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