Re: [PATCH for-4.16 4/4] tools/python: fix python libxc bindings to pass a max grant version

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

On Mon, Nov 15, 2021 at 01:17:41PM +0100, Roger Pau Monne wrote:
> Such max version should be provided by the caller, otherwise the
> bindings will default to specifying a max version of 2, which is
> inline with the current defaults in the hypervisor.
> 
> Fixes: 7379f9e10a ('gnttab: allow setting max version per-domain')
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Acked-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>

> ---
> Cc: Ian Jackson <iwj@xxxxxxxxxxxxxx>
> 
> Without this fix the python bindings won't be usable, as they will
> attempt to pass a max version of 0 which will be refused by the
> hypervisor. The main risk would be breaking the bindings, but given
> the current state it's unlikely to result in a worse outcome.
> ---
>  tools/python/xen/lowlevel/xc/xc.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/python/xen/lowlevel/xc/xc.c 
> b/tools/python/xen/lowlevel/xc/xc.c
> index 6293d205a3..fd00861032 100644
> --- a/tools/python/xen/lowlevel/xc/xc.c
> +++ b/tools/python/xen/lowlevel/xc/xc.c
> @@ -116,7 +116,7 @@ static PyObject *pyxc_domain_create(XcObject *self,
>                                      PyObject *args,
>                                      PyObject *kwds)
>  {
> -    uint32_t dom = 0, target = 0;
> +    uint32_t dom = 0, target = 0, max_grant_version = 2;
>      int      ret;
>      size_t   i;
>      PyObject *pyhandle = NULL;
> @@ -132,12 +132,13 @@ static PyObject *pyxc_domain_create(XcObject *self,
>      };
>  
>      static char *kwd_list[] = { "domid", "ssidref", "handle", "flags",
> -                                "target", "max_vcpus", NULL };
> +                                "target", "max_vcpus", "max_grant_version",
> +                                NULL };
>  
> -    if ( !PyArg_ParseTupleAndKeywords(args, kwds, "|iiOiii", kwd_list,
> +    if ( !PyArg_ParseTupleAndKeywords(args, kwds, "|iiOiiii", kwd_list,
>                                        &dom, &config.ssidref, &pyhandle,
>                                        &config.flags, &target,
> -                                      &config.max_vcpus) )
> +                                      &config.max_vcpus, &max_grant_version) 
> )
>          return NULL;
>      if ( pyhandle != NULL )
>      {
> @@ -162,6 +163,7 @@ static PyObject *pyxc_domain_create(XcObject *self,
>  #else
>  #error Architecture not supported
>  #endif
> +    config.grant_opts = XEN_DOMCTL_GRANT_version(max_grant_version);
>  
>      if ( (ret = xc_domain_create(self->xc_handle, &dom, &config)) < 0 )
>          return pyxc_error_to_exception(self->xc_handle);
> -- 
> 2.33.0
> 

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab

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