çå: [Xen-devel] Re: changeset 22526:7a5ee3800417

["zpfalpc23" <zpfalpc23@xxxxxxxxx>]

Hi George,
        I have read you patch 22526 in xen-testing4.0 and xen-unstable 
carefully. There is one thing confused me a lot. why the patch for 
xen-testing4.0 did not handle the case In ept_set_entry where the superpage 
should be splitted. Maybe the race can't happen in this scene.
        Also When the race of updating p2m table happen, will the normal(be 
changed by ept_get_entry) page be POD again? In this situation, what is it for 
Xen and VM?
        Thanks a lot for enlighten me.

----Pengfei zhang

-----éäåä-----
åää: dunlapg@xxxxxxxxx [mailto:dunlapg@xxxxxxxxx] äè George Dunlap
åéæé: 2011å3æ10æ 17:43
æää: George Dunlap
æé: åéé; xen devel
äé: Re: [Xen-devel] Re: changeset 22526:7a5ee3800417

Oops, forgot to attach the patch...

 -George

On Thu, Mar 10, 2011 at 9:41 AM, George Dunlap <George.Dunlap@xxxxxxxxxxxxx> 
wrote:
> Peng fei,
>
> Can you (1) test this patch, and (2) make sure I've romanized your 
> name properly?
>
> Thanks,
>  -George
>
> On Wed, Mar 9, 2011 at 1:59 PM, George Dunlap 
> <George.Dunlap@xxxxxxxxxxxxx> wrote:
>> Peng fei,
>>
>> I just noticed this patch has a bug -- it doesn't set new_entry.mfn 
>> if the new mfn is the same as the one already in ept_entry!  Standby 
>> for a new one...
>>
>>  -George
>>
>> On Mon, Mar 7, 2011 at 4:41 PM, George Dunlap 
>> <George.Dunlap@xxxxxxxxxxxxx> wrote:
>>> Peng fei,
>>>
>>> Can you test the attached patch (to xen-unstable)?  I don't have 
>>> EPT-enabled hardware handy...
>>>
>>>  -George
>>>
>>> On Mon, Mar 7, 2011 at 4:20 PM, George Dunlap <george.dunlap@xxxxxxxxxx> 
>>> wrote:
>>>> Hmm, yeah, that's obviously not right!  Let me take a look...
>>>>
>>>>  -George
>>>>
>>>> On Mon, 2011-03-07 at 09:55 +0000, åéé wrote:
>>>>> Hi,
>>>>>     Recently, I did a research on the p2m and EPT,and did apply 
>>>>> your
>>>>> patch(22526) to the source code of mine. But there is one place 
>>>>> confused me:
>>>>>
>>>>>
>>>>>
>>>>> ept_entry = table + index;
>>>>> 1.91
>>>>>     1.92 -        ept_entry->emt = epte_get_entry_emt(d, gfn, mfn, 
>>>>> &ipat, direct_mmio);
>>>>>     1.93 -        ept_entry->ipat = ipat;
>>>>>     1.94 -        ept_entry->sp = i ? 1 : 0;
>>>>>     1.95 -        ept_entry->avail1 = p2mt;
>>>>>     1.96 -        ept_entry->avail2 = 0;
>>>>>     1.97 +        new_entry.emt = epte_get_entry_emt(d, gfn, mfn, 
>>>>> &ipat, direct_mmio);
>>>>>     1.98 +        new_entry.ipat = ipat;
>>>>>     1.99 +        new_entry.sp = i ? 1 : 0;
>>>>>    1.100 +        new_entry.avail1 = p2mt;
>>>>>    1.101 +        new_entry.avail2 = 0;
>>>>>    1.102
>>>>>    1.103 -        if ( ept_entry->mfn == mfn_x(mfn) )
>>>>>    1.104 +        if ( new_entry.mfn == mfn_x(mfn) )
>>>>>    1.105               need_modify_vtd_table = 0;
>>>>>    1.106          else /* the caller should take care of the 
>>>>> previous page */
>>>>>    1.107 -            ept_entry->mfn = mfn_x(mfn);
>>>>>    1.108 +            new_entry.mfn = mfn_x(mfn);
>>>>>
>>>>> I think, The new_entry.mfn is used without assigned any value. Maybe 
>>>>> there was something else I did not think of.
>>>>> Thank you for your kindness!
>>>>>
>>>>> http://xenbits.xen.org/xen-unstable.hg/rev/7a5ee3800417
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> Xen-devel mailing list
>>>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>>>> http://lists.xensource.com/xen-devel
>>>>
>>>
>>
>


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