Linux KVM のコードを追いかけてみよう
•
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The document discusses Linux KVM (Kernel-based Virtual Machine) and how it enables full virtualization on x86 hardware. KVM uses Intel VT-x and AMD-V virtualization extensions to allow a Linux kernel to function as a hypervisor. Guest virtual machines see a bare metal interface while the host kernel manages scheduling and resource allocation. Qemu is used as a processor emulator to add missing guest architectures.
![opcode = mem[pc];
execute(opcode);
2009 8 13 21](https://image.slidesharecdn.com/kernel-vm-1st-oza-fixed-090812135434-phpapp02/85/Linux-KVM-21-320.jpg)
![mov
opcode = mem[pc];
execute(opcode);
jmp
2009 8 13 22](https://image.slidesharecdn.com/kernel-vm-1st-oza-fixed-090812135434-phpapp02/85/Linux-KVM-22-320.jpg)
![opcode[0..N] = mem[pc];
mid_ops=compile(opcode);
execute(mid_ops);
2009 8 13 25](https://image.slidesharecdn.com/kernel-vm-1st-oza-fixed-090812135434-phpapp02/85/Linux-KVM-25-320.jpg)
![opcode[0..N] = mem[pc];
mid_ops=compile(opcode);
execute(mid_ops);
2009 8 13 26](https://image.slidesharecdn.com/kernel-vm-1st-oza-fixed-090812135434-phpapp02/85/Linux-KVM-26-320.jpg)
![opcode[0..N] = mem[pc];
mid_ops=compile(opcode);
execute(mid_ops);
2009 8 13 27](https://image.slidesharecdn.com/kernel-vm-1st-oza-fixed-090812135434-phpapp02/85/Linux-KVM-27-320.jpg)
![static void ioport_write(int index, uint32_t address, uint32_t data)
{
static IOPortWriteFunc *default_func[3] = {
default_ioport_writeb,
default_ioport_writew,
default_ioport_writel
};
IOPortWriteFunc *func = ioport_write_table[index][address];
if (!func)
func = default_func[index];
func(ioport_opaque[address], address, data);
}
ioport_write_table
2009 8 13 246](https://image.slidesharecdn.com/kernel-vm-1st-oza-fixed-090812135434-phpapp02/85/Linux-KVM-246-320.jpg)
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Linux KVM のコードを追いかけてみよう
- 1. Linux KVM /VM 1 by Tsuyoshi Ozawa, softlab@univ. of Tsukuba. Twitter: oza_x86 2009 8 13 1
- 2. 2009 8 13 2
- 3. 1. VMM 2. Intel-VT 3. Linux KVM KVM 2009 8 13 3
- 4. VMM 2009 8 13 4
- 5. VMM 2009 8 13 5
- 6. Virtual Machine Monitor 2009 8 13 6
- 7. Virtual Machine Monitor 1. 2. (OS) 2009 8 13 7
- 8. VMM 2009 8 13 8
- 9. 2009 8 13 9
- 10. 2009 8 13 10
- 11. Qemu 2009 8 13 11
- 12. 2009 8 13 12
- 13. 2009 8 13 13
- 14. Qemu 2009 8 13 14
- 15. 2009 8 13 15
- 16. CPU 2009 8 13 16
- 17. Main Memory ... ALU movl %eax %ebx ... 2009 8 13 17
- 18. Main Memory ... ALU movl %eax %ebx ... fetch 2009 8 13 18
- 19. Qemu ... 2009 8 13 19
- 20. Qemu Main Memory ... ALU movl %eax %ebx ... fetch 2009 8 13 20
- 21. opcode = mem[pc]; execute(opcode); 2009 8 13 21
- 22. mov opcode = mem[pc]; execute(opcode); jmp 2009 8 13 22
- 23. • 2009 8 13 23
- 24. 2009 8 13 24
- 25. opcode[0..N] = mem[pc]; mid_ops=compile(opcode); execute(mid_ops); 2009 8 13 25
- 26. opcode[0..N] = mem[pc]; mid_ops=compile(opcode); execute(mid_ops); 2009 8 13 26
- 27. opcode[0..N] = mem[pc]; mid_ops=compile(opcode); execute(mid_ops); 2009 8 13 27
- 28. 2009 8 13 28
- 29. 2009 8 13 29
- 30. • • • 2009 8 13 30
- 31. 2009 8 13 31
- 32. 2009 8 13 32
- 33. VMM 2009 8 13 33
- 34. KVM 2009 8 13 34
