1/* SPDX-License-Identifier: GPL-2.0 */ 2#include <linux/linkage.h> 3#include <asm/asm.h> 4#include <asm/bitsperlong.h> 5#include <asm/kvm_vcpu_regs.h> 6#include <asm/nospec-branch.h> 7#include <asm/segment.h> 8 9#define WORD_SIZE (BITS_PER_LONG / 8) 10 11#define VCPU_RAX __VCPU_REGS_RAX * WORD_SIZE 12#define VCPU_RCX __VCPU_REGS_RCX * WORD_SIZE 13#define VCPU_RDX __VCPU_REGS_RDX * WORD_SIZE 14#define VCPU_RBX __VCPU_REGS_RBX * WORD_SIZE 15/* Intentionally omit RSP as it's context switched by hardware */ 16#define VCPU_RBP __VCPU_REGS_RBP * WORD_SIZE 17#define VCPU_RSI __VCPU_REGS_RSI * WORD_SIZE 18#define VCPU_RDI __VCPU_REGS_RDI * WORD_SIZE 19 20#ifdef CONFIG_X86_64 21#define VCPU_R8 __VCPU_REGS_R8 * WORD_SIZE 22#define VCPU_R9 __VCPU_REGS_R9 * WORD_SIZE 23#define VCPU_R10 __VCPU_REGS_R10 * WORD_SIZE 24#define VCPU_R11 __VCPU_REGS_R11 * WORD_SIZE 25#define VCPU_R12 __VCPU_REGS_R12 * WORD_SIZE 26#define VCPU_R13 __VCPU_REGS_R13 * WORD_SIZE 27#define VCPU_R14 __VCPU_REGS_R14 * WORD_SIZE 28#define VCPU_R15 __VCPU_REGS_R15 * WORD_SIZE 29#endif 30 31.section .noinstr.text, "ax" 32 33/** 34 * vmx_vmenter - VM-Enter the current loaded VMCS 35 * 36 * %RFLAGS.ZF: !VMCS.LAUNCHED, i.e. controls VMLAUNCH vs. VMRESUME 37 * 38 * Returns: 39 * %RFLAGS.CF is set on VM-Fail Invalid 40 * %RFLAGS.ZF is set on VM-Fail Valid 41 * %RFLAGS.{CF,ZF} are cleared on VM-Success, i.e. VM-Exit 42 * 43 * Note that VMRESUME/VMLAUNCH fall-through and return directly if 44 * they VM-Fail, whereas a successful VM-Enter + VM-Exit will jump 45 * to vmx_vmexit. 46 */ 47SYM_FUNC_START(vmx_vmenter) 48 /* EFLAGS.ZF is set if VMCS.LAUNCHED == 0 */ 49 je 2f 50 511: vmresume 52 ret 53 542: vmlaunch 55 ret 56 573: cmpb $0, kvm_rebooting 58 je 4f 59 ret 604: ud2 61 62 _ASM_EXTABLE(1b, 3b) 63 _ASM_EXTABLE(2b, 3b) 64 65SYM_FUNC_END(vmx_vmenter) 66 67/** 68 * vmx_vmexit - Handle a VMX VM-Exit 69 * 70 * Returns: 71 * %RFLAGS.{CF,ZF} are cleared on VM-Success, i.e. VM-Exit 72 * 73 * This is vmx_vmenter's partner in crime. On a VM-Exit, control will jump 74 * here after hardware loads the host's state, i.e. this is the destination 75 * referred to by VMCS.HOST_RIP. 76 */ 77SYM_FUNC_START(vmx_vmexit) 78#ifdef CONFIG_RETPOLINE 79 ALTERNATIVE "jmp .Lvmexit_skip_rsb", "", X86_FEATURE_RETPOLINE 80 /* Preserve guest's RAX, it's used to stuff the RSB. */ 81 push %_ASM_AX 82 83 /* IMPORTANT: Stuff the RSB immediately after VM-Exit, before RET! */ 84 FILL_RETURN_BUFFER %_ASM_AX, RSB_CLEAR_LOOPS, X86_FEATURE_RETPOLINE 85 86 /* Clear RFLAGS.CF and RFLAGS.ZF to preserve VM-Exit, i.e. !VM-Fail. */ 87 or $1, %_ASM_AX 88 89 pop %_ASM_AX 90.Lvmexit_skip_rsb: 91#endif 92 ret 93SYM_FUNC_END(vmx_vmexit) 94 95/** 96 * __vmx_vcpu_run - Run a vCPU via a transition to VMX guest mode 97 * @vmx: struct vcpu_vmx * (forwarded to vmx_update_host_rsp) 98 * @regs: unsigned long * (to guest registers) 99 * @launched: %true if the VMCS has been launched 100 * 101 * Returns: 102 * 0 on VM-Exit, 1 on VM-Fail 103 */ 104SYM_FUNC_START(__vmx_vcpu_run) 105 push %_ASM_BP 106 mov %_ASM_SP, %_ASM_BP 107#ifdef CONFIG_X86_64 108 push %r15 109 push %r14 110 push %r13 111 push %r12 112#else 113 push %edi 114 push %esi 115#endif 116 push %_ASM_BX 117 118 /* 119 * Save @regs, _ASM_ARG2 may be modified by vmx_update_host_rsp() and 120 * @regs is needed after VM-Exit to save the guest's register values. 