1 /*
2 * gtests/tests/vmx_tsc_adjust_test.c
3 *
4 * Copyright (C) 2018, Google LLC.
5 *
6 * This work is licensed under the terms of the GNU GPL, version 2.
7 *
8 *
9 * IA32_TSC_ADJUST test
10 *
11 * According to the SDM, "if an execution of WRMSR to the
12 * IA32_TIME_STAMP_COUNTER MSR adds (or subtracts) value X from the TSC,
13 * the logical processor also adds (or subtracts) value X from the
14 * IA32_TSC_ADJUST MSR.
15 *
16 * Note that when L1 doesn't intercept writes to IA32_TSC, a
17 * WRMSR(IA32_TSC) from L2 sets L1's TSC value, not L2's perceived TSC
18 * value.
19 *
20 * This test verifies that this unusual case is handled correctly.
21 */
22
23 #include "test_util.h"
24 #include "kvm_util.h"
25 #include "x86.h"
26 #include "vmx.h"
27
28 #include <string.h>
29 #include <sys/ioctl.h>
30
31 #include "../kselftest.h"
32
33 #ifndef MSR_IA32_TSC_ADJUST
34 #define MSR_IA32_TSC_ADJUST 0x3b
35 #endif
36
37 #define PAGE_SIZE 4096
38 #define VCPU_ID 5
39
40 #define TSC_ADJUST_VALUE (1ll << 32)
41 #define TSC_OFFSET_VALUE -(1ll << 48)
42
43 enum {
44 PORT_ABORT = 0x1000,
45 PORT_REPORT,
46 PORT_DONE,
47 };
48
49 enum {
50 VMXON_PAGE = 0,
51 VMCS_PAGE,
52 MSR_BITMAP_PAGE,
53
54 NUM_VMX_PAGES,
55 };
56
57 struct kvm_single_msr {
58 struct kvm_msrs header;
59 struct kvm_msr_entry entry;
60 } __attribute__((packed));
61
62 /* The virtual machine object. */
63 static struct kvm_vm *vm;
64
check_ia32_tsc_adjust(int64_t max)65 static void check_ia32_tsc_adjust(int64_t max)
66 {
67 int64_t adjust;
68
69 adjust = rdmsr(MSR_IA32_TSC_ADJUST);
70 GUEST_SYNC(adjust);
71 GUEST_ASSERT(adjust <= max);
72 }
73
l2_guest_code(void)74 static void l2_guest_code(void)
75 {
76 uint64_t l1_tsc = rdtsc() - TSC_OFFSET_VALUE;
77
78 wrmsr(MSR_IA32_TSC, l1_tsc - TSC_ADJUST_VALUE);
79 check_ia32_tsc_adjust(-2 * TSC_ADJUST_VALUE);
80
81 /* Exit to L1 */
82 __asm__ __volatile__("vmcall");
83 }
84
l1_guest_code(struct vmx_pages * vmx_pages)85 static void l1_guest_code(struct vmx_pages *vmx_pages)
86 {
87 #define L2_GUEST_STACK_SIZE 64
88 unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
89 uint32_t control;
90 uintptr_t save_cr3;
91
92 GUEST_ASSERT(rdtsc() < TSC_ADJUST_VALUE);
93 wrmsr(MSR_IA32_TSC, rdtsc() - TSC_ADJUST_VALUE);
94 check_ia32_tsc_adjust(-1 * TSC_ADJUST_VALUE);
95
96 GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages));
97
98 /* Prepare the VMCS for L2 execution. */
99 prepare_vmcs(vmx_pages, l2_guest_code,
100 &l2_guest_stack[L2_GUEST_STACK_SIZE]);
101 control = vmreadz(CPU_BASED_VM_EXEC_CONTROL);
102 control |= CPU_BASED_USE_MSR_BITMAPS | CPU_BASED_USE_TSC_OFFSETING;
103 vmwrite(CPU_BASED_VM_EXEC_CONTROL, control);
104 vmwrite(TSC_OFFSET, TSC_OFFSET_VALUE);
105
106 /* Jump into L2. First, test failure to load guest CR3. */
107 save_cr3 = vmreadz(GUEST_CR3);
108 vmwrite(GUEST_CR3, -1ull);
109 GUEST_ASSERT(!vmlaunch());
110 GUEST_ASSERT(vmreadz(VM_EXIT_REASON) ==
111 (EXIT_REASON_FAILED_VMENTRY | EXIT_REASON_INVALID_STATE));
112 check_ia32_tsc_adjust(-1 * TSC_ADJUST_VALUE);
113 vmwrite(GUEST_CR3, save_cr3);
114
115 GUEST_ASSERT(!vmlaunch());
116 GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
117
118 check_ia32_tsc_adjust(-2 * TSC_ADJUST_VALUE);
119
120 GUEST_DONE();
121 }
122
report(int64_t val)123 void report(int64_t val)
124 {
125 printf("IA32_TSC_ADJUST is %ld (%lld * TSC_ADJUST_VALUE + %lld).\n",
126 val, val / TSC_ADJUST_VALUE, val % TSC_ADJUST_VALUE);
127 }
128
main(int argc,char * argv[])129 int main(int argc, char *argv[])
130 {
131 struct vmx_pages *vmx_pages;
132 vm_vaddr_t vmx_pages_gva;
133 struct kvm_cpuid_entry2 *entry = kvm_get_supported_cpuid_entry(1);
134
135 if (!(entry->ecx & CPUID_VMX)) {
136 fprintf(stderr, "nested VMX not enabled, skipping test\n");
137 exit(KSFT_SKIP);
138 }
139
140 vm = vm_create_default(VCPU_ID, 0, (void *) l1_guest_code);
141 vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
142
143 /* Allocate VMX pages and shared descriptors (vmx_pages). */
144 vmx_pages = vcpu_alloc_vmx(vm, &vmx_pages_gva);
145 vcpu_args_set(vm, VCPU_ID, 1, vmx_pages_gva);
146
147 for (;;) {
148 volatile struct kvm_run *run = vcpu_state(vm, VCPU_ID);
149 struct guest_args args;
150
151 vcpu_run(vm, VCPU_ID);
152 guest_args_read(vm, VCPU_ID, &args);
153 TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
154 "Got exit_reason other than KVM_EXIT_IO: %u (%s)\n",
155 run->exit_reason,
156 exit_reason_str(run->exit_reason));
157
158 switch (args.port) {
159 case GUEST_PORT_ABORT:
160 TEST_ASSERT(false, "%s", (const char *) args.arg0);
161 /* NOT REACHED */
162 case GUEST_PORT_SYNC:
163 report(args.arg1);
164 break;
165 case GUEST_PORT_DONE:
166 goto done;
167 default:
168 TEST_ASSERT(false, "Unknown port 0x%x.", args.port);
169 }
170 }
171
172 kvm_vm_free(vm);
173 done:
174 return 0;
175 }
176