linux-kernel - Re: [PATCH v5 4/4] vdpa_sim: Implement resume vdpa op

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Date:   Mon, 7 Nov 2022 15:43:54 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     sebastien.boeuf@...el.com
Cc:     linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, mst@...hat.com,
        eperezma@...hat.com
Subject: Re: [PATCH v5 4/4] vdpa_sim: Implement resume vdpa op

On Wed, Oct 26, 2022 at 11:09 PM <sebastien.boeuf@...el.com> wrote:
>
> From: Sebastien Boeuf <sebastien.boeuf@...el.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@...el.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

> +       }
> +
>         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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