1. Hardware-assisted Virtual Machine
노용환 (a.k.a. somma)
fixbrain@gmail.com

2. Virtualization…
system utilization
management cost
consolidation
isolation
trusted environment
resource aggregation
GRID system
MPP (Massively Parallel Processing)resource access control
mobility
emulation

3. History…
1960 1970 1999 2006 현재
CP-40, IBM,
Cambridge Scientific Center
full virtualization
System/370, IBM
x86 virtualization, VMWare
application virtualization
(application streaming)
x86,x64, ARM, …
Storage,
Network
…
VMWare, Virtual Box, Xen…
…
OpenStack, CloudStack,…
…
Amazon, Google…

4. Virtualization techniques
Shared Device
Memory and I/O
Virtualization
VMM
CPU CPU MEMORY
Physical H/W
Control
Guest OS Guest OS
physical h/w
virtualized h/w
VMM must …
- support same hardware interface
- can control guest OS when accessing H/W resources.

5. Virtualization techniques
Full Virtualization
- No OS modification
- Binary translation, Trace cache,…
- VMware ESX server
Para Virtualization
- Need OS modification
- Hypercall
- Xen
Direct execution
eflags, control registers, MSR registers, port I/O, privileged instructions, …

6. HVM (Hardware-assisted Virtual Machine)
Virtualize…
CPU
- AMD-V , VT-x
IOMMU
- AMD-Vi, VT-d
Network
- VT-c
VMX operation
VMX root operation
VMX non-root operation

7. HVM (Hardware-assisted Virtual Machine)

8. HVM – new instructions

9. HVM – instruction execution order
VMXON
VMCLEAR
VMPTRLD
VMWRITE
VMLAUNCH
GUEST Exit
VMREAD
VMRESUME
VMXOFF

10. HVM – data…
VMXON Region
- created per logical processor
- used by VMX instructions
VMCS Region
- created per virtual CPU for guest OS
- used by CPU and VMM
- 4Kb aligned
- PHYSICAL_ADDRESS == typedef LARGE_INTEGER
- …

11. HVM – VMM programming summary
check VMX support allocate VMXON region execute VMXON
allocate VMCS regionexecute VMCLEARexecute VMPTRLD
initialize VMCS data
host-state area fields
VM-exit control fields
VM-entry control fields
VM-execution control fields
guest-state area fields
execute VMLAUNCH handling various VM-exits

12. HVM – VMCS data organization
#1 Guest state fields
- saved on VM exits, loaded on VM entries
#2 Host state fields
- loaded on VM exits
#3 Execution control fields
- control VMX-non root operations
#4 Exit control fields
- control VM exits
#5 Entry control fields
- control VM entries
#6 VM Exit info
- saved VM exits information on VM exits
pin-based controls
processor-based controls
exception-bitmap address
I/O bitmap address
Timestamp counter offset
CR0/CR4 guest/host masks
CR3 targets
MSR bitmaps

13. HVM – VMCS data organization

14. HVM – accessing VMCS data
VMWRITE
VMREAD
virtual address / physical address
READ
virtual address / physical address
WRITE

15. HVM – accessing VMCS data

16. HVM – accessing VMCS data

17. HVM – initialize and run VMM

18. HVM – handling VM exits
#6 VM Exit info

19. HVM – handling VM exits

20. Q & A

21. HVM – Blue Pill

22. HVM – related works
Hypersight
- Northsecuritylabs( http://northsecuritylabs.com/ )
- 2011 년 이후 업데이트 없음…
McAfee DeepSAFE
Microsoft
- Countering Kernel Rootkits with Lightweight Hook Protection

23. HVM – related works
HyperDbg
- SoftIce 와 유사
- HVM 을 이용한 커널디버거

24. DEMO
&
Q & A