Next month I have a trip to Spain. I was reading about International driving permission, but I couldn't find information about the exact countries where it's eligible
We've done a lot of research on this tiopic (because it's important from an insurance persepctive) and Wiki is pretty good on this - https://en.wikipedia.org/wiki/International_Driving_Permit.
However, an IDP is simple to get and not too expensive, so get one anyway.
Check out our policy re rental car coverage - https://helpdesk.worldnomads.com/customer/en_us/portal/articles/2658886-is-my-rental-car-covered-
And i know it's not a motorbike you're renting, but this article has a lot of info about the IDP and its validity etc, important stuff to know - https://www.worldnomads.com/travel-safety/southeast-asia/malaysia/do-i-need-a-license-to-ride-a-motorbike about 1 year ago