Re: [PATCH v4 31/33] libxl: Add support for non-PCI passthrough

[Ian Campbell <ian.campbell@citrix.com>]

On Thu, 2015-03-19 at 19:29 +0000, Julien Grall wrote:
> On ARM, every non-PCI device are described in the device tree. Each of
> them can be found via a path.
> 
> This patch introduces a very basic support, only the IOMMU will be set
> up correctly. The user will have to:
>     - Describe the device in the partial device tree
>     - Map manually MMIO/IRQ
> 
> This is a first approach, that will allow to have a basic non-PCI
> passthrough support in Xen. This could be improved later.
> 
> Furthermore add LIBXL_HAVE_DEVICETREE_PASSTHROUGH to indicate we
> support non-PCI passthrough and partial device tree (introduced by a
> previous patch).

Ah, you can ignore my comment on the previous patch then.

The comment with the #define might be an OK place for the
big-scary-warning I mentioned in the previous patch too?

> 
> Signed-off-by: Julien Grall <julien.grall@linaro.org>
> Cc: Ian Jackson <ian.jackson@eu.citrix.com>
> Cc: Wei Liu <wei.liu2@citrix.com>
> 
> ---
>     Changes in v4:
>         - Add LIBXL_HAVE_DEVICTREE_PASSTHROUGH to indicate we support
>         non-PCI passthrough. This is also used in order to indicate
>         partial device tree is supported
>         - Remove libxl_dtdev.c as it contains only a 2 lines functions
>         and call directly xc_* from libxl_create.c
>         - Introduce domcreate_attach_dtdev
> 
>     Changes in v3:
>         - Dynamic allocation has been dropped
>         - Rework the commit message in accordance with the previous
>         item
> 
>     Changes in v2:
>         - Get DT infos earlier
>         - Allocate/map IRQ in libxl__arch_domain_create rather than in
>         libxl__device_dt_add
>         - Use VIRQ rather than the PIRQ to construct the interrupts
>         properties of the device tree
>         - Correct cpumask in make_dtdev_node. We allow the interrupt to
>         be used on the 8 CPUs
>         - Fix LOGE when we map the MMIO region in the guest in
>         libxl__device_dt_add. The domain and the IRQ were inverted
>         - Calculate the number of SPIs to configure the VGIC
>         - xc_physdev_dtdev_* helpers has been renamed to xc_dtdev_*
>         - Rename libxl_device_dt to libxl_device_dtdev
> ---
>  tools/libxl/libxl.h          |  6 ++++++
>  tools/libxl/libxl_create.c   | 32 ++++++++++++++++++++++++++++++++
>  tools/libxl/libxl_internal.h |  5 +++++
>  tools/libxl/libxl_types.idl  |  5 +++++
>  4 files changed, 48 insertions(+)
> 
> diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
> index 6bc75c5..baaf06b 100644
> --- a/tools/libxl/libxl.h
> +++ b/tools/libxl/libxl.h
> @@ -179,6 +179,12 @@
>  #define LIBXL_HAVE_BUILDINFO_HVM_MMIO_HOLE_MEMKB 1
>  
>  /*
> + * libxl_domain_build_info has device_tree and libxl_device_dtdev
> + * exists. This mean non-PCI passthrough is supported for ARM

Rather than non-PCI I'd say device tree here, since I'm sure you aren't
supporting the new flargle-bus I've just invented...

> + *
> +#define LIBXL_HAVE_DEVICETREE_PASSTHROUGH 1
> +
> +/*
>   * libxl ABI compatibility
>   *
>   * The only guarantee which libxl makes regarding ABI compatibility
> diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
> index 15b464e..39c828b 100644
> --- a/tools/libxl/libxl_create.c
> +++ b/tools/libxl/libxl_create.c
> @@ -751,6 +751,8 @@ static void domcreate_attach_vtpms(libxl__egc *egc, libxl__multidev *multidev,
>                                     int ret);
>  static void domcreate_attach_pci(libxl__egc *egc, libxl__multidev *aodevs,
>                                   int ret);
> +static void domcreate_attach_dtdev(libxl__egc *egc,
> +                                   libxl__domain_create_state *dcs);
>  
>  static void domcreate_console_available(libxl__egc *egc,
>                                          libxl__domain_create_state *dcs);
> @@ -1444,6 +1446,36 @@ static void domcreate_attach_pci(libxl__egc *egc, libxl__multidev *multidev,
>          }
>      }
>  
> +    domcreate_attach_dtdev(egc, dcs);
> +    return;
> +
> +error_out:
> +    assert(ret);
> +    domcreate_complete(egc, dcs, ret);
> +}
> +
> +static void domcreate_attach_dtdev(libxl__egc *egc,
> +                                   libxl__domain_create_state *dcs)

I know it isn't strictly needed, but I think for consistency this
function should take a ret and check it + propagate it via
domcreate_complete on error, like the other ones in the call chain do.

Ian.