Re: [PATCH v2 2/8] drm/i915/gtt: add xehpsdv_ppgtt_insert_entry

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On 03/12/2021 16:59, Ramalingam C wrote:
On 2021-12-03 at 12:24:20 +0000, Matthew Auld wrote:
If this is LMEM then we get a 32 entry PT, with each PTE pointing to
some 64K block of memory, otherwise it's just the usual 512 entry PT.
This very much assumes the caller knows what they are doing.

Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>
Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
Cc: Ramalingam C <ramalingam.c@xxxxxxxxx>
---
  drivers/gpu/drm/i915/gt/gen8_ppgtt.c | 50 ++++++++++++++++++++++++++--
  1 file changed, 48 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
index bd3ca0996a23..312b2267bf87 100644
--- a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
+++ b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
@@ -728,13 +728,56 @@ static void gen8_ppgtt_insert_entry(struct i915_address_space *vm,
  		gen8_pdp_for_page_index(vm, idx);
  	struct i915_page_directory *pd =
  		i915_pd_entry(pdp, gen8_pd_index(idx, 2));
+	struct i915_page_table *pt = i915_pt_entry(pd, gen8_pd_index(idx, 1));
  	gen8_pte_t *vaddr;
- vaddr = px_vaddr(i915_pt_entry(pd, gen8_pd_index(idx, 1)));
+	GEM_BUG_ON(pt->is_compact);

Do we have compact PT for smem with 64k pages?

It's technically possible but we don't bother trying to support it in the driver.


+
+	vaddr = px_vaddr(pt);
  	vaddr[gen8_pd_index(idx, 0)] = gen8_pte_encode(addr, level, flags);
  	clflush_cache_range(&vaddr[gen8_pd_index(idx, 0)], sizeof(*vaddr));
  }
+static void __xehpsdv_ppgtt_insert_entry_lm(struct i915_address_space *vm,
+					    dma_addr_t addr,
+					    u64 offset,
+					    enum i915_cache_level level,
+					    u32 flags)
+{
+	u64 idx = offset >> GEN8_PTE_SHIFT;
+	struct i915_page_directory * const pdp =
+		gen8_pdp_for_page_index(vm, idx);
+	struct i915_page_directory *pd =
+		i915_pd_entry(pdp, gen8_pd_index(idx, 2));
+	struct i915_page_table *pt = i915_pt_entry(pd, gen8_pd_index(idx, 1));
+	gen8_pte_t *vaddr;
+
+	GEM_BUG_ON(!IS_ALIGNED(addr, SZ_64K));
+	GEM_BUG_ON(!IS_ALIGNED(offset, SZ_64K));
+
+	if (!pt->is_compact) {
+		vaddr = px_vaddr(pd);
+		vaddr[gen8_pd_index(idx, 1)] |= GEN12_PDE_64K;
+		pt->is_compact = true;
+	}
+
+	vaddr = px_vaddr(pt);
+	vaddr[gen8_pd_index(idx, 0) / 16] = gen8_pte_encode(addr, level, flags);
+}
+
+static void xehpsdv_ppgtt_insert_entry(struct i915_address_space *vm,
+				       dma_addr_t addr,
+				       u64 offset,
+				       enum i915_cache_level level,
+				       u32 flags)
+{
+	if (flags & PTE_LM)
+		return __xehpsdv_ppgtt_insert_entry_lm(vm, addr, offset,
+						       level, flags);
+
+	return gen8_ppgtt_insert_entry(vm, addr, offset, level, flags);
Matt,

Is this call for gen8_*** is for insertion of smem PTE entries on the
64K capable platforms like DG2?

Yeah, this just falls back to the generic 512 entry layout for the PT.


Ram

+}
+
  static int gen8_init_scratch(struct i915_address_space *vm)
  {
  	u32 pte_flags;
@@ -937,7 +980,10 @@ struct i915_ppgtt *gen8_ppgtt_create(struct intel_gt *gt,
ppgtt->vm.bind_async_flags = I915_VMA_LOCAL_BIND;
  	ppgtt->vm.insert_entries = gen8_ppgtt_insert;
-	ppgtt->vm.insert_page = gen8_ppgtt_insert_entry;
+	if (HAS_64K_PAGES(gt->i915))
+		ppgtt->vm.insert_page = xehpsdv_ppgtt_insert_entry;
+	else
+		ppgtt->vm.insert_page = gen8_ppgtt_insert_entry;
  	ppgtt->vm.allocate_va_range = gen8_ppgtt_alloc;
  	ppgtt->vm.clear_range = gen8_ppgtt_clear;
  	ppgtt->vm.foreach = gen8_ppgtt_foreach;
--
2.31.1




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