From 4ae82ae6f7cff750ff8db11a9d01b1e45234dfbd Mon Sep 17 00:00:00 2001
From: Lang Yu <Lang.Yu@amd.com>
Date: Tue, 22 Jun 2021 12:23:35 -0400
Subject: drm/amdgpu: user temporary GTT as bounce buffer
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Git-commit: 3e640f1bb893610378858c2e47c99dc019dfc9e9
Patch-mainline: v5.15-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

Currently, we have a limitted GTT memory size and need a bounce buffer
when doing buffer migration between VRAM and SYSTEM domain.

The problem is under GTT memory pressure we can't do buffer migration
between VRAM and SYSTEM domain. But in some cases we really need that.
Eespecially when validating a VRAM backing store BO which resides in
SYSTEM domain.

v2: still account temporary GTT allocations
v3 (chk): revert to the simpler change for now

Signed-off-by: Lang Yu <Lang.Yu@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Acked-by: Nirmoy Das <nirmoy.das@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210622162339.761651-2-andrey.grodzovsky@amd.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c | 20 ++++++++++++--------
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c     |  2 +-
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
index ec96e0b26b11..3b4520856162 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
@@ -132,14 +132,15 @@ static int amdgpu_gtt_mgr_new(struct ttm_resource_manager *man,
 	struct amdgpu_gtt_node *node;
 	int r;
 
-	spin_lock(&mgr->lock);
-	if (tbo->resource && tbo->resource->mem_type != TTM_PL_TT &&
-	    atomic64_read(&mgr->available) < num_pages) {
+	if (!(place->flags & TTM_PL_FLAG_TEMPORARY)) {
+		spin_lock(&mgr->lock);
+		if (atomic64_read(&mgr->available) < num_pages) {
+			spin_unlock(&mgr->lock);
+			return -ENOSPC;
+		}
+		atomic64_sub(num_pages, &mgr->available);
 		spin_unlock(&mgr->lock);
-		return -ENOSPC;
 	}
-	atomic64_sub(num_pages, &mgr->available);
-	spin_unlock(&mgr->lock);
 
 	node = kzalloc(struct_size(node, base.mm_nodes, 1), GFP_KERNEL);
 	if (!node) {
@@ -175,7 +176,8 @@ static int amdgpu_gtt_mgr_new(struct ttm_resource_manager *man,
 	kfree(node);
 
 err_out:
-	atomic64_add(num_pages, &mgr->available);
+	if (!(place->flags & TTM_PL_FLAG_TEMPORARY))
+		atomic64_add(num_pages, &mgr->available);
 
 	return r;
 }
@@ -198,7 +200,9 @@ static void amdgpu_gtt_mgr_del(struct ttm_resource_manager *man,
 	if (drm_mm_node_allocated(&node->base.mm_nodes[0]))
 		drm_mm_remove_node(&node->base.mm_nodes[0]);
 	spin_unlock(&mgr->lock);
-	atomic64_add(res->num_pages, &mgr->available);
+
+	if (!(res->placement & TTM_PL_FLAG_TEMPORARY))
+		atomic64_add(res->num_pages, &mgr->available);
 
 	kfree(node);
 }
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 3a55f08e00e1..25541bc89006 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -521,7 +521,7 @@ static int amdgpu_bo_move(struct ttm_buffer_object *bo, bool evict,
 			hop->fpfn = 0;
 			hop->lpfn = 0;
 			hop->mem_type = TTM_PL_TT;
-			hop->flags = 0;
+			hop->flags = TTM_PL_FLAG_TEMPORARY;
 			return -EMULTIHOP;
 		}
 
-- 
2.38.1