1 /* 2 * Copyright (C) 2012,2013 - ARM Ltd 3 * Author: Marc Zyngier <marc.zyngier@arm.com> 4 * 5 * Derived from arch/arm/kvm/handle_exit.c: 6 * Copyright (C) 2012 - Virtual Open Systems and Columbia University 7 * Author: Christoffer Dall <c.dall@virtualopensystems.com> 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License version 2 as 11 * published by the Free Software Foundation. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 * 18 * You should have received a copy of the GNU General Public License 19 * along with this program. If not, see <http://www.gnu.org/licenses/>. 20 */ 21 22 #include <linux/kvm.h> 23 #include <linux/kvm_host.h> 24 25 #include <kvm/arm_psci.h> 26 27 #include <asm/esr.h> 28 #include <asm/exception.h> 29 #include <asm/kvm_asm.h> 30 #include <asm/kvm_coproc.h> 31 #include <asm/kvm_emulate.h> 32 #include <asm/kvm_mmu.h> 33 #include <asm/debug-monitors.h> 34 #include <asm/traps.h> 35 36 #define CREATE_TRACE_POINTS 37 #include "trace.h" 38 39 typedef int (*exit_handle_fn)(struct kvm_vcpu *, struct kvm_run *); 40 41 static void kvm_handle_guest_serror(struct kvm_vcpu *vcpu, u32 esr) 42 { 43 if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(NULL, esr)) 44 kvm_inject_vabt(vcpu); 45 } 46 47 static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run) 48 { 49 int ret; 50 51 trace_kvm_hvc_arm64(*vcpu_pc(vcpu), vcpu_get_reg(vcpu, 0), 52 kvm_vcpu_hvc_get_imm(vcpu)); 53 vcpu->stat.hvc_exit_stat++; 54 55 ret = kvm_hvc_call_handler(vcpu); 56 if (ret < 0) { 57 vcpu_set_reg(vcpu, 0, ~0UL); 58 return 1; 59 } 60 61 return ret; 62 } 63 64 static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run) 65 { 66 /* 67 * "If an SMC instruction executed at Non-secure EL1 is 68 * trapped to EL2 because HCR_EL2.TSC is 1, the exception is a 69 * Trap exception, not a Secure Monitor Call exception [...]" 70 * 71 * We need to advance the PC after the trap, as it would 72 * otherwise return to the same address... 73 */ 74 vcpu_set_reg(vcpu, 0, ~0UL); 75 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); 76 return 1; 77 } 78 79 /* 80 * Guest access to FP/ASIMD registers are routed to this handler only 81 * when the system doesn't support FP/ASIMD. 82 */ 83 static int handle_no_fpsimd(struct kvm_vcpu *vcpu, struct kvm_run *run) 84 { 85 kvm_inject_undefined(vcpu); 86 return 1; 87 } 88 89 /** 90 * kvm_handle_wfx - handle a wait-for-interrupts or wait-for-event 91 * instruction executed by a guest 92 * 93 * @vcpu: the vcpu pointer 94 * 95 * WFE: Yield the CPU and come back to this vcpu when the scheduler 96 * decides to. 97 * WFI: Simply call kvm_vcpu_block(), which will halt execution of 98 * world-switches and schedule other host processes until there is an 99 * incoming IRQ or FIQ to the VM. 100 */ 101 static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run) 102 { 103 if (kvm_vcpu_get_hsr(vcpu) & ESR_ELx_WFx_ISS_WFE) { 104 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), true); 105 vcpu->stat.wfe_exit_stat++; 106 kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu)); 107 } else { 108 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), false); 109 vcpu->stat.wfi_exit_stat++; 110 kvm_vcpu_block(vcpu); 111 kvm_clear_request(KVM_REQ_UNHALT, vcpu); 112 } 113 114 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); 115 116 return 1; 117 } 118 119 /** 120 * kvm_handle_guest_debug - handle a debug exception instruction 121 * 122 * @vcpu: the vcpu pointer 123 * @run: access to the kvm_run structure for results 124 * 125 * We route all debug exceptions through the same handler. If both the 126 * guest and host are using the same debug facilities it will be up to 127 * userspace to re-inject the correct exception for guest delivery. 