On Wed, Jun 10, 2026 at 04:43:15PM +0100, Matt Evans wrote: > 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 <[email protected]> > --- > MAINTAINERS | 2 +- > drivers/pci/Kconfig | 10 ++-- > drivers/pci/Makefile | 1 + > drivers/pci/p2pdma.c | 109 ++-------------------------------- > drivers/pci/p2pdma.h | 29 +++++++++ > drivers/pci/p2pdma_core.c | 118 +++++++++++++++++++++++++++++++++++++ > include/linux/pci-p2pdma.h | 24 ++++---- > include/linux/pci.h | 2 +- > 8 files changed, 174 insertions(+), 121 deletions(-) > create mode 100644 drivers/pci/p2pdma.h > create mode 100644 drivers/pci/p2pdma_core.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index c2c6d79275c6..b21523b3bd8b 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -20617,7 +20617,7 @@ B: https://bugzilla.kernel.org > C: irc://irc.oftc.net/linux-pci > T: git git://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git > F: Documentation/driver-api/pci/p2pdma.rst > -F: drivers/pci/p2pdma.c > +F: drivers/pci/p2pdma* > F: include/linux/pci-p2pdma.h > > PCI POWER CONTROL > diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig > index 33c88432b728..59d70bc84cc9 100644 > --- a/drivers/pci/Kconfig > +++ b/drivers/pci/Kconfig > @@ -206,11 +206,7 @@ config PCIE_TPH > config PCI_P2PDMA > bool "PCI peer-to-peer transfer support" > depends on ZONE_DEVICE > - # > - # The need for the scatterlist DMA bus address flag means PCI P2PDMA > - # requires 64bit > - # > - depends on 64BIT > + select PCI_P2PDMA_CORE > select GENERIC_ALLOCATOR > select NEED_SG_DMA_FLAGS > help
Nit: Did we drop depends on 64BIT intentionally here? I guess the full PCI_P2PDMA stack still selects NEED_SG_DMA_FLAGS? IIRC, NEED_SG_DMA_FLAGS doesn't select 64BIT? With the nit (and Bjorn's comments addressed) Reviewed-by: Pranjal Shrivastava <[email protected]> Thanks, Praan
