[Intel-gfx] [PATCH v3] drm/i915: Wa32bitGeneralStateOffset & Wa32bitInstructionBaseOffset

[Chris Wilson]

On Tue, Jun 23, 2015 at 01:21:05PM +0100, Michel Thierry wrote:
> 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 Intructions 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_48BADDRESS flag to indicate if
> they can be allocated above the 32-bit address range.
> 
> v2: Changed flag logic from neeeds_32b, to supports_48b.
> v3: Moved 48-bit support flag back to exec_object. (Chris, Daniel)
> 
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Daniel Vetter <daniel at ffwll.ch>
> Signed-off-by: Michel Thierry <michel.thierry at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h            |  1 +
>  drivers/gpu/drm/i915/i915_gem.c            | 19 +++++++++++++++++--
>  drivers/gpu/drm/i915/i915_gem_execbuffer.c |  7 +++++++
>  include/uapi/drm/i915_drm.h                |  3 ++-
>  4 files changed, 27 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index a6bc27a..57af235 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2739,6 +2739,7 @@ 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_FULL_RANGE	(1<<6)
>  #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 f4ddf6e..db22559 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -3669,6 +3669,8 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	u32 fence_alignment, unfenced_alignment;
>  	u64 size, fence_size;
> +	u32 search_flag = DRM_MM_SEARCH_DEFAULT;
> +	u32 alloc_flag = DRM_MM_CREATE_DEFAULT;
>  	u64 start =
>  		flags & PIN_OFFSET_BIAS ? flags & PIN_OFFSET_MASK : 0;
>  	u64 end =
> @@ -3710,6 +3712,19 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
>  						   obj->tiling_mode,
>  						   false);
>  		size = flags & PIN_MAPPABLE ? fence_size : obj->base.size;
> +
> +		/* Wa32bitGeneralStateOffset & Wa32bitInstructionBaseOffset,
> +		 * limit address to 4GB-1 for objects requiring this wa; for
> +		 * others, set alloc flag to TOP.
> +		 */
> +		if (USES_FULL_48BIT_PPGTT(dev)) {
> +			if (flags & PIN_FULL_RANGE) {

I wanted this as a separate PIN_FLAG. (a) it is generally useful (for
example, I think anything that has PIN_GLOBAL but not PIN_MAPPABLE is a
candidate for this flag), but (b) there are bugs in the drm_mm
implementation for searching below...

> +				search_flag = DRM_MM_SEARCH_BELOW;
> +				alloc_flag = DRM_MM_CREATE_TOP;
> +			} else {

This would be better internally as a PIN_ZONE_4G flag. 

> +				end = ((4ULL << GEN8_PDPE_SHIFT) - 1);

end should not be -1 here (or if that is actually required by the
hardware -4096).
> +			}
> +		}
>  	}
>  
>  	if (alignment == 0)
> @@ -3752,8 +3767,8 @@ search_free:
>  						  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 3336e1c..ec8c72d 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -588,6 +588,9 @@ i915_gem_execbuffer_reserve_vma(struct i915_vma *vma,
>  	if (entry->flags & EXEC_OBJECT_NEEDS_GTT)
>  		flags |= PIN_GLOBAL;
>  
> +	if (entry->flags & EXEC_OBJECT_SUPPORTS_48BBADDRESS)
> +		flags |= PIN_FULL_RANGE;

flags |= PIN_ZONE_4G;
if (entry->flags & EXEC_OBJECT_SUPPORTS_48BBADDRESS)
	flags &= ~PIN_ZONE_4G;

>  	if (!drm_mm_node_allocated(&vma->node)) {
>  		if (entry->flags & __EXEC_OBJECT_NEEDS_MAP)
>  			flags |= PIN_GLOBAL | PIN_MAPPABLE;

if ((flags & PIN_MAPPABLE) == 0)
	flags |= PIN_HIGH;

> @@ -670,6 +673,10 @@ 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_48BBADDRESS) &&
> +	    vma->node.start >= (1ULL << 32))

vma->node.start + vma->node.size > 1<<32
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre