1/* SPDX-License-Identifier: GPL-2.0-only */ 2/* 3 * Copyright (C) 2015 - ARM Ltd 4 * Author: Marc Zyngier <marc.zyngier@arm.com> 5 */ 6 7#include <linux/linkage.h> 8 9#include <asm/alternative.h> 10#include <asm/asm-offsets.h> 11#include <asm/assembler.h> 12#include <asm/fpsimdmacros.h> 13#include <asm/kvm.h> 14#include <asm/kvm_arm.h> 15#include <asm/kvm_asm.h> 16#include <asm/kvm_mmu.h> 17#include <asm/kvm_ptrauth.h> 18 19#define CPU_XREG_OFFSET(x) (CPU_USER_PT_REGS + 8*x) 20#define CPU_SP_EL0_OFFSET (CPU_XREG_OFFSET(30) + 8) 21 22 .text 23 24/* 25 * We treat x18 as callee-saved as the host may use it as a platform 26 * register (e.g. for shadow call stack). 27 */ 28.macro save_callee_saved_regs ctxt 29 str x18, [\ctxt, #CPU_XREG_OFFSET(18)] 30 stp x19, x20, [\ctxt, #CPU_XREG_OFFSET(19)] 31 stp x21, x22, [\ctxt, #CPU_XREG_OFFSET(21)] 32 stp x23, x24, [\ctxt, #CPU_XREG_OFFSET(23)] 33 stp x25, x26, [\ctxt, #CPU_XREG_OFFSET(25)] 34 stp x27, x28, [\ctxt, #CPU_XREG_OFFSET(27)] 35 stp x29, lr, [\ctxt, #CPU_XREG_OFFSET(29)] 36.endm 37 38.macro restore_callee_saved_regs ctxt 39 // We require \ctxt is not x18-x28 40 ldr x18, [\ctxt, #CPU_XREG_OFFSET(18)] 41 ldp x19, x20, [\ctxt, #CPU_XREG_OFFSET(19)] 42 ldp x21, x22, [\ctxt, #CPU_XREG_OFFSET(21)] 43 ldp x23, x24, [\ctxt, #CPU_XREG_OFFSET(23)] 44 ldp x25, x26, [\ctxt, #CPU_XREG_OFFSET(25)] 45 ldp x27, x28, [\ctxt, #CPU_XREG_OFFSET(27)] 46 ldp x29, lr, [\ctxt, #CPU_XREG_OFFSET(29)] 47.endm 48 49.macro save_sp_el0 ctxt, tmp 50 mrs \tmp, sp_el0 51 str \tmp, [\ctxt, #CPU_SP_EL0_OFFSET] 52.endm 53 54.macro restore_sp_el0 ctxt, tmp 55 ldr \tmp, [\ctxt, #CPU_SP_EL0_OFFSET] 56 msr sp_el0, \tmp 57.endm 58 59/* 60 * u64 __guest_enter(struct kvm_vcpu *vcpu, 61 * struct kvm_cpu_context *host_ctxt); 62 */ 63SYM_FUNC_START(__guest_enter) 64 // x0: vcpu 65 // x1: host context 66 // x2-x17: clobbered by macros 67 // x29: guest context 68 69 // Store the host regs 70 save_callee_saved_regs x1 71 72 // Save the host's sp_el0 73 save_sp_el0 x1, x2 74 75 // Now the host state is stored if we have a pending RAS SError it must 76 // affect the host. If any asynchronous exception is pending we defer 77 // the guest entry. The DSB isn't necessary before v8.2 as any SError 78 // would be fatal. 79alternative_if ARM64_HAS_RAS_EXTN 80 dsb nshst 81 isb 82alternative_else_nop_endif 83 mrs x1, isr_el1 84 cbz x1, 1f 85 mov x0, #ARM_EXCEPTION_IRQ 86 ret 87 881: 89 add x29, x0, #VCPU_CONTEXT 90 91 // Macro ptrauth_switch_to_guest format: 92 // ptrauth_switch_to_guest(guest cxt, tmp1, tmp2, tmp3) 93 // The below macro to restore guest keys is not implemented in C code 94 // as it may cause Pointer Authentication key signing mismatch errors 95 // when this feature is enabled for kernel code. 96 ptrauth_switch_to_guest x29, x0, x1, x2 97 98 // Restore the guest's sp_el0 99 restore_sp_el0 x29, x0 100 101 // Restore guest regs x0-x17 102 ldp x0, x1, [x29, #CPU_XREG_OFFSET(0)] 103 ldp x2, x3, [x29, #CPU_XREG_OFFSET(2)] 104 ldp x4, x5, [x29, #CPU_XREG_OFFSET(4)] 105 ldp x6, x7, [x29, #CPU_XREG_OFFSET(6)] 106 ldp x8, x9, [x29, #CPU_XREG_OFFSET(8)] 107 ldp x10, x11, [x29, #CPU_XREG_OFFSET(10)] 108 ldp x12, x13, [x29, #CPU_XREG_OFFSET(12)] 109 ldp x14, x15, [x29, #CPU_XREG_OFFSET(14)] 110 ldp x16, x17, [x29, #CPU_XREG_OFFSET(16)] 111 112 // Restore guest regs x18-x29, lr 