Re: [PATCH v4 14/18] drm/i915: object size needs to be u64

Chris Wilson
2015-07-07T15:27:36Z

On Tue, Jul 07, 2015 at 04:14:59PM +0100, Michel Thierry wrote:
> In a 48b world, users can try to allocate buffers bigger than 4GB; in
> these cases it is important that size is a 64b variable.
>
> Also added a warning for illegal bind with size = 0.
>
> Signed-off-by: Michel Thierry <michel.thierry@intel.com>
> ---
> drivers/gpu/drm/i915/i915_gem.c | 5 +++--
> drivers/gpu/drm/i915/i915_gem_gtt.c | 3 +++
> 2 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index a0bff41..ebfb789 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -3718,7 +3718,8 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
> {
> struct drm_device *dev = obj->base.dev;
> struct drm_i915_private *dev_priv = dev->dev_private;
> - u32 size, fence_size, fence_alignment, unfenced_alignment;
> + u32 fence_alignment, unfenced_alignment;
> + u64 size, fence_size;
> u64 start =
> flags & PIN_OFFSET_BIAS ? flags & PIN_OFFSET_MASK : 0;
> u64 end =
> @@ -3777,7 +3778,7 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
> * attempt to find space.
> */
> if (size > end) {
> - DRM_DEBUG("Attempting to bind an object (view type=%u) larger than the aperture: size=%u > %s aperture=%llu\n",
> + DRM_DEBUG("Attempting to bind an object (view type=%u) larger than the aperture: size=%llu > %s aperture=%llu\n",
> ggtt_view ? ggtt_view->type : 0,
> size,
> flags & PIN_MAPPABLE ? "mappable" : "total",
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 449a245..900bce6 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -3312,6 +3312,9 @@ int i915_vma_bind(struct i915_vma *vma, enum i915_cache_level cache_level,
> if (WARN_ON(flags == 0))
> return -EINVAL;
>
> + if (WARN_ON(vma->node.size == 0))
> + return -EINVAL;

This is superfluous. We don't allow size=0 object creation, and the test
is better (if at all) at vma_create, but what you mean here is
WARN_ON(!drm_mm_node_allocated()) which seems sensisble. And both of
these would be better as ENODEV so we don't confuse the user when they
get propagated back to userspace.
-Chris

--
Chris Wilson, Intel Open Source Technology Centre