[RFC PATCH 6/7] drm/ttm: Introduce a huge page aligning TTM range manager.

["Thomas Hellström (VMware)" <thomas_os@shipmail.org>]

From: Thomas Hellstrom <thellstrom@vmware.com>

Using huge page-table entries require that the start of a buffer object
is huge page size aligned. So introduce a ttm_bo_man_get_node_huge()
function that attempts to accomplish this for allocations that are larger
than the huge page size, and provide a new range-manager instance that
uses that function.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: "Christian König" <christian.koenig@amd.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
---
 drivers/gpu/drm/ttm/ttm_bo_manager.c | 92 ++++++++++++++++++++++++++++
 include/drm/ttm/ttm_bo_driver.h      |  1 +
 2 files changed, 93 insertions(+)

diff --git a/drivers/gpu/drm/ttm/ttm_bo_manager.c b/drivers/gpu/drm/ttm/ttm_bo_manager.c
index 18d3debcc949..26aa1a2ae7f1 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_manager.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_manager.c
@@ -89,6 +89,89 @@ static int ttm_bo_man_get_node(struct ttm_mem_type_manager *man,
 	return 0;
 }
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static int ttm_bo_insert_aligned(struct drm_mm *mm, struct drm_mm_node *node,
+				 unsigned long align_pages,
+				 const struct ttm_place *place,
+				 struct ttm_mem_reg *mem,
+				 unsigned long lpfn,
+				 enum drm_mm_insert_mode mode)
+{
+	if (align_pages >= mem->page_alignment &&
+	    (!mem->page_alignment || align_pages % mem->page_alignment == 0)) {
+		return drm_mm_insert_node_in_range(mm, node,
+						   mem->num_pages,
+						   align_pages, 0,
+						   place->fpfn, lpfn, mode);
+	}
+
+	return -ENOSPC;
+}
+
+static int ttm_bo_man_get_node_huge(struct ttm_mem_type_manager *man,
+				    struct ttm_buffer_object *bo,
+				    const struct ttm_place *place,
+				    struct ttm_mem_reg *mem)
+{
+	struct ttm_range_manager *rman = (struct ttm_range_manager *) man->priv;
+	struct drm_mm *mm = &rman->mm;
+	struct drm_mm_node *node;
+	unsigned long align_pages;
+	unsigned long lpfn;
+	enum drm_mm_insert_mode mode = DRM_MM_INSERT_BEST;
+	int ret;
+
+	node = kzalloc(sizeof(*node), GFP_KERNEL);
+	if (!node)
+		return -ENOMEM;
+
+	lpfn = place->lpfn;
+	if (!lpfn)
+		lpfn = man->size;
+
+	mode = DRM_MM_INSERT_BEST;
+	if (place->flags & TTM_PL_FLAG_TOPDOWN)
+		mode = DRM_MM_INSERT_HIGH;
+
+	spin_lock(&rman->lock);
+	if (IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)) {
+		align_pages = (HPAGE_PUD_SIZE >> PAGE_SHIFT);
+		if (mem->num_pages >= align_pages) {
+			ret = ttm_bo_insert_aligned(mm, node, align_pages,
+						    place, mem, lpfn, mode);
+			if (!ret)
+				goto found_unlock;
+		}
+	}
+
+	align_pages = (HPAGE_PMD_SIZE >> PAGE_SHIFT);
+	if (mem->num_pages >= align_pages) {
+		ret = ttm_bo_insert_aligned(mm, node, align_pages, place, mem,
+					    lpfn, mode);
+		if (!ret)
+			goto found_unlock;
+	}
+
+	ret = drm_mm_insert_node_in_range(mm, node, mem->num_pages,
+					  mem->page_alignment, 0,
+					  place->fpfn, lpfn, mode);
+found_unlock:
+	spin_unlock(&rman->lock);
+
+	if (unlikely(ret)) {
+		kfree(node);
+	} else {
+		mem->mm_node = node;
+		mem->start = node->start;
+	}
+
+	return 0;
+}
+#else
+#define ttm_bo_man_get_node_huge ttm_bo_man_get_node
+#endif
+
+
 static void ttm_bo_man_put_node(struct ttm_mem_type_manager *man,
 				struct ttm_mem_reg *mem)
 {
@@ -154,3 +237,12 @@ const struct ttm_mem_type_manager_func ttm_bo_manager_func = {
 	.debug = ttm_bo_man_debug
 };
 EXPORT_SYMBOL(ttm_bo_manager_func);
+
+const struct ttm_mem_type_manager_func ttm_bo_manager_huge_func = {
+	.init = ttm_bo_man_init,
+	.takedown = ttm_bo_man_takedown,
+	.get_node = ttm_bo_man_get_node_huge,
+	.put_node = ttm_bo_man_put_node,
+	.debug = ttm_bo_man_debug
+};
+EXPORT_SYMBOL(ttm_bo_manager_huge_func);
diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index cac7a8a0825a..868bd0d4be6a 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -888,5 +888,6 @@ int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo);
 pgprot_t ttm_io_prot(uint32_t caching_flags, pgprot_t tmp);
 
 extern const struct ttm_mem_type_manager_func ttm_bo_manager_func;
+extern const struct ttm_mem_type_manager_func ttm_bo_manager_huge_func;
 
 #endif
-- 
2.21.0