xref: /kvm-unit-tests/x86/hyperv_clock.c (revision ddbcb8f4ca8aedc9835851bd9acf2cd5221d7476)
1907ce0f7SPaolo Bonzini #include "libcflat.h"
2907ce0f7SPaolo Bonzini #include "smp.h"
3907ce0f7SPaolo Bonzini #include "atomic.h"
4907ce0f7SPaolo Bonzini #include "processor.h"
5907ce0f7SPaolo Bonzini #include "hyperv.h"
6907ce0f7SPaolo Bonzini #include "vm.h"
75aca024eSPaolo Bonzini #include "alloc_page.h"
8907ce0f7SPaolo Bonzini 
9907ce0f7SPaolo Bonzini #define MAX_CPU 4
10907ce0f7SPaolo Bonzini #define TICKS_PER_SEC (1000000000 / 100)
11907ce0f7SPaolo Bonzini 
12907ce0f7SPaolo Bonzini struct hv_reference_tsc_page *hv_clock;
13907ce0f7SPaolo Bonzini 
14907ce0f7SPaolo Bonzini /*
15907ce0f7SPaolo Bonzini  * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
16907ce0f7SPaolo Bonzini  * yielding a 64-bit result.
17907ce0f7SPaolo Bonzini  */
scale_delta(u64 delta,u64 mul_frac)18907ce0f7SPaolo Bonzini static inline u64 scale_delta(u64 delta, u64 mul_frac)
19907ce0f7SPaolo Bonzini {
20907ce0f7SPaolo Bonzini 	u64 product, unused;
21907ce0f7SPaolo Bonzini 
22907ce0f7SPaolo Bonzini 	__asm__ (
2345276b58SThomas Petazzoni 		"mulq %3"
24907ce0f7SPaolo Bonzini 		: "=d" (product), "=a" (unused) : "1" (delta), "rm" ((u64)mul_frac) );
25907ce0f7SPaolo Bonzini 
26907ce0f7SPaolo Bonzini 	return product;
27907ce0f7SPaolo Bonzini }
28907ce0f7SPaolo Bonzini 
hvclock_tsc_to_ticks(struct hv_reference_tsc_page * shadow,uint64_t tsc)29907ce0f7SPaolo Bonzini static u64 hvclock_tsc_to_ticks(struct hv_reference_tsc_page *shadow, uint64_t tsc)
30907ce0f7SPaolo Bonzini {
31907ce0f7SPaolo Bonzini 	u64 delta = tsc;
32907ce0f7SPaolo Bonzini 	return scale_delta(delta, shadow->tsc_scale) + shadow->tsc_offset;
33907ce0f7SPaolo Bonzini }
34907ce0f7SPaolo Bonzini 
35907ce0f7SPaolo Bonzini /*
36907ce0f7SPaolo Bonzini  * Reads a consistent set of time-base values from hypervisor,
37907ce0f7SPaolo Bonzini  * into a shadow data area.
38907ce0f7SPaolo Bonzini  */
hvclock_get_time_values(struct hv_reference_tsc_page * shadow,struct hv_reference_tsc_page * page)39907ce0f7SPaolo Bonzini static void hvclock_get_time_values(struct hv_reference_tsc_page *shadow,
40907ce0f7SPaolo Bonzini 				    struct hv_reference_tsc_page *page)
41907ce0f7SPaolo Bonzini {
42907ce0f7SPaolo Bonzini 	int seq;
43907ce0f7SPaolo Bonzini 	do {
44907ce0f7SPaolo Bonzini 		seq = page->tsc_sequence;
45907ce0f7SPaolo Bonzini 		rmb();		/* fetch version before data */
46907ce0f7SPaolo Bonzini 		*shadow = *page;
47907ce0f7SPaolo Bonzini 		rmb();		/* test version after fetching data */
48907ce0f7SPaolo Bonzini 	} while (shadow->tsc_sequence != seq);
49907ce0f7SPaolo Bonzini }
50907ce0f7SPaolo Bonzini 
hv_clock_read(void)51db4898e8SThomas Huth static uint64_t hv_clock_read(void)
52907ce0f7SPaolo Bonzini {
53907ce0f7SPaolo Bonzini 	struct hv_reference_tsc_page shadow;
