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From: Zenghui Yu <yuzenghui@huawei.com>
To: Marc Zyngier <maz@kernel.org>, <kvmarm@lists.cs.columbia.edu>,
	<kvm@vger.kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH] KVM: Disable preemption in kvm_get_running_vcpu()
Date: Tue, 11 Feb 2020 09:25:55 +0800	[thread overview]
Message-ID: <2b47b50f-1c78-577a-4216-dcf8d712d96c@huawei.com> (raw)
In-Reply-To: <20200207163410.31276-1-maz@kernel.org>

On 2020/2/8 0:34, Marc Zyngier wrote:
> Accessing a per-cpu variable only makes sense when preemption is
> disabled (and the kernel does check this when the right debug options
> are switched on).
> 
> For kvm_get_running_vcpu(), it is fine to return the value after
> re-enabling preemption, as the preempt notifiers will make sure that
> this is kept consistent across task migration (the comment above the
> function hints at it, but lacks the crucial preemption management).
> 
> While we're at it, move the comment from the ARM code, which explains
> why the whole thing works.
> 
> Fixes: 7495e22bb165 ("KVM: Move running VCPU from ARM to common code").
> Cc: Peter Xu <peterx@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Reported-by: Zenghui Yu <yuzenghui@huawei.com>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> Link: https://lore.kernel.org/r/318984f6-bc36-33a3-abc6-bf2295974b06@huawei.com

Tested-by: Zenghui Yu <yuzenghui@huawei.com>

on top of v5.6-rc1.


Thanks

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  parent reply	other threads:[~2020-02-11  1:26 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-07 16:34 [PATCH] KVM: Disable preemption in kvm_get_running_vcpu() Marc Zyngier
2020-02-07 17:04 ` Peter Xu
2020-02-11  1:25 ` Zenghui Yu [this message]
2020-02-12 11:19 ` Paolo Bonzini

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