[PATCH 2/2] drm/i915/gtt: Avoid using addresses in non-canonical form.

Michał Winiarski
2015-09-15T13:30:29Z

According to bspec, some parts of HW expect the addresses to be in
a canonical form where bits [63:48] == [47]. Lets satisfy the HW by
converting the address prior to allocating/clearing the entries in page
tables.

Cc: Michel Thierry <michel.thierry@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
---
drivers/gpu/drm/i915/i915_gem_gtt.c | 13 +++++++------
drivers/gpu/drm/i915/i915_gem_gtt.h | 5 +++++
2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 7ff7239..f25a33f 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -766,6 +766,7 @@ static void gen8_ppgtt_clear_range(struct i915_address_space *vm,
} else {
uint64_t templ4, pml4e;
struct i915_page_directory_pointer *pdp;
+ start = gen8_canonical_addr(start);

gen8_for_each_pml4e(pdp, &ppgtt->pml4, start, length, templ4, pml4e) {
gen8_ppgtt_clear_pte_range(vm, pdp, start, length,
@@ -1227,15 +1228,10 @@ static int gen8_alloc_va_range_3lvl(struct i915_address_space *vm,
uint32_t pdpes = I915_PDPES_PER_PDP(dev);
int ret;

- /* Wrap is never okay since we can only represent 48b, and we don't
- * actually use the other side of the canonical address space.
- */
+ /* Wrap is never okay */
if (WARN_ON(start + length < start))
return -ENODEV;

- if (WARN_ON(start + length > vm->total))
- return -ENODEV;
-
ret = alloc_gen8_temp_bitmaps(&new_page_dirs, &new_page_tables, pdpes);
if (ret)
return ret;
@@ -1333,6 +1329,8 @@ static int gen8_alloc_va_range_4lvl(struct i915_address_space *vm,
uint64_t temp, pml4e;
int ret = 0;

+ start = gen8_canonical_addr(start);
+
/* Do the pml4 allocations first, so we don't need to track the newly
* allocated tables below the pdp */
bitmap_zero(new_pdps, GEN8_PML4ES_PER_PML4);
@@ -1377,6 +1375,9 @@ static int gen8_alloc_va_range(struct i915_address_space *vm,
struct i915_hw_ppgtt *ppgtt =
container_of(vm, struct i915_hw_ppgtt, base);

+ if (WARN_ON(start + length > vm->total))
+ return -ENODEV;
+
if (USES_FULL_48BIT_PPGTT(vm->dev))
return gen8_alloc_va_range_4lvl(vm, &ppgtt->pml4, start, length);
else
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
index 8275007..9397387 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -503,6 +503,11 @@ static inline size_t gen8_pte_count(uint64_t address, uint64_t length)
return i915_pte_count(address, length, GEN8_PDE_SHIFT);
}

+static inline uint64_t gen8_canonical_addr(uint64_t address)
+{
+ return ((int64_t)address << 16) >> 16;
+}
+
static inline dma_addr_t
i915_page_dir_dma_addr(const struct i915_hw_ppgtt *ppgtt, const unsigned n)
{
--
2.4.3