1 files changed, 24 insertions, 21 deletions

diff --git a/drivers/gpu/drm/i915/gem/i915_gemfs.c b/drivers/gpu/drm/i915/gem/i915_gemfs.c
index 099f3397aada..ee87874e59dc 100644
--- a/drivers/gpu/drm/i915/gem/i915_gemfs.c
+++ b/drivers/gpu/drm/i915/gem/i915_gemfs.c
@@ -6,46 +6,49 @@
 
 #include <linux/fs.h>
 #include <linux/mount.h>
-#include <linux/pagemap.h>
 
 #include "i915_drv.h"
 #include "i915_gemfs.h"
+#include "i915_utils.h"
 
 int i915_gemfs_init(struct drm_i915_private *i915)
 {
+	char huge_opt[] = "huge=within_size"; /* r/w */
 	struct file_system_type *type;
 	struct vfsmount *gemfs;
+	char *opts;
 
 	type = get_fs_type("tmpfs");
 	if (!type)
 		return -ENODEV;
 
-	gemfs = kern_mount(type);
-	if (IS_ERR(gemfs))
-		return PTR_ERR(gemfs);
-
 	/*
-	 * Enable huge-pages for objects that are at least HPAGE_PMD_SIZE, most
-	 * likely 2M. Note that within_size may overallocate huge-pages, if say
-	 * we allocate an object of size 2M + 4K, we may get 2M + 2M, but under
-	 * memory pressure shmem should split any huge-pages which can be
-	 * shrunk.
+	 * By creating our own shmemfs mountpoint, we can pass in
+	 * mount flags that better match our usecase.
+	 *
+	 * One example, although it is probably better with a per-file
+	 * control, is selecting huge page allocations ("huge=within_size").
+	 * However, we only do so to offset the overhead of iommu lookups
+	 * due to bandwidth issues (slow reads) on Broadwell+.
 	 */
 
-	if (has_transparent_hugepage()) {
-		struct super_block *sb = gemfs->mnt_sb;
-		/* FIXME: Disabled until we get W/A for read BW issue. */
-		char options[] = "huge=never";
-		int flags = 0;
-		int err;
-
-		err = sb->s_op->remount_fs(sb, &flags, options);
-		if (err) {
-			kern_unmount(gemfs);
-			return err;
+	opts = NULL;
+	if (i915_vtd_active(i915)) {
+		if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
+			opts = huge_opt;
+			drm_info(&i915->drm,
+				 "Transparent Hugepage mode '%s'\n",
+				 opts);
+		} else {
+			drm_notice(&i915->drm,
+				   "Transparent Hugepage support is recommended for optimal performance when IOMMU is enabled!\n");
 		}
 	}
 
+	gemfs = vfs_kern_mount(type, SB_KERNMOUNT, type->name, opts);
+	if (IS_ERR(gemfs))
+		return PTR_ERR(gemfs);
+
 	i915->mm.gemfs = gemfs;
 
 	return 0;