[Linaro-mm-sig] Re: [PATCH v3 3/9] vfio/pci: Add a helper to create a DMABUF for a BAR-map VMA

From: Matt Evans matt@ozlabs.org Sent: Wednesday, June 10, 2026 11:43 PM

This helper, vfio_pci_core_mmap_prep_dmabuf(), creates a single-range DMABUF for the purpose of mapping a PCI BAR. This is used in a future commit by VFIO's ordinary mmap() path.

This function transfers ownership of the VFIO device fd to the DMABUF, which fput()s when it's released.

Refactor the existing vfio_pci_core_feature_dma_buf() to split out export code common to the two paths, VFIO_DEVICE_FEATURE_DMA_BUF and this new VFIO_BAR mmap().

Signed-off-by: Matt Evans matt@ozlabs.org

Reviewed-by: Kevin Tian kevin.tian@intel.com