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hyperv: Register Hyper-V timer early enough for TSC freq calibration

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The i8254 simulation in Hyper-V is kinda broken and is not available
in Generation 2 Hyper-V VMs, so Hyper-V timer must be registered early
enough so that it can be used to do the TSC freq calibration.

This fixes the notorious warning like this:
calcru: runtime went backwards from 50 usec to 25 usec for pid 0 (kernel)

Submitted by:	Dexuan Cui <decui microsoft com>
Reviewed by:	kib, sephe
Tested by:	kib, sephe
MFC after:	1 week
Sponsored by:	Microsoft OSTC
Differential Revision:	https://reviews.freebsd.org/D5778
This commit is contained in:
Sepherosa Ziehau 2016-04-01 06:17:57 +00:00
parent df04a188af
commit 04c247a1d0
1 changed files with 12 additions and 2 deletions
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14
sys/dev/hyperv/vmbus/hv_hv.c
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@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
#include <sys/malloc.h>
#include <sys/pcpu.h>
#include <sys/timetc.h>
#include <sys/kernel.h>
#include <machine/bus.h>
#include <machine/md_var.h>
#include <vm/vm.h>
@ -207,8 +208,6 @@ hv_vmbus_init(void)
hv_vmbus_g_context.hypercall_page = virt_addr;
tc_init(&hv_timecounter); /* register virtual timecount */
hv_et_init();
return (0);
@ -437,3 +436,14 @@ void hv_vmbus_synic_cleanup(void *arg)
wrmsr(HV_X64_MSR_SIEFP, siefp.as_uint64_t);
}
static void
hv_tc_init(void)
{
if (vm_guest != VM_GUEST_HV)
return;
/* register virtual timecounter */
tc_init(&hv_timecounter);
}
SYSINIT(hv_tc_init, SI_SUB_HYPERVISOR, SI_ORDER_FIRST, hv_tc_init, NULL);