Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2018, Google LLC.
4 *
5 * IA32_TSC_ADJUST test
6 *
7 * According to the SDM, "if an execution of WRMSR to the
8 * IA32_TIME_STAMP_COUNTER MSR adds (or subtracts) value X from the TSC,
9 * the logical processor also adds (or subtracts) value X from the
10 * IA32_TSC_ADJUST MSR.
11 *
12 * Note that when L1 doesn't intercept writes to IA32_TSC, a
13 * WRMSR(IA32_TSC) from L2 sets L1's TSC value, not L2's perceived TSC
14 * value.
15 *
16 * This test verifies that this unusual case is handled correctly.
17 */
18
19#include "test_util.h"
20#include "kvm_util.h"
21#include "processor.h"
22#include "vmx.h"
23#include "svm_util.h"
24
25#include <string.h>
26#include <sys/ioctl.h>
27
28#include "kselftest.h"
29
30#ifndef MSR_IA32_TSC_ADJUST
31#define MSR_IA32_TSC_ADJUST 0x3b
32#endif
33
34#define TSC_ADJUST_VALUE (1ll << 32)
35#define TSC_OFFSET_VALUE -(1ll << 48)
36
37#define L2_GUEST_STACK_SIZE 64
38
39enum {
40 PORT_ABORT = 0x1000,
41 PORT_REPORT,
42 PORT_DONE,
43};
44
45enum {
46 VMXON_PAGE = 0,
47 VMCS_PAGE,
48 MSR_BITMAP_PAGE,
49
50 NUM_VMX_PAGES,
51};
52
53/* The virtual machine object. */
54static struct kvm_vm *vm;
55
56static void check_ia32_tsc_adjust(s64 max)
57{
58 s64 adjust;
59
60 adjust = rdmsr(MSR_IA32_TSC_ADJUST);
61 GUEST_SYNC(adjust);
62 GUEST_ASSERT(adjust <= max);
63}
64
65static void l2_guest_code(void)
66{
67 u64 l1_tsc = rdtsc() - TSC_OFFSET_VALUE;
68
69 wrmsr(MSR_IA32_TSC, l1_tsc - TSC_ADJUST_VALUE);
70 check_ia32_tsc_adjust(-2 * TSC_ADJUST_VALUE);
71
72 /* Exit to L1 */
73 __asm__ __volatile__("vmcall");
74}
75
76static void l1_guest_code(void *data)
77{
78 unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
79
80 /* Set TSC from L1 and make sure TSC_ADJUST is updated correctly */
81 GUEST_ASSERT(rdtsc() < TSC_ADJUST_VALUE);
82 wrmsr(MSR_IA32_TSC, rdtsc() - TSC_ADJUST_VALUE);
83 check_ia32_tsc_adjust(-1 * TSC_ADJUST_VALUE);
84
85 /*
86 * Run L2 with TSC_OFFSET. L2 will write to TSC, and L1 is not
87 * intercepting the write so it should update L1's TSC_ADJUST.
88 */
89 if (this_cpu_has(X86_FEATURE_VMX)) {
90 struct vmx_pages *vmx_pages = data;
91 u32 control;
92
93 GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages));
94 GUEST_ASSERT(load_vmcs(vmx_pages));
95
96 prepare_vmcs(vmx_pages, l2_guest_code,
97 &l2_guest_stack[L2_GUEST_STACK_SIZE]);
98 control = vmreadz(CPU_BASED_VM_EXEC_CONTROL);
99 control |= CPU_BASED_USE_MSR_BITMAPS | CPU_BASED_USE_TSC_OFFSETTING;
100 vmwrite(CPU_BASED_VM_EXEC_CONTROL, control);
101 vmwrite(TSC_OFFSET, TSC_OFFSET_VALUE);
102
103 GUEST_ASSERT(!vmlaunch());
104 GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
105 } else {
106 struct svm_test_data *svm = data;
107
108 generic_svm_setup(svm, l2_guest_code,
109 &l2_guest_stack[L2_GUEST_STACK_SIZE]);
110
111 svm->vmcb->control.tsc_offset = TSC_OFFSET_VALUE;
112 run_guest(svm->vmcb, svm->vmcb_gpa);
113 GUEST_ASSERT(svm->vmcb->control.exit_code == SVM_EXIT_VMMCALL);
114 }
115
116 check_ia32_tsc_adjust(-2 * TSC_ADJUST_VALUE);
117 GUEST_DONE();
118}
119
120static void report(s64 val)
121{
122 pr_info("IA32_TSC_ADJUST is %ld (%lld * TSC_ADJUST_VALUE + %lld).\n",
123 val, val / TSC_ADJUST_VALUE, val % TSC_ADJUST_VALUE);
124}
125
126int main(int argc, char *argv[])
127{
128 gva_t nested_gva;
129 struct kvm_vcpu *vcpu;
130
131 TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX) ||
132 kvm_cpu_has(X86_FEATURE_SVM));
133
134 vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code);
135 if (kvm_cpu_has(X86_FEATURE_VMX))
136 vcpu_alloc_vmx(vm, &nested_gva);
137 else
138 vcpu_alloc_svm(vm, &nested_gva);
139
140 vcpu_args_set(vcpu, 1, nested_gva);
141
142 for (;;) {
143 struct ucall uc;
144
145 vcpu_run(vcpu);
146 TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
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
162done:
163 kvm_vm_free(vm);
164 return 0;
165}