Re: [Qemu-devel] VFIO based vGPU(was Re: [Announcement] 2015-Q3 release of XenGT - a Mediated ...)

[Tian, Kevin]

> From: Neo Jia [mailto:address@hidden
> Sent: Tuesday, January 26, 2016 6:21 PM
> 
> 0. High level overview
> =====================================================
> =============================
> 
> 
>   user space:
>                                 +-----------+  VFIO IOMMU IOCTLs
>                       +---------| QEMU VFIO |-------------------------+
>         VFIO IOCTLs   |         +-----------+                         |
>                       |                                               |
>  
> ---------------------|-----------------------------------------------|---------
>                       |                                               |
>   kernel space:       |  +--->----------->---+  (callback)            V
>                       |  |                   v                 +------V-----+
>   +----------+   +----V--^--+          +--+--+-----+           | VGPU       |
>   |          |   |          |     +----| nvidia.ko +----->-----> TYPE1 IOMMU|
>   | VFIO Bus <===| VGPU.ko  |<----|    +-----------+     |     +---++-------+
>   |          |   |          |     | (register)           ^         ||
>   +----------+   +-------+--+     |    +-----------+     |         ||
>                          V        +----| i915.ko   +-----+     +---VV-------+
>                          |             +-----^-----+           | TYPE1      |
>                          |  (callback)       |                 | IOMMU      |
>                          +-->------------>---+                 +------------+
>  access flow:
> 
>   Guest MMIO / PCI config access
>   |
>   -------------------------------------------------
>   |
>   +-----> KVM VM_EXITs  (kernel)
>           |
>   -------------------------------------------------
>           |
>           +-----> QEMU VFIO driver (user)
>                   |
>   -------------------------------------------------
>                   |
>                   +---->  VGPU kernel driver (kernel)
>                           |
>                           |
>                           +----> vendor driver callback
> 
> 

There is one difference between nvidia and intel implementations. We have
vgpu device model in kernel, as part of i915.ko. So I/O emulation requests
are forwarded directly in kernel side. 

Thanks
Kevin