drm/xe/bo: explicitly reject zero sized BO

In the depths of ttm, when allocating the vma node this should result in
-ENOSPC it seems. However we should probably rather reject as part of
our own ioctl sanity checking, and then treat as programmer error in the
lower levels.
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_bo.c

@@ -971,6 +971,9 @@ struct xe_bo *__xe_bo_create_locked(struct xe_device *xe, struct xe_bo *bo,
 	/* Only kernel objects should set GT */
 	XE_BUG_ON(gt && type != ttm_bo_type_kernel);
 
+	if (XE_WARN_ON(!size))
+		return ERR_PTR(-EINVAL);
+
 	if (!bo) {
 		bo = xe_bo_alloc();
 		if (IS_ERR(bo))
@@ -1524,6 +1527,9 @@ int xe_gem_create_ioctl(struct drm_device *dev, void *data,
 	if (XE_IOCTL_ERR(xe, args->handle))
 		return -EINVAL;
 
+	if (XE_IOCTL_ERR(xe, !args->size))
+		return -EINVAL;
+
 	if (XE_IOCTL_ERR(xe, args->size > SIZE_MAX))
 		return -EINVAL;