[Intel-gfx] [PATCH v5 06/10] drm/i915: add syncobj timeline support

Chris Wilson chris at chris-wilson.co.uk
Thu Jun 27 09:15:49 UTC 2019


Quoting Lionel Landwerlin (2019-06-27 09:00:41)
> Introduces a new parameters to execbuf so that we can specify syncobj
> handles as well as timeline points.
> 
> v2: Reuse i915_user_extension_fn
> 
> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> ---
>  .../gpu/drm/i915/gem/i915_gem_execbuffer.c    | 280 ++++++++++++++----
>  drivers/gpu/drm/i915/i915_drv.c               |   2 +
>  include/uapi/drm/i915_drm.h                   |  37 +++
>  3 files changed, 263 insertions(+), 56 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> index 1970dd8cbac3..476fade6fcab 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> @@ -213,6 +213,13 @@ enum {
>   * the batchbuffer in trusted mode, otherwise the ioctl is rejected.
>   */
>  
> +struct i915_drm_dma_fences {

i915_execbuffer_fences or eb_fences as it is private to the impl.

> +       struct drm_syncobj *syncobj; /* Use with ptr_mask_bits() */
> +       struct dma_fence *dma_fence;
> +       u64 value;
> +       struct dma_fence_chain *chain_fence;
> +};
> +
>  struct i915_execbuffer {
>         struct drm_i915_private *i915; /** i915 backpointer */
>         struct drm_file *file; /** per-file lookup tables and limits */
> @@ -275,6 +282,7 @@ struct i915_execbuffer {
>  
>         struct {
>                 u64 flags; /** Available extensions parameters */
> +               struct drm_i915_gem_execbuffer_ext_timeline_fences timeline_fences;

Another 40b on stack. Getting closer to those warning bells being set off.

>         } extensions;
>  };
>  
> @@ -2224,67 +2232,193 @@ eb_select_engine(struct i915_execbuffer *eb,
>  }
>  
>  static void
> -__free_fence_array(struct drm_syncobj **fences, unsigned int n)
> +__free_fence_array(struct i915_drm_dma_fences *fences, unsigned int n)
>  {
> -       while (n--)
> -               drm_syncobj_put(ptr_mask_bits(fences[n], 2));
> +       while (n--) {
> +               drm_syncobj_put(ptr_mask_bits(fences[n].syncobj, 2));
> +               dma_fence_put(fences[n].dma_fence);
> +               kfree(fences[n].chain_fence);
> +       }
>         kvfree(fences);
>  }
>  
> -static struct drm_syncobj **
> -get_fence_array(struct drm_i915_gem_execbuffer2 *args,
> -               struct drm_file *file)
> +static struct i915_drm_dma_fences *
> +get_timeline_fence_array(struct i915_execbuffer *eb, int *out_n_fences)
>  {
> -       const unsigned long nfences = args->num_cliprects;
> +       struct drm_i915_gem_execbuffer_ext_timeline_fences *timeline_fences =
> +               &eb->extensions.timeline_fences;
> +       struct drm_i915_gem_exec_fence __user *user_fences;
> +       struct i915_drm_dma_fences *fences;
> +       u64 __user *user_values;
> +       unsigned long n;
> +       int err;
> +
> +       *out_n_fences = timeline_fences->handle_count;

I'd encourage using a const num_fences = timeline_fences->handle_count
for readability within the function and then assigning
	*out_n_fences = num_fences;
right before the successful return fences;

> +       /* Check multiplication overflow for access_ok() and kvmalloc_array() */
> +       BUILD_BUG_ON(sizeof(size_t) > sizeof(unsigned long));
> +       if (*out_n_fences > min_t(unsigned long,
> +                                 ULONG_MAX / sizeof(*user_fences),
> +                                 SIZE_MAX / sizeof(*fences)))
> +               return ERR_PTR(-EINVAL);
> +
> +       user_fences = u64_to_user_ptr(timeline_fences->handles_ptr);
> +       if (!access_ok(user_fences, *out_n_fences * sizeof(*user_fences)))
> +               return ERR_PTR(-EFAULT);
> +
> +       user_values = u64_to_user_ptr(timeline_fences->values_ptr);
> +       if (!access_ok(user_values, *out_n_fences * sizeof(*user_values)))
> +               return ERR_PTR(-EFAULT);

> +       fences = kvmalloc_array(*out_n_fences, sizeof(*fences),
> +                               __GFP_NOWARN | GFP_KERNEL);
> +       if (!fences)
> +               return ERR_PTR(-ENOMEM);
> +
> +       BUILD_BUG_ON(~(ARCH_KMALLOC_MINALIGN - 1) &
> +                    ~__I915_EXEC_FENCE_UNKNOWN_FLAGS);
> +
> +       for (n = 0; n < *out_n_fences; n++) {
> +               struct drm_i915_gem_exec_fence user_fence;
> +               struct drm_syncobj *syncobj;
> +               struct dma_fence *fence = NULL;
> +               u64 point;
> +
> +               if (__copy_from_user(&user_fence, user_fences++, sizeof(user_fence))) {
> +                       err = -EFAULT;
> +                       goto err;
> +               }
> +
> +               if (user_fence.flags & __I915_EXEC_FENCE_UNKNOWN_FLAGS) {
> +                       err = -EINVAL;
> +                       goto err;
> +               }
> +
> +               if (__get_user(point, user_values++)) {
> +                       err = -EFAULT;
> +                       goto err;
> +               }
> +
> +               syncobj = drm_syncobj_find(eb->file, user_fence.handle);
> +               if (!syncobj) {
> +                       DRM_DEBUG("Invalid syncobj handle provided\n");
> +                       err = -EINVAL;
> +                       goto err;
> +               }
> +
> +               if (user_fence.flags & I915_EXEC_FENCE_WAIT) {
> +                       fence = drm_syncobj_fence_get(syncobj);
> +                       if (!fence) {
> +                               DRM_DEBUG("Syncobj handle has no fence\n");
> +                               drm_syncobj_put(syncobj);
> +                               err = -EINVAL;
> +                               goto err;
> +                       }
> +
> +                       err = dma_fence_chain_find_seqno(&fence, point);

Is an imported syncobj always a fence-chain?

drm_syncobj_import_sync_file_fence() says no.

Similarly, we put ordinary fences into the syncobj ourselves if
point==0, or the user uses the old path.

I think you need something like

if (dma_fence_is_chain() || point) {
	err = dma_fence_chain_find_seqno(&fence, point);
	if (err) {
	}
}

> +                       if (err) {
> +                               DRM_DEBUG("Syncobj handle missing requested point\n");
> +                               goto err;
> +                       }
> +               }
> +
> +               /*
> +                * For timeline syncobjs we need to create a chain.

"need to preallocate chains for later signaling

> +                */
> +               if (point != 0 && user_fence.flags & I915_EXEC_FENCE_SIGNAL) {
> +                       fences[n].chain_fence =
> +                               kmalloc(sizeof(*fences[n].chain_fence),
> +                                       GFP_KERNEL);
> +                       if (!fences[n].chain_fence) {
> +                               dma_fence_put(fence);
> +                               drm_syncobj_put(syncobj);
> +                               err = -ENOMEM;
> +                               DRM_DEBUG("Unable to alloc chain_fence\n");
> +                               goto err;
> +                       }
> +               } else {
> +                       fences[n].chain_fence = NULL;
> +               }
> +
> +               fences[n].syncobj = ptr_pack_bits(syncobj, user_fence.flags, 2);
> +               fences[n].dma_fence = fence;
> +               fences[n].value = point;
> +       }
> +
> +       return fences;
> +
> +err:
> +       __free_fence_array(fences, n);
> +       return ERR_PTR(err);
> +}
> +
> +static struct i915_drm_dma_fences *
> +get_legacy_fence_array(struct i915_execbuffer *eb,
> +                      int *out_n_fences)
> +{
> +       struct drm_i915_gem_execbuffer2 *args = eb->args;
>         struct drm_i915_gem_exec_fence __user *user;
> -       struct drm_syncobj **fences;
> +       struct i915_drm_dma_fences *fences;
>         unsigned long n;
>         int err;
>  
> -       if (!(args->flags & I915_EXEC_FENCE_ARRAY))
> -               return NULL;
> +       *out_n_fences = args->num_cliprects;

Same suggestion as earlier for a local num_fences.

