This series adds a usbredir server transport to redirect a USB device emulated in one QEMU instance to a USB host controller emulated in another one over the usbredir protocol.
The v1 series included both the usbredir server transport and the ASPEED AST1030 USB Device Controller (UDC) support. Following review feedback, this series contains only the usbredir server transport. The ASPEED AST1030 UDC support will be sent separately. This work is part of a larger plan to model USB device-side support on ASPEED BMC/BIC SoCs, which has three goals: 1. Model the ASPEED UDC (AST2600 / AST1030). The AST2600 also has USB host (EHCI) controllers, so that work targets the AST2600 UDC: its gadget can be attached to the SoC's own EHCI bus, letting the guest enumerate its own gadget and exercise the UDC end-to-end. [Done] https://lore.kernel.org/qemu-devel/[email protected]/ 2. AST1030 UDC. The AST1030 has no USB host controller, so testing its UDC needs a second QEMU instance. The UDC gadget is redirected out of the guest with libusbredir and attached to another QEMU that runs a USB host (a VMM, or an AST2600 / AST2700 guest). [this series] 3. ASPEED vHub, as a longer-term goal towards BMC KVM / Virtual Media support in QEMU. [future] This series implements goal 2. The transport ============= usb-redir-server exports a locally emulated USB device to a remote USB host over the usbredir protocol, so a device emulated in one QEMU instance can be enumerated by a host controller emulated in another one. The left column is a request going to the device. The right column is the answer coming back. The middle hop carries usbredir messages over a socket. The top and bottom hops carry USBPackets inside QEMU. remote QEMU: guest driver -> EHCI/XHCI | ^ USBPacket | | USBPacket v | "usb-redir" (the client) | ^ usbredir | chardev socket | usbredir v | usb-redir-server (the server, this series) | ^ USBPacket | | USBPacket v | any USBDevice, "-device <dev>,bus=<id>.0" "usb-redir" (hw/usb/redirect.c) is the client: - it takes a USBPacket from the remote guest and writes it to the socket as a usbredir message - it reads the answer from the socket and completes the USBPacket usb-redir-server is the server. It does the same thing, but backwards: - it reads a usbredir message from the socket and runs it as a USBPacket on the bus below - it takes the result of that USBPacket and writes it back to the same socket as a usbredir message, for the client to read A USB device has to sit on a USB bus, and in QEMU a USB bus is always made by a host controller. So usb-redir-server makes one and acts as the host controller on this side. It models no real chip: its cable is the chardev socket. The real host is in the other QEMU. usbredir carries one device, not a bus. A hub cannot be exported: the protocol has no device address field. To export several devices, run one usb-redir-server per device, each with its own chardev. Testing ======= A plain usb-storage device was used to test the transport. The storage device is attached to usb-redir-server and exported over a Unix socket: $ qemu-system-aarch64 ... -chardev socket,id=usbredir0,path=/tmp/usbredir0.sock,server=on,wait=off -device usb-redir-server,id=usbredir0,chardev=usbredir0 -drive id=usbdisk,if=none,file=image0.ext4,format=raw -device usb-storage,bus=usbredir0.0,id=mystorage,drive=usbdisk The exported device can then be attached to EHCI bus 3 of an AST2700 guest using the existing usb-redir client: -chardev socket,id=storage,path=/tmp/usbredir0.sock,reconnect-ms=1000 \ -device usb-redir,chardev=storage,bus=usb-bus.3 The AST2700 Linux guest enumerates the redirected USB storage device: root@ast2700-default:~# lsusb unable to initialize usb spec Bus 001 Device 001: ID 1d6b:0001 Linux 6.18.36-v00.08.03-gaf2f426c5786 uhci_hcd Generic UHCI Host Controller Bus 002 Device 001: ID 1d6b:0002 Linux 6.18.36-v00.08.03-gaf2f426c5786 ehci_hcd EHCI Host Controller Bus 002 Device 002: ID 46f4:0001 QEMU QEMU USB HARDDRIVE This also demonstrates that usb-redir-server is not specific to the ASPEED UDC. Any USBDevice can be attached to its USB bus and exported to a host controller in another QEMU instance. v1: 1. Add a usbredir server device 2. Announce the exported device 3. Implement control transfers 4. Implement bulk and interrupt transfers 5. Stream interrupt IN endpoints v2: 1. Split the original series into USB and ASPEED parts as suggested during review. 2. Keep this series focused on the usbredir server transport. 3. Move the ASPEED UDC changes, AST1030 UDC support and its functional test to a separate series. Jamin Lin (8): hw/usb/bus: Let a bus opt out of automatic hub insertion hw/usb/redirect-server: Add a usbredir server device hw/usb/redirect-server: Connect usbredirparser to a chardev hw/usb/redirect-server: Announce the exported device hw/usb/redirect-server: Implement control transfers hw/usb/redirect-server: Implement bulk and interrupt transfers hw/usb/redirect-server: Stream interrupt IN endpoints hw/arm/aspeed: Enable the usbredir server transport include/hw/usb/redirect-server.h | 116 +++ include/hw/usb/usb.h | 1 + hw/arm/aspeed.c | 6 + hw/usb/bus.c | 3 +- hw/usb/redirect-server.c | 1604 ++++++++++++++++++++++++++++++ hw/usb/meson.build | 3 +- hw/usb/trace-events | 27 + 7 files changed, 1758 insertions(+), 2 deletions(-) create mode 100644 include/hw/usb/redirect-server.h create mode 100644 hw/usb/redirect-server.c -- 2.43.0
