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 #include "apic.h" 12 13 #define DR6_BD (1 << 13) 14 #define DR7_GD (1 << 13) 15 16 #define IRQ_VECTOR 0xAA 17 18 /* For testing data access debug BP */ 19 uint32_t guest_value; 20 21 extern unsigned char sw_bp, hw_bp, write_data, ss_start, bd_start; 22 23 static void guest_code(void) 24 { 25 /* Create a pending interrupt on current vCPU */ 26 x2apic_enable(); 27 x2apic_write_reg(APIC_ICR, APIC_DEST_SELF | APIC_INT_ASSERT | 28 APIC_DM_FIXED | IRQ_VECTOR); 29 30 /* 31 * Software BP tests. 32 * 33 * NOTE: sw_bp need to be before the cmd here, because int3 is an 34 * exception rather than a normal trap for KVM_SET_GUEST_DEBUG (we 35 * capture it using the vcpu exception bitmap). 36 */ 37 asm volatile("sw_bp: int3"); 38 39 /* Hardware instruction BP test */ 40 asm volatile("hw_bp: nop"); 41 42 /* Hardware data BP test */ 43 asm volatile("mov $1234,%%rax;\n\t" 44 "mov %%rax,%0;\n\t write_data:" 45 : "=m" (guest_value) : : "rax"); 46 47 /* 48 * Single step test, covers 2 basic instructions and 2 emulated 49 * 50 * Enable interrupts during the single stepping to see that pending 51 * interrupt we raised is not handled due to KVM_GUESTDBG_BLOCKIRQ. 52 * 53 * Write MSR_IA32_TSC_DEADLINE to verify that KVM's fastpath handler 54 * exits to userspace due to single-step being enabled. 55 */ 56 asm volatile("ss_start: " 57 "sti\n\t" 58 "xor %%eax,%%eax\n\t" 59 "cpuid\n\t" 60 "movl $" __stringify(MSR_IA32_TSC_DEADLINE) ", %%ecx\n\t" 61 "wrmsr\n\t" 62 "cli\n\t" 63 : : : "eax", "ebx", "ecx", "edx"); 64 65 /* DR6.BD test */ 66 asm volatile("bd_start: mov %%dr0, %%rax" : : : "rax"); 67 GUEST_DONE(); 68 } 69 70 #define CAST_TO_RIP(v) ((unsigned long long)&(v)) 71 72 static void vcpu_skip_insn(struct kvm_vcpu *vcpu, int insn_len) 73 { 74 struct kvm_regs regs; 75 76 vcpu_regs_get(vcpu, ®s); 77 regs.rip += insn_len; 78 vcpu_regs_set(vcpu, ®s); 79 } 80 81 int main(void) 82 { 83 struct kvm_guest_debug debug; 84 unsigned long long target_dr6, target_rip; 85 struct kvm_vcpu *vcpu; 86 struct kvm_run *run; 87 struct kvm_vm *vm; 88 struct ucall uc; 89 uint64_t cmd; 90 int i; 91 /* Instruction lengths starting at ss_start */ 92 int ss_size[6] = { 93 1, /* sti*/ 94 2, /* xor */ 95 2, /* cpuid */ 96 5, /* mov */ 97 2, /* rdmsr */ 98 1, /* cli */ 99 }; 100 101 TEST_REQUIRE(kvm_has_cap(KVM_CAP_SET_GUEST_DEBUG)); 102 103 vm = vm_create_with_one_vcpu(&vcpu, guest_code); 104 run = vcpu->run; 105 106 /* Test software BPs - int3 */ 107 memset(&debug, 0, sizeof(debug)); 108 debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP; 109 vcpu_guest_debug_set(vcpu, &debug); 110 vcpu_run(vcpu); 111 TEST_ASSERT(run->exit_reason == KVM_EXIT_DEBUG && 112 run->debug.arch.exception == BP_VECTOR && 113 run->debug.arch.pc == CAST_TO_RIP(sw_bp), 114 "INT3: exit %d exception %d rip 0x%llx (should be 0x%llx)", 115 run->exit_reason, run->debug.arch.exception, 116 run->debug.arch.pc, CAST_TO_RIP(sw_bp)); 117 vcpu_skip_insn(vcpu, 1); 118 119 /* Test instruction HW BP over DR[0-3] */ 120 for (i = 0; i < 4; i++) { 121 memset(&debug, 0, sizeof(debug)); 122 debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_HW_BP; 123 debug.arch.debugreg[i] = CAST_TO_RIP(hw_bp); 124 debug.arch.debugreg[7] = 0x400 | (1UL << (2*i+1)); 125 vcpu_guest_debug_set(vcpu, &debug); 126 vcpu_run(vcpu); 127 target_dr6 = 0xffff0ff0 | (1UL << i); 128 