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