arch/arm64/kvm/handle_exit.c

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