- 35. • 2009 8 13 35
- 36. .section .data message: .ascii "hello,gas!n" .section .text .global _start _start: movl $4,%eax movl $1,%ebx movl $message,%ecx movl $12,%edx int $0x80 2009 8 13 36
- 37. ./a.out hello,gas! 2009 8 13 37
- 38. Hello world 2009 8 13 38
- 39. printf(“HelloWorld¥n”) 2009 8 13 39
- 40. printf 2009 8 13 40
- 41. 2009 8 13 41
- 42. 2009 8 13 42
- 43. write 2009 8 13 43
- 44. write out 2009 8 13 44
- 45. .section .data message: .ascii "hello,gas!n" .section .text .global _start _start: movl $4,%eax movl $1,%ebx movl $message,%ecx out movl $12,%edx int $0x80 2009 8 13 45
- 46. ... outb %ax ... 2009 8 13 46
- 47. Program Display CPU outb 2009 8 13 47
- 48. hello,gas! 2009 8 13 48
- 49. • 2009 8 13 49
- 50. • VM 2009 8 13 50
- 51. .section .data message: .ascii "hello,gas!n" .section .text .global _start _start: movl $4,%eax movl $1,%ebx movl $message,%ecx out movl $12,%edx int $0x80 2009 8 13 51
- 52. ... outb $hogehoge ... 2009 8 13 52
- 53. hello,gas! 2009 8 13 53
- 54. OS . 2009 8 13 54
- 55. VM Virtual Program Display VirtualCPU outb 2009 8 13 55
- 56. VM Program Real Display VirtualCPU outb 2009 8 13 56
- 57. hello,gas! on host system?! 2009 8 13 57
- 58. 2009 8 13 58
- 59. 2009 8 13 59
- 60. 2009 8 13 60
- 61. 2009 8 13 61
- 62. VM out Virtual Program Display CPU 2009 8 13 62
- 63. VM out Virtual Program Display CPU outb 2009 8 13 63
- 64. VM out 2009 8 13 64
- 65. Emu Code trap CPU 2009 8 13 65
- 66. Emu Code CPU handle 2009 8 13 66
- 67. VM out Emu ret Code CPU 2009 8 13 67
- 68. VM out ack Virtual Program Display CPU 2009 8 13 68
- 69. VM out out 2009 8 13 69
- 70. 2009 8 13 70
- 71. 2009 8 13 71
- 72. x86 2009 8 13 72
- 73. ? 2009 8 13 73
- 74. 2009 8 13 74
- 75. 2009 8 13 75
- 76. ? 2009 8 13 76
- 77. 2009 8 13 77
- 78. x86 ? 2009 8 13 78
- 79. ... ? 2009 8 13 79
- 80. 2009 8 13 80
- 81. 2009 8 13 81
- 82. x86 • • Hypervisor Call • Xen 2009 8 13 82
- 83. x86 • • LilyVM 2009 8 13 83
- 84. x86 • • (JIT ) • VMWare 2009 8 13 84
- 85. 2009 8 13 85
- 86. Intel ( AMD-V ) 2009 8 13 86
- 87. Intel-VT 2009 8 13 87
- 88. CPU ? 2009 8 13 88
- 89. User Privilege 2009 8 13 89
- 90. User Privilege 2009 8 13 90
- 91. 2009 8 13 91
- 92. User User warp Privilege Privilege 2009 8 13 92
- 93. 2009 8 13 93
- 94. User User Privilege Privilege 2009 8 13 94
- 95. User User Privilege Privilege 2009 8 13 95
- 96. User User Privilege Privilege trap 2009 8 13 96
- 97. User User Privilege Privilege Intel-VT 2009 8 13 97
- 98. User Privilege 2009 8 13 98
- 99. VMX-Root Mode (VM ) 2009 8 13 99
- 100. User Privilege 2009 8 13 100
- 101. VMX-non root Mode ( ) 2009 8 13 101
- 102. VMX non Root Mode 2009 8 13 102
- 103. User User Privilege Privilege 2009 8 13 103
- 104. vmlaunch vmresume 2009 8 13 104
- 105. KVM 2009 8 13 105
- 106. KVM 2009 8 13 106
- 107. Kernel-based Virtul Machine 2009 8 13 107
- 108. KVM 2009 8 13 108
- 109. KVM • •Intel-VT • •Qemu • •Linux • •Linux 2009 8 13 109
- 110. KVM • •Intel-VT • •Qemu • •Linux • •Linux KVM 2009 8 13 110
- 111. KVM • •VM • • • • OS 2009 8 13 111
- 112. 2009 8 13 112
- 113. 2009 8 13 113
- 114. Main loop 2009 8 13 114
- 115. KVM 2009 8 13 115
- 116. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 116
