arch/arm/kvm/handle_exit.c

   1 /*
   2  * Copyright (C) 2012 - Virtual Open Systems and Columbia University
   3  * Author: Christoffer Dall <c.dall@virtualopensystems.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  17  */
  18
  19 #include <linux/kvm.h>
  20 #include <linux/kvm_host.h>
  21 #include <asm/kvm_emulate.h>
  22 #include <asm/kvm_coproc.h>
  23 #include <asm/kvm_mmu.h>
  24 #include <kvm/arm_psci.h>
  25 #include <trace/events/kvm.h>
  26
  27 #include "trace.h"
  28
  29 typedef int (*exit_handle_fn)(struct kvm_vcpu *, struct kvm_run *);
  30
  31 static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
  32 {
  33         int ret;
  34
  35         trace_kvm_hvc(*vcpu_pc(vcpu), *vcpu_reg(vcpu, 0),
  36                       kvm_vcpu_hvc_get_imm(vcpu));
  37         vcpu->stat.hvc_exit_stat++;
  38
  39         ret = kvm_hvc_call_handler(vcpu);
  40         if (ret < 0) {
  41                 vcpu_set_reg(vcpu, 0, ~0UL);
  42                 return 1;
  43         }
  44
  45         return ret;
  46 }
  47
  48 static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run)
  49 {
  50         /*
  51          * "If an SMC instruction executed at Non-secure EL1 is
  52          * trapped to EL2 because HCR_EL2.TSC is 1, the exception is a
  53          * Trap exception, not a Secure Monitor Call exception [...]"
  54          *
  55          * We need to advance the PC after the trap, as it would
  56          * otherwise return to the same address...
  57          */
  58         vcpu_set_reg(vcpu, 0, ~0UL);
  59         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
  60         return 1;
  61 }
  62
  63 /**
  64  * kvm_handle_wfx - handle a WFI or WFE instructions trapped in guests
  65  * @vcpu:       the vcpu pointer
  66  * @run:        the kvm_run structure pointer
  67  *
  68  * WFE: Yield the CPU and come back to this vcpu when the scheduler
  69  * decides to.
  70  * WFI: Simply call kvm_vcpu_block(), which will halt execution of
  71  * world-switches and schedule other host processes until there is an
  72  * incoming IRQ or FIQ to the VM.
  73  */
  74 static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run)
  75 {
  76         if (kvm_vcpu_get_hsr(vcpu) & HSR_WFI_IS_WFE) {
  77                 trace_kvm_wfx(*vcpu_pc(vcpu), true);
  78                 vcpu->stat.wfe_exit_stat++;
  79                 kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu));
  80         } else {
  81                 trace_kvm_wfx(*vcpu_pc(vcpu), false);
  82                 vcpu->stat.wfi_exit_stat++;
  83                 kvm_vcpu_block(vcpu);
  84                 kvm_clear_request(KVM_REQ_UNHALT, vcpu);
  85         }
  86
  87         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
  88
  89         return 1;
  90 }
  91
  92 static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu, struct kvm_run *run)
  93 {
  94         u32 hsr = kvm_vcpu_get_hsr(vcpu);
  95
  96         kvm_pr_unimpl("Unknown exception class: hsr: %#08x\n",
  97                       hsr);
  98
  99         kvm_inject_undefined(vcpu);
 100         return 1;
 101 }
 102
 103 static exit_handle_fn arm_exit_handlers[] = {
 104         [0 ... HSR_EC_MAX]      = kvm_handle_unknown_ec,
 105         [HSR_EC_WFI]            = kvm_handle_wfx,
 106         [HSR_EC_CP15_32]        = kvm_handle_cp15_32,
 107         [HSR_EC_CP15_64]        = kvm_handle_cp15_64,
 108         [HSR_EC_CP14_MR]        = kvm_handle_cp14_32,
 109         [HSR_EC_CP14_LS]        = kvm_handle_cp14_load_store,
 110         [HSR_EC_CP14_64]        = kvm_handle_cp14_64,
 111         [HSR_EC_CP_0_13]        = kvm_handle_cp_0_13_access,
 112         [HSR_EC_CP10_ID]        = kvm_handle_cp10_id,
 113         [HSR_EC_HVC]            = handle_hvc,
 114         [HSR_EC_SMC]            = handle_smc,
 115         [HSR_EC_IABT]           = kvm_handle_guest_abort,
 116         [HSR_EC_DABT]           = kvm_handle_guest_abort,
 117 };
 118
 119 static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
 120 {
 121         u8 hsr_ec = kvm_vcpu_trap_get_class(vcpu);
 122
 123         return arm_exit_handlers[hsr_ec];
 124 }
 125
 126 /*
 127  * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on
 128  * proper exit to userspace.
 129  */
 130 int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 131                        int exception_index)
 132 {
 133         exit_handle_fn exit_handler;
 134
 135         if (ARM_ABORT_PENDING(exception_index)) {
 136                 u8 hsr_ec = kvm_vcpu_trap_get_class(vcpu);
 137
 138                 /*
 139                  * HVC/SMC already have an adjusted PC, which we need
 140                  * to correct in order to return to after having
 141                  * injected the abort.
 142                  */
 143                 if (hsr_ec == HSR_EC_HVC || hsr_ec == HSR_EC_SMC) {
 144                         u32 adj =  kvm_vcpu_trap_il_is32bit(vcpu) ? 4 : 2;
 145                         *vcpu_pc(vcpu) -= adj;
 146                 }
 147
 148                 kvm_inject_vabt(vcpu);
 149                 return 1;
 150         }
 151
 152         exception_index = ARM_EXCEPTION_CODE(exception_index);
 153
 154         switch (exception_index) {
 155         case ARM_EXCEPTION_IRQ:
 156                 return 1;
 157         case ARM_EXCEPTION_HVC:
 158                 /*
 159                  * See ARM ARM B1.14.1: "Hyp traps on instructions
 160                  * that fail their condition code check"
 161                  */
 162                 if (!kvm_condition_valid(vcpu)) {
 163                         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
 164                         return 1;
 165                 }
 166
 167                 exit_handler = kvm_get_exit_handler(vcpu);
 168
 169                 return exit_handler(vcpu, run);
 170         case ARM_EXCEPTION_DATA_ABORT:
 171                 kvm_inject_vabt(vcpu);
 172                 return 1;
 173         case ARM_EXCEPTION_HYP_GONE:
 174                 /*
 175                  * HYP has been reset to the hyp-stub. This happens
 176                  * when a guest is pre-empted by kvm_reboot()'s
 177                  * shutdown call.
 178                  */
 179                 run->exit_reason = KVM_EXIT_FAIL_ENTRY;
 180                 return 0;
 181         default:
 182                 kvm_pr_unimpl("Unsupported exception type: %d",
 183                               exception_index);
 184                 run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
 185                 return 0;
 186         }
 187 }