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 <asm/esr.h> 26 #include <asm/exception.h> 27 #include <asm/kvm_asm.h> 28 #include <asm/kvm_coproc.h> 29 #include <asm/kvm_emulate.h> 30 #include <asm/kvm_mmu.h> 31 #include <asm/kvm_psci.h> 32 #include <asm/debug-monitors.h> 33 #include <asm/traps.h> 34 35 #define CREATE_TRACE_POINTS 36 #include "trace.h" 37 38 typedef int (*exit_handle_fn)(struct kvm_vcpu *, struct kvm_run *); 39 40 static void kvm_handle_guest_serror(struct kvm_vcpu *vcpu, u32 esr) 41 { 42 if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(NULL, esr)) 43 kvm_inject_vabt(vcpu); 44 } 45 46 static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run) 47 { 48 int ret; 49 50 trace_kvm_hvc_arm64(*vcpu_pc(vcpu), vcpu_get_reg(vcpu, 0), 51 kvm_vcpu_hvc_get_imm(vcpu)); 52 vcpu->stat.hvc_exit_stat++; 53 54 ret = kvm_psci_call(vcpu); 55 if (ret < 0) { 56 vcpu_set_reg(vcpu, 0, ~0UL); 57 return 1; 58 } 59 60 return ret; 61 } 62 63 static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run) 64 { 65 vcpu_set_reg(vcpu, 0, ~0UL); 66 return 1; 67 } 68 69 /* 70 * Guest access to FP/ASIMD registers are routed to this handler only 71 * when the system doesn't support FP/ASIMD. 72 */ 73 static int handle_no_fpsimd(struct kvm_vcpu *vcpu, struct kvm_run *run) 74 { 75 kvm_inject_undefined(vcpu); 76 return 1; 77 } 78 79 /** 80 * kvm_handle_wfx - handle a wait-for-interrupts or wait-for-event 81 * instruction executed by a guest 82 * 83 * @vcpu: the vcpu pointer 84 * 85 * WFE: Yield the CPU and come back to this vcpu when the scheduler 86 * decides to. 87 * WFI: Simply call kvm_vcpu_block(), which will halt execution of 88 * world-switches and schedule other host processes until there is an 89 * incoming IRQ or FIQ to the VM. 90 */ 91 static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run) 92 { 93 if (kvm_vcpu_get_hsr(vcpu) & ESR_ELx_WFx_ISS_WFE) { 94 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), true); 95 vcpu->stat.wfe_exit_stat++; 96 kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu)); 97 } else { 98 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), false); 99 vcpu->stat.wfi_exit_stat++; 100 kvm_vcpu_block(vcpu); 101 kvm_clear_request(KVM_REQ_UNHALT, vcpu); 102 } 103 104 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); 105 106 return 1; 107 } 108 109 /** 110 * kvm_handle_guest_debug - handle a debug exception instruction 111 * 112 * @vcpu: the vcpu pointer 113 * @run: access to the kvm_run structure for results 114 * 115 * We route all debug exceptions through the same handler. If both the 116 * guest and host are using the same debug facilities it will be up to 117 * userspace to re-inject the correct exception for guest delivery. 118 * 119 * @return: 0 (while setting run->exit_reason), -1 for error 120 */ 121 static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu, struct kvm_run *run) 122 { 123 u32 hsr = kvm_vcpu_get_hsr(vcpu); 124 int ret = 0; 125 126 run->exit_reason = KVM_EXIT_DEBUG; 127 run->debug.arch.hsr = hsr; 128 129 switch (ESR_ELx_EC(hsr)) { 130 case ESR_ELx_EC_WATCHPT_LOW: 131 run->debug.arch.far = vcpu->arch.fault.far_el2; 132 /* fall through */ 133 case ESR_ELx_EC_SOFTSTP_LOW: 134 case ESR_ELx_EC_BREAKPT_LOW: 135 case ESR_ELx_EC_BKPT32: 136 case ESR_ELx_EC_BRK64: 137 break; 138 default: 139 kvm_err("%s: un-handled case hsr: %#08x\n", 140 __func__, (unsigned int) hsr); 141 ret = -1; 142 break; 143 } 144 145 return ret; 146 } 147 148 static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu, struct kvm_run *run) 149 { 150 u32 hsr = kvm_vcpu_get_hsr(vcpu); 151 152 kvm_pr_unimpl("Unknown exception class: hsr: %#08x -- %s\n", 153 hsr, esr_get_class_string(hsr)); 154 155 kvm_inject_undefined(vcpu); 156 return 1; 157 } 158 159 static int handle_sve(struct kvm_vcpu *vcpu, struct kvm_run *run) 160 { 161 /* Until SVE is supported for guests: */ 162 kvm_inject_undefined(vcpu); 