VFIO In Linux 6.5 Adds Support For The AMD CDX Bus

The Virtual Function I/O "VFIO" changes were merged last week for the ongoing Linux 6.5 kernel merge window. This IOMMU/device agnostic framework has added an AMD CDX driver this cycle along with other improvements for this subsystem that is important to the Linux virtualization stack.

AMD engineers have contributed the "vfio_cdx" driver that is now found in Linux 6.5. The driver allows for querying MMIO regions for CDX devices and to mmap them as well as providing CDX device reset support.

Going back to last summer were AMD-Xilinx engineers working on Linux kernel enablement for the CDX bus. This bus is an interface between APUs and FPGAs:

AMD CDX support was upstreamed in Linux 6.4 and then other bits are ongoing like this now-merged support for VFIO with CDX devices.

The AMD CDX VFIO support was part of this pull along with dynamic MSI-X allocation support, enabling PCIe AtomicOp Completer capabilities, and various fixes.