1/* SPDX-License-Identifier: GPL-2.0 */ 2#include <linux/linkage.h> 3#include <asm/asm.h> 4#include <asm/asm-offsets.h> 5#include <asm/bitsperlong.h> 6#include <asm/kvm_vcpu_regs.h> 7#include <asm/nospec-branch.h> 8#include "kvm-asm-offsets.h" 9 10#define WORD_SIZE (BITS_PER_LONG / 8) 11 12/* Intentionally omit RAX as it's context switched by hardware */ 13#define VCPU_RCX (SVM_vcpu_arch_regs + __VCPU_REGS_RCX * WORD_SIZE) 14#define VCPU_RDX (SVM_vcpu_arch_regs + __VCPU_REGS_RDX * WORD_SIZE) 15#define VCPU_RBX (SVM_vcpu_arch_regs + __VCPU_REGS_RBX * WORD_SIZE) 16/* Intentionally omit RSP as it's context switched by hardware */ 17#define VCPU_RBP (SVM_vcpu_arch_regs + __VCPU_REGS_RBP * WORD_SIZE) 18#define VCPU_RSI (SVM_vcpu_arch_regs + __VCPU_REGS_RSI * WORD_SIZE) 19#define VCPU_RDI (SVM_vcpu_arch_regs + __VCPU_REGS_RDI * WORD_SIZE) 20 21#ifdef CONFIG_X86_64 22#define VCPU_R8 (SVM_vcpu_arch_regs + __VCPU_REGS_R8 * WORD_SIZE) 23#define VCPU_R9 (SVM_vcpu_arch_regs + __VCPU_REGS_R9 * WORD_SIZE) 24#define VCPU_R10 (SVM_vcpu_arch_regs + __VCPU_REGS_R10 * WORD_SIZE) 25#define VCPU_R11 (SVM_vcpu_arch_regs + __VCPU_REGS_R11 * WORD_SIZE) 26#define VCPU_R12 (SVM_vcpu_arch_regs + __VCPU_REGS_R12 * WORD_SIZE) 27#define VCPU_R13 (SVM_vcpu_arch_regs + __VCPU_REGS_R13 * WORD_SIZE) 28#define VCPU_R14 (SVM_vcpu_arch_regs + __VCPU_REGS_R14 * WORD_SIZE) 29#define VCPU_R15 (SVM_vcpu_arch_regs + __VCPU_REGS_R15 * WORD_SIZE) 30#endif 31 32#define SVM_vmcb01_pa (SVM_vmcb01 + KVM_VMCB_pa) 33 34.section .noinstr.text, "ax" 35 36.macro RESTORE_GUEST_SPEC_CTRL 37 /* No need to do anything if SPEC_CTRL is unset or V_SPEC_CTRL is set */ 38 ALTERNATIVE_2 "", \ 39 "jmp 800f", X86_FEATURE_MSR_SPEC_CTRL, \ 40 "", X86_FEATURE_V_SPEC_CTRL 41801: 42.endm 43.macro RESTORE_GUEST_SPEC_CTRL_BODY 44800: 45 /* 46 * SPEC_CTRL handling: if the guest's SPEC_CTRL value differs from the 47 * host's, write the MSR. This is kept out-of-line so that the common 48 * case does not have to jump. 49 * 50 * IMPORTANT: To avoid RSB underflow attacks and any other nastiness, 51 * there must not be any returns or indirect branches between this code 52 * and vmentry. 53 */ 54 movl SVM_spec_ctrl(%_ASM_DI), %eax 55 cmp PER_CPU_VAR(x86_spec_ctrl_current), %eax 56 je 801b 57 mov $MSR_IA32_SPEC_CTRL, %ecx 58 xor %edx, %edx 59 wrmsr 60 jmp 801b 61.endm 62 63.macro RESTORE_HOST_SPEC_CTRL 64 /* No need to do anything if SPEC_CTRL is unset or V_SPEC_CTRL is set */ 65 ALTERNATIVE_2 "", \ 66 "jmp 900f", X86_FEATURE_MSR_SPEC_CTRL, \ 67 "", X86_FEATURE_V_SPEC_CTRL 68901: 69.endm 70.macro RESTORE_HOST_SPEC_CTRL_BODY 71900: 72 /* Same for after vmexit. */ 73 mov $MSR_IA32_SPEC_CTRL, %ecx 74 75 /* 76 * Load the value that the guest had written into MSR_IA32_SPEC_CTRL, 77 * if it was not intercepted during guest execution. 