[Intel-gfx] [PATCH 2/2] drm/i915: move vma sanity checking into i915_vma_bind

[Chris Wilson]

On Tue, Dec 13, 2016 at 04:00:59PM +0000, Matthew Auld wrote:
> If we move the sanity checking from gen8_alloc_va_range_3lvl and
> gen6_alloc_va_range into i915_vma_bind, we will increase our coverage to
> now both callbacks. We also convert each WARN_ON over to a GEM_WARN_ON.
> 
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Suggested-by: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Matthew Auld <matthew.auld at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem_gtt.c | 12 ------------
>  drivers/gpu/drm/i915/i915_vma.c     |  6 ++++++
>  2 files changed, 6 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index ef00d36680c9..4f405b445b6c 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -1303,15 +1303,6 @@ static int gen8_alloc_va_range_3lvl(struct i915_address_space *vm,
>  	uint32_t pdpes = I915_PDPES_PER_PDP(dev_priv);
>  	int ret;
>  
> -	/* Wrap is never okay since we can only represent 48b, and we don't
> -	 * actually use the other side of the canonical address space.
> -	 */
> -	if (WARN_ON(start + length < start))
> -		return -ENODEV;
> -
> -	if (WARN_ON(start + length > vm->total))
> -		return -ENODEV;
> -
>  	ret = alloc_gen8_temp_bitmaps(&new_page_dirs, &new_page_tables, pdpes);
>  	if (ret)
>  		return ret;
> @@ -1929,9 +1920,6 @@ static int gen6_alloc_va_range(struct i915_address_space *vm,
>  	uint32_t pde;
>  	int ret;
>  
> -	if (WARN_ON(start_in + length_in > ppgtt->base.total))
> -		return -ENODEV;
> -
>  	start = start_save = start_in;
>  	length = length_save = length_in;
>  
> diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
> index 37c3eebe8316..9e121222c5eb 100644
> --- a/drivers/gpu/drm/i915/i915_vma.c
> +++ b/drivers/gpu/drm/i915/i915_vma.c
> @@ -176,6 +176,12 @@ int i915_vma_bind(struct i915_vma *vma, enum i915_cache_level cache_level,
>  	if (bind_flags == 0)
>  		return 0;

#define range_overfows(start, size, max) ({
	typeof(start) start__ = (start);
	typeof(size) size__ = (size);
	typeof(max) max__ = (max);
	(void)(&start__ == &size__);
	(void)(&start__ == &max__);
	start > max || size > max - start;
})

if (GEM_WARN_ON(range_overflows(vma->node.start,
				vma->node.size,
				vma->vm->total))
    return -ENODEV;

Then look at pread/pwrite for where we can reuse range_overflows(), e.g.
if (range_overflows(args->offset, args->size, obj->base.size)) {

Might need a range_overflows_t();
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre