1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2012,2013 - ARM Ltd 4 * Author: Marc Zyngier <marc.zyngier@arm.com> 5 * 6 * Derived from arch/arm/kvm/handle_exit.c: 7 * Copyright (C) 2012 - Virtual Open Systems and Columbia University 8 * Author: Christoffer Dall <c.dall@virtualopensystems.com> 9 */ 10 11 #include <linux/kvm.h> 12 #include <linux/kvm_host.h> 13 14 #include <asm/esr.h> 15 #include <asm/exception.h> 16 #include <asm/kvm_asm.h> 17 #include <asm/kvm_coproc.h> 18 #include <asm/kvm_emulate.h> 19 #include <asm/kvm_mmu.h> 20 #include <asm/debug-monitors.h> 21 #include <asm/traps.h> 22 23 #include <kvm/arm_hypercalls.h> 24 25 #define CREATE_TRACE_POINTS 26 #include "trace_handle_exit.h" 27 28 typedef int (*exit_handle_fn)(struct kvm_vcpu *); 29 30 static void kvm_handle_guest_serror(struct kvm_vcpu *vcpu, u32 esr) 31 { 32 if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(NULL, esr)) 33 kvm_inject_vabt(vcpu); 34 } 35 36 static int handle_hvc(struct kvm_vcpu *vcpu) 37 { 38 int ret; 39 40 trace_kvm_hvc_arm64(*vcpu_pc(vcpu), vcpu_get_reg(vcpu, 0), 41 kvm_vcpu_hvc_get_imm(vcpu)); 42 vcpu->stat.hvc_exit_stat++; 43 44 ret = kvm_hvc_call_handler(vcpu); 45 if (ret < 0) { 46 vcpu_set_reg(vcpu, 0, ~0UL); 47 return 1; 48 } 49 50 return ret; 51 } 52 53 static int handle_smc(struct kvm_vcpu *vcpu) 54 { 55 /* 56 * "If an SMC instruction executed at Non-secure EL1 is 57 * trapped to EL2 because HCR_EL2.TSC is 1, the exception is a 58 * Trap exception, not a Secure Monitor Call exception [...]" 59 * 60 * We need to advance the PC after the trap, as it would 61 * otherwise return to the same address... 62 */ 63 vcpu_set_reg(vcpu, 0, ~0UL); 64 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); 65 return 1; 66 } 67 68 /* 69 * Guest access to FP/ASIMD registers are routed to this handler only 70 * when the system doesn't support FP/ASIMD. 71 */ 72 static int handle_no_fpsimd(struct kvm_vcpu *vcpu) 73 { 74 kvm_inject_undefined(vcpu); 75 return 1; 76 } 77 78 /** 79 * kvm_handle_wfx - handle a wait-for-interrupts or wait-for-event 80 * instruction executed by a guest 81 * 82 * @vcpu: the vcpu pointer 83 * 84 * WFE: Yield the CPU and come back to this vcpu when the scheduler 85 * decides to. 86 * WFI: Simply call kvm_vcpu_block(), which will halt execution of 87 * world-switches and schedule other host processes until there is an 88 * incoming IRQ or FIQ to the VM. 89 */ 90 static int kvm_handle_wfx(struct kvm_vcpu *vcpu) 91 { 92 if (kvm_vcpu_get_esr(vcpu) & ESR_ELx_WFx_ISS_WFE) { 93 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), true); 94 vcpu->stat.wfe_exit_stat++; 95 kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu)); 96 } else { 97 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), false); 98 vcpu->stat.wfi_exit_stat++; 99 kvm_vcpu_block(vcpu); 100 kvm_clear_request(KVM_REQ_UNHALT, vcpu); 101 } 102 103 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); 104 105 return 1; 106 } 107 108 /** 109 * kvm_handle_guest_debug - handle a debug exception instruction 110 * 111 * @vcpu: the vcpu pointer 112 * 113 * We route all debug exceptions through the same handler. If both the 114 * guest and host are using the same debug facilities it will be up to 115 * userspace to re-inject the correct exception for guest delivery. 116 * 117 * @return: 0 (while setting vcpu->run->exit_reason), -1 for error 118 */ 119 static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu) 120 { 121 struct kvm_run *run = vcpu->run; 122 u32 esr = kvm_vcpu_get_esr(vcpu); 123 int ret = 0; 124 125 run->exit_reason = KVM_EXIT_DEBUG; 126 run->debug.arch.hsr = esr; 127 128 switch (ESR_ELx_EC(esr)) { 129 case ESR_ELx_EC_WATCHPT_LOW: 130 run->debug.arch.far = vcpu->arch.fault.far_el2; 131 fallthrough; 132 case ESR_ELx_EC_SOFTSTP_LOW: 133 case ESR_ELx_EC_BREAKPT_LOW: 134 case ESR_ELx_EC_BKPT32: 135 case ESR_ELx_EC_BRK64: 136 break; 137 default: 138 kvm_err("%s: un-handled case esr: %#08x\n", 139 __func__, (unsigned int) esr); 140 ret = -1; 141 break; 142 } 143 144 return ret; 145 } 146 147 static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu) 148 { 149 u32 esr = kvm_vcpu_get_esr(vcpu); 150 151 kvm_pr_unimpl("Unknown exception class: esr: %#08x -- %s\n", 152 esr, esr_get_class_string(esr)); 153 154 kvm_inject_undefined(vcpu); 155 return 1; 156 } 157 158 static int handle_sve(struct kvm_vcpu *vcpu) 159 { 160 /* Until SVE is supported for guests: */ 161 kvm_inject_undefined(vcpu); 162 return 1; 163 } 164 165 /* 166 * Guest usage of a ptrauth instruction (which the guest EL1 did not turn into 167 * a NOP). If we get here, it is that we didn't fixup ptrauth on exit, and all 168 * that we can do is give the guest an UNDEF. 169 */ 170 static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu) 171 { 172 kvm_inject_undefined(vcpu); 173 return 1; 174 } 175 176 static exit_handle_fn arm_exit_handlers[] = { 177 [0 ... ESR_ELx_EC_MAX] = kvm_handle_unknown_ec, 178 [ESR_ELx_EC_WFx] = kvm_handle_wfx, 179 [ESR_ELx_EC_CP15_32] = kvm_handle_cp15_32, 180 [ESR_ELx_EC_CP15_64] = kvm_handle_cp15_64, 181 [ESR_ELx_EC_CP14_MR] = kvm_handle_cp14_32, 182 [ESR_ELx_EC_CP14_LS] = kvm_handle_cp14_load_store, 183 [ESR_ELx_EC_CP14_64] = kvm_handle_cp14_64, 184 [ESR_ELx_EC_HVC32] = handle_hvc, 185 [ESR_ELx_EC_SMC32] = handle_smc, 186 [ESR_ELx_EC_HVC64] = handle_hvc, 187 [ESR_ELx_EC_SMC64] = handle_smc, 188 [ESR_ELx_EC_SYS64] = kvm_handle_sys_reg, 189 [ESR_ELx_EC_SVE] = handle_sve, 190 [ESR_ELx_EC_IABT_LOW] = kvm_handle_guest_abort, 191 [ESR_ELx_EC_DABT_LOW] = kvm_handle_guest_abort, 192 [ESR_ELx_EC_SOFTSTP_LOW]= kvm_handle_guest_debug, 193 [ESR_ELx_EC_WATCHPT_LOW]= kvm_handle_guest_debug, 194 [ESR_ELx_EC_BREAKPT_LOW]= kvm_handle_guest_debug, 195 [ESR_ELx_EC_BKPT32] = kvm_handle_guest_debug, 196 [ESR_ELx_EC_BRK64] = kvm_handle_guest_debug, 197 [ESR_ELx_EC_FP_ASIMD] = handle_no_fpsimd, 198 [ESR_ELx_EC_PAC] = kvm_handle_ptrauth, 199 }; 200 201 static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu) 202 { 203 u32 esr = kvm_vcpu_get_esr(vcpu); 204 u8 esr_ec = ESR_ELx_EC(esr); 205 206 return arm_exit_handlers[esr_ec]; 207 } 208 209 /* 210 * We may be single-stepping an emulated instruction. If the emulation 211 * has been completed in the kernel, we can return to userspace with a 212 * KVM_EXIT_DEBUG, otherwise userspace needs to complete its 213 * emulation first. 