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 8#define WORD_SIZE (BITS_PER_LONG / 8) 9 10#define VCPU_RAX __VCPU_REGS_RAX * WORD_SIZE 11#define VCPU_RCX __VCPU_REGS_RCX * WORD_SIZE 12#define VCPU_RDX __VCPU_REGS_RDX * WORD_SIZE 13#define VCPU_RBX __VCPU_REGS_RBX * WORD_SIZE 14/* Intentionally omit RSP as it's context switched by hardware */ 15#define VCPU_RBP __VCPU_REGS_RBP * WORD_SIZE 16#define VCPU_RSI __VCPU_REGS_RSI * WORD_SIZE 17#define VCPU_RDI __VCPU_REGS_RDI * WORD_SIZE 18 19#ifdef CONFIG_X86_64 20#define VCPU_R8 __VCPU_REGS_R8 * WORD_SIZE 21#define VCPU_R9 __VCPU_REGS_R9 * WORD_SIZE 22#define VCPU_R10 __VCPU_REGS_R10 * WORD_SIZE 23#define VCPU_R11 __VCPU_REGS_R11 * WORD_SIZE 24#define VCPU_R12 __VCPU_REGS_R12 * WORD_SIZE 25#define VCPU_R13 __VCPU_REGS_R13 * WORD_SIZE 26#define VCPU_R14 __VCPU_REGS_R14 * WORD_SIZE 27#define VCPU_R15 __VCPU_REGS_R15 * WORD_SIZE 28#endif 29 30 .text 31 32/** 33 * vmx_vmenter - VM-Enter the current loaded VMCS 34 * 35 * %RFLAGS.ZF: !VMCS.LAUNCHED, i.e. controls VMLAUNCH vs. VMRESUME 36 * 37 * Returns: 38 * %RFLAGS.CF is set on VM-Fail Invalid 39 * %RFLAGS.ZF is set on VM-Fail Valid 40 * %RFLAGS.{CF,ZF} are cleared on VM-Success, i.e. VM-Exit 41 * 42 * Note that VMRESUME/VMLAUNCH fall-through and return directly if 43 * they VM-Fail, whereas a successful VM-Enter + VM-Exit will jump 44 * to vmx_vmexit. 45 */ 46ENTRY(vmx_vmenter) 47 /* EFLAGS.ZF is set if VMCS.LAUNCHED == 0 */ 48 je 2f 49 501: vmresume 51 ret 52 532: vmlaunch 54 ret 55 563: cmpb $0, kvm_rebooting 57 je 4f 58 ret 594: ud2 60 61 .pushsection .fixup, "ax" 625: jmp 3b 63 .popsection 64 65 _ASM_EXTABLE(1b, 5b) 66 _ASM_EXTABLE(2b, 5b) 67 68ENDPROC(vmx_vmenter) 69 70/** 71 * vmx_vmexit - Handle a VMX VM-Exit 72 * 73 * Returns: 74 * %RFLAGS.{CF,ZF} are cleared on VM-Success, i.e. VM-Exit 75 * 76 * This is vmx_vmenter's partner in crime. On a VM-Exit, control will jump 77 * here after hardware loads the host's state, i.e. this is the destination 78 * referred to by VMCS.HOST_RIP. 79 */ 80ENTRY(vmx_vmexit) 81#ifdef CONFIG_RETPOLINE 82 ALTERNATIVE "jmp .Lvmexit_skip_rsb", "", X86_FEATURE_RETPOLINE 83 /* Preserve guest's RAX, it's used to stuff the RSB. */ 84 push %_ASM_AX 85 86 /* IMPORTANT: Stuff the RSB immediately after VM-Exit, before RET! */ 87 FILL_RETURN_BUFFER %_ASM_AX, RSB_CLEAR_LOOPS, X86_FEATURE_RETPOLINE 88 89 pop %_ASM_AX 90.Lvmexit_skip_rsb: 91#endif 92 ret 93ENDPROC(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 */ 104ENTRY(__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_RBX(%_ASM_AX), %_ASM_BX 139 mov VCPU_RCX(%_ASM_AX), %_ASM_CX 140 mov VCPU_RDX(%_ASM_AX), %_ASM_DX 141 mov VCPU_RSI(%_ASM_AX), %_ASM_SI 142 mov VCPU_RDI(%_ASM_AX), %_ASM_DI 143 mov VCPU_RBP(%_ASM_AX), %_ASM_BP 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 __ASM_SIZE(pop) VCPU_RAX(%_ASM_AX) 171 mov %_ASM_BX, VCPU_RBX(%_ASM_AX) 172 mov %_ASM_CX, VCPU_RCX(%_ASM_AX) 173 mov %_ASM_DX, VCPU_RDX(%_ASM_AX) 174 mov %_ASM_SI, VCPU_RSI(%_ASM_AX) 175 mov %_ASM_DI, VCPU_RDI(%_ASM_AX) 176 mov %_ASM_BP, VCPU_RBP(%_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 %ebx, %ebx 201 xor %ecx, %ecx 202 xor %edx, %edx 203 xor %esi, %esi 204 xor %edi, %edi 205 xor %ebp, %ebp 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 236ENDPROC(__vmx_vcpu_run) 237