78 */ 79 cmpb $0, (%_ASM_SP) 80 jnz 998f 81 rdmsr 82 movl %eax, SVM_spec_ctrl(%_ASM_DI) 83998: 84 85 /* Now restore the host value of the MSR if different from the guest's. */ 86 movl PER_CPU_VAR(x86_spec_ctrl_current), %eax 87 cmp SVM_spec_ctrl(%_ASM_DI), %eax 88 je 901b 89 xor %edx, %edx 90 wrmsr 91 jmp 901b 92.endm 93 94 95/** 96 * __svm_vcpu_run - Run a vCPU via a transition to SVM guest mode 97 * @svm: struct vcpu_svm * 98 * @spec_ctrl_intercepted: bool 99 */ 100SYM_FUNC_START(__svm_vcpu_run) 101 push %_ASM_BP 102#ifdef CONFIG_X86_64 103 push %r15 104 push %r14 105 push %r13 106 push %r12 107#else 108 push %edi 109 push %esi 110#endif 111 push %_ASM_BX 112 113 /* 114 * Save variables needed after vmexit on the stack, in inverse 115 * order compared to when they are needed. 116 */ 117 118 /* Accessed directly from the stack in RESTORE_HOST_SPEC_CTRL. */ 119 push %_ASM_ARG2 120 121 /* Needed to restore access to percpu variables. */ 122 __ASM_SIZE(push) PER_CPU_VAR(svm_data + SD_save_area_pa) 123 124 /* Finally save @svm. */ 125 push %_ASM_ARG1 126 127.ifnc _ASM_ARG1, _ASM_DI 128 /* 129 * Stash @svm in RDI early. On 32-bit, arguments are in RAX, RCX 130 * and RDX which are clobbered by RESTORE_GUEST_SPEC_CTRL. 131 */ 132 mov %_ASM_ARG1, %_ASM_DI 133.endif 134 135 /* Clobbers RAX, RCX, RDX. */ 136 RESTORE_GUEST_SPEC_CTRL 137 138 /* 139 * Use a single vmcb (vmcb01 because it's always valid) for 140 * context switching guest state via VMLOAD/VMSAVE, that way 141 * the state doesn't need to be copied between vmcb01 and 142 * vmcb02 when switching vmcbs for nested virtualization. 143 */ 144 mov SVM_vmcb01_pa(%_ASM_DI), %_ASM_AX 1451: vmload %_ASM_AX 1462: 147 148 /* Get svm->current_vmcb->pa into RAX. */ 149 mov SVM_current_vmcb(%_ASM_DI), %_ASM_AX 150 mov KVM_VMCB_pa(%_ASM_AX), %_ASM_AX 151 152 /* Load guest registers. */ 153 mov VCPU_RCX(%_ASM_DI), %_ASM_CX 154 mov VCPU_RDX(%_ASM_DI), %_ASM_DX 155 mov VCPU_RBX(%_ASM_DI), %_ASM_BX 156 mov VCPU_RBP(%_ASM_DI), %_ASM_BP 157 mov VCPU_RSI(%_ASM_DI), %_ASM_SI 158#ifdef CONFIG_X86_64 159 mov VCPU_R8 (%_ASM_DI), %r8 160 mov VCPU_R9 (%_ASM_DI), %r9 161 mov VCPU_R10(%_ASM_DI), %r10 162 mov VCPU_R11(%_ASM_DI), %r11 163 mov VCPU_R12(%_ASM_DI), %r12 164 mov VCPU_R13(%_ASM_DI), %r13 165 mov VCPU_R14(%_ASM_DI), %r14 166 mov VCPU_R15(%_ASM_DI), %r15 167#endif 168 mov VCPU_RDI(%_ASM_DI), %_ASM_DI 169 170 /* Enter guest