linux-kernel - Re: [PATCH v2] drm/virtio: fix ring free check

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Date:   Thu, 6 Feb 2020 23:07:27 -0800
From:   Chia-I Wu <olvaffe@...il.com>
To:     Gerd Hoffmann <kraxel@...hat.com>
Cc:     ML dri-devel <dri-devel@...ts.freedesktop.org>,
        Gurchetan Singh <gurchetansingh@...omium.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        "open list:VIRTIO GPU DRIVER" 
        <virtualization@...ts.linux-foundation.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] drm/virtio: fix ring free check

On Thu, Feb 6, 2020 at 10:47 PM Gerd Hoffmann <kraxel@...hat.com> wrote:
>
> If the virtio device supports indirect ring descriptors we need only one
> ring entry for the whole command.  Take that into account when checking
> whenever the virtqueue has enough free entries for our command.
>
> Signed-off-by: Gerd Hoffmann <kraxel@...hat.com>
> ---
>  drivers/gpu/drm/virtio/virtgpu_drv.h     | 1 +
>  drivers/gpu/drm/virtio/virtgpu_debugfs.c | 1 +
>  drivers/gpu/drm/virtio/virtgpu_kms.c     | 3 +++
>  drivers/gpu/drm/virtio/virtgpu_vq.c      | 3 +++
>  4 files changed, 8 insertions(+)
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
> index 7e69c06e168e..d278c8c50f39 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_drv.h
> +++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
> @@ -193,6 +193,7 @@ struct virtio_gpu_device {
>
>         bool has_virgl_3d;
>         bool has_edid;
> +       bool has_indirect;
has_indirect_desc?  Either way,

Reviewed-by: Chia-I Wu <olvaffe@...il.com>
>
>         struct work_struct config_changed_work;
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_debugfs.c b/drivers/gpu/drm/virtio/virtgpu_debugfs.c
> index 5156e6b279db..e27120d512b0 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_debugfs.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_debugfs.c
> @@ -47,6 +47,7 @@ static int virtio_gpu_features(struct seq_file *m, void *data)
>
>         virtio_add_bool(m, "virgl", vgdev->has_virgl_3d);
>         virtio_add_bool(m, "edid", vgdev->has_edid);
> +       virtio_add_bool(m, "indirect", vgdev->has_indirect);
>         virtio_add_int(m, "cap sets", vgdev->num_capsets);
>         virtio_add_int(m, "scanouts", vgdev->num_scanouts);
>         return 0;
> diff --git a/drivers/gpu/drm/virtio/virtgpu_kms.c b/drivers/gpu/drm/virtio/virtgpu_kms.c
> index 2f5773e43557..c1086df49816 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_kms.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_kms.c
> @@ -159,6 +159,9 @@ int virtio_gpu_init(struct drm_device *dev)
>         if (virtio_has_feature(vgdev->vdev, VIRTIO_GPU_F_EDID)) {
>                 vgdev->has_edid = true;
>         }
> +       if (virtio_has_feature(vgdev->vdev, VIRTIO_RING_F_INDIRECT_DESC)) {
> +               vgdev->has_indirect = true;
> +       }
>
>         DRM_INFO("features: %cvirgl %cedid\n",
>                  vgdev->has_virgl_3d ? '+' : '-',
> diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
> index 41e475fbd67b..cc02fc4bab2a 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_vq.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
> @@ -330,6 +330,9 @@ static void virtio_gpu_queue_ctrl_sgs(struct virtio_gpu_device *vgdev,
>         bool notify = false;
>         int ret;
>
> +       if (vgdev->has_indirect)
> +               elemcnt = 1;
> +
>  again:
>         spin_lock(&vgdev->ctrlq.qlock);
>
> --
> 2.18.1
>