Does this mean it's a good idea to reset all keys/passwords for any service that was using Xen?

I don't know much about Xen, so perhaps someone else can chime in on this. This exploit says it's for PV, and not for HVM.

But Xen can apparently run both at the same time. Does this mean even if you were using HVM, and Xen had other guests using PV, you were still exploitable?