1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2021, Red Hat, Inc.
4  *
5  * Tests for Hyper-V clocksources
6  */
7 #include "test_util.h"
8 #include "kvm_util.h"
9 #include "processor.h"
10 #include "hyperv.h"
11 
12 struct ms_hyperv_tsc_page {
13 	volatile u32 tsc_sequence;
14 	u32 reserved1;
15 	volatile u64 tsc_scale;
16 	volatile s64 tsc_offset;
17 } __packed;
18 
19 /* Simplified mul_u64_u64_shr() */
20 static inline u64 mul_u64_u64_shr64(u64 a, u64 b)
21 {
22 	union {
23 		u64 ll;
24 		struct {
25 			u32 low, high;
26 		} l;
27 	} rm, rn, rh, a0, b0;
28 	u64 c;
29 
30 	a0.ll = a;
31 	b0.ll = b;
32 
33 	rm.ll = (u64)a0.l.low * b0.l.high;
34 	rn.ll = (u64)a0.l.high * b0.l.low;
35 	rh.ll = (u64)a0.l.high * b0.l.high;
36 
37 	rh.l.low = c = rm.l.high + rn.l.high + rh.l.low;
38 	rh.l.high = (c >> 32) + rh.l.high;
39 
40 	return rh.ll;
41 }
42 
43 static inline void nop_loop(void)
44 {
45 	int i;
46 
47 	for (i = 0; i < 1000000; i++)
48 		asm volatile("nop");
49 }
50 
51 static inline void check_tsc_msr_rdtsc(void)
52 {
53 	u64 tsc_freq, r1, r2, t1, t2;
54 	s64 delta_ns;
55 
56 	tsc_freq = rdmsr(HV_X64_MSR_TSC_FREQUENCY);
57 	GUEST_ASSERT(tsc_freq > 0);
58 
59 	/* First, check MSR-based clocksource */
60 	r1 = rdtsc();
61 	t1 = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
62 	nop_loop();
63 	r2 = rdtsc();
64 	t2 = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
65 
66 	GUEST_ASSERT(r2 > r1 && t2 > t1);
67 
68 	/* HV_X64_MSR_TIME_REF_COUNT is in 100ns */
69 	delta_ns = ((t2 - t1) * 100) - ((r2 - r1) * 1000000000 / tsc_freq);
70 	if (delta_ns < 0)
71 		delta_ns = -delta_ns;
72 
73 	/* 1% tolerance */
74 	GUEST_ASSERT(delta_ns * 100 < (t2 - t1) * 100);
75 }
76 
77 static inline u64 get_tscpage_ts(struct ms_hyperv_tsc_page *tsc_page)
78 {
79 	return mul_u64_u64_shr64(rdtsc(), tsc_page->tsc_scale) + tsc_page->tsc_offset;
80 }
81 
82 static inline void check_tsc_msr_tsc_page(struct ms_hyperv_tsc_page *tsc_page)
83 {
84 	u64 r1, r2, t1, t2;
85 
86 	/* Compare TSC page clocksource with HV_X64_MSR_TIME_REF_COUNT */
87 	t1 = get_tscpage_ts(tsc_page);
88 	r1 = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
89 
90 	/* 10 ms tolerance */
91 	GUEST_ASSERT(r1 >= t1 && r1 - t1 < 100000);
92 	nop_loop();
93 
94 	t2 = get_tscpage_ts(tsc_page);
95 	r2 = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
96 	GUEST_ASSERT(r2 >= t1 && r2 - t2 < 100000);
97 }
98 
99 static void guest_main(struct ms_hyperv_tsc_page *tsc_page, vm_paddr_t tsc_page_gpa)
100 {
101 	u64 tsc_scale, tsc_offset;
102 
103 	/* Set Guest OS id to enable Hyper-V emulation */
104 	GUEST_SYNC(1);
105 	wrmsr(HV_X64_MSR_GUEST_OS_ID, (u64)0x8100 << 48);
106 	GUEST_SYNC(2);
107 
108 	check_tsc_msr_rdtsc();
109 
110 	GUEST_SYNC(3);
111 
112 	/* Set up TSC page is disabled state, check that it's clean */
113 	wrmsr(HV_X64_MSR_REFERENCE_TSC, tsc_page_gpa);
114 	GUEST_ASSERT(tsc_page->tsc_sequence == 0);
115 	GUEST_ASSERT(tsc_page->tsc_scale == 0);
116 	GUEST_ASSERT(tsc_page->tsc_offset == 0);
117 
118 	GUEST_SYNC(4);
119 
120 	/* Set up TSC page is enabled state */
121 	wrmsr(HV_X64_MSR_REFERENCE_TSC, tsc_page_gpa | 0x1);
122 	GUEST_ASSERT(tsc_page->tsc_sequence != 0);
123 
124 	GUEST_SYNC(5);
125 
126 	check_tsc_msr_tsc_page(tsc_page);
127 
128 	GUEST_SYNC(6);
129 
130 	tsc_offset = tsc_page->tsc_offset;
131 	/* Call KVM_SET_CLOCK from userspace, check that TSC page was updated */
132 
133 	GUEST_SYNC(7);
134 	/* Sanity check TSC page timestamp, it should be close to 0 */
135 	GUEST_ASSERT(get_tscpage_ts(tsc_page) < 100000);
136 
137 	GUEST_ASSERT(tsc_page->tsc_offset != tsc_offset);
138 
139 	nop_loop();
140 
141 	/*
142 	 * Enable Re-enlightenment and check that TSC page stays constant across
143 	 * KVM_SET_CLOCK.
