How to pass parameter between xhtml pages?

I have created a web development project using JSF2.X. My project has the following 2 pages and implements a form validation.

1. index.xhtml : welcome page with login button option
2. login.xhtml : login form validation page that connects to a database

index.xhtml redirects to the login page , when login button is clicked.

login.xhtml validates successfully whether a user belongs to the database or not.

I would like my index.xhtml to have a parameter holding if a user is logged in the site or not.

Is there any possible way to redirect back to the index.xhtml page from login.xhtml page , while passing a parameter about user's state ?

I would like to do it with plain html code if possible , but whatever works !