Re: [kvm-devel] [RFC] [VTD][patch 2/3] vt-d support for pci passthrough: kvm-vtd-user.patch

[Anthony L. <an...@co...>]

Avi Kivity wrote:
> Kay, Allen M wrote:
>   
>> Still todo: move vt.d to kvm-intel.ko module.
>>   
>>     
>
> Not sure it's the right thing to do. If we get the iommus abstracted 
> properly, we can rename vtd.c to dma.c and move it to virt/kvm/.
>
> The code is certainly a lot more about managing memory than anything vmx 
> specific. It's hardly x86 specific, even.
>   

Really, an external interface to KVM that allowed someone to query the 
GPA => PA mapping would suffice.  It should not fault in pages that 
aren't present and we should provide notifications for when the mapping 
changes for a given reason.  Userspace can enforce the requirement that 
memory remains present via mlock().  This allows us to implement a PV 
API for DMA registration without the IOMMU code having any particular 
knowledge of it.

Regards,

Anthony Liguori