Re: [PATCH 14/26] drm/amdgpu: Use the SGT mapping type

[sashiko-bot@kernel.org]

> From: Jason Gunthorpe <jgg@nvidia.com>
> 
> Similar to xe, amdgpu wants to check pci_p2pdma_distance(), and
> only needs that if peer2peer can be supported by the GPU. It can migrate to
> system memory and support non-p2p DMA as well.
> 
> Further it supports a private non-PCI XGMI path. For now hack this on top
> of a SGT type, but eventually this is likely better off as its own mapping
> type.
> 
> Add two exporter SGT mapping types, one that matches P2P and one that
> matches all of the non-p2p. The pin and map code will force migrate if
> the non-p2p one is matched.
> 
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> [ the match set is recorded in attach->matches and the type
>   selected from it at pin or map, so the pin walk, detach and the attach
>   error path ask dma_buf_attach_accepts_sgt_p2p() whether an attachment
>   could take P2P at all, and the XGMI override rewrites the recorded match
>   set entry rather than only attach->map_type. The map path keeps using
>   dma_buf_sgt_p2p_allowed() for the attachment being mapped, which has just
>   been selected. The runtime PM reference follows the same question: held
>   while P2P is in the match set, dropped in detach. - apopple ]
> Signed-off-by: Alistair Popple <apopple@nvidia.com>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261026053623.202642-1-apopple@nvidia.com?part=14