[PATCH v2 (not really v2)] drm/i915: Wa32bitGeneralStateOffset & Wa32bitInstructionBaseOffset

Michel Thierry
2015-10-01T12:34:05Z

There are some allocations that must be only referenced by 32-bit
offsets. To limit the chances of having the first 4GB already full,
objects not requiring this workaround use DRM_MM_SEARCH_BELOW/
DRM_MM_CREATE_TOP flags

In specific, any resource used with flat/heapless (0x00000000-0xfffff000)
General State Heap (GSH) or Instruction State Heap (ISH) must be in a
32-bit range, because the General State Offset and Instruction State
Offset are limited to 32-bits.

Objects must have EXEC_OBJECT_SUPPORTS_48B_ADDRESS flag to indicate if
they can be allocated above the 32-bit address range. To limit the
chances of having the first 4GB already full, objects will use
DRM_MM_SEARCH_BELOW + DRM_MM_CREATE_TOP flags when possible.

The libdrm user of the EXEC_OBJECT_SUPPORTS_48B_ADDRESS flag is here:
http://lists.freedesktop.org/archives/intel-gfx/2015-September/075836.html

v2: Changed flag logic from neeeds_32b, to supports_48b.
v3: Moved 48-bit support flag back to exec_object. (Chris, Daniel)
v4: Split pin flags into PIN_ZONE_4G and PIN_HIGH; update PIN_OFFSET_MASK
to use last PIN_ defined instead of hard-coded value; use correct limit
check in eb_vma_misplaced. (Chris)
v5: Don't touch PIN_OFFSET_MASK and update workaround comment (Chris)
v6: Apply pin-high for ggtt too (Chris)
v7: Handle simultaneous pin-high and pin-mappable end correctly (Akash)
Fix check for entries currently using +4GB addresses, use min_t and
other polish in object_bind_to_vm (Chris)
v8: Commit message updated to point to libdrm patch.
v9: vmas are allocated in the correct ozone, so only check flag when the
vma has not been allocated. (Chris)

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> (v4)
Signed-off-by: Michel Thierry <michel.thierry@intel.com>
---
drivers/gpu/drm/i915/i915_drv.h | 2 ++
drivers/gpu/drm/i915/i915_gem.c | 25 +++++++++++++++++++------
drivers/gpu/drm/i915/i915_gem_execbuffer.c | 11 +++++++++++
include/uapi/drm/i915_drm.h | 3 ++-
4 files changed, 34 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 04d710f..ecc56fa 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2826,6 +2826,8 @@ void i915_gem_vma_destroy(struct i915_vma *vma);
#define PIN_OFFSET_BIAS (1<<3)
#define PIN_USER (1<<4)
#define PIN_UPDATE (1<<5)
+#define PIN_ZONE_4G (1<<6)
+#define PIN_HIGH (1<<7)
#define PIN_OFFSET_MASK (~4095)
int __must_check
i915_gem_object_pin(struct drm_i915_gem_object *obj,
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index bf5ef7a..f0cfbb9 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3354,11 +3354,9 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
struct drm_device *dev = obj->base.dev;
struct drm_i915_private *dev_priv = dev->dev_private;
u32 fence_alignment, unfenced_alignment;
+ u32 search_flag, alloc_flag;
+ u64 start, end;
u64 size, fence_size;
- u64 start =
- flags & PIN_OFFSET_BIAS ? flags & PIN_OFFSET_MASK : 0;
- u64 end =
- flags & PIN_MAPPABLE ? dev_priv->gtt.mappable_end : vm->total;
struct i915_vma *vma;
int ret;

@@ -3398,6 +3396,13 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
size = flags & PIN_MAPPABLE ? fence_size : obj->base.size;
}

+ start = flags & PIN_OFFSET_BIAS ? flags & PIN_OFFSET_MASK : 0;
+ end = vm->total;
+ if (flags & PIN_MAPPABLE)
+ end = min_t(u64, end, dev_priv->gtt.mappable_end);
+ if (flags & PIN_ZONE_4G)
+ end = min_t(u64, end, (1ULL << 32));
+
if (alignment == 0)
alignment = flags & PIN_MAPPABLE ? fence_alignment :
unfenced_alignment;
@@ -3433,13 +3438,21 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
if (IS_ERR(vma))
goto err_unpin;

+ if (flags & PIN_HIGH) {
+ search_flag = DRM_MM_SEARCH_BELOW;
+ alloc_flag = DRM_MM_CREATE_TOP;
+ } else {
+ search_flag = DRM_MM_SEARCH_DEFAULT;
+ alloc_flag = DRM_MM_CREATE_DEFAULT;
+ }
+
search_free:
ret = drm_mm_insert_node_in_range_generic(&vm->mm, &vma->node,
size, alignment,
obj->cache_level,
start, end,
- DRM_MM_SEARCH_DEFAULT,
- DRM_MM_CREATE_DEFAULT);
+ search_flag,
+ alloc_flag);
if (ret) {
ret = i915_gem_evict_something(dev, vm, size, alignment,
obj->cache_level,
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 67ef118..edc17be 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -590,10 +590,17 @@ i915_gem_execbuffer_reserve_vma(struct i915_vma *vma,
flags |= PIN_GLOBAL;

if (!drm_mm_node_allocated(&vma->node)) {
+ /* Wa32bitGeneralStateOffset & Wa32bitInstructionBaseOffset,
+ * limit address to the first 4GBs for unflagged objects.
+ */
+ if ((entry->flags & EXEC_OBJECT_SUPPORTS_48B_ADDRESS) == 0)
+ flags |= PIN_ZONE_4G;
if (entry->flags & __EXEC_OBJECT_NEEDS_MAP)
flags |= PIN_GLOBAL | PIN_MAPPABLE;
if (entry->flags & __EXEC_OBJECT_NEEDS_BIAS)
flags |= BATCH_OFFSET_BIAS | PIN_OFFSET_BIAS;
+ if ((flags & PIN_MAPPABLE) == 0)
+ flags |= PIN_HIGH;
}

ret = i915_gem_object_pin(obj, vma->vm, entry->alignment, flags);
@@ -671,6 +678,10 @@ eb_vma_misplaced(struct i915_vma *vma)
if (entry->flags & __EXEC_OBJECT_NEEDS_MAP && !obj->map_and_fenceable)
return !only_mappable_for_reloc(entry->flags);

+ if ((entry->flags & EXEC_OBJECT_SUPPORTS_48B_ADDRESS) == 0 &&
+ (vma->node.start + vma->node.size - 1) >> 32)
+ return true;
+
return false;
}

diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index fd5aa47..484a9fb 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -690,7 +690,8 @@ struct drm_i915_gem_exec_object2 {
#define EXEC_OBJECT_NEEDS_FENCE (1<<0)
#define EXEC_OBJECT_NEEDS_GTT (1<<1)
#define EXEC_OBJECT_WRITE (1<<2)
-#define __EXEC_OBJECT_UNKNOWN_FLAGS -(EXEC_OBJECT_WRITE<<1)
+#define EXEC_OBJECT_SUPPORTS_48B_ADDRESS (1<<3)
+#define __EXEC_OBJECT_UNKNOWN_FLAGS -(EXEC_OBJECT_SUPPORTS_48B_ADDRESS<<1)
__u64 flags;

__u64 rsvd1;
--
2.6.0