drm/i915/bdw: unleash PPGTT

v2: Squash in fix from Ben: Set PPGTT batches as necessary

This fixes the regression in the last couple of days when we enabled
PPGTT.

v3: Squash in fixup to still use GTT for secure batches from Ville:

BDW doesn't have a separate secure vs. non-secure bit in
MI_BATCH_BUFFER_START. So for secure batches we have to simply
leave the PPGTT bit unset. Fortunately older generations (except
HSW) had similar limitations so execbuffer already creates a GTT
mapping for all secure batches.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem_execbuffer.c

@@ -1146,8 +1146,7 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
 
 	/* snb/ivb/vlv conflate the "batch in ppgtt" bit with the "non-secure
 	 * batch" bit. Hence we need to pin secure batches into the global gtt.
-	 * hsw should have this fixed, but let's be paranoid and do it
-	 * unconditionally for now. */
+	 * hsw should have this fixed, but bdw mucks it up again. */
 	if (flags & I915_DISPATCH_SECURE && !batch_obj->has_global_gtt_mapping)
 		i915_gem_gtt_bind_object(batch_obj, batch_obj->cache_level);
 

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -439,7 +439,7 @@ static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt, uint64_t size)
 			 ppgtt->num_pt_pages,
 			 (ppgtt->num_pt_pages - num_pt_pages) +
 			 size % (1<<30));
-	return -ENOSYS; /* Not ready yet */
+	return 0;
 
 err_out:
 	ppgtt->base.cleanup(&ppgtt->base);

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -1699,6 +1699,9 @@ gen8_ring_dispatch_execbuffer(struct intel_ring_buffer *ring,
 			      u32 offset, u32 len,
 			      unsigned flags)
 {
+	struct drm_i915_private *dev_priv = ring->dev->dev_private;
+	bool ppgtt = dev_priv->mm.aliasing_ppgtt != NULL &&
+		!(flags & I915_DISPATCH_SECURE);
 	int ret;
 
 	ret = intel_ring_begin(ring, 4);
@@ -1706,7 +1709,7 @@ gen8_ring_dispatch_execbuffer(struct intel_ring_buffer *ring,
 		return ret;
 
 	/* FIXME(BDW): Address space and security selectors. */
-	intel_ring_emit(ring, MI_BATCH_BUFFER_START_GEN8);
+	intel_ring_emit(ring, MI_BATCH_BUFFER_START_GEN8 | (ppgtt<<8));
 	intel_ring_emit(ring, offset);
 	intel_ring_emit(ring, 0);
 	intel_ring_emit(ring, MI_NOOP);