54907ce0f7SPaolo Bonzini 
55907ce0f7SPaolo Bonzini 	hvclock_get_time_values(&shadow, hv_clock);
56907ce0f7SPaolo Bonzini 	return hvclock_tsc_to_ticks(&shadow, rdtsc());
57907ce0f7SPaolo Bonzini }
58907ce0f7SPaolo Bonzini 
59907ce0f7SPaolo Bonzini bool ok[MAX_CPU];
60907ce0f7SPaolo Bonzini uint64_t loops[MAX_CPU];
61907ce0f7SPaolo Bonzini 
62907ce0f7SPaolo Bonzini #define iabs(x)   ((x) < 0 ? -(x) : (x))
63907ce0f7SPaolo Bonzini 
hv_clock_test(void * data)64907ce0f7SPaolo Bonzini static void hv_clock_test(void *data)
65907ce0f7SPaolo Bonzini {
66b78f9e64SMetin Kaya 	int i = (long)data;
67*bf2c53fdSVitaly Kuznetsov 	uint64_t t_msr_prev = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
68*bf2c53fdSVitaly Kuznetsov 	uint64_t t_page_prev = hv_clock_read();
69*bf2c53fdSVitaly Kuznetsov 	uint64_t end = t_page_prev + TICKS_PER_SEC;
70907ce0f7SPaolo Bonzini 	bool got_drift = false;
71*bf2c53fdSVitaly Kuznetsov 	bool got_warp_msr = false;
72*bf2c53fdSVitaly Kuznetsov 	bool got_warp_page = false;
73907ce0f7SPaolo Bonzini 
74907ce0f7SPaolo Bonzini 	ok[i] = true;
75907ce0f7SPaolo Bonzini 	do {
76*bf2c53fdSVitaly Kuznetsov 		uint64_t t_page_1, t_page_2, t_msr;
77907ce0f7SPaolo Bonzini 
78*bf2c53fdSVitaly Kuznetsov 		t_page_1 = hv_clock_read();
79*bf2c53fdSVitaly Kuznetsov 		barrier();
80*bf2c53fdSVitaly Kuznetsov 		t_msr = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
81*bf2c53fdSVitaly Kuznetsov 		barrier();
82*bf2c53fdSVitaly Kuznetsov 		t_page_2 = hv_clock_read();
83*bf2c53fdSVitaly Kuznetsov 
84*bf2c53fdSVitaly Kuznetsov 		if (!got_drift && (t_msr < t_page_1 || t_msr > t_page_2)) {
85*bf2c53fdSVitaly Kuznetsov 			printf("drift on CPU %d, MSR value = %ld, acceptable [%ld, %ld]\n", i,
86*bf2c53fdSVitaly Kuznetsov 			       t_msr, t_page_1, t_page_2);
87907ce0f7SPaolo Bonzini 			ok[i] = false;
88907ce0f7SPaolo Bonzini 			got_drift = true;
89907ce0f7SPaolo Bonzini 		}
90907ce0f7SPaolo Bonzini 
91*bf2c53fdSVitaly Kuznetsov 		if (!got_warp_msr && t_msr < t_msr_prev) {
92*bf2c53fdSVitaly Kuznetsov 			printf("warp on CPU %d, MSR value = %ld prev MSR value = %ld!\n", i,
93*bf2c53fdSVitaly Kuznetsov 			       t_msr, t_msr_prev);
94907ce0f7SPaolo Bonzini 			ok[i] = false;
95*bf2c53fdSVitaly Kuznetsov 			got_warp_msr = true;
96907ce0f7SPaolo Bonzini 			break;
97907ce0f7SPaolo Bonzini 		}
98907ce0f7SPaolo Bonzini 
99*bf2c53fdSVitaly Kuznetsov 		if (!got_warp_page && t_page_1 < t_page_prev) {
100*bf2c53fdSVitaly Kuznetsov 			printf("warp on CPU %d, TSC page value = %ld prev TSC page value = %ld!\n", i,
101*bf2c53fdSVitaly Kuznetsov 			       t_page_1, t_page_prev);
102*bf2c53fdSVitaly Kuznetsov 			ok[i] = false;
103*bf2c53fdSVitaly Kuznetsov 			got_warp_page = true;
104*bf2c53fdSVitaly Kuznetsov 			break;
105*bf2c53fdSVitaly Kuznetsov 		}
