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Memory Virtualization
The document discusses virtualization techniques used in KVM. It describes how KVM uses shadow page tables to virtualize memory management. The shadow page tables allow virtual addresses used by a guest OS to be translated to physical addresses on the host machine. Different techniques for implementing shadow page tables are described, including pre-validation of guest page tables and using a virtual translation lookaside buffer to cache translations.
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Memory Virtualization
- 1. /VM Tsuyoshi Ozawa Twitter oza_x86 2009 11 9 1
- 2. 2009 11 9 2
- 3. 2009 11 9 3
- 4. 2009 11 9 4
- 5. 2009 11 9 5
- 6. KVM 2009 11 9 6
- 7. for x86 2009 11 9 7
- 8. Linux on RealMachine Linux on Virtual Machine (=OS) 2009 11 9 8
- 9. 2009 11 9 9
- 10. x86 (Shadow Page Table) 2009 11 9 10
- 11. CPU 0x1000 0x11000 Virtual Physical Memory Memory 0x2000 0x12000 ... ... 2009 11 9 11
- 12. • • 2009 11 9 12
- 13. • • 2009 11 9 13
- 14. • OS • 0x1000 0x11000 • 0x2000 0x12000 ... ... 2009 11 9 14
- 15. • 0x1000 0x11000 • OS 0x2000 0x12000 ... ... 2009 11 9 15
- 16. • ? • swap in Physical swap out Memory 2009 11 9 16
- 17. 1. CR3 2. MMU 3. TLB CPU CR3 x86 CPU MMU TLB 2009 11 9 17
- 18. CR3 • • Control Register 3 2009 11 9 18
- 19. • MMU • Memory Management Unit 2009 11 9 19
- 20. • Translation Look-asideBuffer TLB • • CPU SRAM 2009 11 9 20
- 21. Virtual Address 0xc0003120 3 20bit 12bit 4. CR3 2. MMU Physical Memory TLB 3. 1.TLB 2009 11 9 21
- 22. 2009 11 9 22
- 23. VM 2009 11 9 23
- 24. 2009 11 9 24
- 25. VM 2009 11 9 25
- 26. VM • OS 2009 11 9 26
- 27. VM Virtual Machine Monitor VMM Hardware 2009 11 9 27
- 28. VMM • 3 VMM • Robert P. Goldberg. ,Architectural Principles for Virtual Computer Systems. 2009 11 9 28
- 29. Type I VMM • • Xen,VMware ESX VMM Hardware 2009 11 9 29
- 30. Type II VMM • OS • Qemu Proc VMM LilyVM Bochs OS Hardware 2009 11 9 30
- 31. Hybrid VMM • Type I + Type II • • VMware Proc VMM Workstation Linux KVM OS VMM Hardware 2009 11 9 31
- 32. Hybrid VMM • VMM OS VMM Hardware 2009 11 9 32
- 33. VM 2009 11 9 33
- 34. 2 • Shadow Page Table ( SPT ) • Nested Page Table (Extended Page Table) 2009 11 9 34
- 35. Shadow Page Table • OS Shadow OS • OS Shadow 2009 11 9 35
- 36. SPT Hybrid VMM OS VMM Hardware 2009 11 9 36
- 37. SPT OS VM Guest side vTLB vCR3 Host side VMM Hardware TLB CR3 2009 11 9 37
- 38. SPT create page table OS Guest page table VM Guest side vTLB vCR3 Host side VMM Hardware TLB CR3 2009 11 9 38
- 39. SPT OS Guest page table VM Guest side vTLB vCR3 Host side VMM ... Hardware TLB CR3 2009 11 9 39
- 40. SPT OS Guest page table VM Guest side vTLB vCR3 VMM Host side VMM Hardware TLB CR3 2009 11 9 40
- 41. SPT OS Guest page table VM Guest side vTLB vCR3 VMM Host side VMM PT Hardware TLB CR3 2009 11 9 41
- 42. SPT OS Guest page table VM Guest side vTLB vCR3 create SPT Host side VMM Shadow page table Hardware TLB CR3 2009 11 9 42
- 43. SPT OS Guest page table Guest Physical VM Memory vTLB vCR3 VMM Shadow page table OS vCR3 Host Physical Hardware Memory TLB CR3 2009 11 9 43
- 44. SPT OS Guest page table Guest Physical VM Memory vTLB vCR3 Hook VMM Shadow VMM page table Host Physical Hardware Memory TLB CR3 2009 11 9 44
- 45. SPT OS Guest page table Guest SPT Physical VM Memory vTLB vCR3 CR3 VMM Shadow page table Host Physical Hardware Memory TLB CR3 2009 11 9 45
- 46. 2009 11 9 46
- 47. SPT OS Guest page table Guest Physical VM Memory vTLB vCR3 VMM Shadow page table Host Physical Hardware Memory TLB CR3 2009 11 9 47
- 48. SPT OS Guest page table Guest Physical VM Memory vTLB vCR3 VMM Shadow page table Host Physical Hardware Memory TLB CR3 2009 11 9 48
- 49. SPT OS Guest page table Guest Physical VM Memory vTLB vCR3 VMM Shadow page table Host Physical Hardware Memory TLB CR3 2009 11 9 49
- 50. SPT • OS • VMM SPT 2009 11 9 50
- 51. SPT • Pre-Validation • Virtual TLB • Virtual TLB + Memory Trace 2009 11 9 51