113 restore_callee_saved_regs x29 114 115 // Do not touch any register after this! 116 eret 117 sb 118 119SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL) 120 // x0: return code 121 // x1: vcpu 122 // x2-x29,lr: vcpu regs 123 // vcpu x0-x1 on the stack 124 125 add x1, x1, #VCPU_CONTEXT 126 127 ALTERNATIVE(nop, SET_PSTATE_PAN(1), ARM64_HAS_PAN, CONFIG_ARM64_PAN) 128 129 // Store the guest regs x2 and x3 130 stp x2, x3, [x1, #CPU_XREG_OFFSET(2)] 131 132 // Retrieve the guest regs x0-x1 from the stack 133 ldp x2, x3, [sp], #16 // x0, x1 134 135 // Store the guest regs x0-x1 and x4-x17 136 stp x2, x3, [x1, #CPU_XREG_OFFSET(0)] 137 stp x4, x5, [x1, #CPU_XREG_OFFSET(4)] 138 stp x6, x7, [x1, #CPU_XREG_OFFSET(6)] 139 stp x8, x9, [x1, #CPU_XREG_OFFSET(8)] 140 stp x10, x11, [x1, #CPU_XREG_OFFSET(10)] 141 stp x12, x13, [x1, #CPU_XREG_OFFSET(12)] 142 stp x14, x15, [x1, #CPU_XREG_OFFSET(14)] 143 stp x16, x17, [x1, #CPU_XREG_OFFSET(16)] 144 145 // Store the guest regs x18-x29, lr 146 save_callee_saved_regs x1 147 148 // Store the guest's sp_el0 149 save_sp_el0 x1, x2 150 151 get_host_ctxt x2, x3 152 153 // Macro ptrauth_switch_to_guest format: 154 // ptrauth_switch_to_host(guest cxt, host cxt, tmp1, tmp2, tmp3) 155 // The below macro to save/restore keys is not implemented in C code 156 // as it may cause Pointer Authentication key signing mismatch errors 157 // when this feature is enabled for kernel code. 158 ptrauth_switch_to_host x1, x2, x3, x4, x5 159 160 // Restore the hosts's sp_el0 161 restore_sp_el0 x2, x3 162 163 // Now restore the host regs 164 restore_callee_saved_regs x2 165 166alternative_if ARM64_HAS_RAS_EXTN 167 // If we have the RAS extensions we can consume a pending error 168 // without an unmask-SError and isb. The ESB-instruction consumed any 169 // pending guest error when we took the exception from the guest. 170 mrs_s x2, SYS_DISR_EL1 171 str x2, [x1, #(VCPU_FAULT_DISR - VCPU_CONTEXT)] 172 cbz x2, 1f 173 msr_s SYS_DISR_EL1, xzr 174 orr x0, x0, #(1<<ARM_EXIT_WITH_SERROR_BIT) 1751: ret 176alternative_else 177 dsb sy // Synchronize against in-flight ld/st 178 isb // Prevent an early read of side-effect free ISR 179 mrs x2, isr_el1 180 tbnz x2, #8, 2f // ISR_EL1.A 181 ret 182 nop 1832: 184alternative_endif 185 // We know we have a pending asynchronous abort, now is the 186 // time to flush it out. From your VAXorcist book, page 666: 187 // "Threaten me not, oh Evil one! For I speak with 188 // the power of DEC, and I command thee to show thyself!" 189 mrs x2, elr_el2 190 mrs x3, esr_el2 191 mrs x4, spsr_el2 192 mov x5, x0 193 194 msr daifclr, #4 // Unmask aborts 195 196 // This is our single instruction exception window. A pending 197 // SError is guaranteed to occur at the earliest when we unmask 198 // it, and at the latest just after the ISB. 199 .global abort_guest_exit_start 200abort_guest_exit_start: 201 202 isb 203 204 .global abort_guest_exit_end 205abort_guest_exit_end: 206 207 msr daifset, #4 // Mask aborts 208 209 // If the exception took place, restore the EL1 exception 210 // context so that we can report some information. 211 // Merge the exception code with the SError pending bit. 212 tbz x0, #ARM_EXIT_WITH_SERROR_BIT, 1f 213 msr elr_el2, x2 214 msr esr_el2, x3 215 msr spsr_el2, x4 216 orr x0, x0, x5 2171: ret 218SYM_FUNC_END(__guest_enter) 219