[libvirt] [PATCH V2] libxl: add default controllers for USB devices

[Cedric Bosdonnat]

On Fri, 2017-05-05 at 15:48 -0600, Jim Fehlig wrote:
> Attempting to start a domain with USB hostdevs but no USB controllers
> fails with the rather cryptic error
> 
> libxl: error: libxl_qmp.c:287:qmp_handle_error_response: received an
> error message from QMP server: Bus 'xenusb-0.0' not found
> 
> This can be fixed by creating default USB controllers. When no USB
> controllers are defined, create the number of 8 port controllers
> necessary to accommodate the number of defined USB devices.
> 
> Note that USB controllers are already created as needed in the
> domainAttachDevice code path. E.g. a USB controller will be created,
> if necessary, when attaching a USB device with
> 'virsh attach-device dom usbdev.xml'.
> 
> Signed-off-by: Jim Fehlig <jfehlig at suse.com>
> ---
> 
> V1 here
> 
> https://www.redhat.com/archives/libvir-list/2017-April/msg00965.html
> 
> While further testing of V1 found a libvirtd segfault due to
> incorrectly using virDomainControllerInsertPreAlloced instead of
> virDomainControllerInsert.
> 
>  src/libxl/libxl_conf.c | 82 +++++++++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 71 insertions(+), 11 deletions(-)
> 
> diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
> index 56bc09719..cdf6ec9f3 100644
> --- a/src/libxl/libxl_conf.c
> +++ b/src/libxl/libxl_conf.c
> @@ -1822,34 +1822,94 @@ libxlMakeUSBController(virDomainControllerDefPtr controller,
>  }
>  
>  static int
> +libxlMakeDefaultUSBControllers(virDomainDefPtr def,
> +                               libxl_domain_config *d_config)
> +{
> +    virDomainControllerDefPtr l_controller = NULL;
> +    libxl_device_usbctrl *x_controllers = NULL;
> +    size_t nusbdevs = 0;
> +    size_t ncontrollers;
> +    size_t i;
> +
> +    for (i = 0; i < def->nhostdevs; i++) {
> +        if (def->hostdevs[i]->mode == VIR_DOMAIN_HOSTDEV_MODE_SUBSYS &&
> +            def->hostdevs[i]->source.subsys.type == VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_USB)
> +            nusbdevs++;
> +    }
> +
> +    /* No controllers needed if there are no USB devs */
> +    if (nusbdevs == 0)
> +        return 0;
> +
> +    /* Create USB controllers with 8 ports */
> +    ncontrollers = VIR_DIV_UP(nusbdevs, 8);
> +    if (VIR_ALLOC_N(x_controllers, ncontrollers) < 0)
> +        return -1;
> +
> +    for (i = 0; i < ncontrollers; i++) {
> +        if (!(l_controller = virDomainControllerDefNew(VIR_DOMAIN_CONTROLLER_TYPE_USB)))
> +            goto error;
> +
> +        l_controller->model = VIR_DOMAIN_CONTROLLER_MODEL_USB_QUSB2;
> +        l_controller->idx = i;
> +        l_controller->opts.usbopts.ports = 8;
> +
> +        libxl_device_usbctrl_init(&x_controllers[i]);
> +
> +        if (libxlMakeUSBController(l_controller, &x_controllers[i]) < 0)
> +            goto error;
> +
> +        if (virDomainControllerInsert(def, l_controller) < 0)
> +            goto error;
> +
> +        l_controller = NULL;
> +    }
> +
> +    d_config->usbctrls = x_controllers;
> +    d_config->num_usbctrls = ncontrollers;
> +    return 0;
> +
> + error:
> +     virDomainControllerDefFree(l_controller);
> +     for (i = 0; i < ncontrollers; i++)
> +         libxl_device_usbctrl_dispose(&x_controllers[i]);
> +     VIR_FREE(x_controllers);
> +     return -1;
> +}
> +
> +static int
>  libxlMakeUSBControllerList(virDomainDefPtr def, libxl_domain_config *d_config)
>  {
>      virDomainControllerDefPtr *l_controllers = def->controllers;
>      size_t ncontrollers = def->ncontrollers;
>      size_t nusbctrls = 0;
>      libxl_device_usbctrl *x_usbctrls;
> -    size_t i;
> -
> -    if (ncontrollers == 0)
> -        return 0;
> -
> -    if (VIR_ALLOC_N(x_usbctrls, ncontrollers) < 0)
> -        return -1;
> +    size_t i, j;
>  
>      for (i = 0; i < ncontrollers; i++) {
> +        if (l_controllers[i]->type == VIR_DOMAIN_CONTROLLER_TYPE_USB)
> +            nusbctrls++;
> +    }
> +
> +    if (nusbctrls == 0)
> +        return libxlMakeDefaultUSBControllers(def, d_config);
> +
> +    if (VIR_ALLOC_N(x_usbctrls, nusbctrls) < 0)
> +        return -1;
> +
> +    for (i = 0, j = 0; i < ncontrollers && j < nusbctrls; i++) {
>          if (l_controllers[i]->type != VIR_DOMAIN_CONTROLLER_TYPE_USB)
>              continue;
>  
> -        libxl_device_usbctrl_init(&x_usbctrls[nusbctrls]);
> +        libxl_device_usbctrl_init(&x_usbctrls[j]);
>  
>          if (libxlMakeUSBController(l_controllers[i],
> -                                   &x_usbctrls[nusbctrls]) < 0)
> +                                   &x_usbctrls[j]) < 0)
>              goto error;
>  
> -        nusbctrls++;
> +        j++;
>      }
>  
> -    VIR_SHRINK_N(x_usbctrls, ncontrollers, ncontrollers - nusbctrls);
>      d_config->usbctrls = x_usbctrls;
>      d_config->num_usbctrls = nusbctrls;
>  

ACK

--
Cedric