106*bf2c53fdSVitaly Kuznetsov 
107*bf2c53fdSVitaly Kuznetsov 		t_page_prev = t_page_1;
108*bf2c53fdSVitaly Kuznetsov 		t_msr_prev = t_msr;
109*bf2c53fdSVitaly Kuznetsov 
110*bf2c53fdSVitaly Kuznetsov 	} while(t_page_prev < end);
111*bf2c53fdSVitaly Kuznetsov 
112907ce0f7SPaolo Bonzini 	barrier();
113907ce0f7SPaolo Bonzini }
114907ce0f7SPaolo Bonzini 
check_test(int ncpus)115907ce0f7SPaolo Bonzini static void check_test(int ncpus)
116907ce0f7SPaolo Bonzini {
117907ce0f7SPaolo Bonzini 	int i;
118907ce0f7SPaolo Bonzini 	bool pass;
119907ce0f7SPaolo Bonzini 
120b78f9e64SMetin Kaya 	for (i = ncpus - 1; i >= 0; i--)
121b78f9e64SMetin Kaya 		on_cpu_async(i, hv_clock_test, (void *)(long)i);
122b78f9e64SMetin Kaya 
123b78f9e64SMetin Kaya 	while (cpus_active() > 1)
124b78f9e64SMetin Kaya 		pause();
125907ce0f7SPaolo Bonzini 
126907ce0f7SPaolo Bonzini 	pass = true;
127907ce0f7SPaolo Bonzini 	for (i = ncpus - 1; i >= 0; i--)
128907ce0f7SPaolo Bonzini 		pass &= ok[i];
129907ce0f7SPaolo Bonzini 
130a299895bSThomas Huth 	report(pass, "TSC reference precision test");
131907ce0f7SPaolo Bonzini }
132907ce0f7SPaolo Bonzini 
hv_perf_test(void * data)133907ce0f7SPaolo Bonzini static void hv_perf_test(void *data)
134907ce0f7SPaolo Bonzini {
135b78f9e64SMetin Kaya 	int i = (long)data;
136907ce0f7SPaolo Bonzini 	uint64_t t = hv_clock_read();
137907ce0f7SPaolo Bonzini 	uint64_t end = t + 1000000000 / 100;
138907ce0f7SPaolo Bonzini 	uint64_t local_loops = 0;
139907ce0f7SPaolo Bonzini 
140907ce0f7SPaolo Bonzini 	do {
141907ce0f7SPaolo Bonzini 		t = hv_clock_read();
142907ce0f7SPaolo Bonzini 		local_loops++;
143907ce0f7SPaolo Bonzini 	} while(t < end);
144907ce0f7SPaolo Bonzini 
145b78f9e64SMetin Kaya 	loops[i] = local_loops;
146907ce0f7SPaolo Bonzini }
147907ce0f7SPaolo Bonzini 
perf_test(int ncpus)148907ce0f7SPaolo Bonzini static void perf_test(int ncpus)
149907ce0f7SPaolo Bonzini {
150907ce0f7SPaolo Bonzini 	int i;
151907ce0f7SPaolo Bonzini 	uint64_t total_loops;
152907ce0f7SPaolo Bonzini 
153b78f9e64SMetin Kaya 	for (i = ncpus - 1; i >= 0; i--)
154b78f9e64SMetin Kaya 		on_cpu_async(i, hv_perf_test, (void *)(long)i);
155b78f9e64SMetin Kaya 
156b78f9e64SMetin Kaya 	while (cpus_active() > 1)
157b78f9e64SMetin Kaya 		pause();
158907ce0f7SPaolo Bonzini 
159907ce0f7SPaolo Bonzini 	total_loops = 0;
160907ce0f7SPaolo Bonzini 	for (i = ncpus - 1; i >= 0; i--)
161907ce0f7SPaolo Bonzini 		total_loops += loops[i];
162907ce0f7SPaolo Bonzini 	printf("iterations/sec:  %" PRId64"\n", total_loops / ncpus);
163907ce0f7SPaolo Bonzini }
164907ce0f7SPaolo Bonzini 
main(int ac,char ** av)165907ce0f7SPaolo Bonzini int main(int ac, char **av)
166907ce0f7SPaolo Bonzini {
167907ce0f7SPaolo Bonzini 	int ncpus;
168907ce0f7SPaolo Bonzini 	struct hv_reference_tsc_page shadow;
169907ce0f7SPaolo Bonzini 	uint64_t tsc1, t1, tsc2, t2;
