linux-kernel - [PATCH 0/2] clocksource/Hyper-V: Add Hyper-V specific sched clock function

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Date:   Mon, 29 Jul 2019 15:52:41 +0800
From:   lantianyu1986@...il.com
To:     luto@...nel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, hpa@...or.com, x86@...nel.org, kys@...rosoft.com,
        haiyangz@...rosoft.com, sthemmin@...rosoft.com, sashal@...nel.org,
        daniel.lezcano@...aro.org, arnd@...db.de,
        michael.h.kelley@...rosoft.com, ashal@...nel.org
Cc:     Tianyu Lan <Tianyu.Lan@...rosoft.com>, linux-arch@...r.kernel.org,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 0/2] clocksource/Hyper-V: Add Hyper-V specific sched clock function

From: Tianyu Lan <Tianyu.Lan@...rosoft.com>

Hyper-V guests use the default native_sched_clock() in pv_ops.time.sched_clock
on x86.  But native_sched_clock() directly uses the raw TSC value, which
can be discontinuous in a Hyper-V VM.   Add the generic hv_setup_sched_clock()
to set the sched clock function appropriately.  On x86, this sets
pv_ops.time.sched_clock to read the Hyper-V reference TSC value that is
scaled and adjusted to be continuous.

Also move the Hyper-V reference TSC initialization much earlier in the boot
process so no discontinuity is observed when pv_ops.time.sched_clock
calculates its offset.  This earlier initialization requires that the Hyper-V TSC
page be allocated statically instead of with vmalloc(), so fixup the references
to the TSC page and the method of getting its physical address.

Tianyu Lan (2):
  clocksource/Hyper-v: Allocate Hyper-V tsc page statically
  clocksource/Hyper-V: Add Hyper-V specific sched clock function

 arch/x86/entry/vdso/vma.c          |  2 +-
 arch/x86/hyperv/hv_init.c          |  2 --
 arch/x86/kernel/cpu/mshyperv.c     |  8 ++++++++
 drivers/clocksource/hyperv_timer.c | 34 ++++++++++++++++------------------
 include/asm-generic/mshyperv.h     |  1 +
 5 files changed, 26 insertions(+), 21 deletions(-)

-- 
2.14.5