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/percpu.h> 8#include <asm/segment.h> 9#include "kvm-asm-offsets.h" 10#include "run_flags.h" 11 12#define WORD_SIZE (BITS_PER_LONG / 8) 13 14#define VCPU_RAX __VCPU_REGS_RAX * WORD_SIZE 15#define VCPU_RCX __VCPU_REGS_RCX * WORD_SIZE 16#define VCPU_RDX __VCPU_REGS_RDX * WORD_SIZE 17#define VCPU_RBX __VCPU_REGS_RBX * WORD_SIZE 18/* Intentionally omit RSP as it's context switched by hardware */ 19#define VCPU_RBP __VCPU_REGS_RBP * WORD_SIZE 20#define VCPU_RSI __VCPU_REGS_RSI * WORD_SIZE 21#define VCPU_RDI __VCPU_REGS_RDI * WORD_SIZE 22 23#ifdef CONFIG_X86_64 24#define VCPU_R8 __VCPU_REGS_R8 * WORD_SIZE 25#define VCPU_R9 __VCPU_REGS_R9 * WORD_SIZE 26#define VCPU_R10 __VCPU_REGS_R10 * WORD_SIZE 27#define VCPU_R11 __VCPU_REGS_R11 * WORD_SIZE 28#define VCPU_R12 __VCPU_REGS_R12 * WORD_SIZE 29#define VCPU_R13 __VCPU_REGS_R13 * WORD_SIZE 30#define VCPU_R14 __VCPU_REGS_R14 * WORD_SIZE 31#define VCPU_R15 __VCPU_REGS_R15 * WORD_SIZE 32#endif 33 34.macro VMX_DO_EVENT_IRQOFF call_insn call_target 35 /* 36 * Unconditionally create a stack frame, getting the correct RSP on the 37 * stack (for x86-64) would take two instructions anyways, and RBP can 38 * be used to restore RSP to make objtool happy (see below). 39 */ 40 push %_ASM_BP 41 mov %_ASM_SP, %_ASM_BP 42 43#ifdef CONFIG_X86_64 44 /* 45 * Align RSP to a 16-byte boundary (to emulate CPU behavior) before 46 * creating the synthetic interrupt stack frame for the IRQ/NMI. 47 */ 48 and $-16, %rsp 49 push $__KERNEL_DS 50 push %rbp 51#endif 52 pushf 53 push $__KERNEL_CS 54 \call_insn \call_target 55 56 /* 57 * "Restore" RSP from RBP, even though IRET has already unwound RSP to 58 * the correct value. objtool doesn't know the callee will IRET and, 59 * without the explicit restore, thinks the stack is getting walloped. 60 * Using an unwind hint is problematic due to x86-64's dynamic alignment. 61 */ 62 mov %_ASM_BP, %_ASM_SP 63 pop %_ASM_BP 64 RET 65.endm 66 67.section .noinstr.text, "ax" 68 69/** 70 * __vmx_vcpu_run - Run a vCPU via a transition to VMX guest mode 71 * @vmx: struct vcpu_vmx * 72 * @regs: unsigned long * (to guest registers) 73 * @flags: VMX_RUN_VMRESUME: use VMRESUME instead of VMLAUNCH 74 * VMX_RUN_SAVE_SPEC_CTRL: save guest SPEC_CTRL into vmx->spec_ctrl 75 * 76 * Returns: 77 * 0 on VM-Exit, 1 on VM-Fail 78 */ 79SYM_FUNC_START(__vmx_vcpu_run) 80 push %_ASM_BP 81 mov %_ASM_SP, %_ASM_BP 82#ifdef CONFIG_X86_64 83 push %r15 84 push %r14 85 push %r13 86 push %r12 87#else 88 push %edi 89 push %esi 90#endif 91 push %_ASM_BX 92 93 /* Save @vmx for SPEC_CTRL handling */ 94 push %_ASM_ARG1 95 96 /* Save @flags for SPEC_CTRL handling */ 97 push %_ASM_ARG3 98 99 /* 100 * Save @regs, _ASM_ARG2 may be modified by vmx_update_host_rsp() and 101 * @regs is needed after VM-Exit to save the guest's register values. 102 */ 103 push %_ASM_ARG2 104 105 /* Copy @flags to EBX, _ASM_ARG3 is volatile. */ 106 mov %_ASM_ARG3L, %ebx 107 108 lea (%_ASM_SP), %_ASM_ARG2 109 call vmx_update_host_rsp 110 111 ALTERNATIVE "jmp .Lspec_ctrl_done", "", X86_FEATURE_MSR_SPEC_CTRL 112 113 /* 114 * SPEC_CTRL handling: if the guest's SPEC_CTRL value differs from the 115 * host's, write the MSR. 116 * 117 * IMPORTANT: To avoid RSB underflow attacks and any other nastiness, 118 * there must not be any returns or indirect branches between this code 119 * and vmentry. 