Re: [Xen-users] IOMMU Domain for Dom0

[Alex Merritt <merritt.alex@xxxxxxxxx>]

On Wed, Jun 22, 2011 at 21:48, Todd Deshane <todd.deshane@xxxxxxx> wrote:
> On Wed, Jun 22, 2011 at 1:20 PM, Alex Merritt <merritt.alex@xxxxxxxxx> wrote:
>> Hi,
>>
>> 2011/6/22 sploving <sploving1@xxxxxxx>:
>>>
>>>
>>>
>>> AtÂ2011-06-21Â12:17:56ï"AlexÂMerritt"Â<merritt.alex@xxxxxxxxx>Âwrote:
>>>
>>>>Hello,
>>>>
>>>>I'veÂbeenÂexperimentingÂwithÂVT-dÂsupportedÂPCI-passthroughÂinÂXenÂfor
>>>>HVMÂguests,ÂandÂwasÂwonderingÂifÂitÂisÂpossibleÂtoÂcreateÂanÂIOMMU
>>>>domainÂforÂDom0ÂasÂwell.ÂI'mÂnotÂsureÂifÂI'mÂaskingÂtheÂquestion
>>>>correctly,ÂbutÂtoÂavoidÂchangingÂaÂbare-metalÂdriverÂforÂanÂI/OÂdevice
>>>>toÂtranslateÂsystemÂmemoryÂaddressesÂusedÂbyÂaÂDMAÂengine,ÂwouldÂI
>>>>insteadÂbeÂableÂtoÂallowÂtheÂIOMMUÂtoÂtransparentlyÂtranslate
>>>>addressesÂjustÂlikeÂforÂguestÂVMs,ÂbutÂwithinÂDom0?
>>> why put the IOMMU within Dom0? not in the driver domain?
>>
>> I'm using research code, which currently requires the management
>> extension and driver to exist within the same domain. IOMMUs are meant
>> for guest VMs as far as I can tell. They can be used as driver
>> domains, too, but (unless I'm mistaken) cannot use the management
>> interfaces available in Dom0.
>>
>
> To me, this research sounds similar to "InDriver: Using In-VM
> Isolation to Implement Drivers" that is going to be presented at the
> upcoming Xen Summit
>
> see: http://xen.org/community/xensummit.html
>
> I could be wrong about the relationship, but it does sound like
> similar concepts are being explored.

Hm, there doesn't seem to be a link describing the talk/work in more
detail. I'm attempting to just give the NVIDIA driver an IOMMU domain
in Dom0 for accessing the GPUs within a machine. There's been a lot of
frustration over the years trying to get CUDA to work on Dom0 as well
as 3D support. I'm attempting to determine if this is at all possible
using VT-d.

>
>
>> My driver domain is also Dom0 at the moment.
>>
>>> ÂSomeÂsearchingÂand
>>>>readingÂofÂtheÂwikiÂpagesÂonÂxen.orgÂtellsÂmeÂtheÂanswerÂisÂ"no".ÂBut
>>>>IÂcannotÂdetermineÂifÂthisÂisÂpurelyÂbecauseÂtheÂimplementationÂwithin
>>>>theÂVMMÂdoesn'tÂexist,ÂorÂbecauseÂitÂisÂthatÂDom0ÂisÂpara-virtualized
>>>>andÂthusÂcannotÂuseÂVT-dÂwithoutÂVT-x.ÂI'mÂsuspectingÂitÂisÂnotÂthe
>>>>latter,ÂasÂtheÂVTdHowToÂwikiÂpageÂhintsÂPVÂguestsÂmayÂuseÂVT-dÂandÂthe
>>>>IntelÂmanualÂforÂVT-dÂdescribesÂOSÂdevelopersÂmayÂtakeÂadvantageÂof
>>>>thisÂextension.
>>>>
>>>>MyÂimmediateÂinterestÂisÂmoreÂtoÂseeÂifÂitÂ"canÂbeÂdone"ÂviaÂaÂhackÂor
>>>>something,ÂnotÂnecessarilyÂwhetherÂitÂwouldÂmakeÂsense
>>> forÂXenÂto
>>>>supportÂthisÂinÂtheÂfuture.
>>>>
>>> You should ask this question in xen-dev list.
>>
>> Okay, I'll do that. I'm new to these mailing lists, and wasn't sure
>> where to start. Thanks.
>>
>>>>I'mÂusingÂXenÂ4.1.1ÂandÂpv-opsÂlinuxÂ(notÂupstream)Â2.6.32.40ÂonÂan
>>>>IntelÂX5660ÂwithÂa
>>> TylersburgÂchipset.
>>>>
>>>>Thanks!
>>>>Alex
>>>>
>>>>_______________________________________________
>>>>Xen-usersÂmailingÂlist
>>>>Xen-users@xxxxxxxxxxxxxxxxxxx
>>>>http://lists.xensource.com/xen-users
>>
>> _______________________________________________
>> Xen-users mailing list
>> Xen-users@xxxxxxxxxxxxxxxxxxx
>> http://lists.xensource.com/xen-users
>>
>
>
>
> --
> Todd Deshane
> http://www.linkedin.com/in/deshantm
> http://www.xen.org/products/cloudxen.html
> http://runningxen.com/
>

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