tools/testing/selftests/kvm/x86_64/debug_regs.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * KVM guest debug register tests
   4  *
   5  * Copyright (C) 2020, Red Hat, Inc.
   6  */
   7 #include <stdio.h>
   8 #include <string.h>
   9 #include "kvm_util.h"
  10 #include "processor.h"
  11
  12 #define VCPU_ID 0
  13
  14 #define DR6_BD          (1 << 13)
  15 #define DR7_GD          (1 << 13)
  16
  17 /* For testing data access debug BP */
  18 uint32_t guest_value;
  19
  20 extern unsigned char sw_bp, hw_bp, write_data, ss_start, bd_start;
  21
  22 static void guest_code(void)
  23 {
  24         /*
  25          * Software BP tests.
  26          *
  27          * NOTE: sw_bp need to be before the cmd here, because int3 is an
  28          * exception rather than a normal trap for KVM_SET_GUEST_DEBUG (we
  29          * capture it using the vcpu exception bitmap).
  30          */
  31         asm volatile("sw_bp: int3");
  32
  33         /* Hardware instruction BP test */
  34         asm volatile("hw_bp: nop");
  35
  36         /* Hardware data BP test */
  37         asm volatile("mov $1234,%%rax;\n\t"
  38                      "mov %%rax,%0;\n\t write_data:"
  39                      : "=m" (guest_value) : : "rax");
  40
  41         /* Single step test, covers 2 basic instructions and 2 emulated */
  42         asm volatile("ss_start: "
  43                      "xor %%eax,%%eax\n\t"
  44                      "cpuid\n\t"
  45                      "movl $0x1a0,%%ecx\n\t"
  46                      "rdmsr\n\t"
  47                      : : : "eax", "ebx", "ecx", "edx");
  48
  49         /* DR6.BD test */
  50         asm volatile("bd_start: mov %%dr0, %%rax" : : : "rax");
  51         GUEST_DONE();
  52 }
  53
  54 #define  CLEAR_DEBUG()  memset(&debug, 0, sizeof(debug))
  55 #define  APPLY_DEBUG()  vcpu_set_guest_debug(vm, VCPU_ID, &debug)
  56 #define  CAST_TO_RIP(v)  ((unsigned long long)&(v))
  57 #define  SET_RIP(v)  do {                               \
  58                 vcpu_regs_get(vm, VCPU_ID, &regs);      \
  59                 regs.rip = (v);                         \
  60                 vcpu_regs_set(vm, VCPU_ID, &regs);      \
  61         } while (0)
  62 #define  MOVE_RIP(v)  SET_RIP(regs.rip + (v));
  63
  64 int main(void)
  65 {
  66         struct kvm_guest_debug debug;
  67         unsigned long long target_dr6, target_rip;
  68         struct kvm_regs regs;
  69         struct kvm_run *run;
  70         struct kvm_vm *vm;
  71         struct ucall uc;
  72         uint64_t cmd;
  73         int i;
  74         /* Instruction lengths starting at ss_start */
  75         int ss_size[4] = {
  76                 2,              /* xor */
  77                 2,              /* cpuid */
  78                 5,              /* mov */
  79                 2,              /* rdmsr */
  80         };
  81
  82         if (!kvm_check_cap(KVM_CAP_SET_GUEST_DEBUG)) {
  83                 print_skip("KVM_CAP_SET_GUEST_DEBUG not supported");
  84                 return 0;
  85         }
  86
  87         vm = vm_create_default(VCPU_ID, 0, guest_code);
  88         run = vcpu_state(vm, VCPU_ID);
  89
  90         /* Test software BPs - int3 */
  91         CLEAR_DEBUG();
  92         debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP;
  93         APPLY_DEBUG();
  94         vcpu_run(vm, VCPU_ID);
  95         TEST_ASSERT(run->exit_reason == KVM_EXIT_DEBUG &&
  96                     run->debug.arch.exception == BP_VECTOR &&
  97                     run->debug.arch.pc == CAST_TO_RIP(sw_bp),
  98                     "INT3: exit %d exception %d rip 0x%llx (should be 0x%llx)",
  99                     run->exit_reason, run->debug.arch.exception,
 100                     run->debug.arch.pc, CAST_TO_RIP(sw_bp));
 101         MOVE_RIP(1);
 102
 103         /* Test instruction HW BP over DR[0-3] */
 104         for (i = 0; i < 4; i++) {
 105                 CLEAR_DEBUG();
 106                 debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_HW_BP;
 107                 debug.arch.debugreg[i] = CAST_TO_RIP(hw_bp);
 108                 debug.arch.debugreg[7] = 0x400 | (1UL << (2*i+1));
 109                 APPLY_DEBUG();
 110                 vcpu_run(vm, VCPU_ID);
 111                 target_dr6 = 0xffff0ff0 | (1UL << i);
 112                 TEST_ASSERT(run->exit_reason == KVM_EXIT_DEBUG &&
 113                             run->debug.arch.exception == DB_VECTOR &&
 114                             run->debug.arch.pc == CAST_TO_RIP(hw_bp) &&
