[PATCH v2 12/18] drm/i915/gen8: Initialize PDPs

Michel Thierry
2015-06-10T16:46:57Z

Similar to PDs, while setting up a page directory pointer, make all entries
of the pdp point to the scratch pdp before mapping (and make all its entries
point to the scratch page); this is to be safe in case of out of bound
access or proactive prefetch.

Although the ggtt is always 32-bit, the scratch_pdp will be initialized/destroyed
at the same time as the other scratch pages, to keep it consistent.

v2: Handle scratch_pdp allocation failure correctly, and keep
initialize_px functions together (Akash)
v3: Rebase after Mika's ppgtt cleanup / scratch merge patch series. Rely on
the added macros to initialize the pdps.

Suggested-by: Akash Goel <akash.goel@intel.com>
Signed-off-by: Michel Thierry <michel.thierry@intel.com>
---
drivers/gpu/drm/i915/i915_gem_gtt.c | 53 ++++++++++++++++++++++++++++++++++---
drivers/gpu/drm/i915/i915_gem_gtt.h | 1 +
2 files changed, 51 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 9919c3b..65d0787 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -593,6 +593,27 @@ static void free_pdp(struct drm_device *dev,
}
}

+static void gen8_initialize_pdp(struct i915_address_space *vm,
+ struct i915_page_directory_pointer *pdp)
+{
+ gen8_ppgtt_pdpe_t scratch_pdpe;
+
+ scratch_pdpe = gen8_pdpe_encode(px_dma(vm->scratch_pd), I915_CACHE_LLC);
+
+ fill_px(vm->dev, pdp, scratch_pdpe);
+}
+
+static void gen8_initialize_pml4(struct i915_address_space *vm,
+ struct i915_pml4 *pml4)
+{
+ gen8_ppgtt_pml4e_t scratch_pml4e;
+
+ scratch_pml4e = gen8_pml4e_encode(px_dma(vm->scratch_pdp),
+ I915_CACHE_LLC);
+
+ fill_px(vm->dev, pml4, scratch_pml4e);
+}
+
static void
gen8_setup_page_directory(struct i915_hw_ppgtt *ppgtt,
struct i915_page_directory_pointer *pdp,
@@ -693,12 +714,30 @@ static int setup_scratch_ggtt(struct i915_address_space *vm)

WARN_ON(px_dma(vm->scratch_pt) == 0);
gen8_initialize_pd(vm, vm->scratch_pd);
+
+ /* although scratch_pdp is only needed for 48-bit ppgtt,
+ * keep it with the other scratch pages for consistency.
+ */
+ if (USES_FULL_48BIT_PPGTT(dev)) {
+ WARN_ON(vm->scratch_pdp);
+
+ vm->scratch_pdp = alloc_pdp(vm->dev);
+ if (IS_ERR(vm->scratch_pdp)) {
+ ret = PTR_ERR(vm->scratch_pdp);
+ goto err_pdp;
+ }
+
+ WARN_ON(px_dma(vm->scratch_pd) == 0);
+ gen8_initialize_pdp(vm, vm->scratch_pdp);
+ }
} else {
gen6_initialize_pt(vm, vm->scratch_pt);
}

return 0;

+err_pdp:
+ free_pd(vm->dev, vm->scratch_pd);
err_pd:
free_pt(vm->dev, vm->scratch_pt);
return ret;
@@ -714,6 +753,7 @@ static int setup_scratch(struct i915_address_space *vm)
vm->scratch_page = ggtt_vm->scratch_page;
vm->scratch_pt = ggtt_vm->scratch_pt;
vm->scratch_pd = ggtt_vm->scratch_pd;
+ vm->scratch_pdp = ggtt_vm->scratch_pdp;

return 0;
}
@@ -748,8 +788,12 @@ static void cleanup_scratch_ggtt(struct i915_address_space *vm)

free_pt(vm->dev, vm->scratch_pt);

- if (INTEL_INFO(vm->dev)->gen >= 8)
+ if (INTEL_INFO(vm->dev)->gen >= 8) {
free_pd(vm->dev, vm->scratch_pd);
+
+ if (USES_FULL_48BIT_PPGTT(dev))
+ free_pdp(vm->dev, vm->scratch_pdp);
+ }
}

static void cleanup_scratch(struct i915_address_space *vm)
@@ -760,6 +804,7 @@ static void cleanup_scratch(struct i915_address_space *vm)
vm->scratch_page = NULL;
vm->scratch_pt = NULL;
vm->scratch_pd = NULL;
+ vm->scratch_pdp = NULL;
}

/* Broadwell Page Directory Pointer Descriptors */
@@ -1316,12 +1361,12 @@ static int gen8_alloc_va_range_4lvl(struct i915_address_space *vm,
* and 4 level code. Just allocate the pdps.
*/
gen8_for_each_pml4e(pdp, pml4, start, length, temp, pml4e) {
- if (!pdp) {
- WARN_ON(test_bit(pml4e, pml4->used_pml4es));
+ if (!test_bit(pml4e, pml4->used_pml4es)) {
pdp = alloc_pdp(vm->dev);
if (IS_ERR(pdp))
goto err_out;

+ gen8_initialize_pdp(vm, pdp);
pml4->pdps[pml4e] = pdp;
__set_bit(pml4e, new_pdps);
trace_i915_page_directory_pointer_entry_alloc(&ppgtt->base, pml4e,
@@ -1446,6 +1491,8 @@ static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
if (ret)
goto clear_scratch;

+ gen8_initialize_pml4(&ppgtt->base, &ppgtt->pml4);
+
ppgtt->base.total = 1ULL << 48;
ppgtt->switch_mm = gen8_48b_mm_switch;
} else {
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
index 1803e91..c0a6487 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -272,6 +272,7 @@ struct i915_address_space {
struct i915_page_scratch *scratch_page;
struct i915_page_table *scratch_pt;
struct i915_page_directory *scratch_pd;
+ struct i915_page_directory_pointer *scratch_pdp; /* GEN8+ & 48b PPGTT */

/**
* List of objects currently involved in rendering.
--
2.4.0