[Intel-gfx] [PATCH 07/66] drm/i915: Use drm_mm for PPGTT PDEs

[Ben Widawsky]

When PPGTT support was originally enabled, it was only designed to
support 1 PPGTT. It therefore made sense to simply hide the GGTT space
required to enable this from the drm_mm allocator.

Since we intend to support full PPGTT, which means more than 1, and they
can be created and destroyed ad hoc it will be required to use the
proper allocation techniques we already have.

The first step here is to make the existing single PPGTT use the allocator.

v2: Align PDEs to 64b in GTT
Allocate the node dynamically so we can use drm_mm_put_block
Now tested on IGT
Allocate node at the top to avoid fragmentation (Chris)

v3: Use Chris' top down allocator

v4: Embed drm_mm_node into ppgtt struct (Jesse)
Remove hunks which didn't belong (Jesse)

v5: Don't subtract guard page since we now killed the guard page prior
to this patch. (Ben)

Cc: Chris Wilson <chris at chris-wilson.co.uk>
Reviewed-by: Jesse Barnes <jbarnes at virtuousgeek.org>
Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
---
 drivers/gpu/drm/i915/i915_drv.h     |  1 +
 drivers/gpu/drm/i915/i915_gem_gtt.c | 45 ++++++++++++++++++++++++-------------
 2 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index c677d6c..659b4aa 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -484,6 +484,7 @@ struct i915_gtt {
 #define gtt_total_entries(gtt) ((gtt).total >> PAGE_SHIFT)
 
 struct i915_hw_ppgtt {
+	struct drm_mm_node node;
 	struct drm_device *dev;
 	unsigned num_pd_entries;
 	struct page **pt_pages;
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index fb30d65..5284dc5 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -247,6 +247,8 @@ static void gen6_ppgtt_cleanup(struct i915_hw_ppgtt *ppgtt)
 {
 	int i;
 
+	drm_mm_remove_node(&ppgtt->node);
+
 	if (ppgtt->pt_dma_addr) {
 		for (i = 0; i < ppgtt->num_pd_entries; i++)
 			pci_unmap_page(ppgtt->dev->pdev,
@@ -263,16 +265,27 @@ static void gen6_ppgtt_cleanup(struct i915_hw_ppgtt *ppgtt)
 
 static int gen6_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
 {
+#define GEN6_PD_ALIGN (PAGE_SIZE * 16)
+#define GEN6_PD_SIZE (GEN6_PPGTT_PD_ENTRIES * PAGE_SIZE)
 	struct drm_device *dev = ppgtt->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	unsigned first_pd_entry_in_global_pt;
 	int i;
 	int ret = -ENOMEM;
 
-	/* ppgtt PDEs reside in the global gtt pagetable, which has 512*1024
-	 * entries. For aliasing ppgtt support we just steal them at the end for
-	 * now. */
-	first_pd_entry_in_global_pt = gtt_total_entries(dev_priv->gtt);
+	/* PPGTT PDEs reside in the GGTT stolen space, and consists of 512
+	 * entries. The allocator works in address space sizes, so it's
+	 * multiplied by page size. We allocate at the top of the GTT to avoid
+	 * fragmentation.
+	 */
+	BUG_ON(!drm_mm_initialized(&dev_priv->mm.gtt_space));
+	ret = drm_mm_insert_node_in_range_generic(&dev_priv->mm.gtt_space,
+						  &ppgtt->node, GEN6_PD_SIZE,
+						  GEN6_PD_ALIGN, 0,
+						  dev_priv->gtt.mappable_end,
+						  dev_priv->gtt.total,
+						  DRM_MM_TOPDOWN);
+	if (ret)
+		return ret;
 
 	if (IS_HASWELL(dev)) {
 		ppgtt->pte_encode = hsw_pte_encode;
@@ -288,8 +301,10 @@ static int gen6_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
 	ppgtt->cleanup = gen6_ppgtt_cleanup;
 	ppgtt->pt_pages = kzalloc(sizeof(struct page *)*ppgtt->num_pd_entries,
 				  GFP_KERNEL);
-	if (!ppgtt->pt_pages)
+	if (!ppgtt->pt_pages) {
+		drm_mm_remove_node(&ppgtt->node);
 		return -ENOMEM;
+	}
 
 	for (i = 0; i < ppgtt->num_pd_entries; i++) {
 		ppgtt->pt_pages[i] = alloc_page(GFP_KERNEL);
@@ -319,7 +334,11 @@ static int gen6_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
 	ppgtt->clear_range(ppgtt, 0,
 			   ppgtt->num_pd_entries*I915_PPGTT_PT_ENTRIES);
 
-	ppgtt->pd_offset = first_pd_entry_in_global_pt * sizeof(gen6_gtt_pte_t);
+	DRM_DEBUG_DRIVER("Allocated pde space (%ldM) at GTT entry: %lx\n",
+			 ppgtt->node.size >> 20,
+			 ppgtt->node.start / PAGE_SIZE);
+	ppgtt->pd_offset =
+		ppgtt->node.start / PAGE_SIZE * sizeof(gen6_gtt_pte_t);
 
 	return 0;
 
@@ -336,6 +355,7 @@ err_pt_alloc:
 			__free_page(ppgtt->pt_pages[i]);
 	}
 	kfree(ppgtt->pt_pages);
+	drm_mm_remove_node(&ppgtt->node);
 
 	return ret;
 }
@@ -442,6 +462,9 @@ void i915_gem_restore_gtt_mappings(struct drm_device *dev)
 	dev_priv->gtt.gtt_clear_range(dev, dev_priv->gtt.start / PAGE_SIZE,
 				      dev_priv->gtt.total / PAGE_SIZE);
 
+	if (dev_priv->mm.aliasing_ppgtt)
+		gen6_write_pdes(dev_priv->mm.aliasing_ppgtt);
+
 	list_for_each_entry(obj, &dev_priv->mm.bound_list, global_list) {
 		i915_gem_clflush_object(obj);
 		i915_gem_gtt_bind_object(obj, obj->cache_level);
@@ -711,21 +734,13 @@ void i915_gem_init_global_gtt(struct drm_device *dev)
 	if (intel_enable_ppgtt(dev) && HAS_ALIASING_PPGTT(dev)) {
 		int ret;
 
-		if (INTEL_INFO(dev)->gen <= 7) {
-			/* PPGTT pdes are stolen from global gtt ptes, so shrink the
-			 * aperture accordingly when using aliasing ppgtt. */
-			gtt_size -= GEN6_PPGTT_PD_ENTRIES * PAGE_SIZE;
-		}
-
 		i915_gem_setup_global_gtt(dev, 0, mappable_size, gtt_size, 0);
-
 		ret = i915_gem_init_aliasing_ppgtt(dev);
 		if (!ret)
 			return;
 
 		DRM_ERROR("Aliased PPGTT setup failed %d\n", ret);
 		drm_mm_takedown(&dev_priv->mm.gtt_space);
-		gtt_size += GEN6_PPGTT_PD_ENTRIES * PAGE_SIZE;
 	}
 	i915_gem_setup_global_gtt(dev, 0, mappable_size, gtt_size, PAGE_SIZE);
 }
-- 
1.8.3.1