120 */ 121 mov 2*WORD_SIZE(%_ASM_SP), %_ASM_DI 122 movl VMX_spec_ctrl(%_ASM_DI), %edi 123 movl PER_CPU_VAR(x86_spec_ctrl_current), %esi 124 cmp %edi, %esi 125 je .Lspec_ctrl_done 126 mov $MSR_IA32_SPEC_CTRL, %ecx 127 xor %edx, %edx 128 mov %edi, %eax 129 wrmsr 130 131.Lspec_ctrl_done: 132 133 /* 134 * Since vmentry is serializing on affected CPUs, there's no need for 135 * an LFENCE to stop speculation from skipping the wrmsr. 136 */ 137 138 /* Load @regs to RAX. */ 139 mov (%_ASM_SP), %_ASM_AX 140 141 /* Check if vmlaunch or vmresume is needed */ 142 bt $VMX_RUN_VMRESUME_SHIFT, %ebx 143 144 /* Load guest registers. Don't clobber flags. */ 145 mov VCPU_RCX(%_ASM_AX), %_ASM_CX 146 mov VCPU_RDX(%_ASM_AX), %_ASM_DX 147 mov VCPU_RBX(%_ASM_AX), %_ASM_BX 148 mov VCPU_RBP(%_ASM_AX), %_ASM_BP 149 mov VCPU_RSI(%_ASM_AX), %_ASM_SI 150 mov VCPU_RDI(%_ASM_AX), %_ASM_DI 151#ifdef CONFIG_X86_64 152 mov VCPU_R8 (%_ASM_AX), %r8 153 mov VCPU_R9 (%_ASM_AX), %r9 154 mov VCPU_R10(%_ASM_AX), %r10 155 mov VCPU_R11(%_ASM_AX), %r11 156 mov VCPU_R12(%_ASM_AX), %r12 157 mov VCPU_R13(%_ASM_AX), %r13 158 mov VCPU_R14(%_ASM_AX), %r14 159 mov VCPU_R15(%_ASM_AX), %r15 160#endif 161 /* Load guest RAX. This kills the @regs pointer! */ 162 mov VCPU_RAX(%_ASM_AX), %_ASM_AX 163 164 /* Clobbers EFLAGS.ZF */ 165 CLEAR_CPU_BUFFERS 166 167 /* Check EFLAGS.CF from the VMX_RUN_VMRESUME bit test above. */ 168 jnc .Lvmlaunch 169 170 /* 171 * After a successful VMRESUME/VMLAUNCH, control flow "magically" 172 * resumes below at 'vmx_vmexit' due to the VMCS HOST_RIP setting. 173 * So this isn't a typical function and objtool needs to be told to 174 * save the unwind state here and restore it below. 175 */ 176 UNWIND_HINT_SAVE 177 178/* 179 * If VMRESUME/VMLAUNCH and corresponding vmexit succeed, execution resumes at 180 * the 'vmx_vmexit' label below. 181 */ 182.Lvmresume: 183 vmresume 184 jmp .Lvmfail 185 186.Lvmlaunch: 187 vmlaunch 188 jmp .Lvmfail 189 190 _ASM_EXTABLE(.Lvmresume, .Lfixup) 191 _ASM_EXTABLE(.Lvmlaunch, .Lfixup) 192 193SYM_INNER_LABEL_ALIGN(vmx_vmexit, SYM_L_GLOBAL) 194 195 /* Restore unwind state from before the VMRESUME/VMLAUNCH. */ 196 UNWIND_HINT_RESTORE 197 ENDBR 198 199 /* Temporarily save guest's RAX. */ 200 push %_ASM_AX 201 202 /* Reload @regs to RAX. */ 203 mov WORD_SIZE(%_ASM_SP), %_ASM_AX 204 205 /* Save all guest registers, including RAX from the stack */ 206 pop VCPU_RAX(%_ASM_AX) 207 mov %_ASM_CX, VCPU_RCX(%_ASM_AX) 208 mov %_ASM_DX, VCPU_RDX(%_ASM_AX) 209 mov %_ASM_BX, VCPU_RBX(%_ASM_AX) 210 mov %_ASM_BP, VCPU_RBP(%_ASM_AX) 211 mov %_ASM_SI, VCPU_RSI(%_ASM_AX) 212 mov %_ASM_DI, VCPU_RDI(%_ASM_AX) 213#ifdef CONFIG_X86_64 214 mov %r8, VCPU_R8 (%_ASM_AX) 215 mov %r9, VCPU_R9 (%_ASM_AX) 216 mov %r10, VCPU_R10(%_ASM_AX) 217 mov %r11, VCPU_R11(%_ASM_AX) 218 mov %r12, VCPU_R12(%_ASM_AX) 219 mov %r13, VCPU_R13(%_ASM_AX) 220 mov %r14, VCPU_R14(%_ASM_AX) 221 mov %r15, VCPU_R15(%_ASM_AX) 222#endif 223 224 /* Clear return value to indicate VM-Exit (as opposed to VM-Fail). */ 225 xor %ebx, %ebx 226 227.Lclear_regs: 228 /* Discard @regs. The register is irrelevant, it just can't be RBX. */ 229 pop %_ASM_AX 230 231 /* 232 * Clear all general purpose registers except RSP and RBX to prevent 233 * speculative use of the guest's values, even those that are reloaded 234 * via the stack. In theory, an L1 cache miss when restoring registers 235 * could lead to speculative execution with the guest's values. 