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
guest_code(void)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, ®s); \
59 regs.rip = (v); \
60 vcpu_regs_set(vm, VCPU_ID, ®s); \
61 } while (0)
62 #define MOVE_RIP(v) SET_RIP(regs.rip + (v));
63
main(void)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, ®s);
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 }
202