Re: [Xen-devel] [PATCH v9 15/25] x86: refactor psr: CDP: implement get hw info flow.

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

On 17-03-27 08:08:13, Jan Beulich wrote:
> >>> On 16.03.17 at 12:08, <yi.y.sun@xxxxxxxxxxxxxxx> wrote:
> > --- a/xen/arch/x86/sysctl.c
> > +++ b/xen/arch/x86/sysctl.c
> > @@ -180,10 +180,36 @@ long arch_do_sysctl(
> >  
> >              ret = psr_get_info(sysctl->u.psr_cat_op.target,
> >                                 PSR_CBM_TYPE_L3, data, ARRAY_SIZE(data));
> > -
> > -            sysctl->u.psr_cat_op.u.l3_info.cbm_len = 
> > data[PSR_INFO_IDX_CBM_LEN];
> > -            sysctl->u.psr_cat_op.u.l3_info.cos_max = 
> > data[PSR_INFO_IDX_COS_MAX];
> > -            sysctl->u.psr_cat_op.u.l3_info.flags   = 
> > data[PSR_INFO_IDX_FLAG];
> > +            if ( !ret )
> > +            {
> > +                sysctl->u.psr_cat_op.u.l3_info.cbm_len =
> > +                                               data[PSR_INFO_IDX_CBM_LEN];
> > +                sysctl->u.psr_cat_op.u.l3_info.cos_max =
> > +                                               data[PSR_INFO_IDX_COS_MAX];
> > +                sysctl->u.psr_cat_op.u.l3_info.flags =
> > +                                               data[PSR_INFO_IDX_FLAG];
> > +            }
> > +            else
> > +            {
> > +                /*
> > +                 * Check if CDP is enabled.
> > +                 *
> > +                 * Per spec, L3 CAT and CDP cannot co-exist. So, we need 
> > replace
> > +                 * output values to CDP's if it is enabled.
> > +                 */
> > +                ret = psr_get_info(sysctl->u.psr_cat_op.target,
> > +                                   PSR_CBM_TYPE_L3_CODE, data,
> > +                                   ARRAY_SIZE(data));
> 
> I think this could/should be done without such a strange retry
> mechanism. You can find out which of the features is available,
> can't you?
> 
Ok, I can handle it inside psr_get_info. If L3 CAT feature node is NULL, will
use CDP feature node.

> > +                if ( !ret )
> > +                {
> > +                    sysctl->u.psr_cat_op.u.l3_info.cbm_len =
> > +                                               data[PSR_INFO_IDX_CBM_LEN];
> > +                    sysctl->u.psr_cat_op.u.l3_info.cos_max =
> > +                                               data[PSR_INFO_IDX_COS_MAX];
> > +                    sysctl->u.psr_cat_op.u.l3_info.flags =
> > +                                               data[PSR_INFO_IDX_FLAG];
> > +                }
> > +            }
> >  
> >              if ( !ret && __copy_field_to_guest(u_sysctl, sysctl, 
> > u.psr_cat_op) )
> >                  ret = -EFAULT;
> 
> So where is PSR_CBM_TYPE_L3_DATA being handled?
> 
This interface is to get L3 CAT/CDP HW info. So, either PSR_CBM_TYPE_L3_DATA or
PSR_CBM_TYPE_L3_CODE can be used to get CDP's HW info. Either of them will be
converted to feature type 'PSR_SOCKET_L3_CDP'.

> Jan

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