[PATCH v3] drm/amdgpu: Modify the contiguous flags behaviour

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Now we have two flags for contiguous VRAM buffer allocation.
If the application request for AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS,
it would set the ttm place TTM_PL_FLAG_CONTIGUOUS flag in the
buffer's placement function.

This patch will change the default behaviour of the two flags.

When we set AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS
- This means contiguous is not mandatory.
- we will try to allocate the contiguous buffer. Say if the
  allocation fails, we fallback to allocate the individual pages.

When we setTTM_PL_FLAG_CONTIGUOUS
- This means contiguous allocation is mandatory.
- we are setting this in amdgpu_bo_pin_restricted() before bo validation
  and check this flag in the vram manager file.
- if this is set, we should allocate the buffer pages contiguously.
  the allocation fails, we return -ENOSPC.

v2:
  - keep the mem_flags and bo->flags check as is(Christian)
  - place the TTM_PL_FLAG_CONTIGUOUS flag setting into the
    amdgpu_bo_pin_restricted function placement range iteration
    loop(Christian)
  - rename find_pages with amdgpu_vram_mgr_calculate_pages_per_block
    (Christian)
  - Keep the kernel BO allocation as is(Christain)
  - If BO pin vram allocation failed, we need to return -ENOSPC as
    RDMA cannot work with scattered VRAM pages(Philip)

v3(Christian):
  - keep contiguous flag handling outside of pages_per_block
    calculation
  - remove the hacky implementation in contiguous flag error
    handling code

Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@xxxxxxx>
Suggested-by: Christian König <christian.koenig@xxxxxxx>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_object.c   |  8 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 83 ++++++++++++++------
 2 files changed, 65 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index 492aebc44e51..c594d2a5978e 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -154,8 +154,10 @@ void amdgpu_bo_placement_from_domain(struct amdgpu_bo *abo, u32 domain)
 		else
 			places[c].flags |= TTM_PL_FLAG_TOPDOWN;
 
-		if (flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS)
+		if (abo->tbo.type == ttm_bo_type_kernel &&
+		    flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS)
 			places[c].flags |= TTM_PL_FLAG_CONTIGUOUS;
+
 		c++;
 	}
 
@@ -965,6 +967,10 @@ int amdgpu_bo_pin_restricted(struct amdgpu_bo *bo, u32 domain,
 		if (!bo->placements[i].lpfn ||
 		    (lpfn && lpfn < bo->placements[i].lpfn))
 			bo->placements[i].lpfn = lpfn;
+
+		if (bo->flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS &&
+		    bo->placements[i].mem_type == TTM_PL_VRAM)
+			bo->placements[i].flags |= TTM_PL_FLAG_CONTIGUOUS;
 	}
 
 	r = ttm_bo_validate(&bo->tbo, &bo->placement, &ctx);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
index e494f5bf136a..17c5d9ce9927 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
@@ -88,6 +88,23 @@ static inline u64 amdgpu_vram_mgr_blocks_size(struct list_head *head)
 	return size;
 }
 
+static inline void amdgpu_vram_mgr_limit_min_block_size(unsigned long pages_per_block,
+							u64 size,
+							u64 *min_block_size,
+							bool contiguous_enabled)
+{
+	if (contiguous_enabled)
+		return;
+
+	/*
+	 * if size >= 2MiB, limit the min_block_size to 2MiB
+	 * for better TLB usage.
+	 */
+	if ((size >= (u64)pages_per_block << PAGE_SHIFT) &&
+	    !(size & (((u64)pages_per_block << PAGE_SHIFT) - 1)))
+		*min_block_size = (u64)pages_per_block << PAGE_SHIFT;
+}
+
 /**
  * DOC: mem_info_vram_total
  *
@@ -452,11 +469,12 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
 	struct amdgpu_device *adev = to_amdgpu_device(mgr);
 	struct amdgpu_bo *bo = ttm_to_amdgpu_bo(tbo);
 	u64 vis_usage = 0, max_bytes, min_block_size;
+	struct amdgpu_bo *bo = ttm_to_amdgpu_bo(tbo);
 	struct amdgpu_vram_mgr_resource *vres;
 	u64 size, remaining_size, lpfn, fpfn;
 	struct drm_buddy *mm = &mgr->mm;
-	struct drm_buddy_block *block;
 	unsigned long pages_per_block;
+	struct drm_buddy_block *block;
 	int r;
 
 	lpfn = (u64)place->lpfn << PAGE_SHIFT;
@@ -469,18 +487,14 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
 	if (tbo->type != ttm_bo_type_kernel)
 		max_bytes -= AMDGPU_VM_RESERVED_VRAM;
 