mode */ 171 sti 172 1733: vmrun %_ASM_AX 1744: 175 cli 176 177 /* Pop @svm to RAX while it's the only available register. */ 178 pop %_ASM_AX 179 180 /* Save all guest registers. */ 181 mov %_ASM_CX, VCPU_RCX(%_ASM_AX) 182 mov %_ASM_DX, VCPU_RDX(%_ASM_AX) 183 mov %_ASM_BX, VCPU_RBX(%_ASM_AX) 184 mov %_ASM_BP, VCPU_RBP(%_ASM_AX) 185 mov %_ASM_SI, VCPU_RSI(%_ASM_AX) 186 mov %_ASM_DI, VCPU_RDI(%_ASM_AX) 187#ifdef CONFIG_X86_64 188 mov %r8, VCPU_R8 (%_ASM_AX) 189 mov %r9, VCPU_R9 (%_ASM_AX) 190 mov %r10, VCPU_R10(%_ASM_AX) 191 mov %r11, VCPU_R11(%_ASM_AX) 192 mov %r12, VCPU_R12(%_ASM_AX) 193 mov %r13, VCPU_R13(%_ASM_AX) 194 mov %r14, VCPU_R14(%_ASM_AX) 195 mov %r15, VCPU_R15(%_ASM_AX) 196#endif 197 198 /* @svm can stay in RDI from now on. */ 199 mov %_ASM_AX, %_ASM_DI 200 201 mov SVM_vmcb01_pa(%_ASM_DI), %_ASM_AX 2025: vmsave %_ASM_AX 2036: 204 205 /* Restores GSBASE among other things, allowing access to percpu data. */ 206 pop %_ASM_AX 2077: vmload %_ASM_AX 2088: 209 210#ifdef CONFIG_RETPOLINE 211 /* IMPORTANT: Stuff the RSB immediately after VM-Exit, before RET! */ 212 FILL_RETURN_BUFFER %_ASM_AX, RSB_CLEAR_LOOPS, X86_FEATURE_RETPOLINE 213#endif 214 215 /* Clobbers RAX, RCX, RDX. */ 216 RESTORE_HOST_SPEC_CTRL 217 218 /* 219 * Mitigate RETBleed for AMD/Hygon Zen uarch. RET should be 220 * untrained as soon as we exit the VM and are back to the 221 * kernel. This should be done before re-enabling interrupts 222 * because interrupt handlers won't sanitize 'ret' if the return is 223 * from the kernel. 224 */ 225 UNTRAIN_RET 226 227 /* 228 * Clear all general purpose registers except RSP and RAX to prevent 229 * speculative use of the guest's values, even those that are reloaded 230 * via the stack. In theory, an L1 cache miss when restoring registers 231 * could lead to speculative execution with the guest's values. 232 * Zeroing XORs are dirt cheap, i.e. the extra paranoia is essentially 233 * free. RSP and RAX are exempt as they are restored by hardware 234 * during VM-Exit. 235 */ 236 xor %ecx, %ecx 237 xor %edx, %edx 238 xor %ebx, %ebx 239 xor %ebp, %ebp 240 xor %esi, %esi 241 xor %edi, %edi 242#ifdef CONFIG_X86_64 243 xor %r8d, %r8d 244 xor %r9d, %r9d 245 xor %r10d, %r10d 246 xor %r11d, %r11d 247 xor %r12d, %r12d 248 xor %r13d, %r13d 249 xor %r14d, %r14d 250 xor %r15d, %r15d 251#endif 252 253 /* "Pop" @spec_ctrl_intercepted. */ 254 pop %_ASM_BX 255 256 pop %_ASM_BX 257 258#ifdef CONFIG_X86_64 259 pop %r12 260 pop %r13 261 pop %r14 262 pop %r15 263#else 264 pop %esi 265 pop %edi 266#endif 267 pop %_ASM_BP 268 RET 269 270 RESTORE_GUEST_SPEC_CTRL_BODY 