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Date:   Mon, 19 Dec 2022 01:23:44 -0500
From:   "Michael S. Tsirkin" <mst@redhat.com>
To:     Jason Wang <jasowang@redhat.com>
Cc:     sebastien.boeuf@intel.com, linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org, eperezma@redhat.com
Subject: Re: [PATCH v5 4/4] vdpa_sim: Implement resume vdpa op
Message-ID: <20221219012313-mutt-send-email-mst@kernel.org>
References: <cover.1666796792.git.sebastien.boeuf@intel.com>
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 <CACGkMEt93LU009MVK3cDKAU1fv3ZoaDskWp4hakmeTZyBQa=fg@mail.gmail.com>
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On Mon, Nov 07, 2022 at 03:43:54PM +0800, Jason Wang wrote:
> On Wed, Oct 26, 2022 at 11:09 PM <sebastien.boeuf@intel.com> wrote:
> >
> > From: Sebastien Boeuf <sebastien.boeuf@intel.com>
> >
> > Implement resume operation for vdpa_sim devices, so vhost-vdpa will
> > offer that backend feature and userspace can effectively resume the
> > device.
> >
> > Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
> > ---
> >  drivers/vdpa/vdpa_sim/vdpa_sim.c | 28 ++++++++++++++++++++++++++++
> >  drivers/vdpa/vdpa_sim/vdpa_sim.h |  1 +
> >  2 files changed, 29 insertions(+)
> >
> > diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> > index b071f0d842fb..84fee8bb2929 100644
> > --- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
> > +++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> > @@ -357,6 +357,11 @@ static void vdpasim_kick_vq(struct vdpa_device *vdpa, u16 idx)
> >         struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> >         struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
> >
> > +       if (!vdpasim->running) {
> > +               vdpasim->pending_kick = true;
> > +               return;
> 
> I think we may hit here when the driver kicks vq before DRIVER_OK. Do
> we need to check device status in this case and resume?
> 
> Thanks

Sebastien did you forget to reply here?

> > +       }
> > +
> >         if (vq->ready)
> >                 schedule_work(&vdpasim->work);
> >  }
> > @@ -527,6 +532,27 @@ static int vdpasim_suspend(struct vdpa_device *vdpa)
> >         return 0;
> >  }
> >
> > +static int vdpasim_resume(struct vdpa_device *vdpa)
> > +{
> > +       struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> > +       int i;
> > +
> > +       spin_lock(&vdpasim->lock);
> > +       vdpasim->running = true;
> > +
> > +       if (vdpasim->pending_kick) {
> > +               /* Process pending descriptors */
> > +               for (i = 0; i < vdpasim->dev_attr.nvqs; ++i)
> > +                       vdpasim_kick_vq(vdpa, i);
> > +
> > +               vdpasim->pending_kick = false;
> > +       }
> > +
> > +       spin_unlock(&vdpasim->lock);
> > +
> > +       return 0;
> > +}
> > +
> >  static size_t vdpasim_get_config_size(struct vdpa_device *vdpa)
> >  {
> >         struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> > @@ -717,6 +743,7 @@ static const struct vdpa_config_ops vdpasim_config_ops = {
> >         .set_status             = vdpasim_set_status,
> >         .reset                  = vdpasim_reset,
> >         .suspend                = vdpasim_suspend,
> > +       .resume                 = vdpasim_resume,
> >         .get_config_size        = vdpasim_get_config_size,
> >         .get_config             = vdpasim_get_config,
> >         .set_config             = vdpasim_set_config,
> > @@ -750,6 +777,7 @@ static const struct vdpa_config_ops vdpasim_batch_config_ops = {
> >         .set_status             = vdpasim_set_status,
> >         .reset                  = vdpasim_reset,
> >         .suspend                = vdpasim_suspend,
> > +       .resume                 = vdpasim_resume,
> >         .get_config_size        = vdpasim_get_config_size,
> >         .get_config             = vdpasim_get_config,
> >         .set_config             = vdpasim_set_config,
> > diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.h b/drivers/vdpa/vdpa_sim/vdpa_sim.h
> > index 0e78737dcc16..a745605589e2 100644
> > --- a/drivers/vdpa/vdpa_sim/vdpa_sim.h
> > +++ b/drivers/vdpa/vdpa_sim/vdpa_sim.h
> > @@ -67,6 +67,7 @@ struct vdpasim {
> >         u64 features;
> >         u32 groups;
> >         bool running;
> > +       bool pending_kick;
> >         /* spinlock to synchronize iommu table */
> >         spinlock_t iommu_lock;
> >  };
> > --
> > 2.34.1
> >
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