Hi all, We are proposing to add a new test syste to Linux for PCIe Endpoint. That can be run on QEMU without real hardware. At present, partially we have confirmed that pci-epf-test is working, but it is not yet complete. However, we would appreciate your comments on the architecture design.
# Background The background is as follows. PCI Endpoint function driver is implemented using the PCIe Endpoint framework, but it requires physical boards for testing, and it is difficult to test sufficiently. In order to find bugs and hardware-dependent implementations early, continuous testing is required. Since it is difficult to automate tests that require hardware, this RFC proposes a virtual environment for testing PCI endpoint function drivers. # Architecture The overview of the architecture is as follows. Guest 1 Guest 2 +-------------------------+ +----------------------------+ | Linux kernel | | Linux kernel | | | | | | PCI EP function driver | | | | (e.g. pci-epf-test) | | | |-------------------------| | PCI Device Driver | | (2) QEMU EPC Driver | | (e.g. pci_endpoint_test) | +-------------------------+ +----------------------------+ +-------------------------+ +----------------------------+ | QEMU | | QEMU | |-------------------------| |----------------------------| | (1) QEMU PCI EPC Device *----* (3) QEMU EPF Bridge Device | +-------------------------+ +----------------------------+ At present, it is designed to work guests only on the same host, and communication is done through Unix domain sockets. The three parts shown in the figure were introduced this time. (1) QEMU PCI Endpoint Controller(EPC) Device PCI Endpoint Controller implemented as QEMU PCI device. (2) QEMU PCI Endpoint Controller(EPC) Driver Linux kernel driver that drives the device (1). It registers a epc device to linux kernel and handling each operations for the epc device. (3) QEMU PCI Endpoint function(EPF) Bridge Device QEMU PCI device that cooperates with (1) and performs accesses to pci configuration space, BAR and memory space to communicate each guests, and generates interruptions to the guest 1. Each projects are: (1), (3) https://github.com/ShunsukeMie/qemu/tree/epf-bridge/v1 files: hw/misc/{qemu-epc.{c,h}, epf-bridge.c} (2) https://github.com/ShunsukeMie/linux-virtio-rdma/tree/qemu-epc files: drivers/pci/controller/pcie-qemu-ep.c # Protocol PCI, PCIe has a layer structure that includes Physical, Data Lane and Transaction. The communicates between the bridge(3) and controller (1) mimic the Transaction. Specifically, a protocol is implemented for exchanging fd for communication protocol version check and communication, in addition to the interaction equivalent to PCIe Transaction Layer Packet (Read and Write of I/O, Memory, Configuration space and Message). In my mind, we need to discuss the communication mor. We also are planning to post the patch set after the code is organized and the protocol discussion is matured. Best regards, Shunsuke
