1 files changed, 78 insertions, 21 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 921ee369c74d..5bf96a258509 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -416,14 +416,43 @@ out:
 	return ctx;
 }
 
+static struct i915_gem_context *
+create_kernel_context(struct drm_i915_private *i915, int prio)
+{
+	struct i915_gem_context *ctx;
+
+	ctx = i915_gem_create_context(i915, NULL);
+	if (IS_ERR(ctx))
+		return ctx;
+
+	i915_gem_context_clear_bannable(ctx);
+	ctx->priority = prio;
+	ctx->ring_size = PAGE_SIZE;
+
+	GEM_BUG_ON(!i915_gem_context_is_kernel(ctx));
+
+	return ctx;
+}
+
+static void
+destroy_kernel_context(struct i915_gem_context **ctxp)
+{
+	struct i915_gem_context *ctx;
+
+	/* Keep the context ref so that we can free it immediately ourselves */
+	ctx = i915_gem_context_get(fetch_and_zero(ctxp));
+	GEM_BUG_ON(!i915_gem_context_is_kernel(ctx));
+
+	context_close(ctx);
+	i915_gem_context_free(ctx);
+}
+
 int i915_gem_contexts_init(struct drm_i915_private *dev_priv)
 {
 	struct i915_gem_context *ctx;
+	int err;
 
-	/* Init should only be called once per module load. Eventually the
-	 * restriction on the context_disabled check can be loosened. */
-	if (WARN_ON(dev_priv->kernel_context))
-		return 0;
+	GEM_BUG_ON(dev_priv->kernel_context);
 
 	INIT_LIST_HEAD(&dev_priv->contexts.list);
 	INIT_WORK(&dev_priv->contexts.free_work, contexts_free_worker);
@@ -441,28 +470,38 @@ int i915_gem_contexts_init(struct drm_i915_private *dev_priv)
 	BUILD_BUG_ON(MAX_CONTEXT_HW_ID > INT_MAX);
 	ida_init(&dev_priv->contexts.hw_ida);
 
-	ctx = i915_gem_create_context(dev_priv, NULL);
+	/* lowest priority; idle task */
+	ctx = create_kernel_context(dev_priv, I915_PRIORITY_MIN);
 	if (IS_ERR(ctx)) {
-		DRM_ERROR("Failed to create default global context (error %ld)\n",
-			  PTR_ERR(ctx));
-		return PTR_ERR(ctx);
+		DRM_ERROR("Failed to create default global context\n");
+		err = PTR_ERR(ctx);
+		goto err;
 	}
-
-	/* For easy recognisablity, we want the kernel context to be 0 and then
+	/*
+	 * For easy recognisablity, we want the kernel context to be 0 and then
 	 * all user contexts will have non-zero hw_id.
 	 */
 	GEM_BUG_ON(ctx->hw_id);
-
-	i915_gem_context_clear_bannable(ctx);
-	ctx->priority = I915_PRIORITY_MIN; /* lowest priority; idle task */
 	dev_priv->kernel_context = ctx;
 
-	GEM_BUG_ON(!i915_gem_context_is_kernel(ctx));
+	/* highest priority; preempting task */
+	ctx = create_kernel_context(dev_priv, INT_MAX);
+	if (IS_ERR(ctx)) {
+		DRM_ERROR("Failed to create default preempt context\n");
+		err = PTR_ERR(ctx);
+		goto err_kernel_context;
+	}
+	dev_priv->preempt_context = ctx;
 
 	DRM_DEBUG_DRIVER("%s context support initialized\n",
 			 dev_priv->engine[RCS]->context_size ? "logical" :
 			 "fake");
 	return 0;
+
+err_kernel_context:
+	destroy_kernel_context(&dev_priv->kernel_context);
+err:
+	return err;
 }
 
 void i915_gem_contexts_lost(struct drm_i915_private *dev_priv)
@@ -507,15 +546,10 @@ void i915_gem_contexts_lost(struct drm_i915_private *dev_priv)
 
 void i915_gem_contexts_fini(struct drm_i915_private *i915)
 {
-	struct i915_gem_context *ctx;
-
 	lockdep_assert_held(&i915->drm.struct_mutex);
 
-	/* Keep the context so that we can free it immediately ourselves */
-	ctx = i915_gem_context_get(fetch_and_zero(&i915->kernel_context));
-	GEM_BUG_ON(!i915_gem_context_is_kernel(ctx));
-	context_close(ctx);
-	i915_gem_context_free(ctx);
+	destroy_kernel_context(&i915->preempt_context);
+	destroy_kernel_context(&i915->kernel_context);
 
 	/* Must free all deferred contexts (via flush_workqueue) first */
 	ida_destroy(&i915->contexts.hw_ida);
@@ -1036,6 +1070,9 @@ int i915_gem_context_getparam_ioctl(struct drm_device *dev, void *data,
 	case I915_CONTEXT_PARAM_BANNABLE:
 		args->value = i915_gem_context_is_bannable(ctx);
 		break;
+	case I915_CONTEXT_PARAM_PRIORITY:
+		args->value = ctx->priority;
+		break;
 	default:
 		ret = -EINVAL;
 		break;
@@ -1091,6 +1128,26 @@ int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data,
 		else
 			i915_gem_context_clear_bannable(ctx);
 		break;
+
+	case I915_CONTEXT_PARAM_PRIORITY:
+		{
+			int priority = args->value;
+
+			if (args->size)
+				ret = -EINVAL;
+			else if (!to_i915(dev)->engine[RCS]->schedule)
+				ret = -ENODEV;
+			else if (priority > I915_CONTEXT_MAX_USER_PRIORITY ||
+				 priority < I915_CONTEXT_MIN_USER_PRIORITY)
+				ret = -EINVAL;
+			else if (priority > I915_CONTEXT_DEFAULT_PRIORITY &&
+				 !capable(CAP_SYS_NICE))
+				ret = -EPERM;
+			else
+				ctx->priority = priority;
+		}
+		break;
+
 	default:
 		ret = -EINVAL;
 		break;