121 */ 122 push %_ASM_ARG2 123 124 /* Copy @launched to BL, _ASM_ARG3 is volatile. */ 125 mov %_ASM_ARG3B, %bl 126 127 /* Adjust RSP to account for the CALL to vmx_vmenter(). */ 128 lea -WORD_SIZE(%_ASM_SP), %_ASM_ARG2 129 call vmx_update_host_rsp 130 131 /* Load @regs to RAX. */ 132 mov (%_ASM_SP), %_ASM_AX 133 134 /* Check if vmlaunch or vmresume is needed */ 135 cmpb $0, %bl 136 137 /* Load guest registers. Don't clobber flags. */ 138 mov VCPU_RCX(%_ASM_AX), %_ASM_CX 139 mov VCPU_RDX(%_ASM_AX), %_ASM_DX 140 mov VCPU_RBX(%_ASM_AX), %_ASM_BX 141 mov VCPU_RBP(%_ASM_AX), %_ASM_BP 142 mov VCPU_RSI(%_ASM_AX), %_ASM_SI 143 mov VCPU_RDI(%_ASM_AX), %_ASM_DI 144#ifdef CONFIG_X86_64 145 mov VCPU_R8 (%_ASM_AX), %r8 146 mov VCPU_R9 (%_ASM_AX), %r9 147 mov VCPU_R10(%_ASM_AX), %r10 148 mov VCPU_R11(%_ASM_AX), %r11 149 mov VCPU_R12(%_ASM_AX), %r12 150 mov VCPU_R13(%_ASM_AX), %r13 151 mov VCPU_R14(%_ASM_AX), %r14 152 mov VCPU_R15(%_ASM_AX), %r15 153#endif 154 /* Load guest RAX. This kills the @regs pointer! */ 155 mov VCPU_RAX(%_ASM_AX), %_ASM_AX 156 157 /* Enter guest mode */ 158 call vmx_vmenter 159 160 /* Jump on VM-Fail. */ 161 jbe 2f 162 163 /* Temporarily save guest's RAX. */ 164 push %_ASM_AX 165 166 /* Reload @regs to RAX. */ 167 mov WORD_SIZE(%_ASM_SP), %_ASM_AX 168 169 /* Save all guest registers, including RAX from the stack */ 170 pop VCPU_RAX(%_ASM_AX) 171 mov %_ASM_CX, VCPU_RCX(%_ASM_AX) 172 mov %_ASM_DX, VCPU_RDX(%_ASM_AX) 173 mov %_ASM_BX, VCPU_RBX(%_ASM_AX) 174 mov %_ASM_BP, VCPU_RBP(%_ASM_AX) 175 mov %_ASM_SI, VCPU_RSI(%_ASM_AX) 176 mov %_ASM_DI, VCPU_RDI(%_ASM_AX) 177#ifdef CONFIG_X86_64 178 mov %r8, VCPU_R8 (%_ASM_AX) 179 mov %r9, VCPU_R9 (%_ASM_AX) 180 mov %r10, VCPU_R10(%_ASM_AX) 181 mov %r11, VCPU_R11(%_ASM_AX) 182 mov %r12, VCPU_R12(%_ASM_AX) 183 mov %r13, VCPU_R13(%_ASM_AX) 184 mov %r14, VCPU_R14(%_ASM_AX) 185 mov %r15, VCPU_R15(%_ASM_AX) 186#endif 187 188 /* Clear RAX to indicate VM-Exit (as opposed to VM-Fail). */ 189 xor %eax, %eax 190 191 /* 192 * Clear all general purpose registers except RSP and RAX to prevent 193 * speculative use of the guest's values, even those that are reloaded 194 * via the stack. In theory, an L1 cache miss when restoring registers 195 * could lead to speculative execution with the guest's values. 