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/kvm_asm.h>
  29 #include <asm/kvm_coproc.h>
  30 #include <asm/kvm_emulate.h>
  31 #include <asm/kvm_mmu.h>
  32
  33 #define CREATE_TRACE_POINTS
  34 #include "trace.h"
  35
  36 typedef int (*exit_handle_fn)(struct kvm_vcpu *, struct kvm_run *);
  37
  38 static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
  39 {
  40         int ret;
  41
  42         trace_kvm_hvc_arm64(*vcpu_pc(vcpu), vcpu_get_reg(vcpu, 0),
  43                             kvm_vcpu_hvc_get_imm(vcpu));
  44         vcpu->stat.hvc_exit_stat++;
  45
  46         ret = kvm_hvc_call_handler(vcpu);
  47         if (ret < 0) {
  48                 vcpu_set_reg(vcpu, 0, ~0UL);
  49                 return 1;
  50         }
  51
  52         return ret;
  53 }
  54
  55 static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run)
  56 {
  57         /*
  58          * "If an SMC instruction executed at Non-secure EL1 is
  59          * trapped to EL2 because HCR_EL2.TSC is 1, the exception is a
  60          * Trap exception, not a Secure Monitor Call exception [...]"
  61          *
  62          * We need to advance the PC after the trap, as it would
  63          * otherwise return to the same address...
  64          */
  65         vcpu_set_reg(vcpu, 0, ~0UL);
  66         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
  67         return 1;
  68 }
  69
  70 /*
  71  * Guest access to FP/ASIMD registers are routed to this handler only
  72  * when the system doesn't support FP/ASIMD.
  73  */
  74 static int handle_no_fpsimd(struct kvm_vcpu *vcpu, struct kvm_run *run)
  75 {
  76         kvm_inject_undefined(vcpu);
  77         return 1;
  78 }
  79
  80 /**
  81  * kvm_handle_wfx - handle a wait-for-interrupts or wait-for-event
  82  *                  instruction executed by a guest
  83  *
  84  * @vcpu:       the vcpu pointer
  85  *
  86  * WFE: Yield the CPU and come back to this vcpu when the scheduler
  87  * decides to.
  88  * WFI: Simply call kvm_vcpu_block(), which will halt execution of
  89  * world-switches and schedule other host processes until there is an
  90  * incoming IRQ or FIQ to the VM.
  91  */
  92 static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run)
  93 {
  94         if (kvm_vcpu_get_hsr(vcpu) & ESR_ELx_WFx_ISS_WFE) {
  95                 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), true);
  96                 vcpu->stat.wfe_exit_stat++;
  97                 kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu));
  98         } else {
  99                 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), false);
 100                 vcpu->stat.wfi_exit_stat++;
 101                 kvm_vcpu_block(vcpu);
 102                 kvm_clear_request(KVM_REQ_UNHALT, vcpu);
 103         }
 104
 105         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
 106
 107         return 1;
 108 }
 109
 110 /**
 111  * kvm_handle_guest_debug - handle a debug exception instruction
 112  *
 113  * @vcpu:       the vcpu pointer
 114  * @run:        access to the kvm_run structure for results
 115  *
 116  * We route all debug exceptions through the same handler. If both the
 117  * guest and host are using the same debug facilities it will be up to
 118  * userspace to re-inject the correct exception for guest delivery.
