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TSC: Use 0x40000010 CPUID leaf for all VM types

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While this CPUID leaf was originally only used by VMWare, other
hypervisors now also use it to announce the TSC frequency to guests.

This speeds up the boot process by 100 ms in EC2 and other systems,
by allowing the early calibration DELAY to be skipped.

Reviewed by:	markj
Sponsored by:	https://www.patreon.com/cperciva
This commit is contained in:
Colin Percival 2022-01-03 23:28:36 -08:00
parent fd980feb57
commit 4a432614f6
1 changed files with 21 additions and 8 deletions
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29
sys/x86/x86/tsc.c
View File

@ -121,19 +121,29 @@ static struct timecounter tsc_timecounter = {
#endif
};
static int
tsc_freq_cpuid_vm(void)
{
u_int regs[4];
if (vm_guest == VM_GUEST_NO)
return (false);
if (hv_high < 0x40000010)
return (false);
do_cpuid(0x40000010, regs);
tsc_freq = (uint64_t)(regs[0]) * 1000;
tsc_early_calib_exact = 1;
return (true);
}
static void
tsc_freq_vmware(void)
{
u_int regs[4];
if (hv_high >= 0x40000010) {
do_cpuid(0x40000010, regs);
tsc_freq = regs[0] * 1000;
} else {
vmware_hvcall(VMW_HVCMD_GETHZ, regs);
if (regs[1] != UINT_MAX)
tsc_freq = regs[0] | ((uint64_t)regs[1] << 32);
}
vmware_hvcall(VMW_HVCMD_GETHZ, regs);
if (regs[1] != UINT_MAX)
tsc_freq = regs[0] | ((uint64_t)regs[1] << 32);
tsc_early_calib_exact = 1;
}
@ -305,6 +315,9 @@ probe_tsc_freq(void)
break;
}
if (tsc_freq_cpuid_vm())
return;
if (vm_guest == VM_GUEST_VMWARE) {
tsc_freq_vmware();
return;