Do I need a Schengen visa?

My nationality Obligation to hold a visa (yes/no)
Saudi Arabia  yes (V) 
Yemen yes (V)
Oman  yes (V) (M: D, S, SP) 

(V)
Third state members in possession of both a valid residence permit issued by a Schengen member state or a valid type D visa and a recognized travel document are exempt from visa requirements.

(M: D, S, SP)
Holders of a diplomatic, service or special passport are exempt from visa requirements if they wish to enter into Switzerland: on an official mission or for other travel purposes without exercising a gainful occupation.

Other nationalities

For other nationalities, please refer to the list on the webpage of the State Secretariat for Migration (SEM).

SEM – Overview of ID and visa provisions according to the nationality (Annex 1, List 1: nationality)

If you are obliged to hold a visa, please apply for it and refer to the information on the webpage:

Where to apply for a Schengen visa?

If you are not obliged to hold a visa, you are allowed to enter Switzerland resp. the Schengen territory and stay up to 90 days within a 180-day period without any visa.