arch/arm64/kvm/handle_exit.c

   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 }