HVM guests at Amazon will default to using PV drivers for IO and networking. (Unless using SRIOV/"Enhanced Networking", which will not use the PV drivers)

PVH is actually PV on top of an HVM container and is a bit different. You can think of it as PV sitting on top of enough HVM bits to take advantage of the hardware extensions Intel and AMD have invested so heavily in while still being majority PV. This gives you the best of both worlds, including the remaining PV performance benefits related to interrupts and timers that PV drivers on HVM can't utilize.

hm. thanks. Yeah. I need to spend more time on this as I update my stuff.