Re: [PATCH 6/7] x86/resctrl: Introduce interface to display SDCIAE Capacity Bit Masks

[Reinette Chatre <reinette.chatre@xxxxxxxxx>]

Hi Babu,

On 8/16/24 9:16 AM, Babu Moger wrote:
> When enabled, SDCIAE forces all SDCI lines to be placed into the L3 cache
> partitions identified by the highest-supported L3_MASK_n register where
> n is the maximum CLOSID supported.
>
> Add the interface to display CBMs (Capacity Bit Mask) of the SDCIAE.
>
> Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> ---
>   arch/x86/kernel/cpu/resctrl/ctrlmondata.c |  2 +-
>   arch/x86/kernel/cpu/resctrl/internal.h    |  1 +
>   arch/x86/kernel/cpu/resctrl/rdtgroup.c    | 29 +++++++++++++++++++++++
>   3 files changed, 31 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> index 50fa1fe9a073..fc99f4d17e6c 100644
> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> @@ -439,7 +439,7 @@ u32 resctrl_arch_get_config(struct rdt_resource *r, struct rdt_ctrl_domain *d,
>   	return hw_dom->ctrl_val[idx];
>   }
>   
> -static void show_doms(struct seq_file *s, struct resctrl_schema *schema, int closid)
> +void show_doms(struct seq_file *s, struct resctrl_schema *schema, int closid)
>   {
>   	struct rdt_resource *r = schema->res;
>   	struct rdt_ctrl_domain *dom;
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 9a3da6d49144..f2c87ca37b13 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -663,6 +663,7 @@ void __init thread_throttle_mode_init(void);
>   void __init mbm_config_rftype_init(const char *config);
>   void rdt_staged_configs_clear(void);
>   void __init resctrl_sdciae_rftype_init(void);
> +void show_doms(struct seq_file *s, struct resctrl_schema *schema, int closid);
>   bool closid_allocated(unsigned int closid);
>   int resctrl_find_cleanest_closid(void);
>   
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 58e4df195207..51bc715bb6ae 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -1922,6 +1922,25 @@ static ssize_t resctrl_sdciae_write(struct kernfs_open_file *of, char *buf,
>   	return ret ?: nbytes;
>   }
>   
> +static int resctrl_sdciae_cbm_show(struct kernfs_open_file *of,
> +				   struct seq_file *seq, void *v)
> +{
> +	struct resctrl_schema *s = of->kn->parent->priv;
> +	struct rdt_resource *r = s->res;
> +	u32 sdciae_closid;
> +
> +	if (!resctrl_arch_get_sdciae_enabled(RDT_RESOURCE_L3)) {

(same issue with this file appearing in all cache resources, eg. L2)

> +		rdt_last_cmd_puts("SDCIAE is not enabled\n");
> +		return -EINVAL;
> +	}
> +
> +	sdciae_closid = get_sdciae_closid(r);
> +
> +	show_doms(seq, s, sdciae_closid);
> +
> +	return 0;
> +}

This really needs protection. (You should have encountered warnings
via lockdep_assert_held(&rdtgroup_mutex) and lockdep_assert_cpus_held()
found in the functions called.)

> +
>   /* rdtgroup information files for one cache resource. */
>   static struct rftype res_common_files[] = {
>   	{
> @@ -2081,6 +2100,12 @@ static struct rftype res_common_files[] = {
>   		.seq_show	= resctrl_sdciae_show,
>   		.write		= resctrl_sdciae_write,
>   	},
> +	{
> +		.name		= "sdciae_cbm",
> +		.mode		= 0444,
> +		.kf_ops		= &rdtgroup_kf_single_ops,
> +		.seq_show	= resctrl_sdciae_cbm_show,
> +	},
>   	{
>   		.name		= "mode",
>   		.mode		= 0644,
> @@ -2187,6 +2212,10 @@ void __init resctrl_sdciae_rftype_init(void)
>   	rft = rdtgroup_get_rftype_by_name("sdciae");
>   	if (rft)
>   		rft->fflags = RFTYPE_CTRL_INFO | RFTYPE_RES_CACHE;
> +
> +	rft = rdtgroup_get_rftype_by_name("sdciae_cbm");
> +	if (rft)
> +		rft->fflags = RFTYPE_CTRL_INFO | RFTYPE_RES_CACHE;
>   }
>   
>   /**

Reinette