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, u64 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 u64 esr = kvm_vcpu_get_esr(vcpu); 121 122 run->exit_reason = KVM_EXIT_DEBUG; 123 run->debug.arch.hsr = lower_32_bits(esr); 124 run->debug.arch.hsr_high = upper_32_bits(esr); 125 run->flags = KVM_DEBUG_ARCH_HSR_HIGH_VALID; 126 127 if (ESR_ELx_EC(esr) == ESR_ELx_EC_WATCHPT_LOW) 128 run->debug.arch.far = vcpu->arch.fault.far_el2; 129 130 return 0; 131 } 132 133 static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu) 134 { 135 u64 esr = kvm_vcpu_get_esr(vcpu); 136 137 kvm_pr_unimpl("Unknown exception class: esr: %#016llx -- %s\n", 138 esr, esr_get_class_string(esr)); 139 140 kvm_inject_undefined(vcpu); 141 return 1; 142 } 143 144 /* 145 * Guest access to SVE registers should be routed to this handler only 146 * when the system doesn't support SVE. 147 */ 148 static int handle_sve(struct kvm_vcpu *vcpu) 149 { 150 kvm_inject_undefined(vcpu); 151 return 1; 152 } 153 154 /* 155 * Guest usage of a ptrauth instruction (which the guest EL1 did not turn into 156 * a NOP). If we get here, it is that we didn't fixup ptrauth on exit, and all 157 * that we can do is give the guest an UNDEF. 158 */ 159 static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu) 160 { 161 kvm_inject_undefined(vcpu); 162 return 1; 163 } 164 165 static exit_handle_fn arm_exit_handlers[] = { 166 [0 ... ESR_ELx_EC_MAX] = kvm_handle_unknown_ec, 167 [ESR_ELx_EC_WFx] = kvm_handle_wfx, 168 [ESR_ELx_EC_CP15_32] = kvm_handle_cp15_32, 169 [ESR_ELx_EC_CP15_64] = kvm_handle_cp15_64, 170 [ESR_ELx_EC_CP14_MR] = kvm_handle_cp14_32, 171 [ESR_ELx_EC_CP14_LS] = kvm_handle_cp14_load_store, 172 [ESR_ELx_EC_CP14_64] = kvm_handle_cp14_64, 173 [ESR_ELx_EC_HVC32] = handle_hvc, 174 [ESR_ELx_EC_SMC32] = handle_smc, 175 [ESR_ELx_EC_HVC64] = handle_hvc, 176 [ESR_ELx_EC_SMC64] = handle_smc, 177 [ESR_ELx_EC_SYS64] = kvm_handle_sys_reg, 178 [ESR_ELx_EC_SVE] = handle_sve, 179 [ESR_ELx_EC_IABT_LOW] = kvm_handle_guest_abort, 180 [ESR_ELx_EC_DABT_LOW] = kvm_handle_guest_abort, 181 [ESR_ELx_EC_SOFTSTP_LOW]= kvm_handle_guest_debug, 182 [ESR_ELx_EC_WATCHPT_LOW]= kvm_handle_guest_debug, 183 [ESR_ELx_EC_BREAKPT_LOW]= kvm_handle_guest_debug, 184 [ESR_ELx_EC_BKPT32] = kvm_handle_guest_debug, 185 [ESR_ELx_EC_BRK64] = kvm_handle_guest_debug, 186 [ESR_ELx_EC_FP_ASIMD] = handle_no_fpsimd, 187 [ESR_ELx_EC_PAC] = kvm_handle_ptrauth, 188 }; 189 190 static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu) 191 { 192 u64 esr = kvm_vcpu_get_esr(vcpu); 193 u8 esr_ec = ESR_ELx_EC(esr); 194 195 return arm_exit_handlers[esr_ec]; 196 } 197 198 /* 199 * We may be single-stepping an emulated instruction. If the emulation 200 * has been completed in the kernel, we can return to userspace with a 201 * KVM_EXIT_DEBUG, otherwise userspace needs to complete its 202 * emulation first. 203 */ 204 static int handle_trap_exceptions(struct kvm_vcpu *vcpu) 205 { 206 int handled; 207 208 /* 209 * See ARM ARM B1.14.1: "Hyp traps on instructions 210 * that fail their condition code check" 211 */ 212 if (!kvm_condition_valid(vcpu)) { 213 kvm_incr_pc(vcpu); 214 handled = 1; 215 } else { 216 exit_handle_fn exit_handler; 217 218 exit_handler = kvm_get_exit_handler(vcpu); 219 handled = exit_handler(vcpu); 220 } 221 222 return handled; 223 } 224 225 /* 226 * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on 227 * proper exit to userspace. 