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From:   Vitaly Kuznetsov <vkuznets@redhat.com>
To:     Sasha Levin <sashal@kernel.org>
Cc:     lantianyu1986@gmail.com, Tianyu Lan <Tianyu.Lan@microsoft.com>,
        linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org,
        kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com,
        mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org,
        daniel.lezcano@linaro.org, michael.h.kelley@microsoft.com,
        tglx@linutronix.de
Subject: Re: [PATCH] x86/Hyper-V: Fix build error with CONFIG_HYPERV_TSCPAGE=N
In-Reply-To: <20190824151218.GM1581@sasha-vm>
References: <20190822053852.239309-1-Tianyu.Lan@microsoft.com> <87zhk1pp9p.fsf@vitty.brq.redhat.com> <20190824151218.GM1581@sasha-vm>
Date:   Mon, 26 Aug 2019 09:20:36 +0200
Message-ID: <87d0gso0jf.fsf@vitty.brq.redhat.com>
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Sasha Levin <sashal@kernel.org> writes:

> On Thu, Aug 22, 2019 at 10:39:46AM +0200, Vitaly Kuznetsov wrote:
>>lantianyu1986@gmail.com writes:
>>
>>> From: Tianyu Lan <Tianyu.Lan@microsoft.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@redhat.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@microsoft.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