 119  *
 120  * @return: 0 (while setting run->exit_reason), -1 for error
 121  */
 122 static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu, struct kvm_run *run)
 123 {
 124         u32 hsr = kvm_vcpu_get_hsr(vcpu);
 125         int ret = 0;
 126
 127         run->exit_reason = KVM_EXIT_DEBUG;
 128         run->debug.arch.hsr = hsr;
 129
 130         switch (ESR_ELx_EC(hsr)) {
 131         case ESR_ELx_EC_WATCHPT_LOW:
 132                 run->debug.arch.far = vcpu->arch.fault.far_el2;
 133                 /* fall through */
 134         case ESR_ELx_EC_SOFTSTP_LOW:
 135         case ESR_ELx_EC_BREAKPT_LOW:
 136         case ESR_ELx_EC_BKPT32:
 137         case ESR_ELx_EC_BRK64:
 138                 break;
 139         default:
 140                 kvm_err("%s: un-handled case hsr: %#08x\n",
 141                         __func__, (unsigned int) hsr);
 142                 ret = -1;
 143                 break;
 144         }
 145
 146         return ret;
 147 }
 148
 149 static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu, struct kvm_run *run)
 150 {
 151         u32 hsr = kvm_vcpu_get_hsr(vcpu);
 152
 153         kvm_pr_unimpl("Unknown exception class: hsr: %#08x -- %s\n",
 154                       hsr, esr_get_class_string(hsr));
 155
 156         kvm_inject_undefined(vcpu);
 157         return 1;
 158 }
 159
 160 static exit_handle_fn arm_exit_handlers[] = {
 161         [0 ... ESR_ELx_EC_MAX]  = kvm_handle_unknown_ec,
 162         [ESR_ELx_EC_WFx]        = kvm_handle_wfx,
 163         [ESR_ELx_EC_CP15_32]    = kvm_handle_cp15_32,
 164         [ESR_ELx_EC_CP15_64]    = kvm_handle_cp15_64,
 165         [ESR_ELx_EC_CP14_MR]    = kvm_handle_cp14_32,
 166         [ESR_ELx_EC_CP14_LS]    = kvm_handle_cp14_load_store,
 167         [ESR_ELx_EC_CP14_64]    = kvm_handle_cp14_64,
 168         [ESR_ELx_EC_HVC32]      = handle_hvc,
 169         [ESR_ELx_EC_SMC32]      = handle_smc,
 170         [ESR_ELx_EC_HVC64]      = handle_hvc,
 171         [ESR_ELx_EC_SMC64]      = handle_smc,
 172         [ESR_ELx_EC_SYS64]      = kvm_handle_sys_reg,
 173         [ESR_ELx_EC_IABT_LOW]   = kvm_handle_guest_abort,
 174         [ESR_ELx_EC_DABT_LOW]   = kvm_handle_guest_abort,
 175         [ESR_ELx_EC_SOFTSTP_LOW]= kvm_handle_guest_debug,
 176         [ESR_ELx_EC_WATCHPT_LOW]= kvm_handle_guest_debug,
 177         [ESR_ELx_EC_BREAKPT_LOW]= kvm_handle_guest_debug,
 178         [ESR_ELx_EC_BKPT32]     = kvm_handle_guest_debug,
 179         [ESR_ELx_EC_BRK64]      = kvm_handle_guest_debug,
 180         [ESR_ELx_EC_FP_ASIMD]   = handle_no_fpsimd,
 181 };
 182
 183 static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
 184 {
 185         u32 hsr = kvm_vcpu_get_hsr(vcpu);
 186         u8 hsr_ec = ESR_ELx_EC(hsr);
 187
 188         return arm_exit_handlers[hsr_ec];
 189 }
 190
 191 /*
 192  * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on
 193  * proper exit to userspace.
 194  */
 195 int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 196                        int exception_index)
 197 {
 198         exit_handle_fn exit_handler;
 199
 200         if (ARM_SERROR_PENDING(exception_index)) {
 201                 u8 hsr_ec = ESR_ELx_EC(kvm_vcpu_get_hsr(vcpu));
 202
 203                 /*
 204                  * HVC/SMC already have an adjusted PC, which we need
 205                  * to correct in order to return to after having
 206                  * injected the SError.
 207                  */
 208                 if (hsr_ec == ESR_ELx_EC_HVC32 || hsr_ec == ESR_ELx_EC_HVC64 ||
 209                     hsr_ec == ESR_ELx_EC_SMC32 || hsr_ec == ESR_ELx_EC_SMC64) {
 210                         u32 adj =  kvm_vcpu_trap_il_is32bit(vcpu) ? 4 : 2;
 211                         *vcpu_pc(vcpu) -= adj;
 212                 }
 213
 214                 kvm_inject_vabt(vcpu);
 215                 return 1;
 216         }
 217
 218         exception_index = ARM_EXCEPTION_CODE(exception_index);
 219
 220         switch (exception_index) {
 221         case ARM_EXCEPTION_IRQ:
 222                 return 1;
 223         case ARM_EXCEPTION_EL1_SERROR:
 224                 kvm_inject_vabt(vcpu);
 225                 return 1;
 226         case ARM_EXCEPTION_TRAP:
 227                 /*
 228                  * See ARM ARM B1.14.1: "Hyp traps on instructions
 229                  * that fail their condition code check"
 230                  */
 231                 if (!kvm_condition_valid(vcpu)) {
 232                         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
 233                         return 1;
 234                 }
 235
 236                 exit_handler = kvm_get_exit_handler(vcpu);
 237
 238                 return exit_handler(vcpu, run);
 239         case ARM_EXCEPTION_HYP_GONE:
 240                 /*
 241                  * EL2 has been reset to the hyp-stub. This happens when a guest
 242                  * is pre-empted by kvm_reboot()'s shutdown call.
 243                  */
 244                 run->exit_reason = KVM_EXIT_FAIL_ENTRY;
 245                 return 0;
 246         default:
 247                 kvm_pr_unimpl("Unsupported exception type: %d",
 248                               exception_index);
 249                 run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
 250                 return 0;
 251         }
 252 }