> +static struct i915_drm_dma_fences *
> +get_fence_array(struct i915_execbuffer *eb, int *out_n_fences)
> +{
> +       if (eb->args->flags & I915_EXEC_FENCE_ARRAY)
> +               return get_legacy_fence_array(eb, out_n_fences);

Blank line.

> +       if (eb->extensions.flags & BIT(DRM_I915_GEM_EXECBUFFER_EXT_TIMELINE_FENCES))
> +               return get_timeline_fence_array(eb, out_n_fences);
> +
> +       *out_n_fences = 0;
> +
No blank line, my argument is that both are part of the return value for
the function.
> +       return NULL;
> +}
> +
>  static void
> -put_fence_array(struct drm_i915_gem_execbuffer2 *args,
> -               struct drm_syncobj **fences)
> +put_fence_array(struct i915_drm_dma_fences *fences, int nfences)
>  {
>         if (fences)
> -               __free_fence_array(fences, args->num_cliprects);
> +               __free_fence_array(fences, nfences);
>  }
>  
>  static int
>  await_fence_array(struct i915_execbuffer *eb,
> -                 struct drm_syncobj **fences)
> +                 struct i915_drm_dma_fences *fences,
> +                 int nfences)
>  {
> -       const unsigned int nfences = eb->args->num_cliprects;
>         unsigned int n;
>         int err;
>  
>         for (n = 0; n < nfences; n++) {
>                 struct drm_syncobj *syncobj;
> -               struct dma_fence *fence;
>                 unsigned int flags;
>  
> -               syncobj = ptr_unpack_bits(fences[n], &flags, 2);
> +               syncobj = ptr_unpack_bits(fences[n].syncobj, &flags, 2);
>                 if (!(flags & I915_EXEC_FENCE_WAIT))
>                         continue;
>  
> -               fence = drm_syncobj_fence_get(syncobj);
> -               if (!fence)
> -                       return -EINVAL;
> -
> -               err = i915_request_await_dma_fence(eb->request, fence);
> -               dma_fence_put(fence);
> +               err = i915_request_await_dma_fence(eb->request,
> +                                                  fences[n].dma_fence);
>                 if (err < 0)
>                         return err;
>         }
> @@ -2334,9 +2475,9 @@ await_fence_array(struct i915_execbuffer *eb,
>  
>  static void
>  signal_fence_array(struct i915_execbuffer *eb,
> -                  struct drm_syncobj **fences)
> +                  struct i915_drm_dma_fences *fences,
> +                  int nfences)
>  {
> -       const unsigned int nfences = eb->args->num_cliprects;
>         struct dma_fence * const fence = &eb->request->fence;
>         unsigned int n;
>  
> @@ -2344,15 +2485,43 @@ signal_fence_array(struct i915_execbuffer *eb,
>                 struct drm_syncobj *syncobj;
>                 unsigned int flags;
>  
> -               syncobj = ptr_unpack_bits(fences[n], &flags, 2);
> +               syncobj = ptr_unpack_bits(fences[n].syncobj, &flags, 2);
>                 if (!(flags & I915_EXEC_FENCE_SIGNAL))
>                         continue;
>  
> -               drm_syncobj_replace_fence(syncobj, fence);
> +               if (fences[n].chain_fence) {
> +                       drm_syncobj_add_point(syncobj, fences[n].chain_fence,
> +                                             fence, fences[n].value);
> +                       /*
> +                        * The chain's ownership is transfered to the
> +                        * timeline.
> +                        */
> +                       fences[n].chain_fence = NULL;
> +               } else {
> +                       drm_syncobj_replace_fence(syncobj, fence);
> +               }
>         }
>  }
>  
> +static int parse_timeline_fences(struct i915_user_extension __user *ext, void *data)
> +{
> +       struct i915_execbuffer *eb = data;
> +
> +       /* Timeline fences are incompatible with the fence array flag. */
> +       if (eb->args->flags & I915_EXEC_FENCE_ARRAY)
> +               return -EINVAL;

Also you only allow one timeline_fence extension struct.

