[PATCH v2] drm/amdgpu: Modify the contiguous flags behaviour

[Arunpravin Paneer Selvam]

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)

Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam at amd.com>
Suggested-by: Christian König <christian.koenig at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_object.c   |  8 ++-
 drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 57 +++++++++++++++-----
 2 files changed, 50 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index 8bc79924d171..caaef7b1df49 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -153,8 +153,10 @@ 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++;
 	}
 
@@ -966,6 +968,10 @@ 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 8db880244324..4be8b091099a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
@@ -88,6 +88,29 @@ static inline u64 amdgpu_vram_mgr_blocks_size(struct list_head *head)
 	return size;
 }
 
+static inline unsigned long
+amdgpu_vram_mgr_calculate_pages_per_block(struct ttm_buffer_object *tbo,
+					  const struct ttm_place *place,
+					  unsigned long bo_flags)
+{
+	unsigned long pages_per_block;
+
+	if (bo_flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS) {
+		pages_per_block = ~0ul;
+	} else {
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+		pages_per_block = HPAGE_PMD_NR;
+#else
+		/* default to 2MB */
+		pages_per_block = 2UL << (20UL - PAGE_SHIFT);
+#endif
+		pages_per_block = max_t(uint32_t, pages_per_block,
+					tbo->page_alignment);
+	}
+
+	return pages_per_block;
+}
+
 /**
  * DOC: mem_info_vram_total
  *
@@ -451,8 +474,10 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
 	struct amdgpu_vram_mgr *mgr = to_vram_mgr(man);
 	struct amdgpu_device *adev = to_amdgpu_device(mgr);
 	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;
+	unsigned long bo_flags = bo->flags;
 	struct drm_buddy *mm = &mgr->mm;
 	struct drm_buddy_block *block;
 	unsigned long pages_per_block;
@@ -468,18 +493,9 @@ 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
-		pages_per_block = HPAGE_PMD_NR;
-#else
-		/* default to 2MB */
-		pages_per_block = 2UL << (20UL - PAGE_SHIFT);
-#endif
-		pages_per_block = max_t(uint32_t, pages_per_block,
-					tbo->page_alignment);
-	}
+	pages_per_block =
+		amdgpu_vram_mgr_calculate_pages_per_block(tbo, place,
+							  bo_flags);
 
 	vres = kzalloc(sizeof(*vres), GFP_KERNEL);
 	if (!vres)
@@ -498,7 +514,7 @@ 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 (fpfn || lpfn != mgr->mm.size)
@@ -529,8 +545,21 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
 					   min_block_size,
 					   &vres->blocks,
 					   vres->flags);
-		if (unlikely(r))
+		if (unlikely(r)) {
+			if (bo_flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS &&
+			    !(place->flags & TTM_PL_FLAG_CONTIGUOUS)) {
+				/* Fallback to non contiguous allocation */
+				vres->flags &= ~DRM_BUDDY_CONTIGUOUS_ALLOCATION;
+				bo_flags &= ~AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS;
+
+				pages_per_block =
+					amdgpu_vram_mgr_calculate_pages_per_block(tbo,
+										  place,
+										  bo_flags);
+				continue;
+			}
 			goto error_free_blocks;
+		}
 
 		if (size > remaining_size)
 			remaining_size = 0;
-- 
2.25.1