drm/i915/bdw: Setup global hardware status page in execlists mode

Write HWS_PGA address even in execlists mode as the global hardware status
page is still required.  This address was previously uninitialized and
HWSP writes would clobber whatever buffer happened to reside at GGTT
address 0.

v2: Break out hardware status page setup into a separate function.

Issue: VIZ-2020
Signed-off-by: Thomas Daniel <thomas.daniel@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_lrc.c

@@ -1649,6 +1649,27 @@ static uint32_t get_lr_context_size(struct intel_engine_cs *ring)
 	return ret;
 }
 
+static int lrc_setup_hardware_status_page(struct intel_engine_cs *ring,
+		struct drm_i915_gem_object *default_ctx_obj)
+{
+	struct drm_i915_private *dev_priv = ring->dev->dev_private;
+
+	/* The status page is offset 0 from the default context object
+	 * in LRC mode. */
+	ring->status_page.gfx_addr = i915_gem_obj_ggtt_offset(default_ctx_obj);
+	ring->status_page.page_addr =
+			kmap(sg_page(default_ctx_obj->pages->sgl));
+	if (ring->status_page.page_addr == NULL)
+		return -ENOMEM;
+	ring->status_page.obj = default_ctx_obj;
+
+	I915_WRITE(RING_HWS_PGA(ring->mmio_base),
+			(u32)ring->status_page.gfx_addr);
+	POSTING_READ(RING_HWS_PGA(ring->mmio_base));
+
+	return 0;
+}
+
 /**
  * intel_lr_context_deferred_create() - create the LRC specific bits of a context
  * @ctx: LR context to create.
@@ -1734,14 +1755,11 @@ int intel_lr_context_deferred_create(struct intel_context *ctx,
 	ctx->engine[ring->id].state = ctx_obj;
 
 	if (ctx == ring->default_context) {
-		/* The status page is offset 0 from the default context object
-		 * in LRC mode. */
-		ring->status_page.gfx_addr = i915_gem_obj_ggtt_offset(ctx_obj);
-		ring->status_page.page_addr =
-				kmap(sg_page(ctx_obj->pages->sgl));
-		if (ring->status_page.page_addr == NULL)
-			return -ENOMEM;
-		ring->status_page.obj = ctx_obj;
+		ret = lrc_setup_hardware_status_page(ring, ctx_obj);
+		if (ret) {
+			DRM_ERROR("Failed to setup hardware status page\n");
+			goto error;
+		}
 	}
 
 	if (ring->id == RCS && !ctx->rcs_initialized) {