128 * 129 * @return: 0 (while setting run->exit_reason), -1 for error 130 */ 131 static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu, struct kvm_run *run) 132 { 133 u32 hsr = kvm_vcpu_get_hsr(vcpu); 134 int ret = 0; 135 136 run->exit_reason = KVM_EXIT_DEBUG; 137 run->debug.arch.hsr = hsr; 138 139 switch (ESR_ELx_EC(hsr)) { 140 case ESR_ELx_EC_WATCHPT_LOW: 141 run->debug.arch.far = vcpu->arch.fault.far_el2; 142 /* fall through */ 143 case ESR_ELx_EC_SOFTSTP_LOW: 144 case ESR_ELx_EC_BREAKPT_LOW: 145 case ESR_ELx_EC_BKPT32: 146 case ESR_ELx_EC_BRK64: 147 break; 148 default: 149 kvm_err("%s: un-handled case hsr: %#08x\n", 150 __func__, (unsigned int) hsr); 151 ret = -1; 152 break; 153 } 154 155 return ret; 156 } 157 158 static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu, struct kvm_run *run) 159 { 160 u32 hsr = kvm_vcpu_get_hsr(vcpu); 161 162 kvm_pr_unimpl("Unknown exception class: hsr: %#08x -- %s\n", 163 hsr, esr_get_class_string(hsr)); 164 165 kvm_inject_undefined(vcpu); 166 return 1; 167 } 168 169 static int handle_sve(struct kvm_vcpu *vcpu, struct kvm_run *run) 170 { 171 /* Until SVE is supported for guests: */ 172 kvm_inject_undefined(vcpu); 173 return 1; 174 } 175 176 #define __ptrauth_save_key(regs, key) \ 177 ({ \ 178 regs[key ## KEYLO_EL1] = read_sysreg_s(SYS_ ## key ## KEYLO_EL1); \ 179 regs[key ## KEYHI_EL1] = read_sysreg_s(SYS_ ## key ## KEYHI_EL1); \ 180 }) 181 182 /* 183 * Handle the guest trying to use a ptrauth instruction, or trying to access a 184 * ptrauth register. 185 */ 186 void kvm_arm_vcpu_ptrauth_trap(struct kvm_vcpu *vcpu) 187 { 188 struct kvm_cpu_context *ctxt; 189 190 if (vcpu_has_ptrauth(vcpu)) { 191 vcpu_ptrauth_enable(vcpu); 192 ctxt = vcpu->arch.host_cpu_context; 193 __ptrauth_save_key(ctxt->sys_regs, APIA); 194 __ptrauth_save_key(ctxt->sys_regs, APIB); 195 __ptrauth_save_key(ctxt->sys_regs, APDA); 196 __ptrauth_save_key(ctxt->sys_regs, APDB); 197 __ptrauth_save_key(ctxt->sys_regs, APGA); 198 } else { 199 kvm_inject_undefined(vcpu); 200 } 201 } 202 203 /* 204 * Guest usage of a ptrauth instruction (which the guest EL1 did not turn into 205 * a NOP). 206 */ 207 static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu, struct kvm_run *run) 208 { 209 kvm_arm_vcpu_ptrauth_trap(vcpu); 210 return 1; 211 } 212 213 static exit_handle_fn arm_exit_handlers[] = { 214 [0 ... ESR_ELx_EC_MAX] = kvm_handle_unknown_ec, 215 [ESR_ELx_EC_WFx] = kvm_handle_wfx, 216 [ESR_ELx_EC_CP15_32] = kvm_handle_cp15_32, 217 [ESR_ELx_EC_CP15_64] = kvm_handle_cp15_64, 218 [ESR_ELx_EC_CP14_MR] = kvm_handle_cp14_32, 219 [ESR_ELx_EC_CP14_LS] = kvm_handle_cp14_load_store, 220 [ESR_ELx_EC_CP14_64] = kvm_handle_cp14_64, 221 [ESR_ELx_EC_HVC32] = handle_hvc, 222 [ESR_ELx_EC_SMC32] = handle_smc, 223 [ESR_ELx_EC_HVC64] = handle_hvc, 224 [ESR_ELx_EC_SMC64] = handle_smc, 225 [ESR_ELx_EC_SYS64] = kvm_handle_sys_reg, 226 [ESR_ELx_EC_SVE] = handle_sve, 227 [ESR_ELx_EC_IABT_LOW] = kvm_handle_guest_abort, 228 [ESR_ELx_EC_DABT_LOW] = kvm_handle_guest_abort, 229 [ESR_ELx_EC_SOFTSTP_LOW]= kvm_handle_guest_debug, 230 [ESR_ELx_EC_WATCHPT_LOW]= kvm_handle_guest_debug, 