[PATCH v9 01/24] PCI/P2PDMA: Refactor the p2pdma mapping helpers

[Luis Chamberlain]

On Wed, Apr 23, 2025 at 11:12:52AM +0300, Leon Romanovsky wrote:
> From: Christoph Hellwig <hch at lst.de>
> 
> The current scheme with a single helper to determine the P2P status
> and map a scatterlist segment force users to always use the map_sg
> helper to DMA map, which we're trying to get away from because they
> are very cache inefficient.
> 
> Refactor the code so that there is a single helper that checks the P2P
> state for a page, including the result that it is not a P2P page to
> simplify the callers, and a second one to perform the address translation
> for a bus mapped P2P transfer that does not depend on the scatterlist
> structure.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> Reviewed-by: Logan Gunthorpe <logang at deltatee.com>
> Acked-by: Bjorn Helgaas <bhelgaas at google.com>
> Tested-by: Jens Axboe <axboe at kernel.dk>
> Signed-off-by: Leon Romanovsky <leonro at nvidia.com>

Might make it easier for patch review to split off adding
__pci_p2pdma_update_state() in a seprate patch first. Other than that,
looks good.

Reviewed-by: Luis Chamberlain <mcgrof at kenrel.org>

  Luis