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

[Andrew Lyon <andrew.lyon@xxxxxxxxx>]

On Thu, Jan 21, 2010 at 2:17 PM, Sander Eikelenboom
<linux@xxxxxxxxxxxxxx> wrote:
> Hello Weidong,
>
> The problem is most vendor's just don't fix it and ignore the problem 
> completely.
> Most often hiding them selves behind: come back when it's a problem with 
> Microsoft Windows, that the only single thing we support (and no other 
> software, so no vmware, no xen, no linux, perhaps even no hypervisor)

Supermicro were fairly cooperative but they wanted to know *exactly*
what was wrong, i.e. wanted me to show them the incorrect values and
how to fix them, I tried to work it out but failed :(.

I had the same problem on a Dell system, who went down the "we dont
support xen" route, but again they would have been willing to take it
further if I could show them which values were incorrect.

If we had a diagnostic tool that could verify the settings and output
detailed explanations of any problems that would really help to give
manufacturers the info they need to fix the bios.

Andy

> Well I don't know if the virtual pc in windows 7 supports an iommu now, but 
> it didn't in the past as far as i know, so any complain bounces off, and 
> there it all seems to end for them.
>
> Besides that i don't know if they do know what the problems with there 
> implementation in BIOS is when someone reports it.
> I think some behind the scenes pressure from Intel to vendors might help to 
> solve some of them.
> (my Q35 chipset, "Intel V-PRO" marketed motherboard (so much for that) also 
> suffers RMRR problem when another graphics card is inserted which switches 
> off the IGD).
>
> Although i think in my case your patch will work around that for me. Perhaps 
> a third option is needed, which does all the workarounds possible and warns 
> about potential security problem when requested ?
>
> --
> Sander
>
>
>
>
>
>
> Thursday, January 21, 2010, 1:46:39 PM, you wrote:
>
>> Noboru Iwamatsu wrote:
>>> Hi Weidong,
>>>
>>> I re-send the DRHD-fix patch.
>>>
>>> If DRHD does not have existent devices, ignore it.
>>> If DRHD has both existent and non-existent devices, consider it invalid
>>> and not register.
>>>
>
>> Although you patch workarounds your buggy BIOS, but we still need to
>> enable it for security purpose as I mentioned in previous mail. We
>> needn't workaround / fix all BIOS issues in software. I think security
>> is more important for this specific BIOS issue. Did you report the BIOS
>> issue to your OEM vendor? maybe it's better to get it fixed in BIOS.
>
>> Regards,
>> Weidong
>>> According to this patch and yours, my machine successfully booted
>>> with vt-d enabled.
>>>
>>> Signed-off-by: Noboru Iwamatsu <n_iwamatsu@xxxxxxxxxxxxxx>
>>>
>>>
>>>
>>>> Keir Fraser wrote:
>>>>
>>>>> On 21/01/2010 10:19, "Weidong Han" <weidong.han@xxxxxxxxx> wrote:
>>>>>
>>>>>
>>>>>>> Sorry this is typo.
>>>>>>> I mean:
>>>>>>> So, I think RMRR that has no-existent device is "invalid"
>>>>>>> and whole RMRR should be ignored.
>>>>>>>
>>>>>> looks reasonable.
>>>>>>
>>>>>> Keir, I Acks Noboru's rmrr patch. Or do you want us to merge them to one
>>>>>> patch?
>>>>>>
>>>>> Merge them up, re-send with both sign-off and acked-by all in one email.
>>>>>
>>>>> Thanks,
>>>>> Keir
>>>>>
>>>>>
>>>> Sorry, I disagree with Noboru after thinking it again. If the RMRR has
>>>> both no-existent device and also has existent devices in its scope, we
>>>> should not ignore it because the existent devices under its scope will
>>>> be impacted without the RMRR. so I suggest to print a warning instead of
>>>> ignore it. Attached a patch for it.
>>>>
>>>> Signed-off-by: Weidong Han <weidong.han@xxxxxxxxx>
>>>>
>>>
>>>
>
>
>
>
>
>
> --
> Best regards,
>  Sander                            mailto:linux@xxxxxxxxxxxxxx
>
>
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>

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