docs: Sample driver to demonstrate how to use Mediated device framework.

The Sample driver creates mdev device that simulates serial port over PCI
card.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Signed-off-by: Neo Jia <cjia@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Kirti Wankhede 2016-11-17 02:16:33 +05:30 коммит произвёл Alex Williamson
Родитель 3771bd9697
Коммит 9d1a546c53
3 изменённых файлов: 1618 добавлений и 1 удалений

Просмотреть файл

@ -288,8 +288,109 @@ these callbacks are supported in the TYPE1 IOMMU module. To enable them for
other IOMMU backend modules, such as PPC64 sPAPR module, they need to provide
these two callback functions.
Using the Sample Code
=====================
mtty.c in samples/vfio-mdev/ directory is a sample driver program to
demonstrate how to use the mediated device framework.
The sample driver creates an mdev device that simulates a serial port over a PCI
card.
1. Build and load the mtty.ko module.
This step creates a dummy device, /sys/devices/virtual/mtty/mtty/
Files in this device directory in sysfs are similar to the following:
# tree /sys/devices/virtual/mtty/mtty/
/sys/devices/virtual/mtty/mtty/
|-- mdev_supported_types
| |-- mtty-1
| | |-- available_instances
| | |-- create
| | |-- device_api
| | |-- devices
| | `-- name
| `-- mtty-2
| |-- available_instances
| |-- create
| |-- device_api
| |-- devices
| `-- name
|-- mtty_dev
| `-- sample_mtty_dev
|-- power
| |-- autosuspend_delay_ms
| |-- control
| |-- runtime_active_time
| |-- runtime_status
| `-- runtime_suspended_time
|-- subsystem -> ../../../../class/mtty
`-- uevent
2. Create a mediated device by using the dummy device that you created in the
previous step.
# echo "83b8f4f2-509f-382f-3c1e-e6bfe0fa1001" > \
/sys/devices/virtual/mtty/mtty/mdev_supported_types/mtty-2/create
3. Add parameters to qemu-kvm.
-device vfio-pci,\
sysfsdev=/sys/bus/mdev/devices/83b8f4f2-509f-382f-3c1e-e6bfe0fa1001
4. Boot the VM.
In the Linux guest VM, with no hardware on the host, the device appears
as follows:
# lspci -s 00:05.0 -xxvv
00:05.0 Serial controller: Device 4348:3253 (rev 10) (prog-if 02 [16550])
Subsystem: Device 4348:3253
Physical Slot: 5
Control: I/O+ Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR- FastB2B- DisINTx-
Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort-
<TAbort- <MAbort- >SERR- <PERR- INTx-
Interrupt: pin A routed to IRQ 10
Region 0: I/O ports at c150 [size=8]
Region 1: I/O ports at c158 [size=8]
Kernel driver in use: serial
00: 48 43 53 32 01 00 00 02 10 02 00 07 00 00 00 00
10: 51 c1 00 00 59 c1 00 00 00 00 00 00 00 00 00 00
20: 00 00 00 00 00 00 00 00 00 00 00 00 48 43 53 32
30: 00 00 00 00 00 00 00 00 00 00 00 00 0a 01 00 00
In the Linux guest VM, dmesg output for the device is as follows:
serial 0000:00:05.0: PCI INT A -> Link[LNKA] -> GSI 10 (level, high) -> IRQ
10
0000:00:05.0: ttyS1 at I/O 0xc150 (irq = 10) is a 16550A
0000:00:05.0: ttyS2 at I/O 0xc158 (irq = 10) is a 16550A
5. In the Linux guest VM, check the serial ports.
# setserial -g /dev/ttyS*
/dev/ttyS0, UART: 16550A, Port: 0x03f8, IRQ: 4
/dev/ttyS1, UART: 16550A, Port: 0xc150, IRQ: 10
/dev/ttyS2, UART: 16550A, Port: 0xc158, IRQ: 10
6. Using a minicom or any terminal enulation program, open port /dev/ttyS1 or
/dev/ttyS2 with hardware flow control disabled.
7. Type data on the minicom terminal or send data to the terminal emulation
program and read the data.
Data is loop backed from hosts mtty driver.
8. Destroy the mediated device that you created.
# echo 1 > /sys/bus/mdev/devices/83b8f4f2-509f-382f-3c1e-e6bfe0fa1001/remove
References
----------
==========
[1] See Documentation/vfio.txt for more information on VFIO.
[2] struct mdev_driver in include/linux/mdev.h

Просмотреть файл

@ -0,0 +1,13 @@
#
# Makefile for mtty.c file
#
KERNEL_DIR:=/lib/modules/$(shell uname -r)/build
obj-m:=mtty.o
modules clean modules_install:
$(MAKE) -C $(KERNEL_DIR) SUBDIRS=$(PWD) $@
default: modules
module: modules

1503
samples/vfio-mdev/mtty.c Normal file

Разница между файлами не показана из-за своего большого размера Загрузить разницу