[RFC PATCH 035/162] drm/i915: Make intel_init_workaround_bb more compatible with ww locking.

[Matthew Auld]

From: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>

Make creation separate from pinning, in order to take the lock only
once, and pin the mapping with the lock held.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
---
 .../drm/i915/gt/intel_engine_workaround_bb.c  | 45 +++++++++++++++----
 1 file changed, 37 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_engine_workaround_bb.c b/drivers/gpu/drm/i915/gt/intel_engine_workaround_bb.c
index b03bdfc92bb2..f3636b73cc10 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_workaround_bb.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_workaround_bb.c
@@ -229,7 +229,7 @@ gen10_init_indirectctx_bb(struct intel_engine_cs *engine, u32 *batch)
 
 #define CTX_WA_BB_OBJ_SIZE (PAGE_SIZE)
 
-static int lrc_setup_wa_ctx(struct intel_engine_cs *engine)
+static int lrc_init_wa_ctx(struct intel_engine_cs *engine)
 {
 	struct drm_i915_gem_object *obj;
 	struct i915_vma *vma;
@@ -245,10 +245,6 @@ static int lrc_setup_wa_ctx(struct intel_engine_cs *engine)
 		goto err;
 	}
 
-	err = i915_ggtt_pin(vma, NULL, 0, PIN_HIGH);
-	if (err)
-		goto err;
-
 	engine->wa_ctx.vma = vma;
 	return 0;
 
@@ -257,6 +253,18 @@ static int lrc_setup_wa_ctx(struct intel_engine_cs *engine)
 	return err;
 }
 
+static void lrc_destroy_wa_ctx(struct intel_engine_cs *engine, bool unpin)
+{
+	if (!engine->wa_ctx.vma)
+		return;
+
+	if (unpin)
+		i915_vma_unpin(engine->wa_ctx.vma);
+
+	i915_vma_put(engine->wa_ctx.vma);
+	engine->wa_ctx.vma = NULL;
+}
+
 typedef u32 *(*wa_bb_func_t)(struct intel_engine_cs *engine, u32 *batch);
 
 int intel_init_workaround_bb(struct intel_engine_cs *engine)
@@ -266,6 +274,7 @@ int intel_init_workaround_bb(struct intel_engine_cs *engine)
 					    &wa_ctx->per_ctx };
 	wa_bb_func_t wa_bb_fn[2];
 	void *batch, *batch_ptr;
+	struct i915_gem_ww_ctx ww;
 	unsigned int i;
 	int ret;
 
@@ -293,13 +302,21 @@ int intel_init_workaround_bb(struct intel_engine_cs *engine)
 		return 0;
 	}
 
-	ret = lrc_setup_wa_ctx(engine);
+	ret = lrc_init_wa_ctx(engine);
 	if (ret) {
 		drm_dbg(&engine->i915->drm,
 			"Failed to setup context WA page: %d\n", ret);
 		return ret;
 	}
 
+	i915_gem_ww_ctx_init(&ww, true);
+retry:
+	ret = i915_gem_object_lock(wa_ctx->vma->obj, &ww);
+	if (!ret)
+		ret = i915_ggtt_pin(wa_ctx->vma, &ww, 0, PIN_HIGH);
+	if (ret)
+		goto err;
+
 	batch = i915_gem_object_pin_map(wa_ctx->vma->obj, I915_MAP_WB);
 
 	/*
@@ -323,13 +340,25 @@ int intel_init_workaround_bb(struct intel_engine_cs *engine)
 
 	__i915_gem_object_flush_map(wa_ctx->vma->obj, 0, batch_ptr - batch);
 	__i915_gem_object_release_map(wa_ctx->vma->obj);
+
+	if (ret)
+		i915_vma_unpin(wa_ctx->vma);
+
+err:
+	if (ret == -EDEADLK) {
+		ret = i915_gem_ww_ctx_backoff(&ww);
+		if (!ret)
+			goto retry;
+	}
+	i915_gem_ww_ctx_fini(&ww);
 	if (ret)
-		intel_fini_workaround_bb(engine);
+		lrc_destroy_wa_ctx(engine, false);
 
 	return ret;
 }
 
+
 void intel_fini_workaround_bb(struct intel_engine_cs *engine)
 {
-	i915_vma_unpin_and_release(&engine->wa_ctx.vma, 0);
+	lrc_destroy_wa_ctx(engine, true);
 }
-- 
2.26.2