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From:   Eugenio Perez Martin <eperezma@redhat.com>
Date:   Fri, 19 Jun 2020 19:56:04 +0200
Message-ID: <CAJaqyWcDb5GefbiBkcaMADFzWup7yvmvOekRmRQ40pqxdgB0eg@mail.gmail.com>
Subject: Re: [PATCH RFC v8 02/11] vhost: use batched get_vq_desc version
To:     Jason Wang <jasowang@redhat.com>
Cc:     "Michael S. Tsirkin" <mst@redhat.com>,
        linux-kernel@vger.kernel.org, kvm list <kvm@vger.kernel.org>,
        virtualization@lists.linux-foundation.org, netdev@vger.kernel.org
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On Wed, Jun 17, 2020 at 5:19 AM Jason Wang <jasowang@redhat.com> wrote:
>
>
> On 2020/6/11 =E4=B8=8B=E5=8D=887:34, 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 =3D 0; i < dev->nvqs; ++i) {
> >               vq =3D dev->vqs[i];
> >               vq->max_descs =3D 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.

I tested as

if (dev->use_worker && vhost_vq_num_batch_descs(vq) < 0)

In v9. Please let me know if that is ok for you.

Thanks!

>
> Thanks
>