Re: [Xen-devel] [RFC PATCH] hvm/vpt: fix inconsistent views of vIOAPIC in vmx_intr_assist()

[Chao Gao <chao.gao@xxxxxxxxx>]

On Fri, Apr 21, 2017 at 10:00:16PM +0800, Tian, Kevin wrote:
>btw I'm thinking whether adding lock in vmx_intr_assist is
>necessary... Can you think whether below option may
>work?
>
>Do lock protection within pt_update_irq. Make sure vector
>not changed between setting vIRR and finding pt_irq_vector.
>Within the lock also saves the vector to earliest_pt.
>
>Then vmx_intr_assist will get the exact vector programmed
>to vIRR from pt_irq_vector. Then in pt_intr_post, compare
>saved vector to intack.vector, instead of re-searching
>pt_irq_vector again.
>
>This way even RTE is changed after pt_update_irq it won't
>impact the whole flow here, since new vector hasn't got
>chance to hit vIRR. then we don't need adding lock in 
>vmx_intr_assist at all.

I think it will work and is better than this patch.

Thanks
Chao

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