On 07/03/2022 13:40, Ramalingam C wrote:
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]
Signed-off-by: Ramalingam C <ramalingam.c@xxxxxxxxx>
cc: Christian Koenig <christian.koenig@xxxxxxx>
cc: Hellstrom Thomas <thomas.hellstrom@xxxxxxxxx>
Reviewed-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 23 ++++++++++++++++++++++-
1 file changed, 22 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 1a8262f5f692..c7a36861c38d 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
@@ -255,12 +256,27 @@ static const struct i915_refct_sgt_ops tt_rsgt_ops = {
.release = i915_ttm_tt_release
};
+static inline bool
+i915_gem_object_has_lmem_placement(struct drm_i915_gem_object *obj)
+{
+ int i;
+
+ for (i = 0; i < obj->mm.n_placements; i++)
+ if (obj->mm.placements[i]->type == INTEL_MEMORY_LOCAL)
+ return true;
+
+ return false;
+}
+
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;
@@ -283,7 +299,12 @@ 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_has_lmem_placement(obj))
+ ccs_pages = DIV_ROUND_UP(DIV_ROUND_UP(bo->base.size,
+ NUM_BYTES_PER_CCS_BYTE),
+ PAGE_SIZE);
Did you figure out how to handle the case where we have LMEM + SMEM, and
are unable to place the object into LMEM, and then it just ends up being
kept in SMEM? AFAIK the vm.insert_entries code has always just assumed
that the vma sg_table size is the same as the vma->size, and so will
happily create PTEs for the hidden ccs page(s), which might corrupt the
users vm, depending on the exact layout.
Also it looks like the _shmem_writeback() call should now use
ttm_tt->num_pages, instead of the object size?
+
+ ret = ttm_tt_init(&i915_tt->ttm, bo, page_flags, caching, ccs_pages);
if (ret)
goto err_free;
