Hello

UPSC eligibility is provided below :-

*You must have a bachelor's degree in any discipline from a recognised university

*Minimum age limit :-  21 years

So,to be eligible for UPSC  examination there is no compulsion to be a graduate in a particular subject, all you need to be eligible is that you should be a graduate in any discipline .

So , yes you are definitely eligible for UPSC examination after BSC Computer Science

For detailed information go through

https://competition.careers360.com/articles/upsc-ias-eligibility-criteria/amp

Thank you