- 117. 2009 8 13 117
- 118. VMX VMX non Root Root Mode Mode 2009 8 13 118
- 119. 2009 8 13 119
- 120. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 120
- 121. VMX non Root Mode 2009 8 13 121
- 122. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 122
- 123. User Qemu KVM Program Qemu Linux Guest KVM Kernel Kernel 2009 8 13 123
- 124. ./qemu -hda disk1.img (-hda ) 2009 8 13 124
- 125. User Qemu Program $ ./qemu -hda disk1 Linux Guest KVM Kernel Kernel 2009 8 13 125
- 126. User Qemu Program Qemu Linux Guest KVM Kernel Kernel 2009 8 13 126
- 127. Qemu 2009 8 13 127
- 128. User Qemu Program IOCTL Linux Guest KVM Kernel Kernel 2009 8 13 128
- 129. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 129
- 130. 2009 8 13 130
- 131. 2009 8 13 131
- 132. vmlaunch vmresume 2009 8 13 132
- 133. VMX non Root Mode 2009 8 13 133
- 134. User Qemu Program Linux Guest KVM VT Kernel Kernel 2009 8 13 134
- 135. 2009 8 13 135
- 136. vmlaunch vmresume 2009 8 13 136
- 137. User Qemu Program vmlaunch / vmresume Linux Guest KVM Kernel Kernel 2009 8 13 137
- 138. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 138
- 139. VMX non root Mode 2009 8 13 139
- 140. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 140
- 141. 2009 8 13 141
- 142. VMX non Root Mode IO 2009 8 13 142
- 143. 2009 8 13 143
- 144. outb %ax 2009 8 13 144
- 145. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 145
- 146. User Qemu Program Linux Guest KVM Kernel Kernel outb %ax 2009 8 13 146
- 147. VMX Root Mode 2009 8 13 147
- 148. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 148
- 149. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 149
- 150. 2009 8 13 150
- 151. Qemu 2009 8 13 151
- 152. User Qemu Program IOCTL return Linux Guest KVM Kernel Kernel 2009 8 13 152
- 153. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 153
- 154. User Qemu Program io Linux Guest KVM Kernel Kernel 2009 8 13 154
- 155. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 155
- 156. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 156
- 157. 2009 8 13 157
- 158. IOCTL CPU 2009 8 13 158
- 159. User Qemu Program IOCTL Linux Guest KVM Kernel Kernel 2009 8 13 159
- 160. 2009 8 13 160
- 161. ... 2009 8 13 161
- 162. User Qemu Program IOCTL Linux Guest KVM Kernel Kernel vmlaunch vmresume 2009 8 13 162
- 163. 2009 8 13 163
- 164. 2009 8 13 164
- 165. KVM kvm-85 2009 8 13 165
- 166. 2009 8 13 166
- 167. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 167
- 168. Qemu 2009 8 13 168
- 169. $./qemu -hda disk1 ... 2009 8 13 169
- 170. qemu/vl.c main.c 2009 8 13 170
- 171. 4439 int 4440 { main (int argc, char **argv, char **envp) // . Shadow page table . 5425 kvm_qemu_create_context() // 5493 kvm_init(smp_cpus); ... // qemu/hw/pc.c 5554 machine->init(ram_size, vga_ram_size, boot_devices, 5555 kernel_filename, kernel_cmdline, 5556 initrd_filename, cpu_model); ... ... 5742 main_loop(); ... 5747 } 2009 8 13 171
- 172. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 172
- 173. User Qemu Program Qemu Linux Guest KVM Kernel Kernel 2009 8 13 173
- 174. - •machine->init • • qemu/hw/pc.c pc_init1 2009 8 13 174
- 175. 2009 8 13 175
- 176. 2009 8 13 176
