Re: [Xen-devel] [RESEND][PATCH V16 0/6] xen pvusb toolstack work

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 08/03/16 01:37, Chunyan Liu wrote:
> This patch series is to add pvusb toolstack work, supporting hot add|remove
> USB device to|from guest and specify USB device in domain configuration file.
> 
> RESEND to remove a incorrect rc in 4/6:
> +out:
> +    path = GCSPRINTF(USBBACK_INFO_PATH "/%s", usbdev_encode);
> +    rc = libxl__xs_rm_checked(gc, XBT_NULL, path);
> 'rc' should be removed here.
> +    return rc;
> 
> Sorry for trouble you.

Hey Chunyan,

If you make any change at all to the patch series, you should increase
the revision number.  Otherwise, the person who ultimately commits it is
likely to think that the original version and the resend are the same,
and accidentally commit the original (incorrect) version.  (For
instance, they may already like me have downloaded the original patch
series and imported it into git.)

The best thing to do in this situation would have been to reply to your
own patch, saying "And this 'rc' should be removed.  I'll spin another
version."

I took a brief look at the diff between v14 and v15v1 yesterday, and it
looks good.  IanJ is away this week, and I'm sure he'll want to take a
look at it before Ack-ing it next week.  So would you mind sending a
v16, and I'll review it by the end of the week?

