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

[Yi Sun <yi.y.sun@xxxxxxxxxxxxxxx>]

On 17-03-31 04:19:49, Jan Beulich wrote:
> >>> On 31.03.17 at 11:12, <yi.y.sun@xxxxxxxxxxxxxxx> wrote:
> > On 17-03-31 02:47:25, Jan Beulich wrote:
> >> >>> On 30.03.17 at 14:10, <yi.y.sun@xxxxxxxxxxxxxxx> wrote:
> >> > On 17-03-30 05:55:52, Jan Beulich wrote:
> >> >> >>> 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?
> >> >> 
> >> > I think you can check v9 codes here:
> >> > https://github.com/yisun-git/xen/tree/l2_cat_v9 
> >> 
> >> Looking at this made me notice that cat_get_old_val() passes a
> >> bogus literal 0 to cat_get_val(), which needs taking care of too.
> >> One option I can see is for each feature to make available an
> >> array of type enum cbm_type, with cos_num elements. The order
> >> would match that of the order of values in their arrays. This will
> > 
> > Sorry, not very clear your meaning. How to do that? Could you please
> > provide pieces of codes? Thanks!
> 
> I'm sorry, but I'm afraid I don't see how I would reasonably supply
> code here without taking over your series altogether (which I don't
> intend to do). What is unclear with, at the example of CDP, you
> needing to add an array at initialization time, slot 0 of which holds
> PSR_CBM_TYPE_L3_DATA and slot 1 PSR_CBM_TYPE_L3_CODE (or
> the other way around). Granted I was wrong with the type of the
> array (as the above aren't enum psr_feat_type enumerators, but
> enum cbm_type ones), but I think the basic idea should have been
> clear anyway: You need to provide a way for generic code to pass
> suitable type information into ->get_val().
> 
May I change the 'get_val()' parameter 'enum cbm_type' to a generic type
'unsigned int' to make it be a flexible type,  and then combine feature
type with cos_num together as a flag to indicate which feature it is,
which value to get and distinguish it with cbm_type? For example:

#define CDP_GATHER_BOTH_DATA ( PSR_SOCKET_L3_CDP << 16 )
#define CDP_GATHER_BOTH_CODE ( PSR_SOCKET_L3_CDP << 16 + 1 )
static void l3_cdp_get_val(const struct feat_node *feat, unsigned int cos,
                           unsigned int type, uint32_t *val)
{
    switch ( type )
    {
    case PSR_CBM_TYPE_L3_DATA:
    case CDP_GATHER_BOTH_DATA:
        *val = get_cdp_data(feat, cos);
        break;
    case PSR_CBM_TYPE_L3_CODE:
    case CDP_GATHER_BOTH_CODE:
        *val = get_cdp_code(feat, cos);
        break;
    }
}

/* Example for getting value by cos_num. */
static bool fits_cos_max(...)
{
    enum psr_feat_type feat_type;
...
    for ( j = 0; j < feat->props->cos_num; j++ )
    {
        unsigned int type = feat_type << 16 + j;
        feat->props->get_val(feat, 0, type, &default_val);
...
}

/* Example for getting value by cbm_type. */
int psr_get_val(enum cbm_type type...)
{
...
    feat->props->get_val(feat, cos, type, val);
...
}

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