On Thu, Nov 16, 2017 at 08:04:34PM +0800, Jason Wang wrote:
>
>
> On 2017年11月16日 17:32, Longpeng (Mike) wrote:
> > Hi Jason,
> >
> > On 2017/11/16 17:13, Jason Wang wrote:
> >
> > >
> > > On 2017年11月16日 17:01, Gonglei (Arei) wrote:
> > > > No, Windows guest + vhost-user/DPDK.
> > > >
> > > > BTW pls see virtio spec in :
> > > >
> > > > "If VIRTIO_NET_F_MQ is negotiated, each of receiveq1. . .receiveqN that
> > > > will
> > > > be used SHOULD be populated
> > > > with receive buffers."
> > > >
> > > > It is not mandatory that all queues must be initialized.
> > > I think not, since it said we should fill receive buffers for each queue
> > > which
> > > means we should initialize all queues. May Michael can clarify on this.
> > >
> >
> > I think this doesn't matter, but QEMU should consider this scenario...
> >
> > For example, if one queues isn't initialized (Windows guest), the
> > vring.avail=0,
> > so vq->desc_phys=0, then vq->desc='a avail HVA'(which is the start addr of
> > pc.ram).
> >
> > vq->desc_size = s = l = virtio_queue_get_desc_size(vdev, idx);
> > vq->desc_phys = a = virtio_queue_get_desc_addr(vdev, idx);
> > vq->desc = vhost_memory_map(dev, a, &l, 0);
> > if (!vq->desc || l != s) {
> > r = -ENOMEM;
> > goto fail_alloc_desc;
> > }
> > .....
> > r = vhost_virtqueue_set_addr(dev, vq, vhost_vq_index,
> > dev->log_enabled);
> > if (r < 0) {
> > r = -errno;
> > goto fail_alloc;
> > }
> >
> > Then the HVA is send to the vhost-user.
> >
> > I think this is wrong, because the '0' here means guest driver doesn't init
> > this
> > queues, it should not be used to calculate the HVA for this vq.
>
> Yes, workaround is not hard if windows driver won't use the left 3 queues
> any more. But we should have a complete solution. The main problem is when
> vhost need to be started. For legacy device, there's no easy way to detect
> whether or not a specific virtqueue is ready to be used. For modern device,
> we can probably do this through queue_enable (but this is not implemented in
> current code).
>
> Thanks
What isn't implemented?
Spec is quite explicit:
Client must only process each ring when it is started.
Client must only pass data between the ring and the
backend, when the ring is enabled.
and later:
Client must start ring upon receiving a kick (that is, detecting that file
descriptor is readable) on the descriptor specified by
VHOST_USER_SET_VRING_KICK, and stop ring upon receiving
VHOST_USER_GET_VRING_BASE.
Does someone kick unused rings? What entity does this?
> >
> > > Thanks
> > >
> > > > Thanks,
> > > > -Gonglei
> > > >
> > >
> > >
> > >
> > > .
> > >
> >
