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