linux-kernel - Re: [PATCH RFC v8 02/11] vhost: use batched get_vq

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Date:   Mon, 22 Jun 2020 12:00:48 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Jason Wang <jasowang@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        eperezma@...hat.com
Subject: Re: [PATCH RFC v8 02/11] vhost: use batched get_vq_desc version

On Wed, Jun 17, 2020 at 11:19:26AM +0800, Jason Wang wrote:
> 
> On 2020/6/11 下午7:34, Michael S. Tsirkin wrote:
> >   static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
> >   {
> >   	kfree(vq->descs);
> > @@ -394,6 +400,9 @@ static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
> >   	for (i = 0; i < dev->nvqs; ++i) {
> >   		vq = dev->vqs[i];
> >   		vq->max_descs = dev->iov_limit;
> > +		if (vhost_vq_num_batch_descs(vq) < 0) {
> > +			return -EINVAL;
> > +		}
> 
> 
> This check breaks vdpa which set iov_limit to zero. Consider iov_limit is
> meaningless to vDPA, I wonder we can skip the test when device doesn't use
> worker.
> 
> Thanks

It doesn't need iovecs at all, right?

-- 
MST