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HV: Use the CPUID(0x16) to obtain tsc_hz when zero tsc_hz is returned by 0x15 cpuid

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Sometimes the CPUID(0x15) still returns the zero tsc frequency. In such case
the base frequency of cpuid(0x16) is used as tsc frequency.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
This commit is contained in:
Zhao Yakui 2018-08-14 10:41:25 +08:00 committed by lijinxia
parent 7d83abb4a5
commit 197706ff16
1 changed files with 11 additions and 3 deletions
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14
hypervisor/arch/x86/timer.c
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@ -278,10 +278,12 @@ static uint64_t pit_calibrate_tsc(uint32_t cal_ms_arg)
}
/*
* Determine TSC frequency via CPUID 0x15
* Determine TSC frequency via CPUID 0x15 and 0x16.
*/
static uint64_t native_calibrate_tsc(void)
{
uint64_t tsc_hz = 0;
if (boot_cpu_data.cpuid_level >= 0x15U) {
uint32_t eax_denominator, ebx_numerator, ecx_hz, reserved;
@ -289,12 +291,18 @@ static uint64_t native_calibrate_tsc(void)
&ecx_hz, &reserved);
if ((eax_denominator != 0U) && (ebx_numerator != 0U)) {
return ((uint64_t) ecx_hz *
tsc_hz = ((uint64_t) ecx_hz *
ebx_numerator) / eax_denominator;
}
}
return 0;
if ((tsc_hz == 0) && (boot_cpu_data.cpuid_level >= 0x16U)) {
uint32_t eax_base_mhz, ebx_max_mhz, ecx_bus_mhz, edx;
cpuid(0x16U, &eax_base_mhz, &ebx_max_mhz, &ecx_bus_mhz, &edx);
tsc_hz = (uint64_t) eax_base_mhz * 1000000U;
}
return tsc_hz;
}
void calibrate_tsc(void)