[Intel-gfx] [PATCH 07/18] drm/i915: introduce ppgtt page coloring

[Matthew Auld]

On 5 April 2017 at 14:41, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> On Tue, Apr 04, 2017 at 11:11:17PM +0100, Matthew Auld wrote:
>> To enable 64K pages we need to set the intermediate-page-size(IPS) bit
>> of the pde, therefore a page table is said to be either operating in 64K
>> or 4K mode. To accommodate this vm placement restriction we introduce a
>> color for pages and corresponding color_adjust callback.
>>
>> Signed-off-by: Matthew Auld <matthew.auld at intel.com>
>> ---
>>  drivers/gpu/drm/i915/i915_gem_gtt.c | 25 +++++++++++++++++++++++++
>>  drivers/gpu/drm/i915/i915_gem_gtt.h |  6 ++++++
>>  drivers/gpu/drm/i915/i915_vma.c     |  2 ++
>>  3 files changed, 33 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
>> index 0989af4a17e4..ddc3db345b76 100644
>> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
>> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
>> @@ -1332,6 +1332,28 @@ static int gen8_preallocate_top_level_pdp(struct i915_hw_ppgtt *ppgtt)
>>       return -ENOMEM;
>>  }
>>
>> +static void i915_page_color_adjust(const struct drm_mm_node *node,
>> +                                unsigned long color,
>> +                                u64 *start,
>> +                                u64 *end)
>> +{
>> +     GEM_BUG_ON(!is_valid_gtt_page_size(color));
>> +
>> +     if (!(color & (I915_GTT_PAGE_SIZE_4K | I915_GTT_PAGE_SIZE_64K)))
>> +             return;
>> +
>> +     GEM_BUG_ON(node->allocated && !is_valid_gtt_page_size(node->color));
>> +
>> +     if (i915_node_color_differs(node, color))
>> +             *start = roundup(*start, 1 << GEN8_PDE_SHIFT);
>> +
>> +     node = list_next_entry(node, node_list);
>> +     if (i915_node_color_differs(node, color))
>> +             *end = rounddown(*end, 1 << GEN8_PDE_SHIFT);
>> +
>> +     GEM_BUG_ON(node->allocated && !is_valid_gtt_page_size(node->color));
>> +}
>> +
>>  /*
>>   * GEN8 legacy ppgtt programming is accomplished through a max 4 PDP registers
>>   * with a net effect resembling a 2-level page table in normal x86 terms. Each
>> @@ -1372,6 +1394,9 @@ static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
>>               ppgtt->base.allocate_va_range = gen8_ppgtt_alloc_4lvl;
>>               ppgtt->base.insert_entries = gen8_ppgtt_insert_4lvl;
>>               ppgtt->base.clear_range = gen8_ppgtt_clear_4lvl;
>> +
>> +             if (SUPPORTS_PAGE_SIZE(dev_priv, I915_GTT_PAGE_SIZE_64K))
>> +                     ppgtt->base.mm.color_adjust = i915_page_color_adjust;
>>       } else {
>>               ret = __pdp_init(&ppgtt->base, &ppgtt->pdp);
>>               if (ret)
>> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
>> index 9c592e2de516..8d893ddd98f2 100644
>> --- a/drivers/gpu/drm/i915/i915_gem_gtt.h
>> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
>> @@ -353,6 +353,12 @@ i915_vm_has_cache_coloring(const struct i915_address_space *vm)
>>  }
>>
>>  static inline bool
>> +i915_vm_has_page_coloring(const struct i915_address_space *vm)
>> +{
>> +     return vm->mm.color_adjust && !i915_is_ggtt(vm);
>> +}
>> +
>> +static inline bool
>>  i915_vm_is_48bit(const struct i915_address_space *vm)
>>  {
>>       return (vm->total - 1) >> 32;
>> diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
>> index 8f0041ba328f..4043145b4310 100644
>> --- a/drivers/gpu/drm/i915/i915_vma.c
>> +++ b/drivers/gpu/drm/i915/i915_vma.c
>> @@ -471,6 +471,8 @@ i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
>>
>>       if (i915_vm_has_cache_coloring(vma->vm))
>>               color = obj->cache_level;
>> +     else if (i915_vm_has_page_coloring(vma->vm))
>> +             color = obj->gtt_page_size;
>
> This does not need color_adjust since you are just specifying an
> alignment and size. Why the extra complications? I remember asking the
> same last time.
Hmm, are you saying the whole idea of needing a color_adjust for
4K/64K vm placement is completely unnecessary?