1 #include "libcflat.h" 2 #include "smp.h" 3 #include "atomic.h" 4 #include "processor.h" 5 #include "hyperv.h" 6 #include "vm.h" 7 #include "alloc_page.h" 8 9 #define MAX_CPU 4 10 #define TICKS_PER_SEC (1000000000 / 100) 11 12 struct hv_reference_tsc_page *hv_clock; 13 14 /* 15 * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction, 16 * yielding a 64-bit result. 17 */ 18 static inline u64 scale_delta(u64 delta, u64 mul_frac) 19 { 20 u64 product, unused; 21 22 __asm__ ( 23 "mulq %3" 24 : "=d" (product), "=a" (unused) : "1" (delta), "rm" ((u64)mul_frac) ); 25 26 return product; 27 } 28 29 static u64 hvclock_tsc_to_ticks(struct hv_reference_tsc_page *shadow, uint64_t tsc) 30 { 31 u64 delta = tsc; 32 return scale_delta(delta, shadow->tsc_scale) + shadow->tsc_offset; 33 } 34 35 /* 36 * Reads a consistent set of time-base values from hypervisor, 37 * into a shadow data area. 38 */ 39 static void hvclock_get_time_values(struct hv_reference_tsc_page *shadow, 40 struct hv_reference_tsc_page *page) 41 { 42 int seq; 43 do { 44 seq = page->tsc_sequence; 45 rmb(); /* fetch version before data */ 46 *shadow = *page; 47 rmb(); /* test version after fetching data */ 48 } while (shadow->tsc_sequence != seq); 49 } 50 51 static uint64_t hv_clock_read(void) 52 { 53 struct hv_reference_tsc_page shadow; 54 55 hvclock_get_time_values(&shadow, hv_clock); 56 return hvclock_tsc_to_ticks(&shadow, rdtsc()); 57 } 58 59 bool ok[MAX_CPU]; 60 uint64_t loops[MAX_CPU]; 61 62 #define iabs(x) ((x) < 0 ? -(x) : (x)) 63 64 static void hv_clock_test(void *data) 65 { 66 int i = smp_id(); 67 uint64_t t = rdmsr(HV_X64_MSR_TIME_REF_COUNT); 68 uint64_t end = t + 3 * TICKS_PER_SEC; 69 uint64_t msr_sample = t + TICKS_PER_SEC; 70 int min_delta = 123456, max_delta = -123456; 71 bool got_drift = false; 72 bool got_warp = false; 73 74 ok[i] = true; 75 do { 76 uint64_t now = hv_clock_read(); 77 int delta = rdmsr(HV_X64_MSR_TIME_REF_COUNT) - now; 78 79 min_delta = delta < min_delta ? delta : min_delta; 80 if (t < msr_sample) { 81 max_delta = delta > max_delta ? delta: max_delta; 82 } else if (delta < 0 || delta > max_delta * 3 / 2) { 83 printf("suspecting drift on CPU %d? delta = %d, acceptable [0, %d)\n", smp_id(), 84 delta, max_delta); 85 ok[i] = false; 86 got_drift = true; 87 max_delta *= 2; 88 } 89 90 if (now < t && !got_warp) { 91 printf("warp on CPU %d!\n", smp_id()); 92 ok[i] = false; 93 got_warp = true; 94 break; 95 } 96 t = now; 97 } while(t < end); 98 99 if (!got_drift) 100 printf("delta on CPU %d was %d...%d\n", smp_id(), min_delta, max_delta); 101 barrier(); 102 } 103 104 static void check_test(int ncpus) 105 { 106 int i; 107 bool pass; 108 109 on_cpus(hv_clock_test, NULL); 110 111 pass = true; 112 for (i = ncpus - 1; i >= 0; i--) 113 pass &= ok[i]; 114 115 report(pass, "TSC reference precision test"); 116 } 117 118 static void hv_perf_test(void *data) 119 { 120 uint64_t t = hv_clock_read(); 121 uint64_t end = t + 1000000000 / 100; 122 uint64_t local_loops = 0; 123 124 do { 125 t = hv_clock_read(); 126 local_loops++; 127 } while(t < end); 128 129 loops[smp_id()] = local_loops; 130 } 131 132 static void perf_test(int ncpus) 133 { 134 int i; 135 uint64_t total_loops; 136 137 on_cpus(hv_perf_test, NULL); 138 139 total_loops = 0; 140 for (i = ncpus - 1; i >= 0; i--) 141 total_loops += loops[i]; 142 printf("iterations/sec: %" PRId64"\n", total_loops / ncpus); 143 } 144 145 int main(int ac, char **av) 146 { 147 int nerr = 0; 148 int ncpus; 149 struct hv_reference_tsc_page shadow; 150 uint64_t tsc1, t1, tsc2, t2; 151 uint64_t ref1, ref2; 152 153 if (!hv_time_ref_counter_supported()) { 154 report_skip("time reference counter is unsupported"); 155 return report_summary(); 156 } 157 158 setup_vm(); 159 160 ncpus = cpu_count(); 161 if (ncpus > MAX_CPU) 162 report_abort("number cpus exceeds %d", MAX_CPU); 163 164 hv_clock = alloc_page(); 165 wrmsr(HV_X64_MSR_REFERENCE_TSC, (u64)(uintptr_t)hv_clock | 1); 166 report(rdmsr(HV_X64_MSR_REFERENCE_TSC) == ((u64)(uintptr_t)hv_clock | 1), 167 "MSR value after enabling"); 168 169 hvclock_get_time_values(&shadow, hv_clock); 170 if (shadow.tsc_sequence == 0 || shadow.tsc_sequence == 0xFFFFFFFF) { 171 printf("Reference TSC page not available\n"); 172 exit(1); 173 } 174 175 printf("scale: %" PRIx64" offset: %" PRId64"\n", shadow.tsc_scale, shadow.tsc_offset); 176 ref1 = rdmsr(HV_X64_MSR_TIME_REF_COUNT); 177 tsc1 = rdtsc(); 178 t1 = hvclock_tsc_to_ticks(&shadow, tsc1); 179 printf("refcnt %" PRId64", TSC %" PRIx64", TSC reference %" PRId64"\n", 180 ref1, tsc1, t1); 181 182 do 183 ref2 = rdmsr(HV_X64_MSR_TIME_REF_COUNT); 184 while (ref2 < ref1 + 2 * TICKS_PER_SEC); 185 186 tsc2 = rdtsc(); 187 t2 = hvclock_tsc_to_ticks(&shadow, tsc2); 188 printf("refcnt %" PRId64" (delta %" PRId64"), TSC %" PRIx64", " 189 "TSC reference %" PRId64" (delta %" PRId64")\n", 190 ref2, ref2 - ref1, tsc2, t2, t2 - t1); 191 192 check_test(ncpus); 193 perf_test(ncpus); 194 195 wrmsr(HV_X64_MSR_REFERENCE_TSC, 0LL); 196 report(rdmsr(HV_X64_MSR_REFERENCE_TSC) == 0, 197 "MSR value after disabling"); 198 199 return nerr > 0 ? 1 : 0; 200 } 201