228 */ 229 int handle_exit(struct kvm_vcpu *vcpu, int exception_index) 230 { 231 struct kvm_run *run = vcpu->run; 232 233 if (ARM_SERROR_PENDING(exception_index)) { 234 /* 235 * The SError is handled by handle_exit_early(). If the guest 236 * survives it will re-execute the original instruction. 237 */ 238 return 1; 239 } 240 241 exception_index = ARM_EXCEPTION_CODE(exception_index); 242 243 switch (exception_index) { 244 case ARM_EXCEPTION_IRQ: 245 return 1; 246 case ARM_EXCEPTION_EL1_SERROR: 247 return 1; 248 case ARM_EXCEPTION_TRAP: 249 return handle_trap_exceptions(vcpu); 250 case ARM_EXCEPTION_HYP_GONE: 251 /* 252 * EL2 has been reset to the hyp-stub. This happens when a guest 253 * is pre-emptied by kvm_reboot()'s shutdown call. 254 */ 255 run->exit_reason = KVM_EXIT_FAIL_ENTRY; 256 return 0; 257 case ARM_EXCEPTION_IL: 258 /* 259 * We attempted an illegal exception return. Guest state must 260 * have been corrupted somehow. Give up. 261 */ 262 run->exit_reason = KVM_EXIT_FAIL_ENTRY; 263 return -EINVAL; 264 default: 265 kvm_pr_unimpl("Unsupported exception type: %d", 266 exception_index); 267 run->exit_reason = KVM_EXIT_INTERNAL_ERROR; 268 return 0; 269 } 270 } 271 272 /* For exit types that need handling before we can be preempted */ 273 void handle_exit_early(struct kvm_vcpu *vcpu, int exception_index) 274 { 275 if (ARM_SERROR_PENDING(exception_index)) { 276 if (this_cpu_has_cap(ARM64_HAS_RAS_EXTN)) { 277 u64 disr = kvm_vcpu_get_disr(vcpu); 278 279 kvm_handle_guest_serror(vcpu, disr_to_esr(disr)); 280 } else { 281 kvm_inject_vabt(vcpu); 282 } 283 284 return; 285 } 286 287 exception_index = ARM_EXCEPTION_CODE(exception_index); 288 289 if (exception_index == ARM_EXCEPTION_EL1_SERROR) 290 kvm_handle_guest_serror(vcpu, kvm_vcpu_get_esr(vcpu)); 291 } 292 293 void __noreturn __cold nvhe_hyp_panic_handler(u64 esr, u64 spsr, 294 u64 elr_virt, u64 elr_phys, 295 u64 par, uintptr_t vcpu, 296 u64 far, u64 hpfar) { 297 u64 elr_in_kimg = __phys_to_kimg(elr_phys); 298 u64 hyp_offset = elr_in_kimg - kaslr_offset() - elr_virt; 299 u64 mode = spsr & PSR_MODE_MASK; 300 301 /* 302 * The nVHE hyp symbols are not included by kallsyms to avoid issues 303 * with aliasing. That means that the symbols cannot be printed with the 304 * "%pS" format specifier, so fall back to the vmlinux address if 305 * there's no better option. 306 */ 307 if (mode != PSR_MODE_EL2t && mode != PSR_MODE_EL2h) { 308 kvm_err("Invalid host exception to nVHE hyp!\n"); 309 } else if (ESR_ELx_EC(esr) == ESR_ELx_EC_BRK64 && 310 (esr & ESR_ELx_BRK64_ISS_COMMENT_MASK) == BUG_BRK_IMM) { 311 const char *file = NULL; 312 unsigned int line = 0; 313 314 /* All hyp bugs, including warnings, are treated as fatal. */ 315 if (!is_protected_kvm_enabled() || 316 IS_ENABLED(CONFIG_NVHE_EL2_DEBUG)) { 317 struct bug_entry *bug = find_bug(elr_in_kimg); 318 319 if (bug) 320 bug_get_file_line(bug, &file, &line); 321 } 322 323 if (file) 324 kvm_err("nVHE hyp BUG at: %s:%u!\n", file, line); 325 else 326 kvm_err("nVHE hyp BUG at: %016llx!\n", elr_virt + hyp_offset); 327 } else { 328 kvm_err("nVHE hyp panic at: %016llx!\n", elr_virt + hyp_offset); 329 } 330 331 /* 332 * Hyp has panicked and we're going to handle that by panicking the 333 * kernel. The kernel offset will be revealed in the panic so we're 334 * also safe to reveal the hyp offset as a debugging aid for translating 335 * hyp VAs to vmlinux addresses. 336 */ 337 kvm_err("Hyp Offset: 0x%llx\n", hyp_offset); 338 339 panic("HYP panic:\nPS:%08llx PC:%016llx ESR:%016llx\nFAR:%016llx HPFAR:%016llx PAR:%016llx\nVCPU:%016lx\n", 340 spsr, elr_virt, esr, far, hpfar, par, vcpu); 341 } 342