薛智文 cwhsueh@csie.ntu.edu.tw http://www.csie.ntu.edu.tw/~cwhsueh/ 100 Fall , Nov 4, Fri 678, DTH 104

1. 前瞻資訊科技 -虛擬化 (2) -Virtualization(V12N) 薛智文 cwhsueh@csie.ntu.edu.tw http://www.csie.ntu.edu.tw/~cwhsueh/ 100 Fall,Nov 4, Fri 678, DTH 104

2. Outline • Introduction • Xen • Architecture • Hypercall • CPU Virtualization • Memory Virtualization • I/O Device Virtualization • Hardware Virtual Machine • Benchmark • Domain 1 • Summary /28

3. How to Virtualize ? • Binary translation • Hypercall Trap and emulate Full Virtualization Para Virtualization Hardware Assisted Virtualization Intel VT-x & AMD SVM /28

4. Virtual Machine Monitor (VMM)Hypervisor VM : Virtual Machine, Guest OS + Virtual Devices VM0 VM1 VMN … Hosted VMM, e.g. VMware VM0 VM1 VMN … Hypervisor, e.g. Xen Host Operating System Hardware Hardware Type I - Hypervisor Type II – Hosted VMM /28

5. Hypervisor (VMM) Type Type I • Type I + Microkernel • Xen (open source, Citrix), • Microsoft Hyper-V • Type I + Integrated kernel • VMware ESX, • KVM (kernel-base VM) • Type II (Host OS + Guest OS) • VMware GSX, workstation, • Microsoft virtual PC, • Microsoft virtual server, • Sun Virtual Box Type II /28

6. Xen Architecture (1/2) Domain U Domain U Domain 0 Domain U /28

7. Xen Architecture (2/2) • Compare to common Linux /28

8. Hyper Call System Call • int 0x80 • int 0x82 01 02 03 04 05 06 07 // linux/include/asm/unistd.h #define __NR_restart_syscall 0 #define __NR_exit 1 #define __NR_fork 2 #define __NR_read 3 … Guest OS Hypervisor HYPERVOSIR_sched_op int 82h hypercall Hypercall_table do_sched_op iret Hyper Call resume Guest OS 01 02 03 04 05 06 07 // xen/include/public/xen.h #define __HYPERVISOR_set_trap_table 0 #define __HYPERVISOR_mmu_update 1 #define __HYPERVISOR_set_gdt 2 #define __HYPERVISOR_stack_switch 3 … /28

9. Grant Table Domain A Domain B Domain A Domain B create GR create GR send GR send GR map page transfer page access page inform receive page unmap page release GR inform release GR • Page mapping & Page transferring • Page as a unit • Grant reference (GR)  Grant entry /28

10. Event Channel IDC IPI IPI vIRQ pIRQ • A lightweight signal mechanism • Use “ports” as identifers (pending+mask) • Four major purposes Guest OS Guest OS … VCPU VCPU … … VCPU VCPU Hypervisor VirtualMemory … Virtual CPU Scheduling Hardware PhysicalCPU PhysicalMemory … Eth0 Eth1 /28

11. CPU Virtualization • Architecture • 2 scheduling algorithms (Non-Work Conserving) • Simple Earliest Deadline First (SEDF) • Credit App App Guest OS Guest OS … Hypervisor … VCPU VCPU VCPU Scheduling PCPU PCPU PCPU … /28

12. PIC PIC Interrupt • Physical interrupt • For the hypervisor or for guest OSes • Virtual interrupt • Ask guest OSes to do • 8 for now (max is 24) Guest OS Guest OS … event OS Hypervisor ISR Hardware Hardware Device Device IRQn IRQn /28

13. Memory Virtualization (1/2) • Two-level memory • Three-level memory • Virtual, Pseudo-physical, Machine hypervisor Application - Virtual Memory OS Guest OS -Physical Memory -Pseudo-Physical Memory P2M M2P Hypervisor -Machine Memory /28

14. Memory Virtualization (2/2) 168M memory for hypervisor 0xFC000000 0xFC400000 Heap 0xFFFFFFFF /28

15. Memory Virtualization - Translation • 4 mechanisms to manipulate page tables • Paravirtualized page tables • Write page tables (Only level 1 is writable) • Shadow page tables • Hardware-assisted paging Virtual Memory Page Table Shadow Page Table MMU Page Fault ! (VM->PFN) (VM->MFN or VM->P2M) Pseudo-Physical Memory Second Level PagingHAP P2M Machine Memory /28

16. Memory Virtualization - Shared Info Page Structure Compare with start_info_page MAX : 32 VCPUs event channel TSC memory wall clock /28

17. I/O Device Virtualization • Hypervisor also provides three mechanisms to use devices. • Emulated Devices • ParavirtualizedDriver • Pass-through /28

18. I/O Device Virtualization - Emulated Devices • Implemented by QEMU • e.g. sound card, ac97, sb16, etc QEMU-DM /28

19. I/O Device Virtualization - Paravirtualized Driver • Split Device Driver Model • An example of sending packets Back-End Driver Front-End Driver Native Driver /28

20. I/O Device Virtualization - I/O Ring • Without data, it only transfers request/reply • An example with GR Dom U Dom 0 GR GR GR Grant Table I/O Channel Hypervisor Active Grant Table Device /28

21. I/O Device Virtualization - Pass-Through • Pass and directly use the device Dom U Dom 0 Dom U … NativeDriver NativeDriver Hypervisor VirtualMemory … Virtual CPU Scheduling Hardware PhysicalCPU PhysicalMemory … Eth0 Eth1 /28

22. Hardware Virtual Machine • Intel Virtualization Technology /28

23. CPU Benchmark (1/2) 8.3% Average over 100 tests, Deviation: 0.066~0.128% /28

24. CPU Benchmark (2/2) 5% Calculate the 32M digits of ∏. /28

25. Hard Disk Drive Benchmark /28

26. Network Benchmark (1/2) 59% Testing Time: 180 seconds, Deviation: 0.12~0.26%. /28

27. Network Benchmark (2/2) Average: 9.82% Sample Period: 2 seconds /28

28. Answers for Big Questions • How fast can virtualization achieve? • 95+%  99.9% • What kinds of applications? • Well … • What problems it might incur? • Technical • Data • Security • Business • Politics • Globalization (G11N) = • Internationalization (I18N) + Localization (L10N) • … /28

29. Summary • Stay hungry to be full [of passion]. • Stay foolish to be smart [on absorption]. • 假若真時真亦假 • Virtualized reality. • Real virtualization. • Virtualized to go anywhere. • Key is the system. • System is the key. • E.g. Virtual Tape Library /28