[PATCH libdrm] amdgpu: add amdgpu_bo_handle_type_kms_noimport

[Marek Olšák]

On Thu, Jul 12, 2018, 3:31 AM Michel Dänzer <michel at daenzer.net> wrote:

> On 2018-07-12 02:47 AM, Marek Olšák wrote:
> > From: Marek Olšák <marek.olsak at amd.com>
> >
> > ---
> >  amdgpu/amdgpu.h    | 7 ++++++-
> >  amdgpu/amdgpu_bo.c | 4 ++++
> >  2 files changed, 10 insertions(+), 1 deletion(-)
> >
> > diff --git a/amdgpu/amdgpu.h b/amdgpu/amdgpu.h
> > index 36f91058..be83b457 100644
> > --- a/amdgpu/amdgpu.h
> > +++ b/amdgpu/amdgpu.h
> > @@ -77,21 +77,26 @@ struct drm_amdgpu_info_hw_ip;
> >   *
> >  */
> >  enum amdgpu_bo_handle_type {
> >       /** GEM flink name (needs DRM authentication, used by DRI2) */
> >       amdgpu_bo_handle_type_gem_flink_name = 0,
> >
> >       /** KMS handle which is used by all driver ioctls */
> >       amdgpu_bo_handle_type_kms = 1,
> >
> >       /** DMA-buf fd handle */
> > -     amdgpu_bo_handle_type_dma_buf_fd = 2
> > +     amdgpu_bo_handle_type_dma_buf_fd = 2,
> > +
> > +     /** KMS handle, but re-importing as a DMABUF handle through
> > +      *  drmPrimeHandleToFD is forbidden. (Glamor does that)
> > +      */
> > +     amdgpu_bo_handle_type_kms_noimport = 3,
> >  };
> >
> >  /** Define known types of GPU VM VA ranges */
> >  enum amdgpu_gpu_va_range
> >  {
> >       /** Allocate from "normal"/general range */
> >       amdgpu_gpu_va_range_general = 0
> >  };
> >
> >  enum amdgpu_sw_info {
> > diff --git a/amdgpu/amdgpu_bo.c b/amdgpu/amdgpu_bo.c
> > index 9e37b149..d29be244 100644
> > --- a/amdgpu/amdgpu_bo.c
> > +++ b/amdgpu/amdgpu_bo.c
> > @@ -234,20 +234,22 @@ int amdgpu_bo_export(amdgpu_bo_handle bo,
> >       case amdgpu_bo_handle_type_gem_flink_name:
> >               r = amdgpu_bo_export_flink(bo);
> >               if (r)
> >                       return r;
> >
> >               *shared_handle = bo->flink_name;
> >               return 0;
> >
> >       case amdgpu_bo_handle_type_kms:
> >               amdgpu_add_handle_to_table(bo);
> > +             /* fall through */
> > +     case amdgpu_bo_handle_type_kms_noimport:
> >               *shared_handle = bo->handle;
> >               return 0;
>
> What is the rationale for this? I.e. why do you want to not store some
> handles in the hash table?


Because I have the option.

And how can code using
> amdgpu_bo_handle_type_kms_noimport be sure that the BO will never be
> re-imported via dma-buf?
>

That's for the user to decide and prove when it's safe.


> The experience with the previous patch has shown that it's hard to keep
> track of all possible ways in which BOs are imported, and that if we
> miss one, this breaks pretty spectacularly.
>

You are assuming that it will be used incorrectly based on your previous
bad experience. All I need to do is not to hand the handle to components
that would misuse it.

Marek


>
> --
> Earthling Michel Dänzer               |               http://www.amd.com
> Libre software enthusiast             |             Mesa and X developer
>
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