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Differential D33894

TSC: Use 0x40000010 CPUID leaf for all VM types
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Authored by cperciva on Jan 14 2022, 6:32 AM.
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imp

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Reviewers
markj
Summary

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.

Sponsored by: https://www.patreon.com/cperciva

Diff Detail

Repository
rS FreeBSD src repository - subversion
Lint
Lint Passed
Unit
No Test Coverage
Build Status
Buildable 43933
Build 40821: arc lint + arc unit

Event Timeline

cperciva created this revision.Jan 14 2022, 6:32 AM
Herald added a subscriber: imp. · View Herald TranscriptJan 14 2022, 6:32 AM
cperciva requested review of this revision.Jan 14 2022, 6:32 AM
Harbormaster completed remote builds in B43921: Diff 101449.Jan 14 2022, 6:32 AM
cperciva added a parent revision: D33893: Detect CPU type before asking VMWare for TSC freq.Jan 14 2022, 6:32 AM
cperciva added a child revision: D33895: Use CPUID leaf 0x40000010 for local APIC freq.
markj accepted this revision.Jan 14 2022, 2:50 PM
This revision is now accepted and ready to land.Jan 14 2022, 2:50 PM
markj added inline comments.Jan 14 2022, 2:57 PM
sys/x86/x86/tsc.c
134

I think this multiplication can overflow, actually. The RHS is promoted after the multiplication.

cperciva updated this revision to Diff 101484.Jan 14 2022, 9:47 PM

Fix overflow bug

This revision now requires review to proceed.Jan 14 2022, 9:47 PM
Harbormaster completed remote builds in B43933: Diff 101484.Jan 14 2022, 9:47 PM
cperciva added inline comments.Jan 14 2022, 9:48 PM
sys/x86/x86/tsc.c
134

Thanks, fixed!

markj accepted this revision.Jan 14 2022, 11:28 PM
This revision is now accepted and ready to land.Jan 14 2022, 11:28 PM
cperciva closed this revision.Jan 15 2022, 1:32 AM

Committed. (I forgot to include the Differential Revision tag in the commit message.)

Revision Contents
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sys/
x86/
x86/
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Diff 101484

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sys/x86/x86/tsc.c

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