linux-kernel - Re: [PATCH v3 09/10] KVM: MMU: fix MTRR update

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Message-ID: <20150514001648.GA5206@kernel>
Date:	Thu, 14 May 2015 08:16:49 +0800
From:	Wanpeng Li <wanpeng.li@...ux.intel.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
Cc:	Xiao Guangrong <guangrong.xiao@...ux.intel.com>, gleb@...nel.org,
	mtosatti@...hat.com, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 09/10] KVM: MMU: fix MTRR update

On Wed, May 13, 2015 at 04:10:08PM +0200, Paolo Bonzini wrote:
>
>
>On 13/05/2015 10:43, Wanpeng Li wrote:
>> kvm_mmu_reset_context
>>   kvm_mmu_unload
>>     mmu_free_roots
>> 
>> The original root shadow page will be freed in mmu_free_roots, where I
>> miss?
>> 
>> Another question maybe not related to this patch:
>> 
>> If kvm_mmu_reset_context is just called to destroy the original root 
>> shadow page and all the sptes will remain valid? 
>
>SPTEs are kept around and cached.  The "role" field is used as the hash
>key; if the role doesn't change, SPTEs are reused, so you have to zap
>the SPTEs explicitly.

Thanks for your explanation. :)

Btw, why the patch changelog mentioned that the root shadow page will be
reused, I think it will be zapped in mmu_free_roots. 

Regards,
Wanpeng Li 

>
>Paolo
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