xstate_calculate_size
ksize = xstate_calculate_size(mask, compacted);
usize = xstate_calculate_size(mask & XFEATURE_MASK_USER_SUPPORTED, false);
size = xstate_calculate_size(fpu_kernel_cfg.max_features, compacted);
xstate_calculate_size(fpu_kernel_cfg.default_features, compacted);
xstate_calculate_size(fpu_user_cfg.default_features, false);
xstate_calculate_size(guest_default_cfg.features, compacted);