[PATCH v8 8/9] drm/i915/gem: Add extra pages in ttm_tt for ccs data

[Ramalingam C <ramalingam.c@xxxxxxxxx>]

On Xe-HP and later devices, dedicated compression control state (CCS)
stored in local memory is used for each surface, to support the
3D and media compression formats.

The memory required for the CCS of the entire local memory is 1/256 of
the local memory size. So before the kernel boot, the required memory
is reserved for the CCS data and a secure register will be programmed
with the CCS base address

So when an object is allocated in local memory, dont need to explicitly
allocate the space for ccs data. But when the obj is evicted into the
smem, to hold the compression related data along with the obj extra space
is needed in smem. i.e obj_size + (obj_size/256).

Hence when a smem pages are allocated for an obj with lmem placement
possibility we create with the extra pages required for the ccs data for
the obj size.

v2:
  Used imperative wording [Thomas]
v3:
  Inflate the pages only when obj's placement is lmem only
v4:
  GEM_BUG_ON if the ttm->num_pages > obj page size [Thomas]

Signed-off-by: Ramalingam C <ramalingam.c@xxxxxxxxx>
cc: Christian Koenig <christian.koenig@xxxxxxx>
cc: Hellstrom Thomas <thomas.hellstrom@xxxxxxxxx>
Reviewed-by: Thomas Hellstrom <thomas.hellstrom@xxxxxxxxxxxxxxx>
Reviewed-by: Nirmoy Das <nirmoy.das@xxxxxxxxx>
---
 drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 30 ++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index a878910a563c..4c25d9b2f138 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -20,6 +20,7 @@
 #include "gem/i915_gem_ttm.h"
 #include "gem/i915_gem_ttm_move.h"
 #include "gem/i915_gem_ttm_pm.h"
+#include "gt/intel_gpu_commands.h"
 
 #define I915_TTM_PRIO_PURGE     0
 #define I915_TTM_PRIO_NO_PAGES  1
@@ -265,12 +266,33 @@ static const struct i915_refct_sgt_ops tt_rsgt_ops = {
 	.release = i915_ttm_tt_release
 };
 
+static inline bool
+i915_gem_object_needs_ccs_pages(struct drm_i915_gem_object *obj)
+{
+	bool lmem_placement = false;
+	int i;
+
+	for (i = 0; i < obj->mm.n_placements; i++) {
+		/* Compression is not allowed for the objects with smem placement */
+		if (obj->mm.placements[i]->type == INTEL_MEMORY_SYSTEM)
+			return false;
+		if (!lmem_placement &&
+		    obj->mm.placements[i]->type == INTEL_MEMORY_LOCAL)
+			lmem_placement = true;
+	}
+
+	return lmem_placement;
+}
+
 static struct ttm_tt *i915_ttm_tt_create(struct ttm_buffer_object *bo,
 					 uint32_t page_flags)
 {
+	struct drm_i915_private *i915 = container_of(bo->bdev, typeof(*i915),
+						     bdev);
 	struct ttm_resource_manager *man =
 		ttm_manager_type(bo->bdev, bo->resource->mem_type);
 	struct drm_i915_gem_object *obj = i915_ttm_to_gem(bo);
+	unsigned long ccs_pages = 0;
 	enum ttm_caching caching;
 	struct i915_ttm_tt *i915_tt;
 	int ret;
@@ -293,7 +315,12 @@ static struct ttm_tt *i915_ttm_tt_create(struct ttm_buffer_object *bo,
 		i915_tt->is_shmem = true;
 	}
 
-	ret = ttm_tt_init(&i915_tt->ttm, bo, page_flags, caching, 0);
+	if (HAS_FLAT_CCS(i915) && i915_gem_object_needs_ccs_pages(obj))
+		ccs_pages = DIV_ROUND_UP(DIV_ROUND_UP(bo->base.size,
+						      NUM_BYTES_PER_CCS_BYTE),
+					 PAGE_SIZE);
+
+	ret = ttm_tt_init(&i915_tt->ttm, bo, page_flags, caching, ccs_pages);
 	if (ret)
 		goto err_free;
 
@@ -773,6 +800,7 @@ static int __i915_ttm_get_pages(struct drm_i915_gem_object *obj,
 					    i915_sg_dma_sizes(rsgt->table.sgl));
 	}
 
+	GEM_BUG_ON(bo->ttm && ((obj->base.size >> PAGE_SHIFT) < bo->ttm->num_pages));
 	i915_ttm_adjust_lru(obj);
 	return ret;
 }
-- 
2.20.1