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);
  80         } else {
  81                 trace_kvm_wfx(*vcpu_pc(vcpu), false);
  82                 vcpu->stat.wfi_exit_stat++;
  83                 kvm_vcpu_block(vcpu);
  84         }
  85
  86         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
  87
  88         return 1;
  89 }
  90
  91 static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu, struct kvm_run *run)
  92 {
  93         u32 hsr = kvm_vcpu_get_hsr(vcpu);
  94
  95         kvm_pr_unimpl("Unknown exception class: hsr: %#08x\n",
  96                       hsr);
  97
  98         kvm_inject_undefined(vcpu);
  99         return 1;
 100 }
 101
 102 static exit_handle_fn arm_exit_handlers[] = {
 103         [0 ... HSR_EC_MAX]      = kvm_handle_unknown_ec,
 104         [HSR_EC_WFI]            = kvm_handle_wfx,
 105         [HSR_EC_CP15_32]        = kvm_handle_cp15_32,
 106         [HSR_EC_CP15_64]        = kvm_handle_cp15_64,
 107         [HSR_EC_CP14_MR]        = kvm_handle_cp14_32,
 108         [HSR_EC_CP14_LS]        = kvm_handle_cp14_load_store,
 109         [HSR_EC_CP14_64]        = kvm_handle_cp14_64,
 110         [HSR_EC_CP_0_13]        = kvm_handle_cp_0_13_access,
 111         [HSR_EC_CP10_ID]        = kvm_handle_cp10_id,
 112         [HSR_EC_HVC]            = handle_hvc,
 113         [HSR_EC_SMC]            = handle_smc,
 114         [HSR_EC_IABT]           = kvm_handle_guest_abort,
 115         [HSR_EC_DABT]           = kvm_handle_guest_abort,
 116 };
 117
 118 static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
 119 {
 120         u8 hsr_ec = kvm_vcpu_trap_get_class(vcpu);
 121
 122         return arm_exit_handlers[hsr_ec];
 123 }
 124
 125 /*
 126  * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on
 127  * proper exit to userspace.
 128  */
 129 int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 130                        int exception_index)
 131 {
 132         exit_handle_fn exit_handler;
 133
 134         if (ARM_ABORT_PENDING(exception_index)) {
 135                 u8 hsr_ec = kvm_vcpu_trap_get_class(vcpu);
 136
 137                 /*
 138                  * HVC/SMC already have an adjusted PC, which we need
 139                  * to correct in order to return to after having
 140                  * injected the abort.
 141                  */
 142                 if (hsr_ec == HSR_EC_HVC || hsr_ec == HSR_EC_SMC) {
 143                         u32 adj =  kvm_vcpu_trap_il_is32bit(vcpu) ? 4 : 2;
 144                         *vcpu_pc(vcpu) -= adj;
 145                 }
 146
 147                 kvm_inject_vabt(vcpu);
 148                 return 1;
 149         }
 150
 151         exception_index = ARM_EXCEPTION_CODE(exception_index);
 152
 153         switch (exception_index) {
 154         case ARM_EXCEPTION_IRQ:
 155                 return 1;
 156         case ARM_EXCEPTION_HVC:
 157                 /*
 158                  * See ARM ARM B1.14.1: "Hyp traps on instructions
 159                  * that fail their condition code check"
 160                  */
 161                 if (!kvm_condition_valid(vcpu)) {
 162                         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
 163                         return 1;
 164                 }
 165
 166                 exit_handler = kvm_get_exit_handler(vcpu);
 167
 168                 return exit_handler(vcpu, run);
 169         case ARM_EXCEPTION_DATA_ABORT:
 170                 kvm_inject_vabt(vcpu);
 171                 return 1;
 172         default:
 173                 kvm_pr_unimpl("Unsupported exception type: %d",
 174                               exception_index);
 175                 run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
 176                 return 0;
 177         }
 178 }