Re: [Xen-devel] [PATCH] libxl: Spice usbredirection support for upstream qemu

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

Please don't use HTML in emails

On Thu, 4 Jul 2013, Fabio Fantoni wrote:
> Il 04/07/2013 12:32, Wei Liu ha scritto:
> 
> On Thu, Jul 04, 2013 at 12:16:43PM +0200, Fabio Fantoni wrote:
> 
> Il 04/07/2013 12:12, Wei Liu ha scritto:
> 
> On Thu, Jul 04, 2013 at 12:05:59PM +0200, Fabio Fantoni wrote:
> 
> Usage: spiceusbredirection=1|0 (default=0)
> Enables spice usbredirection. The Spice usbredirection creates usb2
> controller and 4 usbredirection channels for redirection of up to 4
> usb devices from spice client to domU's qemu.
> 
> Signed-off-by: Fabio Fantoni <fabio.fantoni@xxxxxxx>
> ---
>  docs/man/xl.cfg.pod.5       |    8 ++++++++
>  tools/libxl/libxl_create.c  |    1 +
>  tools/libxl/libxl_dm.c      |   18 ++++++++++++++++++
>  tools/libxl/libxl_types.idl |    1 +
>  tools/libxl/xl_cmdimpl.c    |    2 ++
>  5 files changed, 30 insertions(+)
> 
> diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
> index 766862d..a450800 100644
> --- a/docs/man/xl.cfg.pod.5
> +++ b/docs/man/xl.cfg.pod.5
> @@ -1134,6 +1134,14 @@ requires vdagent service installed on domU o.s. to 
> work. The default is 0.
>  =back
> +=item B<spiceusbredirection=BOOLEAN>
> +
> +Enables spice usbredirection. The Spice usbredirection creates usb2
> +controller and 4 usbredirection channels for redirection of up to 4 usb
> +devices from spice client to domU's qemu. The default is 0.
> +
> +=back
> +
>  =head3 Miscellaneous Emulated Hardware
>  =over 4
> diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
> index 8db5460..58df106 100644
> --- a/tools/libxl/libxl_create.c
> +++ b/tools/libxl/libxl_create.c
> @@ -289,6 +289,7 @@ int libxl__domain_build_info_setdefault(libxl__gc *gc,
>                                       false);
>              libxl_defbool_setdefault(&b_info->u.hvm.spice.agent_mouse, true);
>              libxl_defbool_setdefault(&b_info->u.hvm.spice.vdagent, false);
> +            libxl_defbool_setdefault(&b_info->u.hvm.spice.usbredirection, 
> false);
>          }
>          libxl_defbool_setdefault(&b_info->u.hvm.nographic, false);
> diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
> index bc605e4..4f625e0 100644
> --- a/tools/libxl/libxl_dm.c
> +++ b/tools/libxl/libxl_dm.c
> @@ -471,6 +471,24 @@ static char ** 
> libxl__build_device_model_args_new(libxl__gc *gc,
>                      "virtserialport,chardev=vdagent,name=com.redhat.spice.0",
>                      NULL);
>              }
> +
> +            if (libxl_defbool_val(b_info->u.hvm.spice.usbredirection)) {
> +                flexarray_vappend(dm_args, "-device","ich9-usb-ehci1,id=usb,"
> +                    "bus=pci.0,addr=0x1d.0x7", "-device","ich9-usb-uhci1,"
> +                    "masterbus=usb.0,firstport=0,bus=pci.0,multifunction=on,"
> +                    "addr=0x1d.0x0", 
> "-device","ich9-usb-uhci2,masterbus=usb.0,"
> +                    "firstport=2,bus=pci.0,addr=0x1d.0x1", "-device",
> +                    "ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pci.0,"
> +                    "addr=0x1d.0x2", "-chardev","spicevmc,name=usbredir,"
> +                    
> "id=usbrc1","-device","usb-redir,chardev=usbrc1,id=usbrc1,"
> +                    "bus=usb.0", 
> "-chardev","spicevmc,name=usbredir,id=usbrc2",
> +                    "-device","usb-redir,chardev=usbrc2,id=usbrc2,bus=usb.0",
> +                    "-chardev","spicevmc,name=usbredir,id=usbrc3","-device",
> +                    "usb-redir,chardev=usbrc3,id=usbrc3,bus=usb.0", 
> "-chardev",
> +                    "spicevmc,name=usbredir,id=usbrc4","-device","usb-redir,"
> +                    "chardev=usbrc4,id=usbrc4,bus=usb.0", NULL);
> 
> Any reason for so many hardcoded options?
> 
> I searched and requested for one year on spice-devel and qemu-devel
> about alternative methods but nothing found for now.
> Already tried usb=1 which creates usb1 controller that is not
> working with usb redirection.
> 
> What if QEMU upstream changes and these options don't work any more? In
> that case this functionality is broken and users have no way to
> workaround it. IMHO unless they are clearly documented we should not
> consider adding in theses hardcoded options in libxl.
> 
> 
> Added to cc spice-devel and qemu-devel for ask again if there is a better 
> solution to do this.
> 
> @spice-devel and qemu-devel:
> Can someone help to improve qemu options above for enable usb redirection 
> please?
> Thanks for any reply.

It's not about "improving" qemu options for usb redirection (even though
they could use a simplification), it's whether they are guaranteed to be
stable. Are you sure that a future QEMU release is going to work with
these options?
For example, is libvirt using something similar to this?

Usually QEMU cmdline options are considered a stable interface, so I
wouldn't worry too much about it.

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