This is work in progress.
I published patches to enable DMA_buf P2P a few months ago, but now I'm waiting for the PCI subsystem to pick up core support for this.
Great news! Can you give me a link to this series so I can already have a look?
I can prepare you a branch based on current upstream kernel next week if you want to test this.
That would be awesome, thanks.
Cheers Dirk