K 10
svn:author
V 7
git2svn
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svn:date
V 27
2023-01-29T18:57:15.238068Z
K 7
svn:log
V 982
kvmclock: Fix initialization when EARLY_AP_STARTUP is not defined

To attach to the hypervisor, kvmclock needs to write a per-CPU MSR.
When EARLY_AP_STARTUP is not defined, device attach happens too early:
APs are not yet spun up, so smp_rendezvous only runs the callback on the
local CPU.  As a result, the timecounter only gets initialized on the
BSP, and then timekeeping is broken on SMP systems.

Implement handling for !EARLY_AP_STARTUP kernels: keep track of the CPU
on which device attach ran, and then use a SI_SUB_SMP SYSINIT to
register the rest of the CPUs with the hypervisor.

Reported by:	Shrikanth R Kamath <kshrikanth@juniper.net>
Reviewed by:	kib, jhb (earlier versions)
Sponsored by:	Klara, Inc.
Sponsored by:	Juniper Networks, Inc.
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D37705

(cherry picked from commit 568f552b0410f4f72db9ce710f7803acca23f79f)

Git Hash:   870464f11f3c53fcc7114ea406f95655b9821263
Git Author: markj@FreeBSD.org
END