Thanks,
 -George

> 
> Changes to V15:
> * address George's comments (patch 4/6)
> 
> V15:
> http://lists.xen.org/archives/html/xen-devel/2016-03/msg00040.html
> 
> V14:
> http://lists.xenproject.org/archives/html/xen-devel/2016-02/msg02745.html
> 
> V13:
> http://lists.xenproject.org/archives/html/xen-devel/2016-01/msg02125.html
> 
> V12:
> http://lists.xen.org/archives/html/xen-devel/2015-12/msg02697.html
> 
> V11:
> http://lists.xen.org/archives/html/xen-devel/2015-12/msg01626.html
> 
> V10:
> http://lists.xen.org/archives/html/xen-devel/2015-12/msg01172.html
> 
> V9:
> http://lists.xen.org/archives/html/xen-devel/2015-11/msg02744.html
> 
> V8:
> http://lists.xen.org/archives/html/xen-devel/2015-10/msg02178.html
> 
> V7:
> http://lists.xen.org/archives/html/xen-devel/2015-09/msg03115.html
> 
> V6:
> http://lists.xen.org/archives/html/xen-devel/2015-08/msg00750.html
> 
> V5:
> http://lists.xen.org/archives/html/xen-devel/2015-06/msg04052.html
> 
> V4:
> http://lists.xenproject.org/archives/html/xen-devel/2015-06/msg01327.html
> 
> Related Discussion Threads:
> http://www.redhat.com/archives/libvir-list/2014-June/msg00038.html
> http://lists.xen.org/archives/html/xen-devel/2014-06/msg00086.html
> 
>               <<< pvusb work introduction >>>
> 
> 1. Overview
> 
> There are two general methods for passing through individual host
> devices to a guest. The first is via an emulated USB device
> controller; the second is PVUSB.
> 
> Additionally, there are two ways to add USB devices to a guest: via
> the config file at domain creation time, and via hot-plug while the VM
> is running.
> 
> * Emulated USB
> 
> In emulated USB, the device model (qemu) presents an emulated USB
> controller to the guest. The device model process then grabs control
> of the device from domain 0 and and passes the USB commands between
> the guest OS and the host USB device.
> 
> This method is only available to HVM domains, and is not available for
> domains running with device model stubdomains.
> 
> * PVUSB
> 
> PVUSB uses a paravirtialized front-end/back-end interface, similar to
> the traditional Xen PV network and disk protocols. In order to use
> PVUSB, you need usbfront in your guest OS, and usbback in dom0 (or
> your USB driver domain).
> 
> 2. Specifying a host USB device
> 
> QEMU qmp commands allows USB devices to be specified either by their
> bus address (in the form bus.device) or their device tag (in the form
> vendorid:deviceid).
> 
> Each way of specifying has its advantages:
> 
>     Specifying by device tag will always get the same device,
> regardless of where the device ends up in the USB bus topology.
> However, if there are two identical devices, it will not allow you to
> specify which one.
> 
>     Specifying by bus address will always allow you to choose a
> specific device, even if you have duplicates. However, the bus address
> may change depending on which port you plugged the device into, and
> possibly also after a reboot.
> 
> To avoid duplication of vendorid:deviceid, we'll use bus address to
> specify host USB device in xl toolstack.
> 
> You can use lsusb to list the USB devices on the system:
> 
> Bus 001 Device 003: ID 0424:2514 Standard Microsystems Corp. USB 2.0
> Hub
> Bus 003 Device 002: ID f617:0905
> Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
> Bus 001 Device 004: ID 0424:2640 Standard Microsystems Corp. USB 2.0
> Hub
> Bus 001 Device 005: ID 0424:4060 Standard Microsystems Corp. Ultra
> Fast Media Reader
> Bus 001 Device 006: ID 046d:c016 Logitech, Inc. Optical Wheel Mouse
> 
> To pass through the Logitec mouse, for instance, you could specify
> 1.6 (remove leading zeroes).
> 
> Note: USB hubs can not be assigned to guest.
> 
> 3. PVUSB toolstack
> 
> * Specify USB device in xl config file
> 
> You can just specify usb devices, like:
> usbdev=['hostbus=1, hostaddr=6']
> 
> Then it will create a USB controller automatically and attach the USB
> device to the first available USB controller:port.
> 
> or, you can explicitly specify usb controllers and usb devices, like:
> usbctrl=['verison=1, ports=4', 'version=2, ports=8', ]
> usbdev=['hostbus=1, hostaddr=6, controller=0, port=1']
> 
> Then it will create two USB controllers as you specified.
> And if controller and port are specified in usb config, then it will
> attach the USB device to that controller:port. About the controller
> and port value:
> Each USB controller has a index (or called devid) based on 0. The 1st
> controller has index 0, the 2nd controller has index 1, ...
> Under controller, each port has a port number based on 1. In above
> configuration, the 1st controller will have port 1,2,3,4.
> 
> * Hot-Plug USB device
> 
> To attach a USB device, you should first create a USB controller.
> e.g.
> xl usbctrl-attach domain [version=1|2] [ports=value]
> By default, it will create a USB2.0 controller with 8 ports.
> 
> Then you could attach a USB device.
> e.g.
> xl usbdev-attach domain hostbus=1 hostaddr=6 [controller=index port=number]
> By default, it will find the 1st available controller:port to attach
> the USB device.
> 
> You could view USB device status of the domain by usb-list.
> e.g.
> xl usb-list domain
> It will list USB controllers and USB devices under each controller.
> 
> You could detach a USB device with usbdev-detach command by giving
> controller:port
> e.g.
> xl usbdev-detach domain 0 1
> 
> You can also remove the whole USB controller by usbctrl-detach
> command.
> e.g.
> xl usbctrl-detach domain 0
> It will remove the USB controller with index 0 and all USB devices
