1-1 mapping of devices without VT-d

1-1 mapping of devices without VT-d

[Passera, Pablo R]

Hi everyone,
        I want to assign a PCI device directly to a VM (PCI passthrough) in a machine that does not have VT-d. I found something related with this in a presentation done at the 2008 KVM Forum called 1-1 mapping and a patch for this at http://thread.gmane.org/gmane.comp.emulators.kvm.devel/18722/focus=18753. I am wondering if this is included or are there plans to include it in the latest KVM version?

Thanks in advance,

Pablo Pássera

Re: 1-1 mapping of devices without VT-d

[Dor Laor]

Passera, Pablo R wrote:
> Hi everyone,
>         I want to assign a PCI device directly to a VM (PCI passthrough) in a machine that does not have VT-d. I found something related with this in a presentation done at the 2008 KVM Forum called 1-1 mapping and a patch for this at http://thread.gmane.org/gmane.comp.emulators.kvm.devel/18722/focus=18753. I am wondering if this is included or are there plans to include it in the latest KVM version?
>
>   
Although it had worked for us out of tree, there is no immediate need to 
pursue it.
If anyone would like to nurture these patches he is more than welcome.
ps: you also have pv-dma option for Linux guests (same status though).
As time goes by most host will have either vt-d or amd iommu.

Regards,
Dor

> Thanks in advance,
>
> Pablo Pássera
>
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Re: 1-1 mapping of devices without VT-d

[Michael Tokarev]

Dor Laor wrote:
[]
> Although it had worked for us out of tree, there is no immediate need to
> pursue it.
> If anyone would like to nurture these patches he is more than welcome.
> ps: you also have pv-dma option for Linux guests (same status though).
> As time goes by most host will have either vt-d or amd iommu.

Hmm.  Well, as time goes by, most hosts will be 64 bit or more.
But it does not mean that there's no need to maintain 32bits
arch anymore...  i hope anyway :)

Are you saying that PCI passthrough without hardware support will
not be available in (standard) kvm, even if patches exists for that?

/mjt

Re: 1-1 mapping of devices without VT-d

[Dor Laor]

Michael Tokarev wrote:
> Dor Laor wrote:
> []
>   
>> Although it had worked for us out of tree, there is no immediate need to
>> pursue it.
>> If anyone would like to nurture these patches he is more than welcome.
>> ps: you also have pv-dma option for Linux guests (same status though).
>> As time goes by most host will have either vt-d or amd iommu.
>>     
>
> Hmm.  Well, as time goes by, most hosts will be 64 bit or more.
> But it does not mean that there's no need to maintain 32bits
> arch anymore...  i hope anyway :)
>
>   
But of course
> Are you saying that PCI passthrough without hardware support will
> not be available in (standard) kvm, even if patches exists for that?
>
>   
No, just might take a some time to go to mainline. Patches need further 
polishing and we
also need wider demand for it.
Actually pvdma can help vt-d so we won't have to make all the guest 
memory unswappable.
> /mjt
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