TEST_ASSERT(run->exit_reason == KVM_EXIT_DEBUG && 129 run->debug.arch.exception == DB_VECTOR && 130 run->debug.arch.pc == CAST_TO_RIP(hw_bp) && 131 run->debug.arch.dr6 == target_dr6, 132 "INS_HW_BP (DR%d): exit %d exception %d rip 0x%llx " 133 "(should be 0x%llx) dr6 0x%llx (should be 0x%llx)", 134 i, run->exit_reason, run->debug.arch.exception, 135 run->debug.arch.pc, CAST_TO_RIP(hw_bp), 136 run->debug.arch.dr6, target_dr6); 137 } 138 /* Skip "nop" */ 139 vcpu_skip_insn(vcpu, 1); 140 141 /* Test data access HW BP over DR[0-3] */ 142 for (i = 0; i < 4; i++) { 143 memset(&debug, 0, sizeof(debug)); 144 debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_HW_BP; 145 debug.arch.debugreg[i] = CAST_TO_RIP(guest_value); 146 debug.arch.debugreg[7] = 0x00000400 | (1UL << (2*i+1)) | 147 (0x000d0000UL << (4*i)); 148 vcpu_guest_debug_set(vcpu, &debug); 149 vcpu_run(vcpu); 150 target_dr6 = 0xffff0ff0 | (1UL << i); 151 TEST_ASSERT(run->exit_reason == KVM_EXIT_DEBUG && 152 run->debug.arch.exception == DB_VECTOR && 153 run->debug.arch.pc == CAST_TO_RIP(write_data) && 154 run->debug.arch.dr6 == target_dr6, 155 "DATA_HW_BP (DR%d): exit %d exception %d rip 0x%llx " 156 "(should be 0x%llx) dr6 0x%llx (should be 0x%llx)", 157 i, run->exit_reason, run->debug.arch.exception, 158 run->debug.arch.pc, CAST_TO_RIP(write_data), 159 run->debug.arch.dr6, target_dr6); 160 /* Rollback the 4-bytes "mov" */ 161 vcpu_skip_insn(vcpu, -7); 162 } 163 /* Skip the 4-bytes "mov" */ 164 vcpu_skip_insn(vcpu, 7); 165 166 /* Test single step */ 167 target_rip = CAST_TO_RIP(ss_start); 168 target_dr6 = 0xffff4ff0ULL; 169 for (i = 0; i < ARRAY_SIZE(ss_size); i++) { 170 target_rip += ss_size[i]; 171 memset(&debug, 0, sizeof(debug)); 172 debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_SINGLESTEP | 173 KVM_GUESTDBG_BLOCKIRQ; 174 debug.arch.debugreg[7] = 0x00000400; 175 vcpu_guest_debug_set(vcpu, &debug); 176 vcpu_run(vcpu); 177 TEST_ASSERT(run->exit_reason == KVM_EXIT_DEBUG && 178 run->debug.arch.exception == DB_VECTOR && 179 run->debug.arch.pc == target_rip && 180 run->debug.arch.dr6 == target_dr6, 181 "SINGLE_STEP[%d]: exit %d exception %d rip 0x%llx " 182 "(should be 0x%llx) dr6 0x%llx (should be 0x%llx)", 183 i, run->exit_reason, run->debug.arch.exception, 184 run->debug.arch.pc, target_rip, run->debug.arch.dr6, 185 target_dr6); 186 } 187 188 /* Finally test global disable */ 189 memset(&debug, 0, sizeof(debug)); 190 debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_HW_BP; 191 debug.arch.debugreg[7] = 0x400 | DR7_GD; 192 vcpu_guest_debug_set(vcpu, &debug); 193 vcpu_run(vcpu); 194 target_dr6 = 0xffff0ff0 | DR6_BD; 195 TEST_ASSERT(run->exit_reason == KVM_EXIT_DEBUG && 196 run->debug.arch.exception == DB_VECTOR && 197 run->debug.arch.pc == CAST_TO_RIP(bd_start) && 198 run->debug.arch.dr6 == target_dr6, 199 "DR7.GD: exit %d exception %d rip 0x%llx " 200 "(should be 0x%llx) dr6 0x%llx (should be 0x%llx)", 201 run->exit_reason, run->debug.arch.exception, 202 run->debug.arch.pc, target_rip, run->debug.arch.dr6, 203 target_dr6); 204 205 /* Disable all debug controls, run to the end */ 206 memset(&debug, 0, sizeof(debug)); 207 vcpu_guest_debug_set(vcpu, &debug); 208 209 vcpu_run(vcpu); 210 TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO); 211 cmd = get_ucall(vcpu, &uc); 212 TEST_ASSERT(cmd == UCALL_DONE, "UCALL_DONE"); 213 214 kvm_vm_free(vm); 215 216 return 0; 217 } 218