- 177. pc_init1 pc_new_cpu cpu_init = cpu_x86_init kvm_init_cpu pthread_create ap_main_loop kvm_main_loop_cpu 2009 8 13 177
- 178. 2009 8 13 178
- 179. 2009 8 13 179
- 180. User Qemu Program IOCTL Linux Guest KVM Kernel Kernel 2009 8 13 180
- 181. IOCTL 2009 8 13 181
- 182. ... qemu/kvm-all.c kvm_cpu_exec 2009 8 13 182
- 183. 378 static int kvm_main_loop_cpu (CPUState *env) 379 { 394 while (1) { 395 while (!has_work(env)) 396 kvm_main_loop_wait(env, 1000); 397 if (env->interrupt_request & (CPU_INTERRUPT_HARD | CPU_INTERRUPT_NMI)) 398 env->halted = 0; // . .... 404 } 405 if (!env->halted && !env->kvm_cpu_state.init) { 406 kvm_cpu_exec(env); // } } 413 } 2009 8 13 183
- 184. int kvm_cpu_exec(){ ... 461 ret = kvm_vcpu_ioctl(env, KVM_RUN, 0); 478 switch (run->exit_reason) { 479 case KVM_EXIT_IO: 481 ret = kvm_handle_io(env, run->io.port, 482 (uint8_t *)run + run>io.data_offset, 483 run->io.direction, 484 run->io.size, 485 run->io.count); 486 break; case KVM_EXIT_MMIO: .... ... 2009 8 13 184
- 185. 648 int kvm_vcpu_ioctl(CPUState *env, int type, ...) 649 { 658 ret = ioctl(env->kvm_fd, type, arg); 659 if (ret == -1) 660 ret = -errno; 661 662 return ret; 663 } 2009 8 13 185
- 186. 2009 8 13 186
- 187. IOCTL 2009 8 13 187
- 188. User Qemu Program IOCTL Linux Guest KVM Kernel Kernel 2009 8 13 188
- 189. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 189
- 190. 2009 8 13 190
- 191. 2009 8 13 191
- 192. IOCTL 2009 8 13 192
- 193. IOCTL 2009 8 13 193
- 194. 2009 8 13 194
- 195. static struct file_operations kvm_vcpu_fops = { .release = kvm_vcpu_release, .unlocked_ioctl = kvm_vcpu_ioctl, .compat_ioctl = kvm_vcpu_ioctl, .mmap = kvm_vcpu_mmap, }; 2009 8 13 195
- 196. // file->f_op = kvm_vcpu_fops; 2009 8 13 196
- 197. kvm_vcpu_ioctl 2009 8 13 197
- 198. static long kvm_vcpu_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) { switch (ioctl) { case KVM_RUN: r = kvm_arch_vcpu_ioctl_run(vcpu, vcpu->run); break; .... } 2009 8 13 198
- 199. VMX non Root Mode 2009 8 13 199
- 200. User Qemu Program Linux Guest KVM VT Kernel Kernel 2009 8 13 200
- 201. ... 2009 8 13 201
- 202. kvm_arch_vcpu_ioctl_run __vcpu_run vcpu_enter_guest vmx_vcpu_run 2009 8 13 202
- 203. vmx_vcpu_run kernel/x86/vmx.c 2009 8 13 203
- 204. User Qemu Program vmlaunch / vmresume Linux Guest KVM Kernel Kernel 2009 8 13 204
- 205. 2009 8 13 205
- 206. 2009 8 13 206
- 207. include/asm-x86/vmx.h #define ASM_VMX_VMLAUNCH ".byte 0x0f, 0x01, 0xc2" #define ASM_VMX_VMRESUME ".byte 0x0f, 0x01, 0xc3" 2009 8 13 207
- 208. 2009 8 13 208
- 209. vmlaunch/vmresume 2009 8 13 209
- 210. User Qemu Program vmlaunch / vmresume Linux Guest KVM Kernel Kernel 2009 8 13 210
- 211. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 211
- 212. VMX non-root mode 2009 8 13 212
- 213. 2009 8 13 213
- 214. VMX non Root Mode IO 2009 8 13 214
- 215. 2009 8 13 215
- 216. 2009 8 13 216
- 217. outb %ax 2009 8 13 217
- 218. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 218
- 219. User Qemu Program Linux Guest KVM Kernel Kernel outb %ax 2009 8 13 219
- 220. 2009 8 13 220
- 221. "jne .Llaunched nt" __ex(ASM_VMX_VMLAUNCH) "nt" "jmp .Lkvm_vmx_return nt" ".Llaunched: " __ex(ASM_VMX_VMRESUME) "nt" ".Lkvm_vmx_return: " vmlaunch /* */ vmresume ... ... 2009 8 13 221
