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- #include "libcflat.h"
- #include "smp.h"
- #include "atomic.h"
- #include "processor.h"
- #include "hyperv.h"
- #include "vm.h"
- #define MAX_CPU 4
- #define TICKS_PER_SEC (1000000000 / 100)
- struct hv_reference_tsc_page *hv_clock;
- static inline u64 scale_delta(u64 delta, u64 mul_frac)
- {
- u64 product, unused;
- __asm__ (
- "mulq %3"
- : "=d" (product), "=a" (unused) : "1" (delta), "rm" ((u64)mul_frac) );
- return product;
- }
- static u64 hvclock_tsc_to_ticks(struct hv_reference_tsc_page *shadow, uint64_t tsc)
- {
- u64 delta = tsc;
- return scale_delta(delta, shadow->tsc_scale) + shadow->tsc_offset;
- }
- static void hvclock_get_time_values(struct hv_reference_tsc_page *shadow,
- struct hv_reference_tsc_page *page)
- {
- int seq;
- do {
- seq = page->tsc_sequence;
- rmb();
- *shadow = *page;
- rmb();
- } while (shadow->tsc_sequence != seq);
- }
- uint64_t hv_clock_read(void)
- {
- struct hv_reference_tsc_page shadow;
- hvclock_get_time_values(&shadow, hv_clock);
- return hvclock_tsc_to_ticks(&shadow, rdtsc());
- }
- bool ok[MAX_CPU];
- uint64_t loops[MAX_CPU];
- #define iabs(x) ((x) < 0 ? -(x) : (x))
- static void hv_clock_test(void *data)
- {
- int i = smp_id();
- uint64_t t = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
- uint64_t end = t + 3 * TICKS_PER_SEC;
- uint64_t msr_sample = t + TICKS_PER_SEC;
- int min_delta = 123456, max_delta = -123456;
- bool got_drift = false;
- bool got_warp = false;
- ok[i] = true;
- do {
- uint64_t now = hv_clock_read();
- int delta = rdmsr(HV_X64_MSR_TIME_REF_COUNT) - now;
- min_delta = delta < min_delta ? delta : min_delta;
- if (t < msr_sample) {
- max_delta = delta > max_delta ? delta: max_delta;
- } else if (delta < 0 || delta > max_delta * 3 / 2) {
- printf("suspecting drift on CPU %d? delta = %d, acceptable [0, %d)\n", smp_id(),
- delta, max_delta);
- ok[i] = false;
- got_drift = true;
- max_delta *= 2;
- }
- if (now < t && !got_warp) {
- printf("warp on CPU %d!\n", smp_id());
- ok[i] = false;
- got_warp = true;
- break;
- }
- t = now;
- } while(t < end);
- if (!got_drift)
- printf("delta on CPU %d was %d...%d\n", smp_id(), min_delta, max_delta);
- barrier();
- }
- static void check_test(int ncpus)
- {
- int i;
- bool pass;
- on_cpus(hv_clock_test, NULL);
- pass = true;
- for (i = ncpus - 1; i >= 0; i--)
- pass &= ok[i];
- report("TSC reference precision test", pass);
- }
- static void hv_perf_test(void *data)
- {
- uint64_t t = hv_clock_read();
- uint64_t end = t + 1000000000 / 100;
- uint64_t local_loops = 0;
- do {
- t = hv_clock_read();
- local_loops++;
- } while(t < end);
- loops[smp_id()] = local_loops;
- }
- static void perf_test(int ncpus)
- {
- int i;
- uint64_t total_loops;
- on_cpus(hv_perf_test, NULL);
- total_loops = 0;
- for (i = ncpus - 1; i >= 0; i--)
- total_loops += loops[i];
- printf("iterations/sec: %" PRId64"\n", total_loops / ncpus);
- }
- int main(int ac, char **av)
- {
- int nerr = 0;
- int ncpus;
- struct hv_reference_tsc_page shadow;
- uint64_t tsc1, t1, tsc2, t2;
- uint64_t ref1, ref2;
- setup_vm();
- smp_init();
- ncpus = cpu_count();
- if (ncpus > MAX_CPU)
- report_abort("number cpus exceeds %d", MAX_CPU);
- hv_clock = alloc_page();
- wrmsr(HV_X64_MSR_REFERENCE_TSC, (u64)(uintptr_t)hv_clock | 1);
- report("MSR value after enabling",
- rdmsr(HV_X64_MSR_REFERENCE_TSC) == ((u64)(uintptr_t)hv_clock | 1));
- hvclock_get_time_values(&shadow, hv_clock);
- if (shadow.tsc_sequence == 0 || shadow.tsc_sequence == 0xFFFFFFFF) {
- printf("Reference TSC page not available\n");
- exit(1);
- }
- printf("scale: %" PRIx64" offset: %" PRId64"\n", shadow.tsc_scale, shadow.tsc_offset);
- ref1 = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
- tsc1 = rdtsc();
- t1 = hvclock_tsc_to_ticks(&shadow, tsc1);
- printf("refcnt %" PRId64", TSC %" PRIx64", TSC reference %" PRId64"\n",
- ref1, tsc1, t1);
- do
- ref2 = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
- while (ref2 < ref1 + 2 * TICKS_PER_SEC);
- tsc2 = rdtsc();
- t2 = hvclock_tsc_to_ticks(&shadow, tsc2);
- printf("refcnt %" PRId64" (delta %" PRId64"), TSC %" PRIx64", "
- "TSC reference %" PRId64" (delta %" PRId64")\n",
- ref2, ref2 - ref1, tsc2, t2, t2 - t1);
- check_test(ncpus);
- perf_test(ncpus);
- wrmsr(HV_X64_MSR_REFERENCE_TSC, 0LL);
- report("MSR value after disabling", rdmsr(HV_X64_MSR_REFERENCE_TSC) == 0);
- return nerr > 0 ? 1 : 0;
- }
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