CPUM_SF_SDB_PER_TABLE
base = aux->sdbt_index[head / CPUM_SF_SDB_PER_TABLE];
offset = head % CPUM_SF_SDB_PER_TABLE;
n_sdbt = DIV_ROUND_UP(nr_pages, CPUM_SF_SDB_PER_TABLE);
#define CPUM_SF_SDBT_TL_OFFSET (CPUM_SF_SDB_PER_TABLE * 8)