- 52. Pre-validation • CR3 • PT • SPT 2009 11 9 52
- 53. Pre-validation create page table OS Guest page table VM Guest side vTLB vCR3 Host side VMM Hardware TLB CR3 2009 11 9 53
- 54. Pre-validation OS Guest page table VM Guest side vTLB vCR3 OS Host side VMM PT Hardware TLB CR3 2009 11 9 54
- 55. Pre-validation OS Guest page table VM Guest side vTLB vCR3 CR3 Host side VMM Hardware TLB CR3 2009 11 9 55
- 56. Pre-validation OS Guest page table VM Guest side vTLB vCR3 VMM Host side VMM Hardware TLB CR3 2009 11 9 56
- 57. Pre-validation OS Guest page table VM Guest side vTLB vCR3 VMM Host side VMM PT Hardware TLB CR3 2009 11 9 57
- 58. Pre-validation OS Guest page table VM Guest side vTLB vCR3 create SPT Host side VMM Shadow page table Hardware TLB CR3 2009 11 9 58
- 59. Pre-validation OS Guest page table Guest SPT Physical VM Memory vTLB vCR3 CR3 VMM Shadow page table Host Physical Hardware Memory TLB CR3 2009 11 9 59
- 60. SPT OS Guest page table Guest Physical VM Memory vTLB vCR3 VMM Shadow page table Host SPT Physical Hardware Memory TLB CR3 2009 11 9 60
- 61. Pre-validation • ( CR3 ) SPT • 2009 11 9 61
- 62. Virtual TLB • CR3 SPT 1 • TLB SPT • TLB VMM 2009 11 9 62
- 63. Virtual TLB create page table OS Guest page table VM Guest side vTLB vCR3 Host side VMM Hardware TLB CR3 2009 11 9 63
- 64. Virtual TLB OS Guest page table VM Guest side vTLB vCR3 OS Host side VMM PT Hardware TLB CR3 2009 11 9 64
- 65. Virtual TLB OS Guest page table VM Guest side vTLB vCR3 CR3 Host side VMM Hardware TLB CR3 2009 11 9 65
- 66. Virtual TLB OS Guest page table VM Guest side vTLB vCR3 VMM Host side VMM Hardware TLB CR3 2009 11 9 66
- 67. Virtual TLB OS Guest page table VM Guest side vTLB vCR3 VMM Host side VMM PT Hardware TLB CR3 2009 11 9 67
- 68. Virtual TLB OS Guest page table VM Guest side vTLB vCR3 create SPT Host side VMM Shadow page table Hardware 1st stage TLB CR3 2009 11 9 68
- 69. Virtual TLB VMM OS Guest page table VM Guest side 1 vTLB vCR3 create SPT Host side VMM Shadow page table Hardware 1st stage TLB CR3 2009 11 9 69
- 70. Virtual TLB OS Guest page table Guest SPT Physical VM Memory vTLB vCR3 CR3 VMM Shadow page table Host 1st stage Physical Hardware Memory TLB CR3 2009 11 9 70
- 71. Virtual TLB OS Guest page table Guest Physical VM Memory vTLB vCR3 VMM Shadow page table Host 1st stage Physical Hardware Memory TLB CR3 2009 11 9 71
- 72. Virtual TLB OS Guest page table Guest Physical VM Memory vTLB vCR3 VMM Shadow page table Host 1st stage Physical Hardware Memory TLB CR3 2009 11 9 72
- 73. Virtual TLB OS Guest page table Guest Physical VM Memory vTLB vCR3 VMM Shadow page table Host 1st stage Physical Hardware Memory TLB CR3 2009 11 9 73
- 74. Virtual TLB OS Guest page table Guest Physical VM Memory vTLB vCR3 VMM VMM Shadow page table PT Host 1st stage Physical Hardware Memory TLB CR3 2009 11 9 74
- 75. Virtual TLB OS Guest page table 2 Guest Physical VM Memory vTLB vCR3 Shadow VMM page table Host 2nd stage Physical Hardware Memory TLB CR3 2009 11 9 75
- 76. Virtual TLB OS Guest page table Guest Physical VM Memory vTLB vCR3 Shadow VMM page table Host 2nd stage Physical Hardware Memory TLB CR3 ( ) CPU 2009 11 9 76
- 77. Virtual TLB OS OS Guest page table Guest Physical VM Memory vTLB vCR3 Shadow VMM page table Host 2nd stage Physical Hardware Memory TLB CR3 ( ) CPU 2009 11 9 77
- 78. Virtual TLB OS Guest page table Guest Physical VM Memory vTLB vCR3 Shadow VMM page table Host 2nd stage Physical Hardware Memory TLB CR3 ( ) CPU 2009 11 9 78
- 79. Virtual TLB • • • • SPT 2009 11 9 79
- 80. Virtual TLB • TLB • CR3 • invlpg • OS • PTE 2009 11 9 80
- 81. SPT • TLB SPT • OS PT SPT 2009 11 9 81
- 82. Memory Trace • OS PT • OS SPT (Trace) 2009 11 9 82
- 83. • x86 • CPU • Linux KVM 2009 11 9 83
- 84.
- 85. Nested Page Table (Extended Page Table) • 0x1000 0x11000 0x21000 0x2000 0x12000 0x42000 ... ... 2009 11 9 85
- 86. NPT/EPT • AMD CPU CPU • Intel CPU CPU(i7 ) • VMM • SPT 2009 11 9 86
- 87. • VM • SPT • Pre-validation • Virtual TLB • NPT/EPT 2009 11 9 87