GSP_MSG_HDR_SIZE
size = DIV_ROUND_UP(GSP_MSG_HDR_SIZE + gsp_rpc_len,
size = ALIGN(expected + GSP_MSG_HDR_SIZE, GSP_PAGE_SIZE);
len = ALIGN(GSP_MSG_HDR_SIZE + gsp_rpc_len, GSP_PAGE_SIZE);
u32 size = GSP_MSG_HDR_SIZE + gsp_rpc_len;