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_halt(), 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_wfi(vcpu); 99 } 100 101 kvm_incr_pc(vcpu); 102 103 return 1; 104 } 105 106 /** 107 * kvm_handle_guest_debug - handle a debug exception instruction 108 * 109 * @vcpu: the vcpu pointer 110 * 111 * We route all debug exceptions through the same handler. If both the 112 * guest and host are using the same debug facilities it will be up to 113 * userspace to re-inject the correct exception for guest delivery. 114 * 115 * @return: 0 (while setting vcpu->run->exit_reason) 116 */ 117 static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu) 118 { 119 struct kvm_run *run = vcpu->run; 120 u32 esr = kvm_vcpu_get_esr(vcpu); 121 122 run->exit_reason = KVM_EXIT_DEBUG; 123 run->debug.arch.hsr = esr; 124 125 if (ESR_ELx_EC(esr) == ESR_ELx_EC_WATCHPT_LOW) 126 run->debug.arch.far = vcpu->arch.fault.far_el2; 127 128 return 0; 129 } 130 131 static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu) 132 { 133 u32 esr = kvm_vcpu_get_esr(vcpu); 134 135 kvm_pr_unimpl("Unknown exception class: esr: %#08x -- %s\n", 136 esr, esr_get_class_string(esr)); 137 138 kvm_inject_undefined(vcpu); 139 return 1; 140 } 141 142 /* 143 * Guest access to SVE registers should be routed to this handler only 144 * when the system doesn't support SVE. 145 */ 146 static int handle_sve(struct kvm_vcpu *vcpu) 147 { 148 kvm_inject_undefined(vcpu); 149 return 1; 150 } 151 152 /* 153 * Guest usage of a ptrauth instruction (which the guest EL1 did not turn into 154 * a NOP). If we get here, it is that we didn't fixup ptrauth on exit, and all 155 * that we can do is give the guest an UNDEF. 156 */ 157 static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu) 158 { 159 kvm_inject_undefined(vcpu); 160 return 1; 161 } 162 163 static exit_handle_fn arm_exit_handlers[] = { 164 [0 ... ESR_ELx_EC_MAX] = kvm_handle_unknown_ec, 165 [ESR_ELx_EC_WFx] = kvm_handle_wfx, 166 [ESR_ELx_EC_CP15_32] = kvm_handle_cp15_32, 167 [ESR_ELx_EC_CP15_64] = kvm_handle_cp15_64, 168 [ESR_ELx_EC_CP14_MR] = kvm_handle_cp14_32, 169 [ESR_ELx_EC_CP14_LS] = kvm_handle_cp14_load_store, 170 [ESR_ELx_EC_CP14_64] = kvm_handle_cp14_64, 171 [ESR_ELx_EC_HVC32] = handle_hvc, 172 [ESR_ELx_EC_SMC32] = handle_smc, 173 [ESR_ELx_EC_HVC64] = handle_hvc, 174 [ESR_ELx_EC_SMC64] = handle_smc, 175 [ESR_ELx_EC_SYS64] = kvm_handle_sys_reg, 176 [ESR_ELx_EC_SVE] = handle_sve, 177 [ESR_ELx_EC_IABT_LOW] = kvm_handle_guest_abort, 178 [ESR_ELx_EC_DABT_LOW] = kvm_handle_guest_abort, 179 [ESR_ELx_EC_SOFTSTP_LOW]= kvm_handle_guest_debug, 180 [ESR_ELx_EC_WATCHPT_LOW]= kvm_handle_guest_debug, 181 [ESR_ELx_EC_BREAKPT_LOW]= kvm_handle_guest_debug, 182 [ESR_ELx_EC_BKPT32] = kvm_handle_guest_debug, 183 [ESR_ELx_EC_BRK64] = kvm_handle_guest_debug, 184 [ESR_ELx_EC_FP_ASIMD] = handle_no_fpsimd, 185 [ESR_ELx_EC_PAC] = kvm_handle_ptrauth, 186 }; 187 188 static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu) 189 { 190 u32 esr = kvm_vcpu_get_esr(vcpu); 191 u8 esr_ec = ESR_ELx_EC(esr); 192 193 return arm_exit_handlers[esr_ec]; 194 } 195 196 /* 197 * We may be single-stepping an emulated instruction. If the emulation 198 * has been completed in the kernel, we can return to userspace with a 199 * KVM_EXIT_DEBUG, otherwise userspace needs to complete its 200 * emulation first. 201 */ 202 static int handle_trap_exceptions(struct kvm_vcpu *vcpu) 203 { 204 int handled; 205 206 /* 207 * See ARM ARM B1.14.1: "Hyp traps on instructions 208 * that fail their condition code check" 209 */ 210 if (!kvm_condition_valid(vcpu)) { 211 kvm_incr_pc(vcpu); 212 handled = 1; 213 } else { 214 exit_handle_fn exit_handler; 215 216 exit_handler = kvm_get_exit_handler(vcpu); 217 handled = exit_handler(vcpu); 218 } 219 220 return handled; 221 } 222 223 /* 224 * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on 225 * proper exit to userspace. 