Re: [Qemu-devel] [RFC PATCH v3 3/3] VFIO Type1 IOMMU change: to support with iommu and without iommu

[Tian, Kevin]

> From: Neo Jia [mailto:address@hidden
> Sent: Friday, May 13, 2016 2:42 PM
> 
> 
> >
> > We possibly have the same requirement from the mediate driver backend:
> >
> >     a) get a GFN, when guest try to tell hardware;
> >     b) consult the vfio iommu with that GFN[1]: will you find me a proper 
> > dma_addr?
> 
> We will provide you the pfn via vfio_pin_pages, so you can map it for dma
> purpose in your i915 driver, which is what we are doing today.
> 

Can such 'map' operation be consolidated in vGPU core driver? I don't think 
Intel vGPU driver has any feature proactively relying on iommu. The reason 
why we keep talking iommu is just because the kernel may enable iommu 
for physical GPU so we need make sure our device model can work in such
configuration. And this requirement should apply to all vendors, not Intel
specific (like you said you are doing it already today).

Thanks
Kevin