Re: [Xen-devel] [PATCH v8 18/24] x86: L2 CAT: implement get hw info flow.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 15.02.17 at 09:49, <yi.y.sun@xxxxxxxxxxxxxxx> wrote:
> +static bool l2_cat_get_feat_info(const struct feat_node *feat,
> +                                 uint32_t data[], uint32_t array_len)
> +{
> +    if ( !data || 2 > array_len )
> +        return false;
> +
> +    data[CBM_LEN] = feat->info.l2_cat_info.cbm_len;
> +    data[COS_MAX] = feat->info.l2_cat_info.cos_max;

What about PSR_FLAG? Which puts under question the
array_len check at the start of this and its sibling functions: If
more array entries are provided, they'd all be left uninitialized
without the caller having a way to know. Coming back to the
data structures being the same for all features, there should
presumably be a structure instead of an array be used for
communication here, and ...

> @@ -754,6 +755,11 @@ struct xen_sysctl_psr_cat_op {
>  #define XEN_SYSCTL_PSR_CAT_L3_CDP       (1u << 0)
>              uint32_t flags;     /* OUT: CAT flags */
>          } l3_info;
> +
> +        struct {
> +            uint32_t cbm_len;   /* OUT: CBM length */
> +            uint32_t cos_max;   /* OUT: Maximum COS */
> +        } l2_info;

... this should use the same structure as l3_info (flags being
set to zero until a use arises). This would then also allow for
more code to be shared instead of duplicated.

Jan


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