There is disclosed in an example a peripheral component interconnect express (PCIe) controller to provide coherent memory mapping between an accelerator memory and a host memory address space. The PCIe controller may include extensions to provide a coherent accelerator interconnect (CAI) to provide bias-based coherency tracking between the accelerator memory and the host memory address space. The extensions may include: a mapping engine to provide opcode mapping between PCIe instructions and on-chip system fabric (OSF) instructions for the CAI, a tunneling engine to provide scalable memory interconnect (SMI) tunneling of host memory operations to the accelerator memory via the CAI, host-bias-to-device-bias (HBDB) flip engine to enable the accelerator to flush a host cache line, and a QoS engine comprising a plurality of virtual channels.