Re: [PATCH v1 24/31] x86/resctrl: Move get_config_index() to a header

Reinette Chatre
2024-04-09T03:25:53Z

Hi James,

On 3/21/2024 9:50 AM, James Morse wrote:
> get_config_index() is used by the architecture specific code to map a
> CLOSID+type pair to an index in the configuration arrays.
>
> MPAM needs to do this too to preserve the ABI to user-space, there is
> no reason to do it differently.
>
> Move the helper to a header file.
>
> Signed-off-by: James Morse <james.morse@arm.com>
> ---
> arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 19 +++----------------
> include/linux/resctrl.h | 15 +++++++++++++++
> 2 files changed, 18 insertions(+), 16 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> index 3603ade95f1d..b4627ae19291 100644
> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> @@ -277,19 +277,6 @@ static int parse_line(char *line, struct resctrl_schema *s,
> return -EINVAL;
> }
>
> -static u32 get_config_index(u32 closid, enum resctrl_conf_type type)
> -{
> - switch (type) {
> - default:
> - case CDP_NONE:
> - return closid;
> - case CDP_CODE:
> - return closid * 2 + 1;
> - case CDP_DATA:
> - return closid * 2;
> - }
> -}
> -
> static bool apply_config(struct rdt_hw_domain *hw_dom,
> struct resctrl_staged_config *cfg, u32 idx,
> cpumask_var_t cpu_mask)
> @@ -311,7 +298,7 @@ int resctrl_arch_update_one(struct rdt_resource *r, struct rdt_domain *d,
> {
> struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
> struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(d);
> - u32 idx = get_config_index(closid, t);
> + u32 idx = resctrl_get_config_index(closid, t);
> struct msr_param msr_param;
>
> if (!cpumask_test_cpu(smp_processor_id(), &d->cpu_mask))
> @@ -351,7 +338,7 @@ int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid)
> if (!cfg->have_new_ctrl)
> continue;
>
> - idx = get_config_index(closid, t);
> + idx = resctrl_get_config_index(closid, t);
> if (!apply_config(hw_dom, cfg, idx, cpu_mask))
> continue;
>
> @@ -476,7 +463,7 @@ u32 resctrl_arch_get_config(struct rdt_resource *r, struct rdt_domain *d,
> u32 closid, enum resctrl_conf_type type)
> {
> struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(d);
> - u32 idx = get_config_index(closid, type);
> + u32 idx = resctrl_get_config_index(closid, type);
>
> return hw_dom->ctrl_val[idx];
> }
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index 3de5bc63ace0..73c111963433 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -258,6 +258,21 @@ bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt);
> void resctrl_arch_mon_event_config_write(void *info);
> void resctrl_arch_mon_event_config_read(void *info);
>
> +/* For use by arch code to remap resctrl's smaller CDP CLOSID range */
> +static inline u32 resctrl_get_config_index(u32 closid,
> + enum resctrl_conf_type type)
> +{
> + switch (type) {
> + default:
> + case CDP_NONE:
> + return closid;
> + case CDP_CODE:
> + return (closid * 2) + 1;
> + case CDP_DATA:
> + return (closid * 2);
> + }
> +}

(please check the tabs)

This change is unexpected to me. Could you please elaborate how
MPAM's variant of CDP works?

Thank you very much.

Reinette