Trip to Canada

I have U.S green card, chinese passport. Currently I am living in the U.S.

I plan to attend a conference in Canada at the end of this month.I'll stay in Vancouver for at most 12 days before coming back to U.S.  Do I need to apply for a visa in Canadian consulte in U.S in order to enter Canada legally? I assume that U.S. permanent resident doesn't need a visa. Just want to double check.

If no visa is needed, besides my green card and my passport, are there any other indispensable documents I have to bring with me for the immigration inspection?

 

Thanks a lot!