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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 30.03.17 at 03:37, <yi.y.sun@xxxxxxxxxxxxxxx> wrote:
> On 17-03-29 03:57:52, Jan Beulich wrote:
>> >>> On 29.03.17 at 03:36, <yi.y.sun@xxxxxxxxxxxxxxx> wrote:
>> > On 17-03-29 09:20:21, Yi Sun wrote:
>> >> On 17-03-28 06:20:48, Jan Beulich wrote:
>> >> > >>> On 28.03.17 at 13:59, <yi.y.sun@xxxxxxxxxxxxxxx> wrote:
>> >> > > I think we at least need a 'get_val()' hook.
>> >> > 
>> >> > Of course.
>> >> > 
>> >> > > I try to implement CAT/CDP hook.
>> >> > > Please help to check if this is what you thought.
>> >> > 
>> >> > One remark below, but other than that - yes.
>> >> > 
>> >> > > static void cat_get_val(const struct feat_node *feat, unsigned int 
>> >> > > cos,
>> >> > >                         enum cbm_type type, int flag, uint32_t *val)
>> >> > > {
>> >> > >     *val = feat->cos_reg_val[cos];
>> >> > > }
>> >> > > 
>> >> > > static void l3_cdp_get_val(const struct feat_node *feat, unsigned int 
> cos,
>> >> > >                            enum cbm_type type, int flag, uint32_t 
>> >> > > *val)
>> >> > > {
>> >> > >     if ( type == PSR_CBM_TYPE_L3_DATA || flag == 0 )
>> >> > >         *val = get_cdp_data(feat, cos);
>> >> > >     if ( type == PSR_CBM_TYPE_L3_CODE || flag == 1 )
>> >> > >         *val = get_cdp_code(feat, cos);
>> >> > > }
>> >> > 
>> >> > Why the redundancy between type and flag?
>> >> > 
>> >> For psr_get_val, upper layer input the cbm_type to get either DATA or CODE
>> >> value. For other cases, we use flag as cos_num index to get either DATA or
>> >> CODE.
>> >> 
>> > Let me explain more to avoid confusion. For other cases, we use cos_num as
>> > index to get values from a feature. In these cases, we do not know the
>> > cbm_type of the feature. So, I use the cos_num as flag to make 'get_val'
>> > know which value should be returned.
>> 
>> I'm pretty sure this redundancy can be avoided.
>> 
> Then, I think I have to reuse the 'type'. As only CDP needs type to decide
> which value to be returned so far, I think I can implement codes like below
> to make CDP can handle all scenarios.
> 
> static void l3_cdp_get_val(const struct feat_node *feat, unsigned int cos,
>                            enum cbm_type type, uint32_t *val)
> {
>     if ( type == PSR_CBM_TYPE_L3_DATA || flag == 0xF000 )
>         *val = get_cdp_data(feat, cos);
>     if ( type == PSR_CBM_TYPE_L3_CODE || flag == 0xF001 )
>         *val = get_cdp_code(feat, cos);
> }
> 
> static bool fits_cos_max(...)
> {
> ......
>     for (i = 0; i < feat->props->cos_num; i++)
>     {
>         feat->props->get_val(feat, cos, i + 0xF000, &default_val);
>         if ( val[i] == default_val )
>             ......
>     }
> ......
> }
> 
> Is that good for you?

Urgh - no, not really: This is hackery. Do you have a tree
somewhere so I could look at the file after at least the CDP
patches have all been applied, to see whether I have a
better idea? Alternatively, could you attach psr.c the way
you have it right now with the entire series applied?

Jan


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