Re: [Xen-devel] [PATCH v9 12/25] x86: refactor psr: L3 CAT: set value: implement cos id picking flow.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 28.03.17 at 12:31, <yi.y.sun@xxxxxxxxxxxxxxx> wrote:
> On 17-03-28 02:45:13, Jan Beulich wrote:
>> >>> On 28.03.17 at 06:58, <yi.y.sun@xxxxxxxxxxxxxxx> wrote:
>> > On 17-03-27 04:37:37, Jan Beulich wrote:
>> >> >>> On 16.03.17 at 12:08, <yi.y.sun@xxxxxxxxxxxxxxx> wrote:
>> >> > +static bool cat_fits_cos_max(const uint32_t val[],
>> >> > +                             const struct feat_node *feat,
>> >> > +                             unsigned int cos)
>> >> > +{
>> >> > +    if ( cos > feat->info.cat_info.cos_max &&
>> >> > +         val[0] != feat->cos_reg_val[0] )
>> >> > +            /*
>> >> > +             * Exceed cos_max and value to set is not default,
>> >> > +             * return error.
>> >> > +             */
>> >> > +            return false;
>> >> > +
>> >> > +    return true;
>> >> > +}
>> >> 
>> >> Same here - with cos_max moved out, the hook would seem to
>> >> become unnecessary.
>> >> 
>> > As explanation in previous patch, CDP has different behavior.
>> > static bool l3_cdp_fits_cos_max(...)
>> > {
>> >     if ( cos > feat->info.cat_info.cos_max &&
>> >          (val[0] != get_cdp_data(feat, 0) || val[1] != get_cdp_code(feat, 
>> > 0)) )
>> >             /*
>> >              * Exceed cos_max and value to set is not default,
>> >              * return error.
>> >              */
>> >             return false;
>> > 
>> >     return true;
>> > 
>> > }
>> 
>> As said in reply, by making get_val() flexible enough you should
>> be able to avoid this.
> 
> Sorry, I am confused here. 'fits_cos_max' is called during set value process.
> Why "making get_val() flexible enough" can avoid this?

Because that would then replace the get_cdp_data() and
get_cdp_code() calls above.

Jan


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