[PATCH 3/3] reuse-ro-scratch
Chris Wilson
chris at chris-wilson.co.uk
Fri Oct 26 09:34:56 UTC 2018
---
drivers/gpu/drm/i915/i915_gem_gtt.c | 28 +++++++++++++++++++++-------
1 file changed, 21 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 2f92ecb47279..3e1574553234 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -580,14 +580,12 @@ setup_scratch_page(struct i915_address_space *vm, gfp_t gfp)
* region, including any PTEs which happen to point to scratch.
*
* This is only relevant for the 48b PPGTT where we support
- * huge-gtt-pages, see also i915_vma_insert().
- *
- * TODO: we should really consider write-protecting the scratch-page and
- * sharing between ppgtt
+ * huge-gtt-pages, see also i915_vma_insert(). However, as we share the
+ * scratch (read-only) between all vm, we create one 64k scratch page
+ * for all.
*/
size = I915_GTT_PAGE_SIZE_4K;
- if (i915_vm_is_48bit(vm) &&
- HAS_PAGE_SIZES(vm->i915, I915_GTT_PAGE_SIZE_64K)) {
+ if (HAS_PAGE_SIZES(vm->i915, I915_GTT_PAGE_SIZE_64K)) {
size = I915_GTT_PAGE_SIZE_64K;
gfp |= __GFP_NOWARN;
}
@@ -1209,11 +1207,24 @@ static int gen8_init_scratch(struct i915_address_space *vm)
{
int ret;
+ if (vm->has_read_only &&
+ vm->i915->kernel_context &&
+ vm->i915->kernel_context->ppgtt) {
+ struct i915_address_space *clone =
+ &vm->i915->kernel_context->ppgtt->vm;
+
+ vm->scratch_pte = clone->scratch_pte;
+ vm->scratch_pt = clone->scratch_pt;
+ vm->scratch_pd = clone->scratch_pd;
+ vm->scratch_pdp = clone->scratch_pdp;
+ return 0;
+ }
+
ret = setup_scratch_page(vm, __GFP_HIGHMEM);
if (ret)
return ret;
- vm->scratch_pte =
+ vm->scratch_pte =
gen8_pte_encode(vm->scratch_page.daddr,
I915_CACHE_LLC,
PTE_READ_ONLY);
@@ -1289,6 +1300,9 @@ static int gen8_ppgtt_notify_vgt(struct i915_hw_ppgtt *ppgtt, bool create)
static void gen8_free_scratch(struct i915_address_space *vm)
{
+ if (!vm->scratch_page.daddr)
+ return;
+
if (use_4lvl(vm))
free_pdp(vm, vm->scratch_pdp);
free_pd(vm, vm->scratch_pd);
--
2.19.1
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