> under it.
> 
> 4. PVUSB Libxl implementation
> 
> * usbctrl-attach
> To create a usb controller, we need:
> 1) generate usb controler related information
> 2) write usb controller frontend/backend info to xenstore
> PVUSB frontend and backend driver will probe xenstore paths and build
> connection between frontend and backend.
> 
> * usbctrl-detach
> To remove a usb controller, we need:
> 1) check if the usb controller exists or not
> 2) remove all usb devices under controller
> 3) remove usb controller info from xenstore
> 
> * usbdev-attach
> To attach a usb device, we need:
> 1) check if the usb device type is assignable
> 2) check if the usb device is already assigned to a domain
> 3) add 'busid' of the usb device to xenstore contoller/port/.
>    PVUSB driver watches the xenstore changes and detects that,
>    and needs to use 'busid' to do following work.
> 4) unbind usb device from original driver and bind to usbback.
>    If usb device has many interfaces, then:
>    - unbind each interface from its original driver and bind to usbback.
>    - store the original driver to xenstore for later rebinding when
>      detaching the device.
> 
> * usbdev-detach
> To detach a usb device, we need:
> 1) check if the usb device is assigned to the domain
> 2) remove the usb device from xenstore controller/port.
> 3) unbind usb device from usbback and rebind to its original driver.
>    If usb device has many interfaces, do it to each interface.
> 
> * usb-list
> List all USB controllers and USB devices under each controller.
> 
> 5. PVUSB xenstore information
> 
> PVUSB xenstore information includes three parts: frontend, backend
> and /libxl part.
> 
> A USB controller is corresponding to a "vusb" device in xenstore.
> Adding a USB controller will add a new "vusb" device, removing a
> USB controller will delete the related "vusb" device.
> 
> Following is an example xenstore values of a USB controller.
> Backend:
>    backend = ""
>     vusb = ""
>      1 = ""
>       0 = ""
>        frontend = "/local/domain/1/device/vusb/0"
>        frontend-id = "1"
>        online = "1"
>        state = "4"
>        type = "pv"
>        usb-ver = "1"
>        num-ports = "4"
>        port = ""
>         1 = ""
>         2 = ""
>         3 = ""
>         4 = ""
> 
> Frontend:
>    device = ""
>     vusb = ""
>      0 = ""
>       backend = "/local/domain/0/backend/vusb/1/0"
>       backend-id = "0"
>       state = "4"
>       urb-ring-ref = "348"
>       conn-ring-ref = "346"
>       event-channel = "20"
> 
> Adding a USB device won't create a new "vusb" device, but only write
> the USB device busid to one port of USB controller.
> For example, attaching a USB device (busid is 2-1.6) to above USB
> controller port 1, it only need write 2-1.6 to port 1 of this USB
> controller:
> Backend:
>    backend = ""
>     vusb = ""
>      1 = ""
>       0 = ""
>        frontend = "/local/domain/1/device/vusb/0"
>        frontend-id = "1"
>        online = "1"
>        state = "4"
>        type = "pv"
>        usb-ver = "1"
>        num-ports = "4"
>        port = ""
>         1 = "2-1.6"
>         2 = ""
>         3 = ""
>         4 = ""
> Frontend doesn't change.
> 
> Since assign a host USB device to guest, we'll unbind USB interfaces
> from their original drivers and bind them to usbback. After detaching
> this USB device from guest, one would hope the USB interfaces could
> be rebind to their original drivers, so there should some place to
> get the original driver info. To support that, when attaching a USB
> device to guest, we'll save the original driver info in xenstore too,
> the place is /libxl/usbback, for example:
> libxl = ""
>  1 = ""
>   dm-version = "qemu_xen"
>  usbback = ""
>   3-11 = ""
>    3-11@1_0 = ""
>     driver_path = "/sys/bus/usb/drivers/btusb"
> 
> In this example, USB device (busid is 3-11, /sys/bus/usb/devices/3-11).
> It has interface 3-11:1.0, whose original dirver is btusb.
> Since xenstore doesn't allow ':' and '.' in a key, so we encode the
> interface by changing ':' to '@' and changing '.' to '_'.
> 
> When detaching the USB device from guest, we can rebind 3-11:1.0 to
> btusb driver.
> 
> Chunyan Liu (6):
>   libxl: export some functions for pvusb use
>   libxl_utils: add internal function to read sysfs file contents
>   refactor DEFINE_DEVICE_REMOVE to fit for more device types
>   libxl: add pvusb API
>   domcreate: support pvusb in configuration file
>   xl: add pvusb commands
> 
>  docs/man/xl.cfg.pod.5                |   84 ++
>  docs/man/xl.pod.1                    |   37 +
>  tools/libxl/Makefile                 |    3 +-
>  tools/libxl/libxl.c                  |   41 +-
>  tools/libxl/libxl.h                  |   77 ++
>  tools/libxl/libxl_create.c           |   73 +-
>  tools/libxl/libxl_device.c           |   17 +-
>  tools/libxl/libxl_internal.h         |   37 +-
>  tools/libxl/libxl_osdeps.h           |   13 +
>  tools/libxl/libxl_pvusb.c            | 1620 
> ++++++++++++++++++++++++++++++++++
>  tools/libxl/libxl_types.idl          |   46 +
>  tools/libxl/libxl_types_internal.idl |    1 +
>  tools/libxl/libxl_utils.c            |   92 ++
>  tools/libxl/libxl_utils.h            |    5 +
>  tools/libxl/xl.h                     |    5 +
>  tools/libxl/xl_cmdimpl.c             |  297 ++++++-
>  tools/libxl/xl_cmdtable.c            |   25 +
>  17 files changed, 2453 insertions(+), 20 deletions(-)
>  create mode 100644 tools/libxl/libxl_pvusb.c
> 


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