Re: [PATCH 09/16] drm/i915/gen8: Add 4 level support in insert_entries and clear_range

[Michel Thierry <michel.thierry@intel.com>]

On 5/26/2015 3:21 PM, Michel Thierry wrote:
> When 48b is enabled, gen8_ppgtt_insert_entries needs to read the Page Map
> Level 4 (PML4), before it selects which Page Directory Pointer (PDP)
> it will write to.
>
> Similarly, gen8_ppgtt_clear_range needs to get the correct PDP/PD range.
>
> This patch was inspired by Ben's "Depend exclusively on map and
> unmap_vma".
>
> v2: Rebase after s/page_tables/page_table/.
> v3: Remove unnecessary pdpe loop in gen8_ppgtt_clear_range_4lvl and use
> clamp_pdp in gen8_ppgtt_insert_entries (Akash).
> v4: Merge gen8_ppgtt_clear_range_4lvl into gen8_ppgtt_clear_range to
> maintain symmetry with gen8_ppgtt_insert_entries (Akash).
> v5: Do not mix pages and bytes in insert_entries (Akash).
>
> Cc: Akash Goel <akash.goel@intel.com>
> Signed-off-by: Michel Thierry <michel.thierry@intel.com>
> ---
>   drivers/gpu/drm/i915/i915_gem_gtt.c | 51 +++++++++++++++++++++++++++++++------
>   drivers/gpu/drm/i915/i915_gem_gtt.h | 11 ++++++++
>   2 files changed, 54 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 2b6ee8e..dbbf367 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -710,12 +725,31 @@ static void gen8_ppgtt_insert_entries(struct i915_address_space *vm,
>                                        enum i915_cache_level cache_level,
>                                        u32 unused)
>   {
> -       struct i915_hw_ppgtt *ppgtt = container_of(vm, struct i915_hw_ppgtt, base);
> -       struct i915_page_directory_pointer *pdp = &ppgtt->pdp; /* FIXME: 48b */
> +       struct i915_hw_ppgtt *ppgtt =
> +                       container_of(vm, struct i915_hw_ppgtt, base);
>          struct sg_page_iter sg_iter;
>
>          __sg_page_iter_start(&sg_iter, pages->sgl, sg_nents(pages->sgl), 0);
> -       gen8_ppgtt_insert_pte_entries(pdp, &sg_iter, start, cache_level, !HAS_LLC(vm->dev));
> +
> +       if (!USES_FULL_48BIT_PPGTT(vm->dev)) {
> +               gen8_ppgtt_insert_pte_entries(&ppgtt->pdp, &sg_iter, start,
> +                                             sg_nents(pages->sgl),
> +                                             cache_level, !HAS_LLC(vm->dev));
> +       } else {
> +               struct i915_page_directory_pointer *pdp;
> +               uint64_t templ4, pml4e;
> +               uint64_t length = sg_nents(pages->sgl) << PAGE_SHIFT;

Actually, this should be:

	uint64_t length = (uint64_t)sg_nents(pages->sgl) << PAGE_SHIFT;

Otherwise it will overflow if we're inserting 4GB at once.

> +
> +               gen8_for_each_pml4e(pdp, &ppgtt->pml4, start, length, templ4, pml4e) {
> +                       uint64_t pdp_len = gen8_clamp_pdp(start, length) >> PAGE_SHIFT;
> +                       uint64_t pdp_start = start;
> +
> +                       gen8_ppgtt_insert_pte_entries(pdp, &sg_iter,
> +                                                     pdp_start, pdp_len,
> +                                                     cache_level,
> +                                                     !HAS_LLC(vm->dev));
> +               }
> +       }
>   }
>
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