//расчет итоговой цены товара

function ut_before_calculate_totals( $cart_obj ) {
    echo '<pre>';
        var_dump($cart_obj->get_cart());
    echo '</pre>';

    foreach( $cart_obj->get_cart() as $key => $value ) {

        $product_total_price = ( !empty( get_post_meta( $value['data']->get_id(), '_sale_price', true) ) ) ? get_post_meta( $value['data']->get_id(), '_sale_price', true) : get_post_meta( $value['data']->get_id(), '_regular_price', true);
        $volume = ( isset( $value['variation']['attribute_m-3-na-poddone'] ) ) ? $value['variation']['attribute_m-3-na-poddone'] : 1 ;
        $result_price = $product_total_price * $volume ;

        $value['data']->set_price( $result_price );

    }
}
add_action( 'woocommerce_before_calculate_totals', 'ut_before_calculate_totals', 10, 1 );