Re: [PATCH] tools/libxc: Reduce feature handling complexity in xc_cpuid_apply_policy()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Tools ping?

~Andrew

On 03/03/2020 18:23, Andrew Cooper wrote:
> xc_cpuid_apply_policy() is gaining extra parameters to untangle CPUID
> complexity in Xen.  While an improvement in general, it does have the
> unfortunate side effect of duplicating some settings across muliple
> parameters.
>
> Rearrange the logic to only consider 'pae' if no explicit featureset is
> provided.  This reduces the complexity for callers who have already provided a
> pae setting in the featureset.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> CC: Wei Liu <wl@xxxxxxx>
> CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> CC: Ian Jackson <Ian.Jackson@xxxxxxxxxx>
> ---
>  tools/libxc/include/xenctrl.h | 6 ++++++
>  tools/libxc/xc_cpuid_x86.c    | 7 +++++--
>  2 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
> index fc6e57a1a0..8d13a7e20b 100644
> --- a/tools/libxc/include/xenctrl.h
> +++ b/tools/libxc/include/xenctrl.h
> @@ -1798,6 +1798,12 @@ int xc_cpuid_set(xc_interface *xch,
>                   const unsigned int *input,
>                   const char **config,
>                   char **config_transformed);
> +/*
> + * Make adjustments to the CPUID settings for a domain.
> + *
> + * Either pass a full new @featureset (and @nr_features), or adjust 
> individual
> + * features (@pae).
> + */
>  int xc_cpuid_apply_policy(xc_interface *xch,
>                            uint32_t domid,
>                            const uint32_t *featureset,
> diff --git a/tools/libxc/xc_cpuid_x86.c b/tools/libxc/xc_cpuid_x86.c
> index 5ced6d18b9..f045b03223 100644
> --- a/tools/libxc/xc_cpuid_x86.c
> +++ b/tools/libxc/xc_cpuid_x86.c
> @@ -532,6 +532,11 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t 
> domid,
>  
>          cpuid_featureset_to_policy(feat, p);
>      }
> +    else
> +    {
> +        if ( di.hvm )
> +            p->basic.pae = pae;
> +    }
>  
>      if ( !di.hvm )
>      {
> @@ -615,8 +620,6 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t 
> domid,
>              break;
>          }
>  
> -        p->basic.pae = pae;
> -
>          /*
>           * These settings are necessary to cause earlier HVM_PARAM_NESTEDHVM 
> /
>           * XEN_DOMCTL_disable_migrate settings to be reflected correctly in