271 RESTORE_HOST_SPEC_CTRL_BODY 272 27310: cmpb $0, kvm_rebooting 274 jne 2b 275 ud2 27630: cmpb $0, kvm_rebooting 277 jne 4b 278 ud2 27950: cmpb $0, kvm_rebooting 280 jne 6b 281 ud2 28270: cmpb $0, kvm_rebooting 283 jne 8b 284 ud2 285 286 _ASM_EXTABLE(1b, 10b) 287 _ASM_EXTABLE(3b, 30b) 288 _ASM_EXTABLE(5b, 50b) 289 _ASM_EXTABLE(7b, 70b) 290 291SYM_FUNC_END(__svm_vcpu_run) 292 293/** 294 * __svm_sev_es_vcpu_run - Run a SEV-ES vCPU via a transition to SVM guest mode 295 * @svm: struct vcpu_svm * 296 * @spec_ctrl_intercepted: bool 297 */ 298SYM_FUNC_START(__svm_sev_es_vcpu_run) 299 push %_ASM_BP 300#ifdef CONFIG_X86_64 301 push %r15 302 push %r14 303 push %r13 304 push %r12 305#else 306 push %edi 307 push %esi 308#endif 309 push %_ASM_BX 310 311 /* 312 * Save variables needed after vmexit on the stack, in inverse 313 * order compared to when they are needed. 314 */ 315 316 /* Accessed directly from the stack in RESTORE_HOST_SPEC_CTRL. */ 317 push %_ASM_ARG2 318 319 /* Save @svm. */ 320 push %_ASM_ARG1 321 322.ifnc _ASM_ARG1, _ASM_DI 323 /* 324 * Stash @svm in RDI early. On 32-bit, arguments are in RAX, RCX 325 * and RDX which are clobbered by RESTORE_GUEST_SPEC_CTRL. 326 */ 327 mov %_ASM_ARG1, %_ASM_DI 328.endif 329 330 /* Clobbers RAX, RCX, RDX. */ 331 RESTORE_GUEST_SPEC_CTRL 332 333 /* Get svm->current_vmcb->pa into RAX. */ 334 mov SVM_current_vmcb(%_ASM_DI), %_ASM_AX 335 mov KVM_VMCB_pa(%_ASM_AX), %_ASM_AX 336 337 /* Enter guest mode */ 338 sti 339 3401: vmrun %_ASM_AX 341 3422: cli 343 344 /* Pop @svm to RDI, guest registers have been saved already. */ 345 pop %_ASM_DI 346 347#ifdef CONFIG_RETPOLINE 348 /* IMPORTANT: Stuff the RSB immediately after VM-Exit, before RET! */ 349 FILL_RETURN_BUFFER %_ASM_AX, RSB_CLEAR_LOOPS, X86_FEATURE_RETPOLINE 350#endif 351 352 /* Clobbers RAX, RCX, RDX. */ 353 RESTORE_HOST_SPEC_CTRL 354 355 /* 356 * Mitigate RETBleed for AMD/Hygon Zen uarch. RET should be 357 * untrained as soon as we exit the VM and are back to the 358 * kernel. This should be done before re-enabling interrupts 359 * because interrupt handlers won't sanitize RET if the return is 360 * from the kernel. 361 */ 362 UNTRAIN_RET 363 364 /* "Pop" @spec_ctrl_intercepted. */ 365 pop %_ASM_BX 366 367 pop %_ASM_BX 368 369#ifdef CONFIG_X86_64 370 pop %r12 371 pop %r13 372 pop %r14 373 pop %r15 374#else 375 pop %esi 376 pop %edi 377#endif 378 pop %_ASM_BP 379 RET 380 381 RESTORE_GUEST_SPEC_CTRL_BODY 382 RESTORE_HOST_SPEC_CTRL_BODY 383 3843: cmpb $0, kvm_rebooting 385 jne 2b 386 ud2 387 388 _ASM_EXTABLE(1b, 3b) 389 390SYM_FUNC_END(__svm_sev_es_vcpu_run) 391