196 * Zeroing XORs are dirt cheap, i.e. the extra paranoia is essentially 197 * free. RSP and RAX are exempt as RSP is restored by hardware during 198 * VM-Exit and RAX is explicitly loaded with 0 or 1 to return VM-Fail. 199 */ 2001: xor %ecx, %ecx 201 xor %edx, %edx 202 xor %ebx, %ebx 203 xor %ebp, %ebp 204 xor %esi, %esi 205 xor %edi, %edi 206#ifdef CONFIG_X86_64 207 xor %r8d, %r8d 208 xor %r9d, %r9d 209 xor %r10d, %r10d 210 xor %r11d, %r11d 211 xor %r12d, %r12d 212 xor %r13d, %r13d 213 xor %r14d, %r14d 214 xor %r15d, %r15d 215#endif 216 217 /* "POP" @regs. */ 218 add $WORD_SIZE, %_ASM_SP 219 pop %_ASM_BX 220 221#ifdef CONFIG_X86_64 222 pop %r12 223 pop %r13 224 pop %r14 225 pop %r15 226#else 227 pop %esi 228 pop %edi 229#endif 230 pop %_ASM_BP 231 ret 232 233 /* VM-Fail. Out-of-line to avoid a taken Jcc after VM-Exit. */ 2342: mov $1, %eax 235 jmp 1b 236SYM_FUNC_END(__vmx_vcpu_run) 237 238 239.section .text, "ax" 240 241/** 242 * vmread_error_trampoline - Trampoline from inline asm to vmread_error() 243 * @field: VMCS field encoding that failed 244 * @fault: %true if the VMREAD faulted, %false if it failed 245 246 * Save and restore volatile registers across a call to vmread_error(). Note, 247 * all parameters are passed on the stack. 248 */ 249SYM_FUNC_START(vmread_error_trampoline) 250 push %_ASM_BP 251 mov %_ASM_SP, %_ASM_BP 252 253 push %_ASM_AX 254 push %_ASM_CX 255 push %_ASM_DX 256#ifdef CONFIG_X86_64 257 push %rdi 258 push %rsi 259 push %r8 260 push %r9 261 push %r10 262 push %r11 263#endif 264#ifdef CONFIG_X86_64 265 /* Load @field and @fault to arg1 and arg2 respectively. */ 266 mov 3*WORD_SIZE(%rbp), %_ASM_ARG2 267 mov 2*WORD_SIZE(%rbp), %_ASM_ARG1 268#else 269 /* Parameters are passed on the stack for 32-bit (see asmlinkage). */ 270 push 3*WORD_SIZE(%ebp) 271 push 2*WORD_SIZE(%ebp) 272#endif 273 274 call vmread_error 275 276#ifndef CONFIG_X86_64 277 add $8, %esp 278#endif 279 280 /* Zero out @fault, which will be popped into the result register. */ 281 _ASM_MOV $0, 3*WORD_SIZE(%_ASM_BP) 282 283#ifdef CONFIG_X86_64 284 pop %r11 285 pop %r10 286 pop %r9 287 pop %r8 288 pop %rsi 289 pop %rdi 290#endif 291 pop %_ASM_DX 292 pop %_ASM_CX 293 pop %_ASM_AX 294 pop %_ASM_BP 295 296 ret 297SYM_FUNC_END(vmread_error_trampoline) 298 299SYM_FUNC_START(vmx_do_interrupt_nmi_irqoff) 300 /* 301 * Unconditionally create a stack frame, getting the correct RSP on the 302 * stack (for x86-64) would take two instructions anyways, and RBP can 303 * be used to restore RSP to make objtool happy (see below). 304 */ 305 push %_ASM_BP 306 mov %_ASM_SP, %_ASM_BP 307 308#ifdef CONFIG_X86_64 309 /* 310 * Align RSP to a 16-byte boundary (to emulate CPU behavior) before 311 * creating the synthetic interrupt stack frame for the IRQ/NMI. 312 */ 313 and $-16, %rsp 314 push $__KERNEL_DS 315 push %rbp 316#endif 317 pushf 318 push $__KERNEL_CS 319 CALL_NOSPEC _ASM_ARG1 320 321 /* 322 * "Restore" RSP from RBP, even though IRET has already unwound RSP to 323 * the correct value. objtool doesn't know the callee will IRET and, 324 * without the explicit restore, thinks the stack is getting walloped. 325 * Using an unwind hint is problematic due to x86-64's dynamic alignment. 326 */ 327 mov %_ASM_BP, %_ASM_SP 328 pop %_ASM_BP 329 ret 330SYM_FUNC_END(vmx_do_interrupt_nmi_irqoff) 331