> +
> +       if (copy_from_user(&eb->extensions.timeline_fences, ext,
> +                          sizeof(eb->extensions.timeline_fences)))
> +               return -EFAULT;
> +
> +       eb->extensions.flags |= BIT(DRM_I915_GEM_EXECBUFFER_EXT_TIMELINE_FENCES);
> +
> +       return 0;
> +}
> +
>  static const i915_user_extension_fn execbuf_extensions[] = {
> +        [DRM_I915_GEM_EXECBUFFER_EXT_TIMELINE_FENCES] = parse_timeline_fences,
>  };
>  
>  static int
> @@ -2372,14 +2541,15 @@ static int
>  i915_gem_do_execbuffer(struct drm_device *dev,
>                        struct drm_file *file,
>                        struct drm_i915_gem_execbuffer2 *args,
> -                      struct drm_i915_gem_exec_object2 *exec,
> -                      struct drm_syncobj **fences)
> +                      struct drm_i915_gem_exec_object2 *exec)
>  {
>         struct i915_execbuffer eb;
>         struct dma_fence *in_fence = NULL;
>         struct dma_fence *exec_fence = NULL;
>         struct sync_file *out_fence = NULL;
> +       struct i915_drm_dma_fences *fences = NULL;
>         int out_fence_fd = -1;
> +       int nfences = 0;
>         int err;
>  
>         BUILD_BUG_ON(__EXEC_INTERNAL_FLAGS & ~__I915_EXEC_ILLEGAL_FLAGS);
> @@ -2421,10 +2591,16 @@ i915_gem_do_execbuffer(struct drm_device *dev,
>                         return err;
>         }
>  
> +       fences = get_fence_array(&eb, &nfences);
> +       if (IS_ERR(fences))
> +               return PTR_ERR(fences);
> +
>         if (args->flags & I915_EXEC_FENCE_IN) {
>                 in_fence = sync_file_get_fence(lower_32_bits(args->rsvd2));
> -               if (!in_fence)
> -                       return -EINVAL;
> +               if (!in_fence) {
> +                       err = -EINVAL;
> +                       goto err_fences;
> +               }
>         }
>  
>         if (args->flags & I915_EXEC_FENCE_SUBMIT) {
> @@ -2582,7 +2758,7 @@ i915_gem_do_execbuffer(struct drm_device *dev,
>         }
>  
>         if (fences) {
> -               err = await_fence_array(&eb, fences);
> +               err = await_fence_array(&eb, fences, nfences);
>                 if (err)
>                         goto err_request;
>         }
> @@ -2611,7 +2787,7 @@ i915_gem_do_execbuffer(struct drm_device *dev,
>         i915_request_add(eb.request);
>  
>         if (fences)
> -               signal_fence_array(&eb, fences);
> +               signal_fence_array(&eb, fences, nfences);
>  
>         if (out_fence) {
>                 if (err == 0) {
> @@ -2646,6 +2822,8 @@ i915_gem_do_execbuffer(struct drm_device *dev,
>         dma_fence_put(exec_fence);
>  err_in_fence:
>         dma_fence_put(in_fence);
> +err_fences:
> +       put_fence_array(fences, nfences);
>         return err;
>  }
>  
> @@ -2739,7 +2917,7 @@ i915_gem_execbuffer_ioctl(struct drm_device *dev, void *data,
>                         exec2_list[i].flags = 0;
>         }
>  
> -       err = i915_gem_do_execbuffer(dev, file, &exec2, exec2_list, NULL);
> +       err = i915_gem_do_execbuffer(dev, file, &exec2, exec2_list);
>         if (exec2.flags & __EXEC_HAS_RELOC) {
>                 struct drm_i915_gem_exec_object __user *user_exec_list =
>                         u64_to_user_ptr(args->buffers_ptr);
> @@ -2770,7 +2948,6 @@ i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data,
>  {
>         struct drm_i915_gem_execbuffer2 *args = data;
>         struct drm_i915_gem_exec_object2 *exec2_list;
> -       struct drm_syncobj **fences = NULL;
>         const size_t count = args->buffer_count;
>         int err;
>  
> @@ -2798,15 +2975,7 @@ i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data,
>                 return -EFAULT;
>         }
>  
> -       if (args->flags & I915_EXEC_FENCE_ARRAY) {
> -               fences = get_fence_array(args, file);
> -               if (IS_ERR(fences)) {
> -                       kvfree(exec2_list);
> -                       return PTR_ERR(fences);
> -               }
> -       }
> -
> -       err = i915_gem_do_execbuffer(dev, file, args, exec2_list, fences);
> +       err = i915_gem_do_execbuffer(dev, file, args, exec2_list);
>  
>         /*
>          * Now that we have begun execution of the batchbuffer, we ignore
> @@ -2846,7 +3015,6 @@ end:;
>         }
>  
>         args->flags &= ~__I915_EXEC_UNKNOWN_FLAGS;
> -       put_fence_array(args, fences);
>         kvfree(exec2_list);
>         return err;
>  }
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 7c3c3b8ab339..48f9009a6318 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -456,6 +456,7 @@ static int i915_getparam_ioctl(struct drm_device *dev, void *data,
>         case I915_PARAM_HAS_EXEC_BATCH_FIRST:
>         case I915_PARAM_HAS_EXEC_FENCE_ARRAY:
>         case I915_PARAM_HAS_EXEC_SUBMIT_FENCE:
> +       case I915_PARAM_HAS_EXEC_TIMELINE_FENCES:
>                 /* For the time being all of these are always true;
>                  * if some supported hardware does not have one of these
>                  * features this value needs to be provided from
> @@ -3220,6 +3221,7 @@ static struct drm_driver driver = {
>         .driver_features =
>             DRIVER_GEM |
>             DRIVER_RENDER | DRIVER_MODESET | DRIVER_ATOMIC | DRIVER_SYNCOBJ,
> +           DRIVER_SYNCOBJ_TIMELINE,

