=
> > > > > > > > > > ~cpu_to_le16(VRING_AVAIL_F_NO_INTERRUPT);
> > > > > > > > > > + }
> > > > > > > > > > +
> > > > > > > > > > + /* Make sure the event is enabled before the read of
> > > > > > > > > > used_idx */
> > > > > > > > > > smp_mb();
> > > > > > > > > > return !vhost_svq_more_used(svq);
> > > > > > > > > > }
> > > > > > > > > >
> > > > > > > > > > static void
> > > > > > > > > > vhost_svq_disable_notification(VhostShadowVirtqueue *svq)
> > > > > > > > > > {
> > > > > > > > > > - svq->vring.avail->flags |=
> > > > > > > > > > cpu_to_le16(VRING_AVAIL_F_NO_INTERRUPT);
> > > > > > > > > > + /*
> > > > > > > > > > + * No need to disable notification in the event idx
> > > > > > > > > > case, since used event
> > > > > > > > > > + * index is already an index too far away.
> > > > > > > > > > + */
> > > > > > > > > > + if (!virtio_vdev_has_feature(svq->vdev,
> > > > > > > > > > VIRTIO_RING_F_EVENT_IDX)) {
> > > > > > > > > > + svq->vring.avail->flags |=
> > > > > > > > > > cpu_to_le16(VRING_AVAIL_F_NO_INTERRUPT);
> > > > > > > > > > + }
> > > > > > > > > > }
> > > > > > > > > >
> > > > > > > > > > static uint16_t vhost_svq_last_desc_of_chain(const
> > > > > > > > > > VhostShadowVirtqueue *svq,
> > > > > > > > > > --
> > > > > > > > > > 2.31.1
> > > > > > > > > >
> > > > > > > > >
> > > > > > >
> > > > > >
> > > >
> >
