RE: [PATCH v3 1/9] PCI/P2PDMA: Add CONFIG_PCI_P2PDMA_CORE

[Tian, Kevin]

> From: Matt Evans <matt@xxxxxxxxxx>
> Sent: Wednesday, June 10, 2026 11:43 PM
> 
> The P2PDMA code currently provides two features under the same
> CONFIG_PCI_P2PDMA option:
> 
>  1.  Locate providers via pcim_p2pdma_provider()
>  2.  Manage actual P2P DMA
> 
> Some drivers (such as vfio-pci) depend on 1, without having a hard
> dependency on 2.
> 
> A future commit expands the use of DMABUF in vfio-pci for non-P2P
> scenarios, relying on pcim_p2pdma_provider() always being present.  If
> that depended on CONFIG_PCI_P2PDMA, it would make vfio-pci only
> available if CONFIG_ZONE_DEVICE is present (e.g. 64-bit systems), even
> when P2P is not needed.
> 
> To resolve this, introduce CONFIG_PCI_P2PDMA_CORE and refactor the
> basic provider functionality into a new p2pdma_core.c file.  This is
> available even if the CONFIG_PCI_P2PDMA feature is disabled (or
> unavailable due to !CONFIG_ZONE_DEVICE).  Then, drivers can enable any
> additional P2P features with the original CONFIG_PCI_P2PDMA (available
> when CONFIG_ZONE_DEVICE is set).
> 
> Signed-off-by: Matt Evans <matt@xxxxxxxxxx>

Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>