236 * Zeroing XORs are dirt cheap, i.e. the extra paranoia is essentially 237 * free. RSP and RBX are exempt as RSP is restored by hardware during 238 * VM-Exit and RBX is explicitly loaded with 0 or 1 to hold the return 239 * value. 240 */ 241 xor %eax, %eax 242 xor %ecx, %ecx 243 xor %edx, %edx 244 xor %ebp, %ebp 245 xor %esi, %esi 246 xor %edi, %edi 247#ifdef CONFIG_X86_64 248 xor %r8d, %r8d 249 xor %r9d, %r9d 250 xor %r10d, %r10d 251 xor %r11d, %r11d 252 xor %r12d, %r12d 253 xor %r13d, %r13d 254 xor %r14d, %r14d 255 xor %r15d, %r15d 256#endif 257 258 /* 259 * IMPORTANT: RSB filling and SPEC_CTRL handling must be done before 260 * the first unbalanced RET after vmexit! 261 * 262 * For retpoline or IBRS, RSB filling is needed to prevent poisoned RSB 263 * entries and (in some cases) RSB underflow. 264 * 265 * eIBRS has its own protection against poisoned RSB, so it doesn't 266 * need the RSB filling sequence. But it does need to be enabled, and a 267 * single call to retire, before the first unbalanced RET. 268 */ 269 270 FILL_RETURN_BUFFER %_ASM_CX, RSB_CLEAR_LOOPS, X86_FEATURE_RSB_VMEXIT,\ 271 X86_FEATURE_RSB_VMEXIT_LITE 272 273 pop %_ASM_ARG2 /* @flags */ 274 pop %_ASM_ARG1 /* @vmx */ 275 276 call vmx_spec_ctrl_restore_host 277 278 /* Put return value in AX */ 279 mov %_ASM_BX, %_ASM_AX 280 281 pop %_ASM_BX 282#ifdef CONFIG_X86_64 283 pop %r12 284 pop %r13 285 pop %r14 286 pop %r15 287#else 288 pop %esi 289 pop %edi 290#endif 291 pop %_ASM_BP 292 RET 293 294.Lfixup: 295 cmpb $0, kvm_rebooting 296 jne .Lvmfail 297 ud2 298.Lvmfail: 299 /* VM-Fail: set return value to 1 */ 300 mov $1, %_ASM_BX 301 jmp .Lclear_regs 302 303SYM_FUNC_END(__vmx_vcpu_run) 304 305SYM_FUNC_START(vmx_do_nmi_irqoff) 306 VMX_DO_EVENT_IRQOFF call asm_exc_nmi_kvm_vmx 307SYM_FUNC_END(vmx_do_nmi_irqoff) 308 309#ifndef CONFIG_CC_HAS_ASM_GOTO_OUTPUT 310 311/** 312 * vmread_error_trampoline - Trampoline from inline asm to vmread_error() 313 * @field: VMCS field encoding that failed 314 * @fault: %true if the VMREAD faulted, %false if it failed 315 * 316 * Save and restore volatile registers across a call to vmread_error(). Note, 317 * all parameters are passed on the stack. 318 */ 319SYM_FUNC_START(vmread_error_trampoline) 320 push %_ASM_BP 321 mov %_ASM_SP, %_ASM_BP 322 323 push %_ASM_AX 324 push %_ASM_CX 325 push %_ASM_DX 326#ifdef CONFIG_X86_64 327 push %rdi 328 push %rsi 329 push %r8 330 push %r9 331 push %r10 332 push %r11 333#endif 334 335 /* Load @field and @fault to arg1 and arg2 respectively. */ 336 mov 3*WORD_SIZE(%_ASM_BP), %_ASM_ARG2 337 mov 2*WORD_SIZE(%_ASM_BP), %_ASM_ARG1 338 339 call vmread_error_trampoline2 340 341 /* Zero out @fault, which will be popped into the result register. */ 342 _ASM_MOV $0, 3*WORD_SIZE(%_ASM_BP) 343 344#ifdef CONFIG_X86_64 345 pop %r11 346 pop %r10 347 pop %r9 348 pop %r8 349 pop %rsi 350 pop %rdi 351#endif 352 pop %_ASM_DX 353 pop %_ASM_CX 354 pop %_ASM_AX 355 pop %_ASM_BP 356 357 RET 358SYM_FUNC_END(vmread_error_trampoline) 359#endif 360 361.section .text, "ax" 362 363SYM_FUNC_START(vmx_do_interrupt_irqoff) 364 VMX_DO_EVENT_IRQOFF CALL_NOSPEC _ASM_ARG1 365SYM_FUNC_END(vmx_do_interrupt_irqoff) 366