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 /* The virtual machine object. */
53 static struct kvm_vm *vm;
54 
check_ia32_tsc_adjust(int64_t max)55 static void check_ia32_tsc_adjust(int64_t max)
56 {
57 	int64_t adjust;
58 
59 	adjust = rdmsr(MSR_IA32_TSC_ADJUST);
60 	GUEST_SYNC(adjust);
61 	GUEST_ASSERT(adjust <= max);
62 }
63 
l2_guest_code(void)64 static void l2_guest_code(void)
65 {
66 	uint64_t l1_tsc = rdtsc() - TSC_OFFSET_VALUE;
67 
68 	wrmsr(MSR_IA32_TSC, l1_tsc - TSC_ADJUST_VALUE);
69 	check_ia32_tsc_adjust(-2 * TSC_ADJUST_VALUE);
70 
71 	/* Exit to L1 */
72 	__asm__ __volatile__("vmcall");
73 }
74 
l1_guest_code(struct vmx_pages * vmx_pages)75 static void l1_guest_code(struct vmx_pages *vmx_pages)
76 {
77 #define L2_GUEST_STACK_SIZE 64
78 	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
79 	uint32_t control;
80 	uintptr_t save_cr3;
81 
82 	GUEST_ASSERT(rdtsc() < TSC_ADJUST_VALUE);
83 	wrmsr(MSR_IA32_TSC, rdtsc() - TSC_ADJUST_VALUE);
84 	check_ia32_tsc_adjust(-1 * TSC_ADJUST_VALUE);
85 
86 	GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages));
87 	GUEST_ASSERT(load_vmcs(vmx_pages));
88 
89 	/* Prepare the VMCS for L2 execution. */
90 	prepare_vmcs(vmx_pages, l2_guest_code,
91 		     &l2_guest_stack[L2_GUEST_STACK_SIZE]);
92 	control = vmreadz(CPU_BASED_VM_EXEC_CONTROL);
93 	control |= CPU_BASED_USE_MSR_BITMAPS | CPU_BASED_USE_TSC_OFFSETTING;
94 	vmwrite(CPU_BASED_VM_EXEC_CONTROL, control);
95 	vmwrite(TSC_OFFSET, TSC_OFFSET_VALUE);
96 
97 	/* Jump into L2.  First, test failure to load guest CR3.  */
98 	save_cr3 = vmreadz(GUEST_CR3);
99 	vmwrite(GUEST_CR3, -1ull);
100 	GUEST_ASSERT(!vmlaunch());
101 	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) ==
102 		     (EXIT_REASON_FAILED_VMENTRY | EXIT_REASON_INVALID_STATE));
103 	check_ia32_tsc_adjust(-1 * TSC_ADJUST_VALUE);
104 	vmwrite(GUEST_CR3, save_cr3);
105 
106 	GUEST_ASSERT(!vmlaunch());
107 	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
108 
109 	check_ia32_tsc_adjust(-2 * TSC_ADJUST_VALUE);
110 
111 	GUEST_DONE();
112 }
113 
report(int64_t val)114 static void report(int64_t val)
115 {
116 	pr_info("IA32_TSC_ADJUST is %ld (%lld * TSC_ADJUST_VALUE + %lld).\n",
117 		val, val / TSC_ADJUST_VALUE, val % TSC_ADJUST_VALUE);
118 }
119 
main(int argc,char * argv[])120 int main(int argc, char *argv[])
121 {
122 	vm_vaddr_t vmx_pages_gva;
123 	struct kvm_vcpu *vcpu;
124 
125 	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX));
126 
127 	vm = vm_create_with_one_vcpu(&vcpu, (void *) l1_guest_code);
128 
129 	/* Allocate VMX pages and shared descriptors (vmx_pages). */
130 	vcpu_alloc_vmx(vm, &vmx_pages_gva);
131 	vcpu_args_set(vcpu, 1, vmx_pages_gva);
132 
133 	for (;;) {
134 		struct ucall uc;
135 
136 		vcpu_run(vcpu);
137 		TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
138 
139 		switch (get_ucall(vcpu, &uc)) {
140 		case UCALL_ABORT:
141 			REPORT_GUEST_ASSERT(uc);
142 			/* NOT REACHED */
143 		case UCALL_SYNC:
144 			report(uc.args[1]);
145 			break;
146 		case UCALL_DONE:
147 			goto done;
148 		default:
149 			TEST_FAIL("Unknown ucall %lu", uc.cmd);
150 		}
151 	}
152 
153 done:
154 	kvm_vm_free(vm);
155 	return 0;
156 }
157