blob: 1f26b7a7609801e051c5d79564eeee370c25d04f [file] [log] [blame] [edit]
#include "libcflat.h"
#include "processor.h"
int main(void)
{
u64 t1, t2, t3, t4, t5;
u64 est_delta_time;
if (this_cpu_has(X86_FEATURE_TSC_ADJUST)) { // MSR_IA32_TSC_ADJUST Feature is enabled?
report(rdmsr(MSR_IA32_TSC_ADJUST) == 0x0,
"MSR_IA32_TSC_ADJUST msr initialization");
t3 = 100000000000ull;
t1 = rdtsc();
wrmsr(MSR_IA32_TSC_ADJUST, t3);
t2 = rdtsc();
report(rdmsr(MSR_IA32_TSC_ADJUST) == t3,
"MSR_IA32_TSC_ADJUST msr read / write");
report((t2 - t1) >= t3,
"TSC adjustment for MSR_IA32_TSC_ADJUST value");
t3 = 0x0;
wrmsr(MSR_IA32_TSC_ADJUST, t3);
report(rdmsr(MSR_IA32_TSC_ADJUST) == t3,
"MSR_IA32_TSC_ADJUST msr read / write");
t4 = 100000000000ull;
t1 = rdtsc();
wrtsc(t4);
t2 = rdtsc();
t5 = rdmsr(MSR_IA32_TSC_ADJUST);
// est of time between reading tsc and writing tsc,
// (based on MSR_IA32_TSC_ADJUST msr value) should be small
est_delta_time = t4 - t5 - t1;
// arbitray 2x latency (wrtsc->rdtsc) threshold
report(est_delta_time <= (2 * (t2 - t4)),
"MSR_IA32_TSC_ADJUST msr adjustment on tsc write");
}
else {
report(true, "MSR_IA32_TSC_ADJUST feature not enabled");
}
return report_summary();
}