226 */ 227 int handle_exit(struct kvm_vcpu *vcpu, int exception_index) 228 { 229 struct kvm_run *run = vcpu->run; 230 231 if (ARM_SERROR_PENDING(exception_index)) { 232 /* 233 * The SError is handled by handle_exit_early(). If the guest 234 * survives it will re-execute the original instruction. 235 */ 236 return 1; 237 } 238 239 exception_index = ARM_EXCEPTION_CODE(exception_index); 240 241 switch (exception_index) { 242 case ARM_EXCEPTION_IRQ: 243 return 1; 244 case ARM_EXCEPTION_EL1_SERROR: 245 return 1; 246 case ARM_EXCEPTION_TRAP: 247 return handle_trap_exceptions(vcpu); 248 case ARM_EXCEPTION_HYP_GONE: 249 /* 250 * EL2 has been reset to the hyp-stub. This happens when a guest 251 * is pre-empted by kvm_reboot()'s shutdown call. 252 */ 253 run->exit_reason = KVM_EXIT_FAIL_ENTRY; 254 return 0; 255 case ARM_EXCEPTION_IL: 256 /* 257 * We attempted an illegal exception return. Guest state must 258 * have been corrupted somehow. Give up. 259 */ 260 run->exit_reason = KVM_EXIT_FAIL_ENTRY; 261 return -EINVAL; 262 default: 263 kvm_pr_unimpl("Unsupported exception type: %d", 264 exception_index); 265 run->exit_reason = KVM_EXIT_INTERNAL_ERROR; 266 return 0; 267 } 268 } 269 270 /* For exit types that need handling before we can be preempted */ 271 void handle_exit_early(struct kvm_vcpu *vcpu, int exception_index) 272 { 273 if (ARM_SERROR_PENDING(exception_index)) { 274 if (this_cpu_has_cap(ARM64_HAS_RAS_EXTN)) { 275 u64 disr = kvm_vcpu_get_disr(vcpu); 276 277 kvm_handle_guest_serror(vcpu, disr_to_esr(disr)); 278 } else { 279 kvm_inject_vabt(vcpu); 280 } 281 282 return; 283 } 284 285 exception_index = ARM_EXCEPTION_CODE(exception_index); 286 287 if (exception_index == ARM_EXCEPTION_EL1_SERROR) 288 kvm_handle_guest_serror(vcpu, kvm_vcpu_get_esr(vcpu)); 289 } 290 291 void __noreturn __cold nvhe_hyp_panic_handler(u64 esr, u64 spsr, 292 u64 elr_virt, u64 elr_phys, 293 u64 par, uintptr_t vcpu, 294 u64 far, u64 hpfar) { 295 u64 elr_in_kimg = __phys_to_kimg(elr_phys); 296 u64 hyp_offset = elr_in_kimg - kaslr_offset() - elr_virt; 297 u64 mode = spsr & PSR_MODE_MASK; 298 299 /* 300 * The nVHE hyp symbols are not included by kallsyms to avoid issues 301 * with aliasing. That means that the symbols cannot be printed with the 302 * "%pS" format specifier, so fall back to the vmlinux address if 303 * there's no better option. 304 */ 305 if (mode != PSR_MODE_EL2t && mode != PSR_MODE_EL2h) { 306 kvm_err("Invalid host exception to nVHE hyp!\n"); 307 } else if (ESR_ELx_EC(esr) == ESR_ELx_EC_BRK64 && 308 (esr & ESR_ELx_BRK64_ISS_COMMENT_MASK) == BUG_BRK_IMM) { 309 const char *file = NULL; 310 unsigned int line = 0; 311 312 /* All hyp bugs, including warnings, are treated as fatal. */ 313 if (!is_protected_kvm_enabled() || 314 IS_ENABLED(CONFIG_NVHE_EL2_DEBUG)) { 315 struct bug_entry *bug = find_bug(elr_in_kimg); 316 317 if (bug) 318 bug_get_file_line(bug, &file, &line); 319 } 320 321 if (file) 322 kvm_err("nVHE hyp BUG at: %s:%u!\n", file, line); 323 else 324 kvm_err("nVHE hyp BUG at: %016llx!\n", elr_virt + hyp_offset); 325 } else { 326 kvm_err("nVHE hyp panic at: %016llx!\n", elr_virt + hyp_offset); 327 } 328 329 /* 330 * Hyp has panicked and we're going to handle that by panicking the 331 * kernel. The kernel offset will be revealed in the panic so we're 332 * also safe to reveal the hyp offset as a debugging aid for translating 333 * hyp VAs to vmlinux addresses. 334 */ 335 kvm_err("Hyp Offset: 0x%llx\n", hyp_offset); 336 337 panic("HYP panic:\nPS:%08llx PC:%016llx ESR:%08llx\nFAR:%016llx HPFAR:%016llx PAR:%016llx\nVCPU:%016lx\n", 338 spsr, elr_virt, esr, far, hpfar, par, vcpu); 339 } 340