[Intel-gfx] [PATCH 4/4] drm/i915: ILK + VT-d workaround

[Ben Widawsky]

Idle the GPU before doing any unmaps. We know if VT-d is in use through
an exported variable from iommu code.

This should avoid a known HW issue.

Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
---
 drivers/char/agp/intel-gtt.c        |   28 ++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/i915_drv.h     |    2 +-
 drivers/gpu/drm/i915/i915_gem.c     |    4 +++-
 drivers/gpu/drm/i915/i915_gem_gtt.c |   19 ++++++++++++++++++-
 include/drm/intel-gtt.h             |    2 ++
 5 files changed, 52 insertions(+), 3 deletions(-)

diff --git a/drivers/char/agp/intel-gtt.c b/drivers/char/agp/intel-gtt.c
index 8515101..80a7ed0 100644
--- a/drivers/char/agp/intel-gtt.c
+++ b/drivers/char/agp/intel-gtt.c
@@ -923,6 +923,9 @@ static int intel_fake_agp_insert_entries(struct agp_memory *mem,
 {
 	int ret = -EINVAL;
 
+	if (intel_private.base.do_idle_maps)
+		return -ENODEV;
+
 	if (intel_private.clear_fake_agp) {
 		int start = intel_private.base.stolen_size / PAGE_SIZE;
 		int end = intel_private.base.gtt_mappable_entries;
@@ -985,6 +988,9 @@ static int intel_fake_agp_remove_entries(struct agp_memory *mem,
 	if (mem->page_count == 0)
 		return 0;
 
+	if (intel_private.base.do_idle_maps)
+		return -ENODEV;
+
 	intel_gtt_clear_range(pg_start, mem->page_count);
 
 	if (intel_private.base.needs_dmar) {
@@ -1177,6 +1183,25 @@ static void gen6_cleanup(void)
 {
 }
 
+/* Certain Gen5 chipsets require require idling the GPU before
+ * unmapping anything from the GTT when VT-d is enabled.
+ */
+extern int intel_iommu_gfx_mapped;
+static inline int needs_idle_maps(void)
+{
+	const unsigned short gpu_devid = intel_private.pcidev->device;
+
+	/* Query intel_iommu to see if we need the workaround. Presumably that
+	 * was loaded first.
+	 */
+	if ((gpu_devid == PCI_DEVICE_ID_INTEL_IRONLAKE_M_HB ||
+	     gpu_devid == PCI_DEVICE_ID_INTEL_IRONLAKE_M_IG) &&
+	     intel_iommu_gfx_mapped)
+		return 1;
+
+	return 0;
+}
+
 static int i9xx_setup(void)
 {
 	u32 reg_addr;
@@ -1211,6 +1236,9 @@ static int i9xx_setup(void)
 		intel_private.gtt_bus_addr = reg_addr + gtt_offset;
 	}
 
+	if (needs_idle_maps());
+		intel_private.base.do_idle_maps = 1;
+
 	intel_i9xx_setup_flush();
 
 	return 0;
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 15c0ca5..3aa8612 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1219,7 +1219,7 @@ void i915_gem_restore_gtt_mappings(struct drm_device *dev);
 int __must_check i915_gem_gtt_bind_object(struct drm_i915_gem_object *obj);
 void i915_gem_gtt_rebind_object(struct drm_i915_gem_object *obj,
 				enum i915_cache_level cache_level);
-void i915_gem_gtt_unbind_object(struct drm_i915_gem_object *obj);
+int i915_gem_gtt_unbind_object(struct drm_i915_gem_object *obj);
 
 /* i915_gem_evict.c */
 int __must_check i915_gem_evict_something(struct drm_device *dev, int min_size,
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index a925141..89d22eb 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2130,7 +2130,9 @@ i915_gem_object_unbind(struct drm_i915_gem_object *obj)
 
 	trace_i915_gem_object_unbind(obj);
 
-	i915_gem_gtt_unbind_object(obj);
+	ret = i915_gem_gtt_unbind_object(obj);
+	if (ret == -ERESTARTSYS)
+		return ret;
 	i915_gem_object_put_pages_gtt(obj);
 
 	list_del_init(&obj->gtt_list);
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 7a709cd..1df6395 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -49,6 +49,15 @@ static unsigned int cache_level_to_agp_type(struct drm_device *dev,
 	}
 }
 
+static bool do_idling(struct drm_i915_private *dev_priv)
+{
+	if (dev_priv->mm.gtt->do_idle_maps)
+		if (i915_gpu_idle(dev_priv->dev))
+			return false;
+
+	return true;
+}
+
 void i915_gem_restore_gtt_mappings(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -115,8 +124,14 @@ void i915_gem_gtt_rebind_object(struct drm_i915_gem_object *obj,
 				       agp_type);
 }
 
-void i915_gem_gtt_unbind_object(struct drm_i915_gem_object *obj)
+int i915_gem_gtt_unbind_object(struct drm_i915_gem_object *obj)
 {
+	struct drm_device *dev = obj->base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	if (do_idling(dev_priv) == false)
+		return -ERESTARTSYS;
+
 	intel_gtt_clear_range(obj->gtt_space->start >> PAGE_SHIFT,
 			      obj->base.size >> PAGE_SHIFT);
 
@@ -124,4 +139,6 @@ void i915_gem_gtt_unbind_object(struct drm_i915_gem_object *obj)
 		intel_gtt_unmap_memory(obj->sg_list, obj->num_sg);
 		obj->sg_list = NULL;
 	}
+
+	return 0;
 }
diff --git a/include/drm/intel-gtt.h b/include/drm/intel-gtt.h
index 9e343c0..b174620 100644
--- a/include/drm/intel-gtt.h
+++ b/include/drm/intel-gtt.h
@@ -13,6 +13,8 @@ const struct intel_gtt {
 	unsigned int gtt_mappable_entries;
 	/* Whether i915 needs to use the dmar apis or not. */
 	unsigned int needs_dmar : 1;
+	/* Whether we idle the gpu before mapping/unmapping */
+	unsigned int do_idle_maps : 1;
 } *intel_gtt_get(void);
 
 void intel_gtt_chipset_flush(void);
-- 
1.7.7