163 return 1; 164 } 165 166 static exit_handle_fn arm_exit_handlers[] = { 167 [0 ... ESR_ELx_EC_MAX] = kvm_handle_unknown_ec, 168 [ESR_ELx_EC_WFx] = kvm_handle_wfx, 169 [ESR_ELx_EC_CP15_32] = kvm_handle_cp15_32, 170 [ESR_ELx_EC_CP15_64] = kvm_handle_cp15_64, 171 [ESR_ELx_EC_CP14_MR] = kvm_handle_cp14_32, 172 [ESR_ELx_EC_CP14_LS] = kvm_handle_cp14_load_store, 173 [ESR_ELx_EC_CP14_64] = kvm_handle_cp14_64, 174 [ESR_ELx_EC_HVC32] = handle_hvc, 175 [ESR_ELx_EC_SMC32] = handle_smc, 176 [ESR_ELx_EC_HVC64] = handle_hvc, 177 [ESR_ELx_EC_SMC64] = handle_smc, 178 [ESR_ELx_EC_SYS64] = kvm_handle_sys_reg, 179 [ESR_ELx_EC_SVE] = handle_sve, 180 [ESR_ELx_EC_IABT_LOW] = kvm_handle_guest_abort, 181 [ESR_ELx_EC_DABT_LOW] = kvm_handle_guest_abort, 182 [ESR_ELx_EC_SOFTSTP_LOW]= kvm_handle_guest_debug, 183 [ESR_ELx_EC_WATCHPT_LOW]= kvm_handle_guest_debug, 184 [ESR_ELx_EC_BREAKPT_LOW]= kvm_handle_guest_debug, 185 [ESR_ELx_EC_BKPT32] = kvm_handle_guest_debug, 186 [ESR_ELx_EC_BRK64] = kvm_handle_guest_debug, 187 [ESR_ELx_EC_FP_ASIMD] = handle_no_fpsimd, 188 }; 189 190 static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu) 191 { 192 u32 hsr = kvm_vcpu_get_hsr(vcpu); 193 u8 hsr_ec = ESR_ELx_EC(hsr); 194 195 return arm_exit_handlers[hsr_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, struct kvm_run *run) 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_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(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, run); 220 } 221 222 /* 223 * kvm_arm_handle_step_debug() sets the exit_reason on the kvm_run 224 * structure if we need to return to userspace. 225 */ 226 if (handled > 0 && kvm_arm_handle_step_debug(vcpu, run)) 227 handled = 0; 228 229 return handled; 230 } 231 232 /* 233 * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on 234 * proper exit to userspace. 235 */ 236 int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run, 237 int exception_index) 238 { 239 if (ARM_SERROR_PENDING(exception_index)) { 240 u8 hsr_ec = ESR_ELx_EC(kvm_vcpu_get_hsr(vcpu)); 241 242 /* 243 * HVC/SMC already have an adjusted PC, which we need 244 * to correct in order to return to after having 245 * injected the SError. 246 */ 247 if (hsr_ec == ESR_ELx_EC_HVC32 || hsr_ec == ESR_ELx_EC_HVC64 || 248 hsr_ec == ESR_ELx_EC_SMC32 || hsr_ec == ESR_ELx_EC_SMC64) { 249 u32 adj = kvm_vcpu_trap_il_is32bit(vcpu) ? 4 : 2; 250 *vcpu_pc(vcpu) -= adj; 251 } 252 253 return 1; 254 } 255 256 exception_index = ARM_EXCEPTION_CODE(exception_index); 257 258 switch (exception_index) { 259 case ARM_EXCEPTION_IRQ: 260 return 1; 261 case ARM_EXCEPTION_EL1_SERROR: 262 /* We may still need to return for single-step */ 263 if (!(*vcpu_cpsr(vcpu) & DBG_SPSR_SS) 264 && kvm_arm_handle_step_debug(vcpu, run)) 265 return 0; 266 else 267 return 1; 268 case ARM_EXCEPTION_TRAP: 269 return handle_trap_exceptions(vcpu, run); 270 case ARM_EXCEPTION_HYP_GONE: 271 /* 272 * EL2 has been reset to the hyp-stub. This happens when a guest 273 * is pre-empted by kvm_reboot()'s shutdown call. 274 */ 275 run->exit_reason = KVM_EXIT_FAIL_ENTRY; 276 return 0; 277 default: 278 kvm_pr_unimpl("Unsupported exception type: %d", 279 exception_index); 280 run->exit_reason = KVM_EXIT_INTERNAL_ERROR; 281 return 0; 282 } 283 } 284 285 /* For exit types that need handling before we can be preempted */ 286 void handle_exit_early(struct kvm_vcpu *vcpu, struct kvm_run *run, 287 int exception_index) 288 { 289 if (ARM_SERROR_PENDING(exception_index)) { 290 if (this_cpu_has_cap(ARM64_HAS_RAS_EXTN)) { 291 u64 disr = kvm_vcpu_get_disr(vcpu); 292 293 kvm_handle_guest_serror(vcpu, disr_to_esr(disr)); 294 } else { 295 kvm_inject_vabt(vcpu); 296 } 297 298 return; 299 } 300 301 exception_index = ARM_EXCEPTION_CODE(exception_index); 302 303 if (exception_index == ARM_EXCEPTION_EL1_SERROR) 304 kvm_handle_guest_serror(vcpu, kvm_vcpu_get_hsr(vcpu)); 305 } 306