From mboxrd@z Thu Jan  1 00:00:00 1970
From: Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>
Subject: Re: x86: kvm: Revert "remove sched notifier for cross-cpu migrations"
Date: Tue, 24 Mar 2015 16:34:12 +0100
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References: <20150323232151.GA12772@amt.cnet>
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Cc: kvm-devel <kvm@vger.kernel.org>, stable@vger.kernel.org,
	Paolo Bonzini <pbonzini@redhat.com>,
	Andy Lutomirski <luto@amacapital.net>
To: Marcelo Tosatti <mtosatti@redhat.com>
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2015-03-23 20:21-0300, Marcelo Tosatti:
> The following point:
> 
>     2. per-CPU pvclock time info is updated if the
>        underlying CPU changes.
> 
> Is not true anymore since "KVM: x86: update pvclock area conditionally,
> on cpu migration".

I think that the revert doesn't fix point 2.:  "KVM: x86: update pvclock
[...]" changed the host to skip clock update on physical CPU change, but
guest's task migration notifier isn't tied to it at all.
(Guest can have all tasks pinned, so the revert changed nothing.)

> Add task migration notification back.
> 
> Problem noticed by Andy Lutomirski.

What is the problem?

Thanks.