From mboxrd@z Thu Jan  1 00:00:00 1970
From: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Subject: Re: EPT questions!
Date: Wed, 1 Mar 2017 11:40:31 +0800
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To: "jack.chen" <zhunxun@gmail.com>, KVM maillist <kvm@vger.kernel.org>
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Hash list is used as a cache. KVM is always trying to reuse the
existing SP if possible.


On 03/01/2017 10:46 AM, jack.chen wrote:
> hello,I am confused about kvm_mmu_get_page function in KVM source
> code,why it look for a the hash list first rather than alloc a new
> page, what is the function of the hash list.thanks!
> for_each_gfn_sp(vcpu->kvm, sp, gfn) {
>
> if (is_obsolete_sp(vcpu->kvm, sp))
> continue;
>
> if (!need_sync && sp->unsync)
> need_sync = true;
>
> if (sp->role.word != role.word)
> continue;
>
> if (sp->unsync && kvm_sync_page_transient(vcpu, sp))
> break;
>
> mmu_page_add_parent_pte(vcpu, sp, parent_pte);
> if (sp->unsync_children) {
> kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
> kvm_mmu_mark_parents_unsync(sp);
> } else if (sp->unsync)
> kvm_mmu_mark_parents_unsync(sp);
>
> __clear_sp_write_flooding_count(sp);
> trace_kvm_mmu_get_page(sp, false);
> return sp;
> }
>