With a comma ? i.e. .ioctls = DRIVER_SYNCOBJ_TIMELINE

>         .release = i915_driver_release,
>         .open = i915_driver_open,
>         .lastclose = i915_driver_lastclose,
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index efa195d6994e..b7fe1915e34d 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -617,6 +617,12 @@ typedef struct drm_i915_irq_wait {
>   */
>  #define I915_PARAM_PERF_REVISION       54
>  
> +/* Query whether DRM_I915_GEM_EXECBUFFER2 supports supplying an array of
> + * timeline syncobj through drm_i915_gem_execbuf_ext_timeline_fences. See
> + * I915_EXEC_EXT.
> + */
> +#define I915_PARAM_HAS_EXEC_TIMELINE_FENCES 55
> +
>  /* Must be kept compact -- no holes and well documented */
>  
>  typedef struct drm_i915_getparam {
> @@ -1014,9 +1020,40 @@ struct drm_i915_gem_exec_fence {
>  };
>  
>  enum drm_i915_gem_execbuffer_ext {
> +       /**
> +        * This identifier is associated with
> +        * drm_i915_gem_execbuf_ext_timeline_fences.

Or just "See drm_i915_gem_execbuf_ext_timeline_fences
> +        */
> +       DRM_I915_GEM_EXECBUFFER_EXT_TIMELINE_FENCES,
 = 0
don't leave it up to the compiler.
> +
>         DRM_I915_GEM_EXECBUFFER_EXT_MAX /* non-ABI */
>  };
>  
> +/**
> + * This structure describes an array of drm_syncobj and associated points for
> + * timeline variants of drm_syncobj. It is invalid to append this structure to
> + * the execbuf if I915_EXEC_FENCE_ARRAY is set.
> + */
> +struct drm_i915_gem_execbuffer_ext_timeline_fences {
> +       struct i915_user_extension base;
> +
> +       /**
> +        * Number of element in the handles_ptr & value_ptr arrays.
> +        */
> +       __u64 handle_count;

Since it is used for both, I would use something like fence_count, or
num_fences (although _count is in the majority).

> +       /**
> +        * Pointer to an array of struct drm_i915_gem_exec_fence of size handle_count.

s/size/length/

I think we typically use size for byte sizes around the uAPI.

> +        */
> +       __u64 handles_ptr;
> +
> +       /**
> +        * Pointer to an array of u64 values of size handle_count. Values must
> +        * be 0 for a binary drm_syncobj.
> +        */
> +       __u64 values_ptr;
> +};
> +
>  struct drm_i915_gem_execbuffer2 {
>         /**
>          * List of gem_exec_object2 structs
> -- 
> 2.21.0.392.gf8f6787159e
> 
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