netdev - Re: [PATCH v10 05/17] vhost-vdpa: Fail the vhost_vdpa_set

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Date:   Tue, 3 Aug 2021 17:50:44 +0800
From:   Yongji Xie <xieyongji@...edance.com>
To:     Jason Wang <jasowang@...hat.com>
Cc:     "Michael S. Tsirkin" <mst@...hat.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        Stefano Garzarella <sgarzare@...hat.com>,
        Parav Pandit <parav@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        Christian Brauner <christian.brauner@...onical.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Matthew Wilcox <willy@...radead.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Jens Axboe <axboe@...nel.dk>, bcrl@...ck.org,
        Jonathan Corbet <corbet@....net>,
        Mika Penttilä <mika.penttila@...tfour.com>,
        Dan Carpenter <dan.carpenter@...cle.com>, joro@...tes.org,
        Greg KH <gregkh@...uxfoundation.org>,
        He Zhe <zhe.he@...driver.com>,
        Liu Xiaodong <xiaodong.liu@...el.com>,
        Joe Perches <joe@...ches.com>, songmuchun@...edance.com,
        virtualization <virtualization@...ts.linux-foundation.org>,
        netdev@...r.kernel.org, kvm <kvm@...r.kernel.org>,
        linux-fsdevel@...r.kernel.org, iommu@...ts.linux-foundation.org,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v10 05/17] vhost-vdpa: Fail the vhost_vdpa_set_status() on
 reset failure

On Tue, Aug 3, 2021 at 4:10 PM Jason Wang <jasowang@...hat.com> wrote:
>
>
> 在 2021/7/29 下午3:34, Xie Yongji 写道:
> > Re-read the device status to ensure it's set to zero during
> > resetting. Otherwise, fail the vhost_vdpa_set_status() after timeout.
> >
> > Signed-off-by: Xie Yongji <xieyongji@...edance.com>
> > ---
> >   drivers/vhost/vdpa.c | 11 ++++++++++-
> >   1 file changed, 10 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> > index b07aa161f7ad..dd05c1e1133c 100644
> > --- a/drivers/vhost/vdpa.c
> > +++ b/drivers/vhost/vdpa.c
> > @@ -157,7 +157,7 @@ static long vhost_vdpa_set_status(struct vhost_vdpa *v, u8 __user *statusp)
> >       struct vdpa_device *vdpa = v->vdpa;
> >       const struct vdpa_config_ops *ops = vdpa->config;
> >       u8 status, status_old;
> > -     int nvqs = v->nvqs;
> > +     int timeout = 0, nvqs = v->nvqs;
> >       u16 i;
> >
> >       if (copy_from_user(&status, statusp, sizeof(status)))
> > @@ -173,6 +173,15 @@ static long vhost_vdpa_set_status(struct vhost_vdpa *v, u8 __user *statusp)
> >               return -EINVAL;
> >
> >       ops->set_status(vdpa, status);
> > +     if (status == 0) {
> > +             while (ops->get_status(vdpa)) {
> > +                     timeout += 20;
> > +                     if (timeout > VDPA_RESET_TIMEOUT_MS)
> > +                             return -EIO;
> > +
> > +                     msleep(20);
> > +             }
>
>
> Spec has introduced the reset a one of the basic facility. And consider
> we differ reset here.
>
> This makes me think if it's better to introduce a dedicated vdpa ops for
> reset?
>

Do you mean replace the ops.set_status(vdev, 0) with the ops.reset()?
Then we can remove the timeout processing which is device specific
stuff.

Thanks,
Yongji