All the cool kids are doing it!

Zachary Amsden
Jeremy Fitzhardinge
Rusty Russell, IBM
Chris Wright, Redhat

Shadow page tables

• twice as much memory
• two copies page tables
• changes by guest erquire trapping hypervisor

or alternative:

• security
• I/O - emulate
• create simplified drivers

cupid

• identify CPU features
• not trappable
• not a privileged instruction

popf, pushf

• kernel can’t run except in ring 0

puppies

Paravirtualization

• rewrite code in kernel not to use problem instructions
• Xen

Xen interrupts

• GPL hypervisor
• IDT interrupt descriptor table
• virtual IRQs

VMI

• cute cuddly lawyer
• one kernel can run anywhere
• different OS run on different hypervisors without making code changes
• published by hypervisor
• called by kernel

https://sf.net/projects/vmi-linux

lhype

lguest - rusty visor

virtbench - VT

KVM hypervisor

can you run a hypervisor under a hypervisor?

standard video card, etC?

we should fix the OS, but it isn’t as cool.