1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
|
/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/linkage.h>
#include <asm/asm.h>
#include <asm/bitsperlong.h>
#include <asm/kvm_vcpu_regs.h>
#include <asm/nospec-branch.h>
#define WORD_SIZE (BITS_PER_LONG / 8)
#define VCPU_RAX __VCPU_REGS_RAX * WORD_SIZE
#define VCPU_RCX __VCPU_REGS_RCX * WORD_SIZE
#define VCPU_RDX __VCPU_REGS_RDX * WORD_SIZE
#define VCPU_RBX __VCPU_REGS_RBX * WORD_SIZE
/* Intentionally omit RSP as it's context switched by hardware */
#define VCPU_RBP __VCPU_REGS_RBP * WORD_SIZE
#define VCPU_RSI __VCPU_REGS_RSI * WORD_SIZE
#define VCPU_RDI __VCPU_REGS_RDI * WORD_SIZE
#ifdef CONFIG_X86_64
#define VCPU_R8 __VCPU_REGS_R8 * WORD_SIZE
#define VCPU_R9 __VCPU_REGS_R9 * WORD_SIZE
#define VCPU_R10 __VCPU_REGS_R10 * WORD_SIZE
#define VCPU_R11 __VCPU_REGS_R11 * WORD_SIZE
#define VCPU_R12 __VCPU_REGS_R12 * WORD_SIZE
#define VCPU_R13 __VCPU_REGS_R13 * WORD_SIZE
#define VCPU_R14 __VCPU_REGS_R14 * WORD_SIZE
#define VCPU_R15 __VCPU_REGS_R15 * WORD_SIZE
#endif
.text
/**
* vmx_vmenter - VM-Enter the current loaded VMCS
*
* %RFLAGS.ZF: !VMCS.LAUNCHED, i.e. controls VMLAUNCH vs. VMRESUME
*
* Returns:
* %RFLAGS.CF is set on VM-Fail Invalid
* %RFLAGS.ZF is set on VM-Fail Valid
* %RFLAGS.{CF,ZF} are cleared on VM-Success, i.e. VM-Exit
*
* Note that VMRESUME/VMLAUNCH fall-through and return directly if
* they VM-Fail, whereas a successful VM-Enter + VM-Exit will jump
* to vmx_vmexit.
*/
SYM_FUNC_START(vmx_vmenter)
/* EFLAGS.ZF is set if VMCS.LAUNCHED == 0 */
je 2f
1: vmresume
ret
2: vmlaunch
ret
3: cmpb $0, kvm_rebooting
je 4f
ret
4: ud2
_ASM_EXTABLE(1b, 3b)
_ASM_EXTABLE(2b, 3b)
SYM_FUNC_END(vmx_vmenter)
/**
* vmx_vmexit - Handle a VMX VM-Exit
*
* Returns:
* %RFLAGS.{CF,ZF} are cleared on VM-Success, i.e. VM-Exit
*
* This is vmx_vmenter's partner in crime. On a VM-Exit, control will jump
* here after hardware loads the host's state, i.e. this is the destination
* referred to by VMCS.HOST_RIP.
*/
SYM_FUNC_START(vmx_vmexit)
#ifdef CONFIG_RETPOLINE
ALTERNATIVE "jmp .Lvmexit_skip_rsb", "", X86_FEATURE_RETPOLINE
/* Preserve guest's RAX, it's used to stuff the RSB. */
push %_ASM_AX
/* IMPORTANT: Stuff the RSB immediately after VM-Exit, before RET! */
FILL_RETURN_BUFFER %_ASM_AX, RSB_CLEAR_LOOPS, X86_FEATURE_RETPOLINE
pop %_ASM_AX
.Lvmexit_skip_rsb:
#endif
ret
SYM_FUNC_END(vmx_vmexit)
/**
* __vmx_vcpu_run - Run a vCPU via a transition to VMX guest mode
* @vmx: struct vcpu_vmx * (forwarded to vmx_update_host_rsp)
* @regs: unsigned long * (to guest registers)
* @launched: %true if the VMCS has been launched
*
* Returns:
* 0 on VM-Exit, 1 on VM-Fail
*/
SYM_FUNC_START(__vmx_vcpu_run)
push %_ASM_BP
mov %_ASM_SP, %_ASM_BP
#ifdef CONFIG_X86_64
push %r15
push %r14
push %r13
push %r12
#else
push %edi
push %esi
#endif
push %_ASM_BX
/*
* Save @regs, _ASM_ARG2 may be modified by vmx_update_host_rsp() and
* @regs is needed after VM-Exit to save the guest's register values.