-	if (place->flags & TTM_PL_FLAG_CONTIGUOUS) {
-		pages_per_block = ~0ul;
-	} else {
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
 		pages_per_block = HPAGE_PMD_NR;
-#else
-		/* default to 2MB */
+	else
+		/* default to 2MiB */
 		pages_per_block = 2UL << (20UL - PAGE_SHIFT);
-#endif
-		pages_per_block = max_t(uint32_t, pages_per_block,
-					tbo->page_alignment);
-	}
+
+	pages_per_block = max_t(uint32_t, pages_per_block,
+				tbo->page_alignment);
 
 	vres = kzalloc(sizeof(*vres), GFP_KERNEL);
 	if (!vres)
@@ -499,7 +513,7 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
 	if (place->flags & TTM_PL_FLAG_TOPDOWN)
 		vres->flags |= DRM_BUDDY_TOPDOWN_ALLOCATION;
 
-	if (place->flags & TTM_PL_FLAG_CONTIGUOUS)
+	if (bo->flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS)
 		vres->flags |= DRM_BUDDY_CONTIGUOUS_ALLOCATION;
 
 	if (bo->flags & AMDGPU_GEM_CREATE_VRAM_CLEARED)
@@ -509,23 +523,23 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
 		/* Allocate blocks in desired range */
 		vres->flags |= DRM_BUDDY_RANGE_ALLOCATION;
 
+	if (tbo->page_alignment)
+		min_block_size = (u64)tbo->page_alignment << PAGE_SHIFT;
+	else
+		min_block_size = mgr->default_page_size;
+
 	remaining_size = (u64)vres->base.size;
 
 	mutex_lock(&mgr->lock);
 	while (remaining_size) {
-		if (tbo->page_alignment)
-			min_block_size = (u64)tbo->page_alignment << PAGE_SHIFT;
-		else
-			min_block_size = mgr->default_page_size;
-
-		BUG_ON(min_block_size < mm->chunk_size);
-
 		/* Limit maximum size to 2GiB due to SG table limitations */
 		size = min(remaining_size, 2ULL << 30);
-
-		if ((size >= (u64)pages_per_block << PAGE_SHIFT) &&
-				!(size & (((u64)pages_per_block << PAGE_SHIFT) - 1)))
-			min_block_size = (u64)pages_per_block << PAGE_SHIFT;
+		amdgpu_vram_mgr_limit_min_block_size(pages_per_block,
+						     size,
+						     &min_block_size,
+						     bo->flags &
+						     AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS);
+		BUG_ON(min_block_size < mm->chunk_size);
 
 		r = drm_buddy_alloc_blocks(mm, fpfn,
 					   lpfn,
@@ -533,8 +547,27 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
 					   min_block_size,
 					   &vres->blocks,
 					   vres->flags);
-		if (unlikely(r))
-			goto error_free_blocks;
+		if (unlikely(r)) {
+			if (bo->flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS &&
+			    !(place->flags & TTM_PL_FLAG_CONTIGUOUS)) {
+				/* Fallback to non-contiguous allocation */
+				amdgpu_vram_mgr_limit_min_block_size(pages_per_block,
+								     size,
+								     &min_block_size,
+								     !(bo->flags &
+								     AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS));
+				r = drm_buddy_alloc_blocks(mm, fpfn,
+							   lpfn,
+							   size,
+							   min_block_size,
+							   &vres->blocks,
+							   vres->flags);
+				if (unlikely(r))
+					goto error_free_blocks;
+			} else {
+				goto error_free_blocks;
+			}
+		}
 
 		if (size > remaining_size)
 			remaining_size = 0;
-- 
2.25.1




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