Subject: Re: [PATCH 3/4] KVM: MMU: reduce the size of mmu_page_path
To: Paolo Bonzini <pbonzini@redhat.com>
References: <1458911978-19430-1-git-send-email-guangrong.xiao@linux.intel.com>
 <1458911978-19430-3-git-send-email-guangrong.xiao@linux.intel.com>
 <56F54103.6020508@redhat.com>
Cc: gleb@kernel.org, mtosatti@redhat.com, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org
From: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Message-ID: <56F541C5.6090904@linux.intel.com>
Date: Fri, 25 Mar 2016 21:48:53 +0800
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On 03/25/2016 09:45 PM, Paolo Bonzini wrote:
>
>
> On 25/03/2016 14:19, Xiao Guangrong wrote:
>> Currently only PT64_ROOT_LEVEL - 1 levels are used, one additional entry
>> in .parent[] is used as a sentinel, the additional entry in .idx[] is
>> purely wasted
>>
>> This patch reduces its size and sets the sentinel on the upper level of
>> the place where we start from
>
> This patch and the previous one are basically redoing commit
> 0a47cd85833e ("KVM: MMU: Fix ubsan warnings", 2016-03-04).  While you
> find your version easier to understand, I of course find mine easier.
>
> Rather than getting stuck in a ko fight, the solution is to stick with
> the code in KVM and add comments.  I'll give it a try...

If you do not like this one, we can just make the .index is
[PT64_ROOT_LEVEL - 1] and keep the sentinel in .parents[], that little
change and nice code shape.