drm/i915: Use i915_gem_context_get_eb_vm in ctx_getparam

Consolidates the "which is the vm my execbuf runs in" code a bit. We
do some get/put which isn't really required, but all the other users
want the refcounting, and I figured doing a function just for this
getparam to avoid 2 atomis is a bit much.

Reviewed-by: Maarten Lankhorst <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>
Cc: Jon Bloomfield <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Maarten Lankhorst <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: "Thomas Hellström" <[email protected]>
Cc: Matthew Auld <[email protected]>
Cc: Lionel Landwerlin <[email protected]>
Cc: Dave Airlie <[email protected]>
Cc: Jason Ekstrand <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

drivers/gpu/drm/i915/gem/i915_gem_context.c

@@ -2108,6 +2108,7 @@ int i915_gem_context_getparam_ioctl(struct drm_device *dev, void *data,
 	struct drm_i915_file_private *file_priv = file->driver_priv;
 	struct drm_i915_gem_context_param *args = data;
 	struct i915_gem_context *ctx;
+	struct i915_address_space *vm;
 	int ret = 0;
 
 	ctx = i915_gem_context_lookup(file_priv, args->ctx_id);
@@ -2117,12 +2118,10 @@ int i915_gem_context_getparam_ioctl(struct drm_device *dev, void *data,
 	switch (args->param) {
 	case I915_CONTEXT_PARAM_GTT_SIZE:
 		args->size = 0;
-		rcu_read_lock();
-		if (rcu_access_pointer(ctx->vm))
-			args->value = rcu_dereference(ctx->vm)->total;
-		else
-			args->value = to_i915(dev)->ggtt.vm.total;
-		rcu_read_unlock();
+		vm = i915_gem_context_get_eb_vm(ctx);
+		args->value = vm->total;
+		i915_vm_put(vm);
+
 		break;
 
 	case I915_CONTEXT_PARAM_NO_ERROR_CAPTURE: