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