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From:   Chia-I Wu <olvaffe@gmail.com>
Date:   Wed, 3 Jul 2019 12:52:19 -0700
Message-ID: <CAPaKu7RFd4EVsV8VbNtNbVv2cPmSbpQ7pkBPpbbeUDz+i=nEfQ@mail.gmail.com>
Subject: Re: [PATCH v6 07/18] drm/virtio: add virtio_gpu_object_array & helpers
To:     Gerd Hoffmann <kraxel@redhat.com>
Cc:     ML dri-devel <dri-devel@lists.freedesktop.org>,
        Gurchetan Singh <gurchetansingh@chromium.org>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        "open list:VIRTIO GPU DRIVER" 
        <virtualization@lists.linux-foundation.org>,
        open list <linux-kernel@vger.kernel.org>
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On Wed, Jul 3, 2019 at 11:31 AM Chia-I Wu <olvaffe@gmail.com> wrote:
>
> On Tue, Jul 2, 2019 at 7:19 AM Gerd Hoffmann <kraxel@redhat.com> wrote:
> >
> > Some helper functions to manage an array of gem objects.
> >
> > v6:
> >  - add ticket to struct virtio_gpu_object_array.
> >  - add virtio_gpu_array_{lock,unlock}_resv helpers.
> >  - add virtio_gpu_array_add_fence helper.
> > v5: some small optimizations (Chia-I Wu).
> > v4: make them virtio-private instead of generic helpers.
> >
> > Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> > ---
> >  drivers/gpu/drm/virtio/virtgpu_drv.h | 17 ++++++
> >  drivers/gpu/drm/virtio/virtgpu_gem.c | 83 ++++++++++++++++++++++++++++
> >  2 files changed, 100 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
> > index 07f6001ea91e..abb078a5dedf 100644
> > --- a/drivers/gpu/drm/virtio/virtgpu_drv.h
> > +++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
> > @@ -84,6 +84,12 @@ struct virtio_gpu_object {
> >  #define gem_to_virtio_gpu_obj(gobj) \
> >         container_of((gobj), struct virtio_gpu_object, gem_base)
> >
> > +struct virtio_gpu_object_array {
> > +       struct ww_acquire_ctx ticket;
> > +       u32 nents, total;
> > +       struct drm_gem_object *objs[];
> > +};
> > +
> >  struct virtio_gpu_vbuffer;
> >  struct virtio_gpu_device;
> >
> > @@ -251,6 +257,17 @@ int virtio_gpu_mode_dumb_mmap(struct drm_file *file_priv,
> >                               struct drm_device *dev,
> >                               uint32_t handle, uint64_t *offset_p);
> >
> > +struct virtio_gpu_object_array *virtio_gpu_array_alloc(u32 nents);
> > +struct virtio_gpu_object_array*
> > +virtio_gpu_array_from_handles(struct drm_file *drm_file, u32 *handles, u32 nents);
> > +void virtio_gpu_array_add_obj(struct virtio_gpu_object_array *objs,
> > +                             struct drm_gem_object *obj);
> > +int virtio_gpu_array_lock_resv(struct virtio_gpu_object_array *objs);
> > +void virtio_gpu_array_unlock_resv(struct virtio_gpu_object_array *objs);
> > +void virtio_gpu_array_add_fence(struct virtio_gpu_object_array *objs,
> > +                               struct dma_fence *fence);
> > +void virtio_gpu_array_put_free(struct virtio_gpu_object_array *objs);
> > +
> >  /* virtio vg */
> >  int virtio_gpu_alloc_vbufs(struct virtio_gpu_device *vgdev);
> >  void virtio_gpu_free_vbufs(struct virtio_gpu_device *vgdev);
> > diff --git a/drivers/gpu/drm/virtio/virtgpu_gem.c b/drivers/gpu/drm/virtio/virtgpu_gem.c
> > index 9c9ad3b14080..e88df5e06d06 100644
> > --- a/drivers/gpu/drm/virtio/virtgpu_gem.c
> > +++ b/drivers/gpu/drm/virtio/virtgpu_gem.c
> > @@ -169,3 +169,86 @@ void virtio_gpu_gem_object_close(struct drm_gem_object *obj,
> >                                                 qobj->hw_res_handle);
> >         virtio_gpu_object_unreserve(qobj);
> >  }
> > +
> > +struct virtio_gpu_object_array *virtio_gpu_array_alloc(u32 nents)
> > +{
> > +       struct virtio_gpu_object_array *objs;
> > +       size_t size = sizeof(*objs) + sizeof(objs->objs[0]) * nents;
> > +
> > +       objs = kmalloc(size, GFP_KERNEL);
> > +       if (!objs)
> > +               return NULL;
> > +
> > +       objs->nents = 0;
> > +       objs->total = nents;
> > +       return objs;
> > +}
> > +
> > +static void virtio_gpu_array_free(struct virtio_gpu_object_array *objs)
> > +{
> > +       kfree(objs);
> > +}
> > +
> > +struct virtio_gpu_object_array*
> > +virtio_gpu_array_from_handles(struct drm_file *drm_file, u32 *handles, u32 nents)
> > +{
> > +       struct virtio_gpu_object_array *objs;
> > +       u32 i;
> > +
> > +       objs = virtio_gpu_array_alloc(nents);
> > +       if (!objs)
> > +               return NULL;
> > +
> > +       for (i = 0; i < nents; i++) {
> > +               objs->nents = i;
> This line can be moved into the if-block just below.
> > +               objs->objs[i] = drm_gem_object_lookup(drm_file, handles[i]);
> > +               if (!objs->objs[i]) {
> > +                       virtio_gpu_array_put_free(objs);
> > +                       return NULL;
> > +               }
> > +       }
> > +       objs->nents = i;
> > +       return objs;
> > +}
> > +
> > +void virtio_gpu_array_add_obj(struct virtio_gpu_object_array *objs,
> > +                             struct drm_gem_object *obj)
> > +{
> > +       if (WARN_ON_ONCE(objs->nents == objs->total))
> > +               return;
> > +
> > +       drm_gem_object_get(obj);
> > +       objs->objs[objs->nents] = obj;
> > +       objs->nents++;
> > +}
> > +
> > +int virtio_gpu_array_lock_resv(struct virtio_gpu_object_array *objs)
> > +{
> > +       return drm_gem_lock_reservations(objs->objs, objs->nents,
> > +                                        &objs->ticket);
Unlike in other drivers where an "object array" is only needed in
execbuffer, we will use this in several places, and often with only 1
object in the array.  Can we special case that and do a quick
reservation_object_lock?

> > +}
> > +
> > +void virtio_gpu_array_unlock_resv(struct virtio_gpu_object_array *objs)
> > +{
> > +       drm_gem_unlock_reservations(objs->objs, objs->nents,
> > +                                   &objs->ticket);
> > +}
> > +
> > +void virtio_gpu_array_add_fence(struct virtio_gpu_object_array *objs,
> > +                               struct dma_fence *fence)
> > +{
> > +       int i;
> > +
> > +       for (i = 0; i < objs->nents; i++)
> > +               reservation_object_add_excl_fence(objs->objs[i]->resv,
> > +                                                 fence);
> > +}
> > +
> > +void virtio_gpu_array_put_free(struct virtio_gpu_object_array *objs)
> > +{
> > +       u32 i;
> > +
> > +       for (i = 0; i < objs->nents; i++)
> > +               drm_gem_object_put_unlocked(objs->objs[i]);
> > +       virtio_gpu_array_free(objs);
> > +}
> > --
> > 2.18.1
> >