144 	 */
145 	wrmsr(HV_X64_MSR_REENLIGHTENMENT_CONTROL, 0x1 << 16 | 0xff);
146 	wrmsr(HV_X64_MSR_TSC_EMULATION_CONTROL, 0x1);
147 	tsc_offset = tsc_page->tsc_offset;
148 	tsc_scale = tsc_page->tsc_scale;
149 	GUEST_SYNC(8);
150 	GUEST_ASSERT(tsc_page->tsc_offset == tsc_offset);
151 	GUEST_ASSERT(tsc_page->tsc_scale == tsc_scale);
152 
153 	GUEST_SYNC(9);
154 
155 	check_tsc_msr_tsc_page(tsc_page);
156 
157 	/*
158 	 * Disable re-enlightenment and TSC page, check that KVM doesn't update
159 	 * it anymore.
160 	 */
161 	wrmsr(HV_X64_MSR_REENLIGHTENMENT_CONTROL, 0);
162 	wrmsr(HV_X64_MSR_TSC_EMULATION_CONTROL, 0);
163 	wrmsr(HV_X64_MSR_REFERENCE_TSC, 0);
164 	memset(tsc_page, 0, sizeof(*tsc_page));
165 
166 	GUEST_SYNC(10);
167 	GUEST_ASSERT(tsc_page->tsc_sequence == 0);
168 	GUEST_ASSERT(tsc_page->tsc_offset == 0);
169 	GUEST_ASSERT(tsc_page->tsc_scale == 0);
170 
171 	GUEST_DONE();
172 }
173 
174 #define VCPU_ID 0
175 
176 static void host_check_tsc_msr_rdtsc(struct kvm_vm *vm)
177 {
178 	u64 tsc_freq, r1, r2, t1, t2;
179 	s64 delta_ns;
180 
181 	tsc_freq = vcpu_get_msr(vm, VCPU_ID, HV_X64_MSR_TSC_FREQUENCY);
182 	TEST_ASSERT(tsc_freq > 0, "TSC frequency must be nonzero");
183 
184 	/* First, check MSR-based clocksource */
185 	r1 = rdtsc();
186 	t1 = vcpu_get_msr(vm, VCPU_ID, HV_X64_MSR_TIME_REF_COUNT);
187 	nop_loop();
188 	r2 = rdtsc();
189 	t2 = vcpu_get_msr(vm, VCPU_ID, HV_X64_MSR_TIME_REF_COUNT);
190 
191 	TEST_ASSERT(t2 > t1, "Time reference MSR is not monotonic (%ld <= %ld)", t1, t2);
192 
193 	/* HV_X64_MSR_TIME_REF_COUNT is in 100ns */
194 	delta_ns = ((t2 - t1) * 100) - ((r2 - r1) * 1000000000 / tsc_freq);
195 	if (delta_ns < 0)
196 		delta_ns = -delta_ns;
197 
198 	/* 1% tolerance */
199 	TEST_ASSERT(delta_ns * 100 < (t2 - t1) * 100,
200 		    "Elapsed time does not match (MSR=%ld, TSC=%ld)",
201 		    (t2 - t1) * 100, (r2 - r1) * 1000000000 / tsc_freq);
202 }
203 
204 int main(void)
205 {
206 	struct kvm_vm *vm;
207 	struct kvm_run *run;
208 	struct ucall uc;
209 	vm_vaddr_t tsc_page_gva;
210 	int stage;
211 
212 	vm = vm_create_default(VCPU_ID, 0, guest_main);
213 	run = vcpu_state(vm, VCPU_ID);
214 
215 	vcpu_set_hv_cpuid(vm, VCPU_ID);
216 
217 	tsc_page_gva = vm_vaddr_alloc_page(vm);
218 	memset(addr_gpa2hva(vm, tsc_page_gva), 0x0, getpagesize());
219 	TEST_ASSERT((addr_gva2gpa(vm, tsc_page_gva) & (getpagesize() - 1)) == 0,
220 		"TSC page has to be page aligned\n");
221 	vcpu_args_set(vm, VCPU_ID, 2, tsc_page_gva, addr_gva2gpa(vm, tsc_page_gva));
222 
223 	host_check_tsc_msr_rdtsc(vm);
224 
225 	for (stage = 1;; stage++) {
226 		_vcpu_run(vm, VCPU_ID);
227 		TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
228 			    "Stage %d: unexpected exit reason: %u (%s),\n",
229 			    stage, run->exit_reason,
230 			    exit_reason_str(run->exit_reason));
231 
232 		switch (get_ucall(vm, VCPU_ID, &uc)) {
233 		case UCALL_ABORT:
234 			TEST_FAIL("%s at %s:%ld", (const char *)uc.args[0],
235 				  __FILE__, uc.args[1]);
236 			/* NOT REACHED */
237 		case UCALL_SYNC:
238 			break;
239 		case UCALL_DONE:
240 			/* Keep in sync with guest_main() */
241 			TEST_ASSERT(stage == 11, "Testing ended prematurely, stage %d\n",
242 				    stage);
243 			goto out;
244 		default:
245 			TEST_FAIL("Unknown ucall %lu", uc.cmd);
246 		}
247 
248 		TEST_ASSERT(!strcmp((const char *)uc.args[0], "hello") &&
249 			    uc.args[1] == stage,
250 			    "Stage %d: Unexpected register values vmexit, got %lx",
251 			    stage, (ulong)uc.args[1]);
252 
253 		/* Reset kvmclock triggering TSC page update */
254 		if (stage == 7 || stage == 8 || stage == 10) {
255 			struct kvm_clock_data clock = {0};
256 
257 			vm_ioctl(vm, KVM_SET_CLOCK, &clock);
258 		}
259 	}
260 
261 out:
262 	kvm_vm_free(vm);
263 }
264