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