- 222. "jne .Llaunched nt" __ex(ASM_VMX_VMLAUNCH) "nt" "jmp .Lkvm_vmx_return nt" ".Llaunched: " __ex(ASM_VMX_VMRESUME) "nt" ".Lkvm_vmx_return: " /* */ ... 2009 8 13 222
- 223. 2009 8 13 223
- 224. 2009 8 13 224
- 225. out 2009 8 13 225
- 226. out in . 2009 8 13 226
- 227. Intel-VT 2009 8 13 227
- 228. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 228
- 229. 2009 8 13 229
- 230. Qemu 2009 8 13 230
- 231. User Qemu Program IOCTL return Linux Guest KVM Kernel Kernel 2009 8 13 231
- 232. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 232
- 233. int kvm_cpu_exec(){ ... 461 ret = kvm_vcpu_ioctl(env, KVM_RUN, 0); 478 switch (run->exit_reason) { 479 case KVM_EXIT_IO: 481 ret = kvm_handle_io(env, run->io.port, 482 (uint8_t *)run + run>io.data_offset, 483 run->io.direction, 484 run->io.size, 485 run->io.count); 486 break; case KVM_EXIT_MMIO: .... ... 2009 8 13 233
- 234. outb 2009 8 13 234
- 235. int kvm_cpu_exec(){ ... // 461 ret = kvm_vcpu_ioctl(env, KVM_RUN, 0); 478 switch (run->exit_reason) { 479 case KVM_EXIT_IO: 481 ret = kvm_handle_io(env, run->io.port, 482 (uint8_t *)run + run>io.data_offset, 483 run->io.direction, 484 run->io.size, 485 run->io.count); 486 break; case KVM_EXIT_MMIO: outb .... ... 2009 8 13 235
- 236. 2009 8 13 236
- 237. IO 2009 8 13 237
- 238. User Qemu Program io Linux Guest KVM Kernel Kernel 2009 8 13 238
- 239. 2009 8 13 239
- 240. out 2009 8 13 240
- 241. outb %al 2009 8 13 241
- 242. outb %al 2009 8 13 242
- 243. ( ) 2009 8 13 243
- 244. int kvm_cpu_exec(){ ... // 461 ret = kvm_vcpu_ioctl(env, KVM_RUN, 0); 478 switch (run->exit_reason) { 479 case KVM_EXIT_IO: 481 ret = kvm_handle_io(env, run->io.port, 482 (uint8_t *)run + run>io.data_offset, 483 run->io.direction, 484 run->io.size, 485 run->io.count); 486 break; case KVM_EXIT_MMIO: .... ... 2009 8 13 244
- 245. kvm_handle_io cpu_outb ioport_write 2009 8 13 245
- 246. static void ioport_write(int index, uint32_t address, uint32_t data) { static IOPortWriteFunc *default_func[3] = { default_ioport_writeb, default_ioport_writew, default_ioport_writel }; IOPortWriteFunc *func = ioport_write_table[index][address]; if (!func) func = default_func[index]; func(ioport_opaque[address], address, data); } ioport_write_table 2009 8 13 246
- 247. ( ) 2009 8 13 247
- 248. User Qemu Program io Linux Guest KVM Kernel Kernel 2009 8 13 248
- 249. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 249
- 250. User Qemu Program Linux Guest KVM Kernel Kernel 2009 8 13 250
- 251. 2009 8 13 251
- 252. IOCTL CPU 2009 8 13 252
- 253. User Qemu Program IOCTL Linux Guest KVM Kernel Kernel 2009 8 13 253
- 254. 2009 8 13 254
- 255. ... 2009 8 13 255
- 256. User Qemu Program IOCTL Linux Guest KVM Kernel Kernel vmlaunch 2009 8 13 vmresume 256
- 257. 2009 8 13 257
- 258. 378 static int kvm_main_loop_cpu(CPUState *env) 379 { 394 while (1) { 395 while (!has_work(env)) 396 kvm_main_loop_wait(env, 1000); 397 if (env->interrupt_request & (CPU_INTERRUPT_HARD | CPU_INTERRUPT_NMI)) 398 env->halted = 0; // . .... 404 } 405 if (!env->halted && !env->kvm_cpu_state.init) { 406 kvm_cpu_exec(env); // } } 413 } 2009 8 13 258
- 259. 2009 8 13 259
- 260. Twitter 2009 8 13 260