Re: [PATCH] VT-d: improve RMRR validity checking

[Weidong Han <weidong.han@intel.com>]

Seems you inserted a discrete gfx card, then the IGD is disabled. right? 
can you provide the platform info and  BIOS version?

Regards,
Weidong

Noboru Iwamatsu wrote:
> Hi Weidong,
>
> Here is the log.
> Xen version is:
> xen-unstable c/s 20829 + return.patch + rmrr.patch
>
> Regards,
> Noboru
>
>   
>> Noboru Iwamatsu wrote:
>>     
>>> Hi,
>>>
>>> After registered invalid DRHDs, Xen hangs in boot time.
>>>       
>> Can you post the logs?
>>
>> Regards,
>> Weidong
>>     
>>> About RMRR, I understood the logic.
>>> In my mainboard, unfortunately, RMRR has non-existent device under
>>> its scope, and to make matters worse, the RMRR range is invalid.
>>> So, I think RMRR that has no-existent device is valid.
>>>
>>> How do you think about these?
>>>
>>>       
>>>> Hi Noboru,
>>>>
>>>> You should not ignore DRHD even if devices under its scope are not
>>>> pci discoverable. For the sake of security, we still enable these
>>>> DRHDs but don't set any context mappings. In that case, any DMA that
>>>> comes from these "supposedly disabled" devices will get blocked by
>>>> VT-d, and hence avoid any security vulnerability with malicious s/w
>>>> re-enabling these devices.
>>>>
>>>> You RMRR validity fixing is wrong. My RMRR patch is no problem. Pls
>>>> note that the RMRR checking logic is:
>>>> If all devices under RMRR's scope are not pci discoverable
>>>> Ignore the RMRR
>>>> Else if base_address> end_address
>>>> Return error
>>>> Else
>>>> Register RMRR
>>>>
>>>> Regards,
>>>> Weidong
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: Noboru Iwamatsu [mailto:n_iwamatsu@jp.fujitsu.com]
>>>> Sent: Thursday, January 21, 2010 4:26 PM
>>>> To: Han, Weidong
>>>> Cc: xen-devel@lists.xensource.com; keir.fraser@eu.citrix.com
>>>> Subject: Re: [Xen-devel] [PATCH] VT-d: improve RMRR validity checking
>>>>
>>>> Hi,
>>>>
>>>> Some Q35 mainboard that has buggy BIOS, I have one of this, reports
>>>> invalid DRHD in addition to the invalid RMRR.
>>>>
>>>> Attached patch fixes this DRHD issue in the same way as RMRR.
>>>> And also, I fixed RMRR validity checking loop.
>>>>
>>>> Noboru.
>>>>
>>>> Signed-off-by: Noboru Iwamatsu<n_iwamatsu@jp.fujitsu.com>
>>>>
>>>>
>>>> -------- Original Message --------
>>>> Subject: [Xen-devel] [PATCH] VT-d: improve RMRR validity checking
>>>> From: Han, Weidong<weidong.han@intel.com>
>>>> To: xen-devel@lists.xensource.com<xen-devel@lists.xensource.com>
>>>> Date: Thu Jan 21 2010 11:46:12 GMT+0900
>>>>
>>>>         
>>>>> Currently, Xen checks RMRR range and disables VT-d if RMRR range is
>>>>> set incorrectly in BIOS rigorously. But, actually we can ignore the
>>>>> RMRR if the device under its scope are not pci discoverable, because
>>>>> the RMRR won't be used by non-existed or disabled devices.
>>>>>
>>>>> This patch ignores the RMRR if the device under its scope are not
>>>>> pci discoverable, and only checks the validity of RMRRs that are
>>>>> actually used. In order to avoid duplicate pci device detection
>>>>> code, this patch defines a function pci_device_detect for it.
>>>>>
>>>>> Signed-off-by: Weidong Han<weidong.han@intel.com>
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Xen-devel mailing list
>>>>> Xen-devel@lists.xensource.com
>>>>> http://lists.xensource.com/xen-devel
>>>>>           
>>>       
>
>