[Intel-gfx] [PATCH 3/6] drm/i915: Reset scratch pages when using debug_flags

[Ben Widawsky]

Instead of waiting an indeterminate amount of time for ranges to get
cleared with the PTEs that will fault, do it immediately.

Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
---
 drivers/gpu/drm/i915/i915_debugfs.c |  7 +++++++
 drivers/gpu/drm/i915/i915_drv.h     |  4 +++-
 drivers/gpu/drm/i915/i915_gem_gtt.c | 20 ++++++++++++++++++++
 3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 5d6a020..86e750c 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2198,6 +2198,7 @@ i915_debug_flags_set(void *data, u64 val)
 {
 	struct drm_device *dev = data;
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	u64 old_flags = dev_priv->debug_flags;
 	int ret;
 
 	/* FIXME?: Nothing prevents this from working pre GEN6; but don't want
@@ -2209,7 +2210,13 @@ i915_debug_flags_set(void *data, u64 val)
 	ret = mutex_lock_interruptible(&dev->struct_mutex);
 	if (ret)
 		return ret;
+
 	dev_priv->debug_flags = val;
+
+	/* If setting or unsetting scratch faults, we need special handling */
+	if ((old_flags ^ val) & I915_SCRATCH_FAULTS)
+		i915_gem_rewrite_scratch_ptes(dev);
+
 	mutex_unlock(&dev_priv->dev->struct_mutex);
 	return 0;
 }
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 7a98f7e..b99087f8 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1865,7 +1865,9 @@ static inline void i915_gem_chipset_flush(struct drm_device *dev)
 	if (INTEL_INFO(dev)->gen < 6)
 		intel_gtt_chipset_flush();
 }
-
+#ifdef CONFIG_DEBUG_FS
+void i915_gem_rewrite_scratch_ptes(struct drm_device *dev);
+#endif
 
 /* 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_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 982c791..f71636e 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -889,3 +889,23 @@ int i915_gem_gtt_init(struct drm_device *dev)
 
 	return 0;
 }
+
+#ifdef CONFIG_DEBUG_FS
+void i915_gem_rewrite_scratch_ptes(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_mm_node *n;
+	unsigned long start, end;
+	struct i915_hw_ppgtt *ppgtt = dev_priv->mm.aliasing_ppgtt;
+
+	drm_mm_for_each_hole(n, &dev_priv->mm.gtt_space, start, end) {
+		dev_priv->gtt.gtt_clear_range(dev,
+					      start >> PAGE_SHIFT,
+					      (end - start) >> PAGE_SHIFT);
+		if (ppgtt)
+			ppgtt->clear_range(ppgtt,
+					   start >> PAGE_SHIFT,
+					   (end - start) >> PAGE_SHIFT);
+	}
+}
+#endif
-- 
1.8.3.1