170907ce0f7SPaolo Bonzini 	uint64_t ref1, ref2;
171907ce0f7SPaolo Bonzini 
1725067df40SNadav Amit 	if (!hv_time_ref_counter_supported()) {
1735067df40SNadav Amit 		report_skip("time reference counter is unsupported");
17487ba477aSVitaly Kuznetsov 		goto done;
1755067df40SNadav Amit 	}
1765067df40SNadav Amit 
177907ce0f7SPaolo Bonzini 	setup_vm();
178907ce0f7SPaolo Bonzini 
179eb8445a9SAndrew Jones 	ncpus = cpu_count();
180eb8445a9SAndrew Jones 	if (ncpus > MAX_CPU)
181eb8445a9SAndrew Jones 		report_abort("number cpus exceeds %d", MAX_CPU);
182eb8445a9SAndrew Jones 
183907ce0f7SPaolo Bonzini 	hv_clock = alloc_page();
184907ce0f7SPaolo Bonzini 	wrmsr(HV_X64_MSR_REFERENCE_TSC, (u64)(uintptr_t)hv_clock | 1);
185a299895bSThomas Huth 	report(rdmsr(HV_X64_MSR_REFERENCE_TSC) == ((u64)(uintptr_t)hv_clock | 1),
186a299895bSThomas Huth 	       "MSR value after enabling");
187907ce0f7SPaolo Bonzini 
188907ce0f7SPaolo Bonzini 	hvclock_get_time_values(&shadow, hv_clock);
18987ba477aSVitaly Kuznetsov 	if (shadow.tsc_sequence == 0 || shadow.tsc_sequence == 0xFFFFFFFF)
19087ba477aSVitaly Kuznetsov 		report_abort("Reference TSC page not available\n");
191907ce0f7SPaolo Bonzini 
1920d6cb7b2SMetin Kaya 	printf("sequence: %u. scale: %" PRIx64" offset: %" PRId64"\n",
1930d6cb7b2SMetin Kaya 	       shadow.tsc_sequence, shadow.tsc_scale, shadow.tsc_offset);
194907ce0f7SPaolo Bonzini 	ref1 = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
195907ce0f7SPaolo Bonzini 	tsc1 = rdtsc();
196907ce0f7SPaolo Bonzini 	t1 = hvclock_tsc_to_ticks(&shadow, tsc1);
197907ce0f7SPaolo Bonzini 	printf("refcnt %" PRId64", TSC %" PRIx64", TSC reference %" PRId64"\n",
198907ce0f7SPaolo Bonzini 	       ref1, tsc1, t1);
199907ce0f7SPaolo Bonzini 
200907ce0f7SPaolo Bonzini 	do
201907ce0f7SPaolo Bonzini 		ref2 = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
202907ce0f7SPaolo Bonzini 	while (ref2 < ref1 + 2 * TICKS_PER_SEC);
203907ce0f7SPaolo Bonzini 
204907ce0f7SPaolo Bonzini 	tsc2 = rdtsc();
205907ce0f7SPaolo Bonzini 	t2 = hvclock_tsc_to_ticks(&shadow, tsc2);
206907ce0f7SPaolo Bonzini 	printf("refcnt %" PRId64" (delta %" PRId64"), TSC %" PRIx64", "
207907ce0f7SPaolo Bonzini 	       "TSC reference %" PRId64" (delta %" PRId64")\n",
208907ce0f7SPaolo Bonzini 	       ref2, ref2 - ref1, tsc2, t2, t2 - t1);
209907ce0f7SPaolo Bonzini 
210907ce0f7SPaolo Bonzini 	check_test(ncpus);
211907ce0f7SPaolo Bonzini 	perf_test(ncpus);
212907ce0f7SPaolo Bonzini 
213907ce0f7SPaolo Bonzini 	wrmsr(HV_X64_MSR_REFERENCE_TSC, 0LL);
214a299895bSThomas Huth 	report(rdmsr(HV_X64_MSR_REFERENCE_TSC) == 0,
215a299895bSThomas Huth 	       "MSR value after disabling");
216907ce0f7SPaolo Bonzini 
21787ba477aSVitaly Kuznetsov done:
21887ba477aSVitaly Kuznetsov 	return report_summary();
219907ce0f7SPaolo Bonzini }
220