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 #include <asm/debug-monitors.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_psci_call(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         vcpu_set_reg(vcpu, 0, ~0UL);
  58         return 1;
  59 }
  60
  61 /*
  62  * Guest access to FP/ASIMD registers are routed to this handler only
  63  * when the system doesn't support FP/ASIMD.
  64  */
  65 static int handle_no_fpsimd(struct kvm_vcpu *vcpu, struct kvm_run *run)
  66 {
  67         kvm_inject_undefined(vcpu);
  68         return 1;
  69 }
  70
  71 /**
  72  * kvm_handle_wfx - handle a wait-for-interrupts or wait-for-event
  73  *                  instruction executed by a guest
  74  *
  75  * @vcpu:       the vcpu pointer
  76  *
  77  * WFE: Yield the CPU and come back to this vcpu when the scheduler
  78  * decides to.
  79  * WFI: Simply call kvm_vcpu_block(), which will halt execution of
  80  * world-switches and schedule other host processes until there is an
  81  * incoming IRQ or FIQ to the VM.
  82  */
  83 static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run)
  84 {
  85         if (kvm_vcpu_get_hsr(vcpu) & ESR_ELx_WFx_ISS_WFE) {
  86                 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), true);
  87                 vcpu->stat.wfe_exit_stat++;
  88                 kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu));
  89         } else {
  90                 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), false);
  91                 vcpu->stat.wfi_exit_stat++;
  92                 kvm_vcpu_block(vcpu);
  93                 kvm_clear_request(KVM_REQ_UNHALT, 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 int handle_sve(struct kvm_vcpu *vcpu, struct kvm_run *run)
 152 {
 153         /* Until SVE is supported for guests: */
 154         kvm_inject_undefined(vcpu);
 155         return 1;
 156 }
 157
 158 static exit_handle_fn arm_exit_handlers[] = {
 159         [0 ... ESR_ELx_EC_MAX]  = kvm_handle_unknown_ec,
 160         [ESR_ELx_EC_WFx]        = kvm_handle_wfx,
 161         [ESR_ELx_EC_CP15_32]    = kvm_handle_cp15_32,
 162         [ESR_ELx_EC_CP15_64]    = kvm_handle_cp15_64,
 163         [ESR_ELx_EC_CP14_MR]    = kvm_handle_cp14_32,
 164         [ESR_ELx_EC_CP14_LS]    = kvm_handle_cp14_load_store,
 165         [ESR_ELx_EC_CP14_64]    = kvm_handle_cp14_64,
 166         [ESR_ELx_EC_HVC32]      = handle_hvc,
 167         [ESR_ELx_EC_SMC32]      = handle_smc,
 168         [ESR_ELx_EC_HVC64]      = handle_hvc,
 169         [ESR_ELx_EC_SMC64]      = handle_smc,
 170         [ESR_ELx_EC_SYS64]      = kvm_handle_sys_reg,
 171         [ESR_ELx_EC_SVE]        = handle_sve,
 172         [ESR_ELx_EC_IABT_LOW]   = kvm_handle_guest_abort,
 173         [ESR_ELx_EC_DABT_LOW]   = kvm_handle_guest_abort,
 174         [ESR_ELx_EC_SOFTSTP_LOW]= kvm_handle_guest_debug,
 175         [ESR_ELx_EC_WATCHPT_LOW]= kvm_handle_guest_debug,
 176         [ESR_ELx_EC_BREAKPT_LOW]= kvm_handle_guest_debug,
 177         [ESR_ELx_EC_BKPT32]     = kvm_handle_guest_debug,
 178         [ESR_ELx_EC_BRK64]      = kvm_handle_guest_debug,
 179         [ESR_ELx_EC_FP_ASIMD]   = handle_no_fpsimd,
 180 };
 181
 182 static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
 183 {
 184         u32 hsr = kvm_vcpu_get_hsr(vcpu);
 185         u8 hsr_ec = ESR_ELx_EC(hsr);
 186
 187         return arm_exit_handlers[hsr_ec];
 188 }
 189
 190 /*
 191  * We may be single-stepping an emulated instruction. If the emulation
 192  * has been completed in the kernel, we can return to userspace with a
 193  * KVM_EXIT_DEBUG, otherwise userspace needs to complete its
 194  * emulation first.
 195  */
 196 static int handle_trap_exceptions(struct kvm_vcpu *vcpu, struct kvm_run *run)
 197 {
 198         int handled;
 199
 200         /*
 201          * See ARM ARM B1.14.1: "Hyp traps on instructions
 202          * that fail their condition code check"
 203          */
 204         if (!kvm_condition_valid(vcpu)) {
 205                 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
 206                 handled = 1;
 207         } else {
 208                 exit_handle_fn exit_handler;
 209
 210                 exit_handler = kvm_get_exit_handler(vcpu);
 211                 handled = exit_handler(vcpu, run);
 212         }
 213
 214         /*
 215          * kvm_arm_handle_step_debug() sets the exit_reason on the kvm_run
 216          * structure if we need to return to userspace.
 217          */
 218         if (handled > 0 && kvm_arm_handle_step_debug(vcpu, run))
 219                 handled = 0;
 220
 221         return handled;
 222 }
 223
 224 /*
 225  * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on
 226  * proper exit to userspace.
 227  */
 228 int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 229                        int exception_index)
 230 {
 231         if (ARM_SERROR_PENDING(exception_index)) {
 232                 u8 hsr_ec = ESR_ELx_EC(kvm_vcpu_get_hsr(vcpu));
 233
 234                 /*
 235                  * HVC/SMC already have an adjusted PC, which we need
 236                  * to correct in order to return to after having
 237                  * injected the SError.
 238                  */
 239                 if (hsr_ec == ESR_ELx_EC_HVC32 || hsr_ec == ESR_ELx_EC_HVC64 ||
 240                     hsr_ec == ESR_ELx_EC_SMC32 || hsr_ec == ESR_ELx_EC_SMC64) {
 241                         u32 adj =  kvm_vcpu_trap_il_is32bit(vcpu) ? 4 : 2;
 242                         *vcpu_pc(vcpu) -= adj;
 243                 }
 244
 245                 kvm_inject_vabt(vcpu);
 246                 return 1;
 247         }
 248
 249         exception_index = ARM_EXCEPTION_CODE(exception_index);
 250
 251         switch (exception_index) {
 252         case ARM_EXCEPTION_IRQ:
 253                 return 1;
 254         case ARM_EXCEPTION_EL1_SERROR:
 255                 kvm_inject_vabt(vcpu);
 256                 /* We may still need to return for single-step */
 257                 if (!(*vcpu_cpsr(vcpu) & DBG_SPSR_SS)
 258                         && kvm_arm_handle_step_debug(vcpu, run))
 259                         return 0;
 260                 else
 261                         return 1;
 262         case ARM_EXCEPTION_TRAP:
 263                 return handle_trap_exceptions(vcpu, run);
 264         case ARM_EXCEPTION_HYP_GONE:
 265                 /*
 266                  * EL2 has been reset to the hyp-stub. This happens when a guest
 267                  * is pre-empted by kvm_reboot()'s shutdown call.
 268                  */
 269                 run->exit_reason = KVM_EXIT_FAIL_ENTRY;
 270                 return 0;
 271         default:
 272                 kvm_pr_unimpl("Unsupported exception type: %d",
 273                               exception_index);
 274                 run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
 275                 return 0;
 276         }
 277 }