[PATCH 3/3] drm/i915: Move ioremap_wc tracking onto VMA

[Chris Wilson <chris@chris-wilson.co.uk>]

By tracking the iomapping on the VMA itself, we can share that area
between multiple users. Also by only revoking the iomapping upon
unbinding from the mappable portion of the GGTT, we can keep that iomap
across multiple invocations (e.g. execlists context pinning).

Note that by moving the iounnmap tracking to the VMA, we actually end up
fixing a leak of the iomapping in intel_fbdev.

v1.5: Rebase prompted by Tvrtko
v2: Drop dev_priv parameter, we can recover the i915_ggtt from the vma.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c     |  2 ++
 drivers/gpu/drm/i915/i915_gem_gtt.c | 42 +++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/i915_gem_gtt.h | 13 ++++++++++++
 drivers/gpu/drm/i915/intel_fbdev.c  | 20 +++++++++---------
 4 files changed, 67 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index b37ffea8b458..6a485630595e 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3393,6 +3393,8 @@ static int __i915_vma_unbind(struct i915_vma *vma, bool wait)
 		ret = i915_gem_object_put_fence(obj);
 		if (ret)
 			return ret;
+
+		i915_vma_iounmap(vma);
 	}
 
 	trace_i915_vma_unbind(vma);
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index c5cb04907525..e759f8cafd9e 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -93,6 +93,12 @@
  *
  */
 
+static inline struct i915_ggtt *to_ggtt(struct i915_address_space *vm)
+{
+	BUG_ON(!i915_is_ggtt(vm));
+	return container_of(vm, struct i915_ggtt, base);
+}
+
 static int
 i915_get_ggtt_vma_pages(struct i915_vma *vma);
 
@@ -3626,3 +3632,39 @@ i915_ggtt_view_size(struct drm_i915_gem_object *obj,
 		return obj->base.size;
 	}
 }
+
+void *i915_vma_iomap(struct i915_vma *vma)
+{
+	if (WARN_ON(!vma->obj->map_and_fenceable))
+		return ERR_PTR(-ENODEV);
+
+	BUG_ON(!vma->is_ggtt);
+	BUG_ON((vma->bound & GLOBAL_BIND) == 0);
+
+	if (vma->iomap == NULL) {
+		struct i915_ggtt *ggtt = to_ggtt(vma->vm);
+		void *ptr;
+
+		ptr = io_mapping_map_wc(ggtt->mappable,
+					vma->node.start,
+					vma->node.size);
+		if (ptr == NULL) {
+			int ret;
+
+			/* Too many areas already allocated? */
+			ret = i915_gem_evict_vm(vma->vm, true);
+			if (ret)
+				return ERR_PTR(ret);
+
+			ptr = io_mapping_map_wc(ggtt->mappable,
+						vma->node.start,
+						vma->node.size);
+			if (ptr == NULL)
+				return ERR_PTR(-ENOMEM);
+		}
+
+		vma->iomap = ptr;
+	}
+
+	return vma->iomap;
+}
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
index d7dd3d8a8758..4b8ffc1c3d33 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -34,6 +34,8 @@
 #ifndef __I915_GEM_GTT_H__
 #define __I915_GEM_GTT_H__
 
+#include <linux/io-mapping.h>
+
 struct drm_i915_file_private;
 
 typedef uint32_t gen6_pte_t;
@@ -175,6 +177,7 @@ struct i915_vma {
 	struct drm_mm_node node;
 	struct drm_i915_gem_object *obj;
 	struct i915_address_space *vm;
+	void *iomap;
 
 	/** Flags and address space this VMA is bound to */
 #define GLOBAL_BIND	(1<<0)
@@ -559,4 +562,14 @@ size_t
 i915_ggtt_view_size(struct drm_i915_gem_object *obj,
 		    const struct i915_ggtt_view *view);
 
+void *i915_vma_iomap(struct i915_vma *vma);
+static inline void i915_vma_iounmap(struct i915_vma *vma)
+{
+	if (vma->iomap == NULL)
+		return;
+
+	io_mapping_unmap(vma->iomap);
+	vma->iomap = NULL;
+}
+
 #endif
diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
index 79ac202f3870..a01bfc33e3d7 100644
--- a/drivers/gpu/drm/i915/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/intel_fbdev.c
@@ -186,9 +186,10 @@ static int intelfb_create(struct drm_fb_helper *helper,
 	struct i915_ggtt *ggtt = &dev_priv->ggtt;
 	struct fb_info *info;
 	struct drm_framebuffer *fb;
+	struct i915_vma *vma;
 	struct drm_i915_gem_object *obj;
-	int size, ret;
 	bool prealloc = false;
+	int ret;
 
 	if (intel_fb &&
 	    (sizes->fb_width > intel_fb->base.width ||
@@ -214,7 +215,6 @@ static int intelfb_create(struct drm_fb_helper *helper,
 	}
 
 	obj = intel_fb->obj;
-	size = obj->base.size;
 
 	mutex_lock(&dev->struct_mutex);
 
@@ -244,22 +244,22 @@ static int intelfb_create(struct drm_fb_helper *helper,
 	info->flags = FBINFO_DEFAULT | FBINFO_CAN_FORCE_OUTPUT;
 	info->fbops = &intelfb_ops;
 
+	vma = i915_gem_obj_to_ggtt(obj);
+
 	/* setup aperture base/size for vesafb takeover */
 	info->apertures->ranges[0].base = dev->mode_config.fb_base;
 	info->apertures->ranges[0].size = ggtt->mappable_end;
 
-	info->fix.smem_start = dev->mode_config.fb_base + i915_gem_obj_ggtt_offset(obj);
-	info->fix.smem_len = size;
+	info->fix.smem_start = dev->mode_config.fb_base + vma->node.start;
+	info->fix.smem_len = vma->node.size;
 
-	info->screen_base =
-		ioremap_wc(ggtt->mappable_base + i915_gem_obj_ggtt_offset(obj),
-			   size);
-	if (!info->screen_base) {
+	info->screen_base = i915_vma_iomap(vma);
+	if (IS_ERR(info->screen_base)) {
 		DRM_ERROR("Failed to remap framebuffer into virtual memory\n");
-		ret = -ENOSPC;
+		ret = PTR_ERR(info->screen_base);
 		goto out_destroy_fbi;
 	}
-	info->screen_size = size;
+	info->screen_size = vma->node.size;
 
 	/* This driver doesn't need a VT switch to restore the mode on resume */
 	info->skip_vt_switch = true;
-- 
2.8.0.rc3

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