drm/i915/gvt: Fix shadow context descriptor

We need to be careful to only update addr mode for gvt shadow context
descriptor but keep other valid config. This fixes GPU hang caused by
invalid descriptor submitted for gvt workload.
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

drivers/gpu/drm/i915/gvt/scheduler.c

@@ -169,7 +169,8 @@ static int dispatch_workload(struct intel_vgpu_workload *workload)
 	gvt_dbg_sched("ring id %d prepare to dispatch workload %p\n",
 		ring_id, workload);
 
-	shadow_ctx->desc_template = workload->ctx_desc.addressing_mode <<
+	shadow_ctx->desc_template &= ~(0x3 << GEN8_CTX_ADDRESSING_MODE_SHIFT);
+	shadow_ctx->desc_template |= workload->ctx_desc.addressing_mode <<
 				    GEN8_CTX_ADDRESSING_MODE_SHIFT;
 
 	mutex_lock(&dev_priv->drm.struct_mutex);