arch/arm/kvm/handle_exit.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2012 - Virtual Open Systems and Columbia University
   4  * Author: Christoffer Dall <c.dall@virtualopensystems.com>
   5  */
   6
   7 #include <linux/kvm.h>
   8 #include <linux/kvm_host.h>
   9 #include <asm/kvm_emulate.h>
  10 #include <asm/kvm_coproc.h>
  11 #include <asm/kvm_mmu.h>
  12 #include <kvm/arm_psci.h>
  13 #include <trace/events/kvm.h>
  14
  15 #include "trace.h"
  16
  17 typedef int (*exit_handle_fn)(struct kvm_vcpu *, struct kvm_run *);
  18
  19 static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
  20 {
  21         int ret;
  22
  23         trace_kvm_hvc(*vcpu_pc(vcpu), *vcpu_reg(vcpu, 0),
  24                       kvm_vcpu_hvc_get_imm(vcpu));
  25         vcpu->stat.hvc_exit_stat++;
  26
  27         ret = kvm_hvc_call_handler(vcpu);
  28         if (ret < 0) {
  29                 vcpu_set_reg(vcpu, 0, ~0UL);
  30                 return 1;
  31         }
  32
  33         return ret;
  34 }
  35
  36 static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run)
  37 {
  38         /*
  39          * "If an SMC instruction executed at Non-secure EL1 is
  40          * trapped to EL2 because HCR_EL2.TSC is 1, the exception is a
  41          * Trap exception, not a Secure Monitor Call exception [...]"
  42          *
  43          * We need to advance the PC after the trap, as it would
  44          * otherwise return to the same address...
  45          */
  46         vcpu_set_reg(vcpu, 0, ~0UL);
  47         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
  48         return 1;
  49 }
  50
  51 /**
  52  * kvm_handle_wfx - handle a WFI or WFE instructions trapped in guests
  53  * @vcpu:       the vcpu pointer
  54  * @run:        the kvm_run structure pointer
  55  *
  56  * WFE: Yield the CPU and come back to this vcpu when the scheduler
  57  * decides to.
  58  * WFI: Simply call kvm_vcpu_block(), which will halt execution of
  59  * world-switches and schedule other host processes until there is an
  60  * incoming IRQ or FIQ to the VM.
  61  */
  62 static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run)
  63 {
  64         if (kvm_vcpu_get_hsr(vcpu) & HSR_WFI_IS_WFE) {
  65                 trace_kvm_wfx(*vcpu_pc(vcpu), true);
  66                 vcpu->stat.wfe_exit_stat++;
  67                 kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu));
  68         } else {
  69                 trace_kvm_wfx(*vcpu_pc(vcpu), false);
  70                 vcpu->stat.wfi_exit_stat++;
  71                 kvm_vcpu_block(vcpu);
  72                 kvm_clear_request(KVM_REQ_UNHALT, vcpu);
  73         }
  74
  75         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
  76
  77         return 1;
  78 }
  79
  80 static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu, struct kvm_run *run)
  81 {
  82         u32 hsr = kvm_vcpu_get_hsr(vcpu);
  83
  84         kvm_pr_unimpl("Unknown exception class: hsr: %#08x\n",
  85                       hsr);
  86
  87         kvm_inject_undefined(vcpu);
  88         return 1;
  89 }
  90
  91 static exit_handle_fn arm_exit_handlers[] = {
  92         [0 ... HSR_EC_MAX]      = kvm_handle_unknown_ec,
  93         [HSR_EC_WFI]            = kvm_handle_wfx,
  94         [HSR_EC_CP15_32]        = kvm_handle_cp15_32,
  95         [HSR_EC_CP15_64]        = kvm_handle_cp15_64,
  96         [HSR_EC_CP14_MR]        = kvm_handle_cp14_32,
  97         [HSR_EC_CP14_LS]        = kvm_handle_cp14_load_store,
  98         [HSR_EC_CP14_64]        = kvm_handle_cp14_64,
  99         [HSR_EC_CP_0_13]        = kvm_handle_cp_0_13_access,
 100         [HSR_EC_CP10_ID]        = kvm_handle_cp10_id,
 101         [HSR_EC_HVC]            = handle_hvc,
 102         [HSR_EC_SMC]            = handle_smc,
 103         [HSR_EC_IABT]           = kvm_handle_guest_abort,
 104         [HSR_EC_DABT]           = kvm_handle_guest_abort,
 105 };
 106
 107 static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
 108 {
 109         u8 hsr_ec = kvm_vcpu_trap_get_class(vcpu);
 110
 111         return arm_exit_handlers[hsr_ec];
 112 }
 113
 114 /*
 115  * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on
 116  * proper exit to userspace.
 117  */
 118 int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 119                        int exception_index)
 120 {
 121         exit_handle_fn exit_handler;
 122
 123         if (ARM_ABORT_PENDING(exception_index)) {
 124                 u8 hsr_ec = kvm_vcpu_trap_get_class(vcpu);
 125
 126                 /*
 127                  * HVC/SMC already have an adjusted PC, which we need
 128                  * to correct in order to return to after having
 129                  * injected the abort.
 130                  */
 131                 if (hsr_ec == HSR_EC_HVC || hsr_ec == HSR_EC_SMC) {
 132                         u32 adj =  kvm_vcpu_trap_il_is32bit(vcpu) ? 4 : 2;
 133                         *vcpu_pc(vcpu) -= adj;
 134                 }
 135
 136                 kvm_inject_vabt(vcpu);
 137                 return 1;
 138         }
 139
 140         exception_index = ARM_EXCEPTION_CODE(exception_index);
 141
 142         switch (exception_index) {
 143         case ARM_EXCEPTION_IRQ:
 144                 return 1;
 145         case ARM_EXCEPTION_HVC:
 146                 /*
 147                  * See ARM ARM B1.14.1: "Hyp traps on instructions
 148                  * that fail their condition code check"
 149                  */
 150                 if (!kvm_condition_valid(vcpu)) {
 151                         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
 152                         return 1;
 153                 }
 154
 155                 exit_handler = kvm_get_exit_handler(vcpu);
 156
 157                 return exit_handler(vcpu, run);
 158         case ARM_EXCEPTION_DATA_ABORT:
 159                 kvm_inject_vabt(vcpu);
 160                 return 1;
 161         case ARM_EXCEPTION_HYP_GONE:
 162                 /*
 163                  * HYP has been reset to the hyp-stub. This happens
 164                  * when a guest is pre-empted by kvm_reboot()'s
 165                  * shutdown call.
 166                  */
 167                 run->exit_reason = KVM_EXIT_FAIL_ENTRY;
 168                 return 0;
 169         default:
 170                 kvm_pr_unimpl("Unsupported exception type: %d",
 171                               exception_index);
 172                 run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
 173                 return 0;
 174         }
 175 }