You do not need a work Visa to work for CX and based in Canada. This is because you will not work IN Canada! You will be operating an international flight to and from Canada and thus will require the same credentials as a Hong Kong based guy flying a YVR trip. Check with your countrymen working in Hong Kong if you need any type of Visa.
If you decide to live in Canada, that is a different matter. Either get the proper Visa or don't get caught.