Local Display Direct Flip Feature Discussion

[Zhenyu Wang]

On 2018.12.13 17:17:38 +0800, Zhang, Tina wrote:
> The proposed userspace interface:
> 
> Each plane of the vGPU is exposed as a DRM framebuffer object in the host-side
> during the vGPU creation. So host userspace can assign the HW display planes to
> vGPU’s planes by using existing DRM/KMS APIs. After the assignment, host kernel
> can directly help guest to update the information to the display registers of
> the assigned display resources. However, the only problem is how we return the
> DRM framebuffer id to host userspace.
> 
>  
> 
> Currently, we have two options:
> 
> 1.       Through “/sys/bus/pci/devices/0000:00:02.0/$UUID/intel_vgpu/
> plane_id_index”
> 
> With the proposed “plane_id_index” attribute, userspace can echo the plane number to the attribute and then use cat to dump the userspace id of the DRM framebuffer standing for that vGPU’s plane in the host-side.

I had sent NACK on this, so pls move forward on ioctl way.

> 
> 2.       Through vfio ioctl:
> 
> We can extend VFIO_DEVICE_QUERY_GFX_PLANE ABI by proposing
> “VFIO_GFX_PLANE_TYPE_DRM_FB” type. So that vendor driver can return the
> framebuffer id when userspace invoking “VFIO_DEVICE_QUERY_GFX_PLANE” ioctl with
> flags as “VFIO_GFX_PLANE_TYPE_DRM_FB | VFIO_GFX_PLANE_TYPE_PROBE”
> 
>  
> 
> The patches are on:
> 
> https://github.com/intel/igvtg-qemu/tree/topic/local_display_direct_flip
> 
> https://github.com/intel/gvt-linux/tree/topic/local_display_direct_flip
>

Could you send kernel patches for vfio ioctl change so we can review the design?

thanks

-- 
Open Source Technology Center, Intel ltd.

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