231 [ESR_ELx_EC_BREAKPT_LOW]= kvm_handle_guest_debug, 232 [ESR_ELx_EC_BKPT32] = kvm_handle_guest_debug, 233 [ESR_ELx_EC_BRK64] = kvm_handle_guest_debug, 234 [ESR_ELx_EC_FP_ASIMD] = handle_no_fpsimd, 235 [ESR_ELx_EC_PAC] = kvm_handle_ptrauth, 236 }; 237 238 static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu) 239 { 240 u32 hsr = kvm_vcpu_get_hsr(vcpu); 241 u8 hsr_ec = ESR_ELx_EC(hsr); 242 243 return arm_exit_handlers[hsr_ec]; 244 } 245 246 /* 247 * We may be single-stepping an emulated instruction. If the emulation 248 * has been completed in the kernel, we can return to userspace with a 249 * KVM_EXIT_DEBUG, otherwise userspace needs to complete its 250 * emulation first. 251 */ 252 static int handle_trap_exceptions(struct kvm_vcpu *vcpu, struct kvm_run *run) 253 { 254 int handled; 255 256 /* 257 * See ARM ARM B1.14.1: "Hyp traps on instructions 258 * that fail their condition code check" 259 */ 260 if (!kvm_condition_valid(vcpu)) { 261 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); 262 handled = 1; 263 } else { 264 exit_handle_fn exit_handler; 265 266 exit_handler = kvm_get_exit_handler(vcpu); 267 handled = exit_handler(vcpu, run); 268 } 269 270 return handled; 271 } 272 273 /* 274 * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on 275 * proper exit to userspace. 276 */ 277 int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run, 278 int exception_index) 279 { 280 if (ARM_SERROR_PENDING(exception_index)) { 281 u8 hsr_ec = ESR_ELx_EC(kvm_vcpu_get_hsr(vcpu)); 282 283 /* 284 * HVC/SMC already have an adjusted PC, which we need 285 * to correct in order to return to after having 286 * injected the SError. 287 */ 288 if (hsr_ec == ESR_ELx_EC_HVC32 || hsr_ec == ESR_ELx_EC_HVC64 || 289 hsr_ec == ESR_ELx_EC_SMC32 || hsr_ec == ESR_ELx_EC_SMC64) { 290 u32 adj = kvm_vcpu_trap_il_is32bit(vcpu) ? 4 : 2; 291 *vcpu_pc(vcpu) -= adj; 292 } 293 294 return 1; 295 } 296 297 exception_index = ARM_EXCEPTION_CODE(exception_index); 298 299 switch (exception_index) { 300 case ARM_EXCEPTION_IRQ: 301 return 1; 302 case ARM_EXCEPTION_EL1_SERROR: 303 return 1; 304 case ARM_EXCEPTION_TRAP: 305 return handle_trap_exceptions(vcpu, run); 306 case ARM_EXCEPTION_HYP_GONE: 307 /* 308 * EL2 has been reset to the hyp-stub. This happens when a guest 309 * is pre-empted by kvm_reboot()'s shutdown call. 310 */ 311 run->exit_reason = KVM_EXIT_FAIL_ENTRY; 312 return 0; 313 case ARM_EXCEPTION_IL: 314 /* 315 * We attempted an illegal exception return. Guest state must 316 * have been corrupted somehow. Give up. 317 */ 318 run->exit_reason = KVM_EXIT_FAIL_ENTRY; 319 return -EINVAL; 320 default: 321 kvm_pr_unimpl("Unsupported exception type: %d", 322 exception_index); 323 run->exit_reason = KVM_EXIT_INTERNAL_ERROR; 324 return 0; 325 } 326 } 327 328 /* For exit types that need handling before we can be preempted */ 329 void handle_exit_early(struct kvm_vcpu *vcpu, struct kvm_run *run, 330 int exception_index) 331 { 332 if (ARM_SERROR_PENDING(exception_index)) { 333 if (this_cpu_has_cap(ARM64_HAS_RAS_EXTN)) { 334 u64 disr = kvm_vcpu_get_disr(vcpu); 335 336 kvm_handle_guest_serror(vcpu, disr_to_esr(disr)); 337 } else { 338 kvm_inject_vabt(vcpu); 339 } 340 341 return; 342 } 343 344 exception_index = ARM_EXCEPTION_CODE(exception_index); 345 346 if (exception_index == ARM_EXCEPTION_EL1_SERROR) 347 kvm_handle_guest_serror(vcpu, kvm_vcpu_get_hsr(vcpu)); 348 } 349