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