Patch "drm/i915: Guard against i915_ggtt_disable_guc() being invoked unconditionally" has been added to the 4.11-stable tree

This is a note to let you know that I've just added the patch titled

drm/i915: Guard against i915_ggtt_disable_guc() being invoked unconditionally

to the 4.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-i915-guard-against-i915_ggtt_disable_guc-being-invoked-unconditionally.patch
and it can be found in the queue-4.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Chris Wilson <[email protected]>
Date: Wed, 31 May 2017 20:05:14 +0100
Subject: drm/i915: Guard against i915_ggtt_disable_guc() being invoked unconditionally
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From: Chris Wilson <[email protected]>

commit d90c98905afd00c15d5d255d845b646a37173ce9 upstream.

Commit 7c3f86b6dc51 ("drm/i915: Invalidate the guc ggtt TLB upon insertion") added the restoration of the invalidation routine after the GuC was disabled, but missed that the GuC was unconditionally disabled when not used. This then overwrites the invalidate routine for the older chipsets, causing havoc and breaking resume as the most obvious victim.

We place the guard inside i915_ggtt_disable_guc() to be backport friendly (the bug was introduced into v4.11) but it would be preferred to be in more control over when this was guard (i.e. do not try and teardown the data structures before we have enabled them). That should be true with the reorganisation of the guc loaders.

---
 drivers/gpu/drm/i915/i915_gem_gtt.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

@@ -3282,7 +3282,8 @@ void i915_ggtt_enable_guc(struct drm_i91
 
 void i915_ggtt_disable_guc(struct drm_i915_private *i915)
 {
-	i915->ggtt.invalidate = gen6_ggtt_invalidate;
+	if (i915->ggtt.invalidate == guc_ggtt_invalidate)
+		i915->ggtt.invalidate = gen6_ggtt_invalidate;
 }
 
 void i915_gem_restore_gtt_mappings(struct drm_i915_private *dev_priv)

Patches currently in stable-queue which might be from [email protected] are

queue-4.11/drm-i915-do-not-drop-pagetables-when-empty.patch queue-4.11/revert-drm-i915-restore-lost-initialized-i915-welcome-message.patch queue-4.11/drm-i915-guard-against-i915_ggtt_disable_guc-being-invoked-unconditionally.patch queue-4.11/drm-i915-prevent-the-system-suspend-complete-optimization.patch