From bdae33b8b82bb379a5b11040b0b37df25c7871c9 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Thu, 18 Jul 2019 15:54:05 +0100
Subject: drm/i915: Use maximum write flush for pwrite_gtt
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Git-commit: bdae33b8b82bb379a5b11040b0b37df25c7871c9
Patch-mainline: v5.4-rc1
References: bsc#1152489

As recently disovered by forcing big-core (!llc) machines to use the GTT
paths, we need our full GTT write flush before manipulating the GTT PTE
or else the writes may be directed to the wrong page.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Matthew Auld <matthew.william.auld@gmail.com>
Cc: Ville Syrj채l채 <ville.syrjala@linux.intel.com>
Cc: stable@vger.kernel.org
Reviewed-by: Ville Syrj채l채 <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190718145407.21352-2-chris@chris-wilson.co.uk
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/i915/i915_gem.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index fed0bc421a55..c6ba350e6e4f 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -610,7 +610,8 @@ i915_gem_gtt_pwrite_fast(struct drm_i915_gem_object *obj,
 		unsigned int page_length = PAGE_SIZE - page_offset;
 		page_length = remain < page_length ? remain : page_length;
 		if (node.allocated) {
-			wmb(); /* flush the write before we modify the GGTT */
+			/* flush the write before we modify the GGTT */
+			intel_gt_flush_ggtt_writes(ggtt->vm.gt);
 			ggtt->vm.insert_page(&ggtt->vm,
 					     i915_gem_object_get_dma_address(obj, offset >> PAGE_SHIFT),
 					     node.start, I915_CACHE_NONE, 0);
@@ -639,8 +640,8 @@ i915_gem_gtt_pwrite_fast(struct drm_i915_gem_object *obj,
 	i915_gem_object_unlock_fence(obj, fence);
 out_unpin:
 	mutex_lock(&i915->drm.struct_mutex);
+	intel_gt_flush_ggtt_writes(ggtt->vm.gt);
 	if (node.allocated) {
-		wmb();
 		ggtt->vm.clear_range(&ggtt->vm, node.start, node.size);
 		remove_mappable_node(&node);
 	} else {
-- 
2.28.0