214 */ 215 static int handle_trap_exceptions(struct kvm_vcpu *vcpu) 216 { 217 int handled; 218 219 /* 220 * See ARM ARM B1.14.1: "Hyp traps on instructions 221 * that fail their condition code check" 222 */ 223 if (!kvm_condition_valid(vcpu)) { 224 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); 225 handled = 1; 226 } else { 227 exit_handle_fn exit_handler; 228 229 exit_handler = kvm_get_exit_handler(vcpu); 230 handled = exit_handler(vcpu); 231 } 232 233 return handled; 234 } 235 236 /* 237 * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on 238 * proper exit to userspace. 239 */ 240 int handle_exit(struct kvm_vcpu *vcpu, int exception_index) 241 { 242 struct kvm_run *run = vcpu->run; 243 244 if (ARM_SERROR_PENDING(exception_index)) { 245 u8 esr_ec = ESR_ELx_EC(kvm_vcpu_get_esr(vcpu)); 246 247 /* 248 * HVC/SMC already have an adjusted PC, which we need 249 * to correct in order to return to after having 250 * injected the SError. 251 */ 252 if (esr_ec == ESR_ELx_EC_HVC32 || esr_ec == ESR_ELx_EC_HVC64 || 253 esr_ec == ESR_ELx_EC_SMC32 || esr_ec == ESR_ELx_EC_SMC64) { 254 u32 adj = kvm_vcpu_trap_il_is32bit(vcpu) ? 4 : 2; 255 *vcpu_pc(vcpu) -= adj; 256 } 257 258 return 1; 259 } 260 261 exception_index = ARM_EXCEPTION_CODE(exception_index); 262 263 switch (exception_index) { 264 case ARM_EXCEPTION_IRQ: 265 return 1; 266 case ARM_EXCEPTION_EL1_SERROR: 267 return 1; 268 case ARM_EXCEPTION_TRAP: 269 return handle_trap_exceptions(vcpu); 270 case ARM_EXCEPTION_HYP_GONE: 271 /* 272 * EL2 has been reset to the hyp-stub. This happens when a guest 273 * is pre-empted by kvm_reboot()'s shutdown call. 274 */ 275 run->exit_reason = KVM_EXIT_FAIL_ENTRY; 276 return 0; 277 case ARM_EXCEPTION_IL: 278 /* 279 * We attempted an illegal exception return. Guest state must 280 * have been corrupted somehow. Give up. 281 */ 282 run->exit_reason = KVM_EXIT_FAIL_ENTRY; 283 return -EINVAL; 284 default: 285 kvm_pr_unimpl("Unsupported exception type: %d", 286 exception_index); 287 run->exit_reason = KVM_EXIT_INTERNAL_ERROR; 288 return 0; 289 } 290 } 291 292 /* For exit types that need handling before we can be preempted */ 293 void handle_exit_early(struct kvm_vcpu *vcpu, int exception_index) 294 { 295 if (ARM_SERROR_PENDING(exception_index)) { 296 if (this_cpu_has_cap(ARM64_HAS_RAS_EXTN)) { 297 u64 disr = kvm_vcpu_get_disr(vcpu); 298 299 kvm_handle_guest_serror(vcpu, disr_to_esr(disr)); 300 } else { 301 kvm_inject_vabt(vcpu); 302 } 303 304 return; 305 } 306 307 exception_index = ARM_EXCEPTION_CODE(exception_index); 308 309 if (exception_index == ARM_EXCEPTION_EL1_SERROR) 310 kvm_handle_guest_serror(vcpu, kvm_vcpu_get_esr(vcpu)); 311 } 312