101 lines
3.4 KiB
ReStructuredText
101 lines
3.4 KiB
ReStructuredText
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Using the mtty vfio-mdev sample code
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====================================
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mtty is a sample vfio-mdev driver that demonstrates how to use the mediated
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device framework.
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The sample driver creates an mdev device that simulates a serial port over a PCI
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card.
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1. Build and load the mtty.ko module.
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This step creates a dummy device, /sys/devices/virtual/mtty/mtty/
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Files in this device directory in sysfs are similar to the following::
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# tree /sys/devices/virtual/mtty/mtty/
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/sys/devices/virtual/mtty/mtty/
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|-- mdev_supported_types
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| |-- mtty-1
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| | |-- available_instances
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| | |-- create
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| | |-- device_api
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| | |-- devices
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| | `-- name
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| `-- mtty-2
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| |-- available_instances
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| |-- create
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| |-- device_api
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| |-- devices
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| `-- name
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|-- mtty_dev
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| `-- sample_mtty_dev
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|-- power
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| |-- autosuspend_delay_ms
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| |-- control
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| |-- runtime_active_time
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| |-- runtime_status
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| `-- runtime_suspended_time
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|-- subsystem -> ../../../../class/mtty
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`-- uevent
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2. Create a mediated device by using the dummy device that you created in the
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previous step::
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# echo "83b8f4f2-509f-382f-3c1e-e6bfe0fa1001" > \
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/sys/devices/virtual/mtty/mtty/mdev_supported_types/mtty-2/create
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3. Add parameters to qemu-kvm::
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-device vfio-pci,\
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sysfsdev=/sys/bus/mdev/devices/83b8f4f2-509f-382f-3c1e-e6bfe0fa1001
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4. Boot the VM.
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In the Linux guest VM, with no hardware on the host, the device appears
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as follows::
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# lspci -s 00:05.0 -xxvv
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00:05.0 Serial controller: Device 4348:3253 (rev 10) (prog-if 02 [16550])
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Subsystem: Device 4348:3253
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Physical Slot: 5
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Control: I/O+ Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr-
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Stepping- SERR- FastB2B- DisINTx-
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Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort-
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<TAbort- <MAbort- >SERR- <PERR- INTx-
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Interrupt: pin A routed to IRQ 10
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Region 0: I/O ports at c150 [size=8]
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Region 1: I/O ports at c158 [size=8]
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Kernel driver in use: serial
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00: 48 43 53 32 01 00 00 02 10 02 00 07 00 00 00 00
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10: 51 c1 00 00 59 c1 00 00 00 00 00 00 00 00 00 00
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20: 00 00 00 00 00 00 00 00 00 00 00 00 48 43 53 32
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30: 00 00 00 00 00 00 00 00 00 00 00 00 0a 01 00 00
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In the Linux guest VM, dmesg output for the device is as follows:
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serial 0000:00:05.0: PCI INT A -> Link[LNKA] -> GSI 10 (level, high) -> IRQ 10
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0000:00:05.0: ttyS1 at I/O 0xc150 (irq = 10) is a 16550A
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0000:00:05.0: ttyS2 at I/O 0xc158 (irq = 10) is a 16550A
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5. In the Linux guest VM, check the serial ports::
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# setserial -g /dev/ttyS*
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/dev/ttyS0, UART: 16550A, Port: 0x03f8, IRQ: 4
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/dev/ttyS1, UART: 16550A, Port: 0xc150, IRQ: 10
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/dev/ttyS2, UART: 16550A, Port: 0xc158, IRQ: 10
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6. Using minicom or any terminal emulation program, open port /dev/ttyS1 or
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/dev/ttyS2 with hardware flow control disabled.
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7. Type data on the minicom terminal or send data to the terminal emulation
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program and read the data.
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Data is loop backed from hosts mtty driver.
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8. Destroy the mediated device that you created::
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# echo 1 > /sys/bus/mdev/devices/83b8f4f2-509f-382f-3c1e-e6bfe0fa1001/remove
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