linux-kernel - Re: [PATCH] x86/Hyper-V: Fix build error with CONFIG_HYPERV

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Date:   Mon, 26 Aug 2019 09:20:36 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Sasha Levin <sashal@...nel.org>
Cc:     lantianyu1986@...il.com, Tianyu Lan <Tianyu.Lan@...rosoft.com>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
        kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
        mingo@...hat.com, bp@...en8.de, hpa@...or.com, x86@...nel.org,
        daniel.lezcano@...aro.org, michael.h.kelley@...rosoft.com,
        tglx@...utronix.de
Subject: Re: [PATCH] x86/Hyper-V: Fix build error with CONFIG_HYPERV_TSCPAGE=N

Sasha Levin <sashal@...nel.org> writes:

> On Thu, Aug 22, 2019 at 10:39:46AM +0200, Vitaly Kuznetsov wrote:
>>lantianyu1986@...il.com writes:
>>
>>> From: Tianyu Lan <Tianyu.Lan@...rosoft.com>
>>>
>>> Both Hyper-V tsc page and Hyper-V tsc MSR code use variable
>>> hv_sched_clock_offset for their sched clock callback and so
>>> define the variable regardless of CONFIG_HYPERV_TSCPAGE setting.
>>
>>CONFIG_HYPERV_TSCPAGE is gone after my "x86/hyper-v: enable TSC page
>>clocksource on 32bit" patch. Do we still have an issue to fix?
>
> Yes. Let's get it fixed on older kernels (as such we need to tag this
> one for stable). The 32bit TSC patch won't come in before 5.4 anyway.
>
> Vitaly, does can you ack this patch? It might require you to re-spin
> your patch.
>

Sure, no problem,

Acked-by: Vitaly Kuznetsov <vkuznets@...hat.com>

I, however, was under the impression the patch fixes the issue with the
newly introduced sched clock:

commit b74e1d61dbc614ff35ef3ad9267c61ed06b09051
Author: Tianyu Lan <Tianyu.Lan@...rosoft.com>
Date:   Wed Aug 14 20:32:16 2019 +0800

    clocksource/hyperv: Add Hyper-V specific sched clock function

(and Fixes: tag is missing)

and this is not in mainline as of v5.3-rc6. In tip/timers/core Thomas
already picked my "clocksource/drivers/hyperv: Enable TSC page
clocksource on 32bit" which also resolves the issue.

So my question is - which older/stable kernel do you have in mind?

-- 
Vitaly