 115                             run->debug.arch.dr6 == target_dr6,
 116                             "INS_HW_BP (DR%d): exit %d exception %d rip 0x%llx "
 117                             "(should be 0x%llx) dr6 0x%llx (should be 0x%llx)",
 118                             i, run->exit_reason, run->debug.arch.exception,
 119                             run->debug.arch.pc, CAST_TO_RIP(hw_bp),
 120                             run->debug.arch.dr6, target_dr6);
 121         }
 122         /* Skip "nop" */
 123         MOVE_RIP(1);
 124
 125         /* Test data access HW BP over DR[0-3] */
 126         for (i = 0; i < 4; i++) {
 127                 CLEAR_DEBUG();
 128                 debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_HW_BP;
 129                 debug.arch.debugreg[i] = CAST_TO_RIP(guest_value);
 130                 debug.arch.debugreg[7] = 0x00000400 | (1UL << (2*i+1)) |
 131                     (0x000d0000UL << (4*i));
 132                 APPLY_DEBUG();
 133                 vcpu_run(vm, VCPU_ID);
 134                 target_dr6 = 0xffff0ff0 | (1UL << i);
 135                 TEST_ASSERT(run->exit_reason == KVM_EXIT_DEBUG &&
 136                             run->debug.arch.exception == DB_VECTOR &&
 137                             run->debug.arch.pc == CAST_TO_RIP(write_data) &&
 138                             run->debug.arch.dr6 == target_dr6,
 139                             "DATA_HW_BP (DR%d): exit %d exception %d rip 0x%llx "
 140                             "(should be 0x%llx) dr6 0x%llx (should be 0x%llx)",
 141                             i, run->exit_reason, run->debug.arch.exception,
 142                             run->debug.arch.pc, CAST_TO_RIP(write_data),
 143                             run->debug.arch.dr6, target_dr6);
 144                 /* Rollback the 4-bytes "mov" */
 145                 MOVE_RIP(-7);
 146         }
 147         /* Skip the 4-bytes "mov" */
 148         MOVE_RIP(7);
 149
 150         /* Test single step */
 151         target_rip = CAST_TO_RIP(ss_start);
 152         target_dr6 = 0xffff4ff0ULL;
 153         vcpu_regs_get(vm, VCPU_ID, &regs);
 154         for (i = 0; i < (sizeof(ss_size) / sizeof(ss_size[0])); i++) {
 155                 target_rip += ss_size[i];
 156                 CLEAR_DEBUG();
 157                 debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_SINGLESTEP;
 158                 debug.arch.debugreg[7] = 0x00000400;
 159                 APPLY_DEBUG();
 160                 vcpu_run(vm, VCPU_ID);
 161                 TEST_ASSERT(run->exit_reason == KVM_EXIT_DEBUG &&
 162                             run->debug.arch.exception == DB_VECTOR &&
 163                             run->debug.arch.pc == target_rip &&
 164                             run->debug.arch.dr6 == target_dr6,
 165                             "SINGLE_STEP[%d]: exit %d exception %d rip 0x%llx "
 166                             "(should be 0x%llx) dr6 0x%llx (should be 0x%llx)",
 167                             i, run->exit_reason, run->debug.arch.exception,
 168                             run->debug.arch.pc, target_rip, run->debug.arch.dr6,
 169                             target_dr6);
 170         }
 171
 172         /* Finally test global disable */
 173         CLEAR_DEBUG();
 174         debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_HW_BP;
 175         debug.arch.debugreg[7] = 0x400 | DR7_GD;
 176         APPLY_DEBUG();
 177         vcpu_run(vm, VCPU_ID);
 178         target_dr6 = 0xffff0ff0 | DR6_BD;
 179         TEST_ASSERT(run->exit_reason == KVM_EXIT_DEBUG &&
 180                     run->debug.arch.exception == DB_VECTOR &&
 181                     run->debug.arch.pc == CAST_TO_RIP(bd_start) &&
 182                     run->debug.arch.dr6 == target_dr6,
 183                             "DR7.GD: exit %d exception %d rip 0x%llx "
 184                             "(should be 0x%llx) dr6 0x%llx (should be 0x%llx)",
 185                             run->exit_reason, run->debug.arch.exception,
 186                             run->debug.arch.pc, target_rip, run->debug.arch.dr6,
 187                             target_dr6);
 188
 189         /* Disable all debug controls, run to the end */
 190         CLEAR_DEBUG();
 191         APPLY_DEBUG();
 192
 193         vcpu_run(vm, VCPU_ID);
 194         TEST_ASSERT(run->exit_reason == KVM_EXIT_IO, "KVM_EXIT_IO");
 195         cmd = get_ucall(vm, VCPU_ID, &uc);
 196         TEST_ASSERT(cmd == UCALL_DONE, "UCALL_DONE");
 197
 198         kvm_vm_free(vm);
 199
 200         return 0;
 201 }