Re: [PATCH v3 1/7] KVM: MMU: fix release noslot pfn

From: Gleb Natapov
Date: Mon Sep 24 2012 - 07:24:11 EST


On Mon, Sep 24, 2012 at 12:59:32PM +0800, Xiao Guangrong wrote:
> On 09/23/2012 05:13 PM, Gleb Natapov wrote:
> > On Fri, Sep 21, 2012 at 02:57:19PM +0800, Xiao Guangrong wrote:
> >> We can not directly call kvm_release_pfn_clean to release the pfn
> >> since we can meet noslot pfn which is used to cache mmio info into
> >> spte
> >>
> > Wouldn't it be better to move the check into kvm_release_pfn_clean()?
>
> I think there is no reason for us to prefer to adding this branch in
> the common code. :)

Is the function performance critical? Is function called without the check
on a hot path? The function already contains much heavier kvm_is_mmio_pfn()
check. If most/all function invocation require check before call it's
better to move it inside.

--
Gleb.
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