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Subject: Re: [PATCH] KVM: x86: move steal time initialization to vcpu entry
 time
To: Liang Chen <liangchen.linux@gmail.com>, <stable@vger.kernel.org>
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	<sasha.levin@oracle.com>
From: Zefan Li <lizefan@huawei.com>
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Date: Mon, 14 Mar 2016 08:41:49 +0800
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On 2016/3/11 16:53, Liang Chen wrote:
> From: Marcelo Tosatti <mtosatti@redhat.com>
> 
> commit 7cae2bedcbd4680b155999655e49c27b9cf020fa upstream
> 
> This patch is needed on lts 3.4, 3.10, 3.12, 3.14, 3.18, and 4.1 for
> the same issue. Can you please to pick it up?
> 

Sure. I'll queue it up for 3.4.y. Thanks!

> As reported at https://bugs.launchpad.net/qemu/+bug/1494350,
> it is possible to have vcpu->arch.st.last_steal initialized
> from a thread other than vcpu thread, say the iothread, via
> KVM_SET_MSRS.
> 
> Which can cause an overflow later (when subtracting from vcpu threads
> sched_info.run_delay).
> 
> To avoid that, move steal time accumulation to vcpu entry time,
> before copying steal time data to guest.
> 
> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
> Reviewed-by: David Matlack <dmatlack@google.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>