1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * vmx_tsc_adjust_test
4 *
5 * Copyright (C) 2018, Google LLC.
6 *
7 * IA32_TSC_ADJUST test
8 *
9 * According to the SDM, "if an execution of WRMSR to the
10 * IA32_TIME_STAMP_COUNTER MSR adds (or subtracts) value X from the TSC,
11 * the logical processor also adds (or subtracts) value X from the
12 * IA32_TSC_ADJUST MSR.
13 *
14 * Note that when L1 doesn't intercept writes to IA32_TSC, a
15 * WRMSR(IA32_TSC) from L2 sets L1's TSC value, not L2's perceived TSC
16 * value.
17 *
18 * This test verifies that this unusual case is handled correctly.
19 */
20
21 #include "test_util.h"
22 #include "kvm_util.h"
23 #include "processor.h"
24 #include "vmx.h"
25
26 #include <string.h>
27 #include <sys/ioctl.h>
28
29 #include "kselftest.h"
30
31 #ifndef MSR_IA32_TSC_ADJUST
32 #define MSR_IA32_TSC_ADJUST 0x3b
33 #endif
34
35 #define TSC_ADJUST_VALUE (1ll << 32)
36 #define TSC_OFFSET_VALUE -(1ll << 48)
37
38 enum {
39 PORT_ABORT = 0x1000,
40 PORT_REPORT,
41 PORT_DONE,
42 };
43
44 enum {
45 VMXON_PAGE = 0,
46 VMCS_PAGE,
47 MSR_BITMAP_PAGE,
48
49 NUM_VMX_PAGES,
50 };
51
52 struct kvm_single_msr {
53 struct kvm_msrs header;
54 struct kvm_msr_entry entry;
55 } __attribute__((packed));
56
57 /* The virtual machine object. */
58 static struct kvm_vm *vm;
59
check_ia32_tsc_adjust(int64_t max)60 static void check_ia32_tsc_adjust(int64_t max)
61 {
62 int64_t adjust;
63
64 adjust = rdmsr(MSR_IA32_TSC_ADJUST);
65 GUEST_SYNC(adjust);
66 GUEST_ASSERT(adjust <= max);
67 }
68
l2_guest_code(void)69 static void l2_guest_code(void)
70 {
71 uint64_t l1_tsc = rdtsc() - TSC_OFFSET_VALUE;
72
73 wrmsr(MSR_IA32_TSC, l1_tsc - TSC_ADJUST_VALUE);
74 check_ia32_tsc_adjust(-2 * TSC_ADJUST_VALUE);
75
76 /* Exit to L1 */
77 __asm__ __volatile__("vmcall");
78 }
79
l1_guest_code(struct vmx_pages * vmx_pages)80 static void l1_guest_code(struct vmx_pages *vmx_pages)
81 {
82 #define L2_GUEST_STACK_SIZE 64
83 unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
84 uint32_t control;
85 uintptr_t save_cr3;
86
87 GUEST_ASSERT(rdtsc() < TSC_ADJUST_VALUE);
88 wrmsr(MSR_IA32_TSC, rdtsc() - TSC_ADJUST_VALUE);
89 check_ia32_tsc_adjust(-1 * TSC_ADJUST_VALUE);
90
91 GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages));
92 GUEST_ASSERT(load_vmcs(vmx_pages));
93
94 /* Prepare the VMCS for L2 execution. */
95 prepare_vmcs(vmx_pages, l2_guest_code,
96 &l2_guest_stack[L2_GUEST_STACK_SIZE]);
97 control = vmreadz(CPU_BASED_VM_EXEC_CONTROL);
98 control |= CPU_BASED_USE_MSR_BITMAPS | CPU_BASED_USE_TSC_OFFSETTING;
99 vmwrite(CPU_BASED_VM_EXEC_CONTROL, control);
100 vmwrite(TSC_OFFSET, TSC_OFFSET_VALUE);
101
102 /* Jump into L2. First, test failure to load guest CR3. */
103 save_cr3 = vmreadz(GUEST_CR3);
104 vmwrite(GUEST_CR3, -1ull);
105 GUEST_ASSERT(!vmlaunch());
106 GUEST_ASSERT(vmreadz(VM_EXIT_REASON) ==
107 (EXIT_REASON_FAILED_VMENTRY | EXIT_REASON_INVALID_STATE));
108 check_ia32_tsc_adjust(-1 * TSC_ADJUST_VALUE);
109 vmwrite(GUEST_CR3, save_cr3);
110
111 GUEST_ASSERT(!vmlaunch());
112 GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
113
114 check_ia32_tsc_adjust(-2 * TSC_ADJUST_VALUE);
115
116 GUEST_DONE();
117 }
118
report(int64_t val)119 static void report(int64_t val)
120 {
121 pr_info("IA32_TSC_ADJUST is %ld (%lld * TSC_ADJUST_VALUE + %lld).\n",
122 val, val / TSC_ADJUST_VALUE, val % TSC_ADJUST_VALUE);
123 }
124
main(int argc,char * argv[])125 int main(int argc, char *argv[])
126 {
127 vm_vaddr_t vmx_pages_gva;
128 struct kvm_vcpu *vcpu;
129
130 TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX));
131
132 vm = vm_create_with_one_vcpu(&vcpu, (void *) l1_guest_code);
133
134 /* Allocate VMX pages and shared descriptors (vmx_pages). */
135 vcpu_alloc_vmx(vm, &vmx_pages_gva);
136 vcpu_args_set(vcpu, 1, vmx_pages_gva);
137
138 for (;;) {
139 volatile struct kvm_run *run = vcpu->run;
140 struct ucall uc;
141
142 vcpu_run(vcpu);
143 TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
144 "Got exit_reason other than KVM_EXIT_IO: %u (%s)\n",
145 run->exit_reason,
146 exit_reason_str(run->exit_reason));
147
148 switch (get_ucall(vcpu, &uc)) {
149 case UCALL_ABORT:
150 REPORT_GUEST_ASSERT(uc);
151 /* NOT REACHED */
152 case UCALL_SYNC:
153 report(uc.args[1]);
154 break;
155 case UCALL_DONE:
156 goto done;
157 default:
158 TEST_FAIL("Unknown ucall %lu", uc.cmd);
159 }
160 }
161
162 done:
163 kvm_vm_free(vm);
164 return 0;
165 }
166