Re: qemu/kvm: support for pci passthrough

Re: qemu/kvm: support for pci passthrough

[Anthony Liguori]

Dor Laor wrote:
> On Thu, 2008-05-08 at 12:03 +0200, Nicolas Daneau wrote:
>> Hi,
>>
>> I saw there was an active discussion about pci passthrough support in
>> KVM. I'm not a Dev, only a sys admin that need this support. As i saw
>> on the KVM home page that this feature is plan for 2H2008 in the
>> roadmap, I wondered if you already have a more precise time frame for
>> this release? Xen already have this feature but for the rest i prfer
>> KVM. As this is a key point for the final decsion (we have a Digium
>> TDM11B FXO/FXS pci card for an Asterisk VM), i'm waiting for an update
>> about this feature.
>>
> 
> This is feature is indeed work in progress. We have floating patches for
> several solutions:
> 1. Using Intel's VT-d - hw iommu support.
>    Patches were sent, needs some more scrubbing. The good thing is that 
>    it can live withing the kvm module and does not have to wait for 
>    kernel inclusion like the two below.

Nope, it uses the existing Linux VT-d support and requires patches to 
the existing code.  It can't live entirely within the external module.

Regards,

Anthony Liguori


> 2. PV dma - good only for Linux guests. Some locking issues needs to be 
>    solved + get into mainline kernel (>=2.6.27)
> 3. 1-1 mapping of the guest-host addresses. 
>    Will work for any guest, no need for special hw, good only for 
>    single guest and not 100% secure.
>    Needs a little more attention, worked in the past privately.
> 
> Bottom line, soon you'll have more than one option for pci pass through
> using kvm. There is no assurance we'll make it exactly in Q2.
> You can help by applying patches and sending results.
> Cheers,
> Dor
> 
>> Thanks for your answer
>>


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