*/
push %_ASM_ARG2
/* Copy @launched to BL, _ASM_ARG3 is volatile. */
mov %_ASM_ARG3B, %bl
/* Adjust RSP to account for the CALL to vmx_vmenter(). */
lea -WORD_SIZE(%_ASM_SP), %_ASM_ARG2
call vmx_update_host_rsp
/* Load @regs to RAX. */
mov (%_ASM_SP), %_ASM_AX
/* Check if vmlaunch or vmresume is needed */
cmpb $0, %bl
/* Load guest registers. Don't clobber flags. */
mov VCPU_RCX(%_ASM_AX), %_ASM_CX
mov VCPU_RDX(%_ASM_AX), %_ASM_DX
mov VCPU_RBX(%_ASM_AX), %_ASM_BX
mov VCPU_RBP(%_ASM_AX), %_ASM_BP
mov VCPU_RSI(%_ASM_AX), %_ASM_SI
mov VCPU_RDI(%_ASM_AX), %_ASM_DI
#ifdef CONFIG_X86_64
mov VCPU_R8 (%_ASM_AX), %r8
mov VCPU_R9 (%_ASM_AX), %r9
mov VCPU_R10(%_ASM_AX), %r10
mov VCPU_R11(%_ASM_AX), %r11
mov VCPU_R12(%_ASM_AX), %r12
mov VCPU_R13(%_ASM_AX), %r13
mov VCPU_R14(%_ASM_AX), %r14
mov VCPU_R15(%_ASM_AX), %r15
#endif
/* Load guest RAX. This kills the @regs pointer! */
mov VCPU_RAX(%_ASM_AX), %_ASM_AX
/* Enter guest mode */
call vmx_vmenter
/* Jump on VM-Fail. */
jbe 2f
/* Temporarily save guest's RAX. */
push %_ASM_AX
/* Reload @regs to RAX. */
mov WORD_SIZE(%_ASM_SP), %_ASM_AX
/* Save all guest registers, including RAX from the stack */
__ASM_SIZE(pop) VCPU_RAX(%_ASM_AX)
mov %_ASM_CX, VCPU_RCX(%_ASM_AX)
mov %_ASM_DX, VCPU_RDX(%_ASM_AX)
mov %_ASM_BX, VCPU_RBX(%_ASM_AX)
mov %_ASM_BP, VCPU_RBP(%_ASM_AX)
mov %_ASM_SI, VCPU_RSI(%_ASM_AX)
mov %_ASM_DI, VCPU_RDI(%_ASM_AX)
#ifdef CONFIG_X86_64
mov %r8, VCPU_R8 (%_ASM_AX)
mov %r9, VCPU_R9 (%_ASM_AX)
mov %r10, VCPU_R10(%_ASM_AX)
mov %r11, VCPU_R11(%_ASM_AX)
mov %r12, VCPU_R12(%_ASM_AX)
mov %r13, VCPU_R13(%_ASM_AX)
mov %r14, VCPU_R14(%_ASM_AX)
mov %r15, VCPU_R15(%_ASM_AX)
#endif
/* Clear RAX to indicate VM-Exit (as opposed to VM-Fail). */
xor %eax, %eax
/*
* Clear all general purpose registers except RSP and RAX to prevent
* speculative use of the guest's values, even those that are reloaded
* via the stack. In theory, an L1 cache miss when restoring registers
* could lead to speculative execution with the guest's values.
* Zeroing XORs are dirt cheap, i.e. the extra paranoia is essentially
* free. RSP and RAX are exempt as RSP is restored by hardware during
* VM-Exit and RAX is explicitly loaded with 0 or 1 to return VM-Fail.
*/
1: xor %ecx, %ecx
xor %edx, %edx
xor %ebx, %ebx
xor %ebp, %ebp
xor %esi, %esi
xor %edi, %edi
#ifdef CONFIG_X86_64
xor %r8d, %r8d
xor %r9d, %r9d
xor %r10d, %r10d
xor %r11d, %r11d
xor %r12d, %r12d
xor %r13d, %r13d
xor %r14d, %r14d
xor %r15d, %r15d
#endif
/* "POP" @regs. */
add $WORD_SIZE, %_ASM_SP
pop %_ASM_BX
#ifdef CONFIG_X86_64
pop %r12
pop %r13
pop %r14
pop %r15
#else
pop %esi
pop %edi
#endif
pop %_ASM_BP
ret
/* VM-Fail. Out-of-line to avoid a taken Jcc after VM-Exit. */
2: mov $1, %eax
jmp 1b
SYM_FUNC_END(__vmx_vcpu_run)
/**
* vmread_error_trampoline - Trampoline from inline asm to vmread_error()
* @field: VMCS field encoding that failed
* @fault: %true if the VMREAD faulted, %false if it failed
* Save and restore volatile registers across a call to vmread_error(). Note,
* all parameters are passed on the stack.
*/
SYM_FUNC_START(vmread_error_trampoline)
push %_ASM_BP
mov %_ASM_SP, %_ASM_BP
push %_ASM_AX
push %_ASM_CX
push %_ASM_DX
#ifdef CONFIG_X86_64
push %rdi
push %rsi
push %r8
push %r9
push %r10
push %r11
#endif
#ifdef CONFIG_X86_64
/* Load @field and @fault to arg1 and arg2 respectively. */
mov 3*WORD_SIZE(%rbp), %_ASM_ARG2
mov 2*WORD_SIZE(%rbp), %_ASM_ARG1
#else
/* Parameters are passed on the stack for 32-bit (see asmlinkage). */
push 3*WORD_SIZE(%ebp)
push 2*WORD_SIZE(%ebp)
#endif
call vmread_error
#ifndef CONFIG_X86_64
add $8, %esp
#endif
/* Zero out @fault, which will be popped into the result register. */
_ASM_MOV $0, 3*WORD_SIZE(%_ASM_BP)
#ifdef CONFIG_X86_64
pop %r11
pop %r10
pop %r9
pop %r8
pop %rsi
pop %rdi
#endif
pop %_ASM_DX
pop %_ASM_CX
pop %_ASM_AX
pop %_ASM_BP
ret
SYM_FUNC_END(vmread_error_trampoline)
|
