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drm/i915: Use page coloring to provide the guard page at the end of the GTT 

As we now mark the reserved hole (drm_mm.head_node) with the special
UNEVICTABLE color, we can use the page coloring to avoid prefetching of
the CS beyond the end of the GTT.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170206084547.27921-3-chris@chris-wilson.co.uk
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
This commit is contained in:
Chris Wilson 2017-02-06 08:45:47 +00:00
parent 47db922fa1
commit a6508ded2a
2 changed files with 20 additions and 9 deletions
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10
drivers/gpu/drm/i915/i915_gem_evict.c
View File

@ -253,6 +253,9 @@ int i915_gem_evict_for_node(struct i915_address_space *vm,
int ret = 0;
lockdep_assert_held(&vm->i915->drm.struct_mutex);
GEM_BUG_ON(!IS_ALIGNED(start, I915_GTT_PAGE_SIZE));
GEM_BUG_ON(!IS_ALIGNED(end, I915_GTT_PAGE_SIZE));
trace_i915_gem_evict_node(vm, target, flags);
/* Retire before we search the active list. Although we have
@ -268,9 +271,11 @@ int i915_gem_evict_for_node(struct i915_address_space *vm,
/* Expand search to cover neighbouring guard pages (or lack!) */
if (start > vm->start)
start -= I915_GTT_PAGE_SIZE;
if (end < vm->start + vm->total)
end += I915_GTT_PAGE_SIZE;
/* Always look at the page afterwards to avoid the end-of-GTT */
end += I915_GTT_PAGE_SIZE;
}
GEM_BUG_ON(start >= end);
drm_mm_for_each_node_in_range(node, &vm->mm, start, end) {
/* If we find any non-objects (!vma), we cannot evict them */
@ -279,6 +284,7 @@ int i915_gem_evict_for_node(struct i915_address_space *vm,
break;
}
GEM_BUG_ON(!node->allocated);
vma = container_of(node, typeof(*vma), node);
/* If we are using coloring to insert guard pages between

19
drivers/gpu/drm/i915/i915_gem_gtt.c
View File

@ -2718,11 +2718,16 @@ static void i915_gtt_color_adjust(const struct drm_mm_node *node,
u64 *start,
u64 *end)
{
if (node->color != color)
if (node->allocated && node->color != color)
*start += I915_GTT_PAGE_SIZE;
/* Also leave a space between the unallocated reserved node after the
* GTT and any objects within the GTT, i.e. we use the color adjustment
* to insert a guard page to prevent prefetches crossing over the
* GTT boundary.
*/
node = list_next_entry(node, node_list);
if (node->allocated && node->color != color)
if (node->color != color)
*end -= I915_GTT_PAGE_SIZE;
}
@ -3243,14 +3248,14 @@ int i915_ggtt_init_hw(struct drm_i915_private *dev_priv)
INIT_LIST_HEAD(&dev_priv->vm_list);
/* Subtract the guard page before address space initialization to
* shrink the range used by drm_mm.
/* Note that we use page colouring to enforce a guard page at the
* end of the address space. This is required as the CS may prefetch
* beyond the end of the batch buffer, across the page boundary,
* and beyond the end of the GTT if we do not provide a guard.
*/
mutex_lock(&dev_priv->drm.struct_mutex);
ggtt->base.total -= I915_GTT_PAGE_SIZE;
i915_address_space_init(&ggtt->base, dev_priv, "[global]");
ggtt->base.total += I915_GTT_PAGE_SIZE;
if (!HAS_LLC(dev_priv))
if (!HAS_LLC(dev_priv) && !USES_PPGTT(dev_priv))
ggtt->base.mm.color_adjust = i915_gtt_color_adjust;
mutex_unlock(&dev_priv->drm.struct_mutex);