Re: [Qemu-devel] [RFC PATCH v2 3/3] VFIO: Type1 IOMMU mapping support for vGPU

[Neo Jia]

On Thu, Mar 10, 2016 at 11:10:10AM +0800, Jike Song wrote:
> 
> >> Is it supposed to be the caller who should set
> >> up IOMMU by DMA api such as dma_map_page(), after calling
> >> vgpu_dma_do_translate()?
> >>
> > 
> > Don't think you need to call dma_map_page here. Once you have the pfn 
> > available
> > to your GPU kernel driver, you can just go ahead to setup the mapping as you
> > normally do such as calling pci_map_sg and its friends.
> > 
> 
> Technically it's definitely OK to call DMA API from the caller rather than 
> here,
> however personally I think it is a bit counter-intuitive: IOMMU page tables
> should be constructed within the VFIO IOMMU driver.
> 

Hi Jike,

For vGPU, what we have is just a virtual device and a fake IOMMU group, 
therefore 
the actual interaction with the real GPU should be managed by the GPU vendor 
driver.

With the default TYPE1 IOMMU, it works with the vfio-pci as it owns the device.

Thanks,
Neo

> --
> Thanks,
> Jike
>