On ti, 2016-04-12 at 16:57 +0100, Matthew Auld wrote:
> For the gen6/gen8_allocate_va_range functions remove the WARN_ON range
> sanity checks in favour of simply hardening the allocation paths. This
> also fixes the inconsistency in which we don't always handle the
> potential overflow in our checks.
>
Not sure this is the right thing to do. I think I do prefer erroring
out on invalid arguments as we're talking of internal programmer
interface.
Regards, Joonas
> Cc: Chris Wilson <ch...@chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com>
> Signed-off-by: Matthew Auld <matthew.a...@intel.com>
> ---
> drivers/gpu/drm/i915/i915_gem_gtt.c | 17 ++++-------------
> 1 file changed, 4 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c
> b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 5ed713d..fa583d5 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -1220,15 +1220,6 @@ static int gen8_alloc_va_range_3lvl(struct
> i915_address_space *vm,
> uint32_t pdpes = I915_PDPES_PER_PDP(dev);
> 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;
> @@ -1370,6 +1361,8 @@ static int gen8_alloc_va_range(struct
> i915_address_space *vm,
> {
> struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
>
> + length = min_t(uint64_t, length, vm->total);
> +
> if (USES_FULL_48BIT_PPGTT(vm->dev))
> return gen8_alloc_va_range_4lvl(vm, &ppgtt->pml4, start,
> length);
> else
> @@ -1860,11 +1853,9 @@ static int gen6_alloc_va_range(struct
> i915_address_space *vm,
> uint32_t pde, temp;
> int ret;
>
> - if (WARN_ON(start_in + length_in > ppgtt->base.total))
> - return -ENODEV;
> -
> start = start_save = start_in;
> - length = length_save = length_in;
> + length = length_save = length_in = min_t(uint64_t, length_in,
> + ppgtt->base.total);
>
> bitmap_zero(new_page_tables, I915_PDES);
>
--
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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