[RFC PATCH 08/29] drm/xe: Clear GGTT in xe_bo_restore_kernel

[Matthew Brost <matthew.brost@intel.com>]

Part of what xe_bo_restore_kernel does, is restore BO's GGTT mappings
which may have been lost during a power state change. Missing is
restoring the GGTT entries without BO mappings to a known state (e.g.,
scratch pages). Update xe_bo_restore_kernel to clear the entire GGTT
before restoring BO's GGTT mappings.

v2:
 - Include missing local change of tile and id variable (CI)
v3:
 - Fixed kernel doc (CI)
v4:
 - Only clear holes (CI)

Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Cc: <stable@vger.kernel.org> # v6.8+
---
 drivers/gpu/drm/xe/xe_bo_evict.c |  8 +++++++-
 drivers/gpu/drm/xe/xe_ggtt.c     | 19 ++++++++++++++++---
 drivers/gpu/drm/xe/xe_ggtt.h     |  2 ++
 3 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_bo_evict.c b/drivers/gpu/drm/xe/xe_bo_evict.c
index 8fb2be061003..d7bb3dbb41d6 100644
--- a/drivers/gpu/drm/xe/xe_bo_evict.c
+++ b/drivers/gpu/drm/xe/xe_bo_evict.c
@@ -123,7 +123,8 @@ int xe_bo_evict_all(struct xe_device *xe)
  * @xe: xe device
  *
  * Move kernel BOs from temporary (typically system) memory to VRAM via CPU. All
- * moves done via TTM calls.
+ * moves done via TTM calls. All GGTT are restored too, first by clearing GGTT
+ * to known state and then restoring individual BO's GGTT mappings.
  *
  * This function should be called early, before trying to init the GT, on device
  * resume.
@@ -131,8 +132,13 @@ int xe_bo_evict_all(struct xe_device *xe)
 int xe_bo_restore_kernel(struct xe_device *xe)
 {
 	struct xe_bo *bo;
+	struct xe_tile *tile;
+	u8 id;
 	int ret;
 
+	for_each_tile(tile, xe, id)
+		xe_ggtt_clear(tile->mem.ggtt);
+
 	spin_lock(&xe->pinned.lock);
 	for (;;) {
 		bo = list_first_entry_or_null(&xe->pinned.evicted,
diff --git a/drivers/gpu/drm/xe/xe_ggtt.c b/drivers/gpu/drm/xe/xe_ggtt.c
index 558fac8bb6fb..2fc498b89878 100644
--- a/drivers/gpu/drm/xe/xe_ggtt.c
+++ b/drivers/gpu/drm/xe/xe_ggtt.c
@@ -140,7 +140,7 @@ static void xe_ggtt_set_pte_and_flush(struct xe_ggtt *ggtt, u64 addr, u64 pte)
 	ggtt_update_access_counter(ggtt);
 }
 
-static void xe_ggtt_clear(struct xe_ggtt *ggtt, u64 start, u64 size)
+static void __xe_ggtt_clear(struct xe_ggtt *ggtt, u64 start, u64 size)
 {
 	u16 pat_index = tile_to_xe(ggtt->tile)->pat.idx[XE_CACHE_WB];
 	u64 end = start + size - 1;
@@ -160,6 +160,19 @@ static void xe_ggtt_clear(struct xe_ggtt *ggtt, u64 start, u64 size)
 	}
 }
 
+static void xe_ggtt_initial_clear(struct xe_ggtt *ggtt);
+
+/**
+ * xe_ggtt_clear() - GGTT clear
+ * @ggtt: the &xe_ggtt to be cleared
+ *
+ * Clear all GGTT to a known state
+ */
+void xe_ggtt_clear(struct xe_ggtt *ggtt)
+{
+	xe_ggtt_initial_clear(ggtt);
+}
+
 static void ggtt_fini_early(struct drm_device *drm, void *arg)
 {
 	struct xe_ggtt *ggtt = arg;
@@ -277,7 +290,7 @@ static void xe_ggtt_initial_clear(struct xe_ggtt *ggtt)
 	/* Display may have allocated inside ggtt, so be careful with clearing here */
 	mutex_lock(&ggtt->lock);
 	drm_mm_for_each_hole(hole, &ggtt->mm, start, end)
-		xe_ggtt_clear(ggtt, start, end - start);
+		__xe_ggtt_clear(ggtt, start, end - start);
 
 	xe_ggtt_invalidate(ggtt);
 	mutex_unlock(&ggtt->lock);
@@ -294,7 +307,7 @@ static void ggtt_node_remove(struct xe_ggtt_node *node)
 
 	mutex_lock(&ggtt->lock);
 	if (bound)
-		xe_ggtt_clear(ggtt, node->base.start, node->base.size);
+		__xe_ggtt_clear(ggtt, node->base.start, node->base.size);
 	drm_mm_remove_node(&node->base);
 	node->base.size = 0;
 	mutex_unlock(&ggtt->lock);
diff --git a/drivers/gpu/drm/xe/xe_ggtt.h b/drivers/gpu/drm/xe/xe_ggtt.h
index 27e7d67de004..b7ae440cdebf 100644
--- a/drivers/gpu/drm/xe/xe_ggtt.h
+++ b/drivers/gpu/drm/xe/xe_ggtt.h
@@ -13,6 +13,8 @@ struct drm_printer;
 int xe_ggtt_init_early(struct xe_ggtt *ggtt);
 int xe_ggtt_init(struct xe_ggtt *ggtt);
 
+void xe_ggtt_clear(struct xe_ggtt *ggtt);
+
 struct xe_ggtt_node *xe_ggtt_node_init(struct xe_ggtt *ggtt);
 void xe_ggtt_node_fini(struct xe_ggtt_node *node);
 int xe_ggtt_node_insert_balloon(struct xe_ggtt_node *node,
-- 
2.34.1