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
-----邮件原件-----
发件人: dunlapg@xxxxxxxxx [mailto:dunlapg@xxxxxxxxx] 代表 George Dunlap
发送时间: 2011年3月10日 17:43
收件人: George Dunlap
抄送: 张鹏飞; xen devel
主题: 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, 张鹏飞 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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