Re: [Xen-devel] [PATCH v9 12/14] tools/libxl: read from config if passing through primary GPU

[Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>]

On Wed, 2014-07-02 at 20:42 +0200, Arianna Avanzini wrote:
> This commit adds a new option available for any domU libxl
> configuration that allows the user to specify if one of the
> VGA adapters passed through to the domain is the primary one.
> This way, libxl can arrange the correct I/O-memory access
> permission for its stubdomain.

How does this differ from the existing gfx_passthru option? It doesn't
look like anything here consumes the setting so I can't guess.

> Signed-off-by: Arianna Avanzini <avanzini.arianna@xxxxxxxxx>
> Cc: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
> Cc: Paolo Valente <paolo.valente@xxxxxxxxxx>
> Cc: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>
> Cc: Julien Grall <julien.grall@xxxxxxxxxx>
> Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> Cc: Jan Beulich <JBeulich@xxxxxxxx>
> Cc: Keir Fraser <keir@xxxxxxx>
> Cc: Tim Deegan <tim@xxxxxxx>
> Cc: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: Eric Trudeau <etrudeau@xxxxxxxxxxxx>
> Cc: Viktor Kleinik <viktor.kleinik@xxxxxxxxxxxxxxx>
> ---
>  docs/man/xl.cfg.pod.5       | 7 +++++++
>  tools/libxl/libxl.h         | 7 +++++++
>  tools/libxl/libxl_create.c  | 1 +
>  tools/libxl/libxl_types.idl | 3 ++-
>  tools/libxl/xl_cmdimpl.c    | 2 ++
>  5 files changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
> index 025df27..07f9723 100644
> --- a/docs/man/xl.cfg.pod.5
> +++ b/docs/man/xl.cfg.pod.5
> @@ -601,6 +601,13 @@ More information about Xen gfx_passthru feature is 
> available
>  on the XenVGAPassthrough L<http://wiki.xen.org/wiki/XenVGAPassthrough>
>  wiki page.
>  
> +=item B<gfx_passthru_primary=BOOLEAN>
> +
> +If set to true, indicates that one of the GPUs passed through to the
> +domain is the primary one; therefore allows to the domain's stubdoman
> +access permissions for the VGA framebuffer. Note that this option
> +defaults to true.

Under what circumstances would I set it to false?

Is this purely a stubdom related flag or does it affect non-stub qemu
too?

> +
>  =item B<ioports=[ "IOPORT_RANGE", "IOPORT_RANGE", ... ]>
>  
>  Allow guest to access specific legacy I/O ports. Each B<IOPORT_RANGE>
> diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
> index ce0d2c2..c59b3c7 100644
> --- a/tools/libxl/libxl.h
> +++ b/tools/libxl/libxl.h
> @@ -84,6 +84,13 @@
>  #define LIBXL_HAVE_FIRMWARE_PASSTHROUGH 1
>  
>  /*
> + * LIBXL_HAVE_GFX_PASSTHROUGH_PRIMARY indicates that the user must

Not must, can. It's a defbool so they can (and normally will) just
accept the default.

> + * specify in the domain configuration whether one of the passthru
> + * VGA devices is the primary one.
> + */
> +#define LIBXL_HAVE_GFX_PASSTHROUGH_PRIMARY 1
> +
> +/*
>   * LIBXL_HAVE_DOMAIN_NODEAFFINITY indicates that a 'nodemap' field
>   * (of libxl_bitmap type) is present in libxl_domain_build_info,
>   * containing the node-affinity for the domain.
> diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
> index b5506b1..a44c42a 100644
> --- a/tools/libxl/libxl_create.c
> +++ b/tools/libxl/libxl_create.c
> @@ -349,6 +349,7 @@ int libxl__domain_build_info_setdefault(libxl__gc *gc,
>          libxl_defbool_setdefault(&b_info->u.hvm.nographic, false);
>  
>          libxl_defbool_setdefault(&b_info->u.hvm.gfx_passthru, false);
> +        libxl_defbool_setdefault(&b_info->u.hvm.gfx_passthru_primary, true);
>  
>          break;
>      case LIBXL_DOMAIN_TYPE_PV:
> diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
> index e37e579..754e89d 100644
> --- a/tools/libxl/libxl_types.idl
> +++ b/tools/libxl/libxl_types.idl
> @@ -367,7 +367,8 @@ libxl_domain_build_info = Struct("domain_build_info",[
>                                         ("sdl",              libxl_sdl_info),
>                                         ("spice",            
> libxl_spice_info),
>                                         
> -                                       ("gfx_passthru",     libxl_defbool),
> +                                       ("gfx_passthru",             
> libxl_defbool),
> +                                       ("gfx_passthru_primary",     
> libxl_defbool),
>                                         
>                                         ("serial",           string),
>                                         ("boot",             string),
> diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
> index 513b404..98b5a6e 100644
> --- a/tools/libxl/xl_cmdimpl.c
> +++ b/tools/libxl/xl_cmdimpl.c
> @@ -1645,6 +1645,8 @@ skip_vfb:
>          xlu_cfg_get_defbool(config, "nographic", &b_info->u.hvm.nographic, 
> 0);
>          xlu_cfg_get_defbool(config, "gfx_passthru", 
>                              &b_info->u.hvm.gfx_passthru, 0);
> +        xlu_cfg_get_defbool(config, "gfx_passthru_primary",
> +                            &b_info->u.hvm.gfx_passthru_primary, 0);
>          xlu_cfg_replace_string (config, "serial", &b_info->u.hvm.serial, 0);
>          xlu_cfg_replace_string (config, "boot", &b_info->u.hvm.boot, 0);
>          xlu_cfg_get_defbool(config, "usb", &b_info->u.hvm.usb, 0);



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