Re: [RFC PATCH v2 14/22] iommufd: Add TIO calls

[Jason Gunthorpe <jgg@ziepe.ca>]

On Thu, Mar 06, 2025 at 02:47:23PM +0800, Xu Yilun wrote:

> While for AMD:
>         ...
>         b.guest_device_id = guest_rid;  //TDI ID, it is the vBDF
>         b.gctx_paddr = gctx_paddr;      //AMDs CoCo-VM ID
> 
>         ret = sev_tio_do_cmd(SEV_CMD_TIO_TDI_BIND, &b, ...
> 
> 
> Neither of them use vIOMMU ID or any IOMMU info, so the only concern is
> vBDF.

I think that is enough, we should not be putting this in VFIO if it
cannot execute it for AMD :\

> > You could also issue the TSM bind against the idev on the iommufd
> > side..
> 
> But I cannot figure out how idev could ensure no mmap on VFIO, and how
> idev could call dma_buf_move_notify.

I suggest you start out this way from the VFIO. Put the device in a CC
mode which bans the mmap entirely and pass that CC capable as a flag
into iommufd when creating the idev.

If it really needs to be dyanmic a VFIO feature could change the CC
mode and that could call back to iommufd to synchronize if that is
allowed.

Jason