Re: [PATCH v6 02/42] x86/resctrl: Add a helper to avoid reaching into the arch code resource list

["Moger, Babu" <babu.moger@amd.com>]

Hi James,

 You probably missed few cases here.

static int logical_rmid_to_physical_rmid(int cpu, int lrmid)
{
  struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
--

}

Any reason not use the new call resctrl_arch_get_resource() here?

Thanks
Babu

On 2/7/25 12:17, James Morse wrote:
> Resctrl occasionally wants to know something about a specific resource,
> in these cases it reaches into the arch code's rdt_resources_all[]
> array.
> 
> Once the filesystem parts of resctrl are moved to /fs/, this means it
> will need visibility of the architecture specific struct
> rdt_hw_resource definition, and the array of all resources.  All
> architectures would also need a r_resctrl member in this struct.
> 
> Instead, abstract this via a helper to allow architectures to do
> different things here. Move the level enum to the resctrl header and
> add a helper to retrieve the struct rdt_resource by 'rid'.
> 
> resctrl_arch_get_resource() should not return NULL for any value in
> the enum, it may instead return a dummy resource that is
> !alloc_enabled && !mon_enabled.
> 
> Co-developed-by: Dave Martin <Dave.Martin@arm.com>
> Signed-off-by: Dave Martin <Dave.Martin@arm.com>
> Signed-off-by: James Morse <james.morse@arm.com>
> Tested-by: Peter Newman <peternewman@google.com>
> Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
> Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
> Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
> Reviewed-by: Tony Luck <tony.luck@intel.com>
> ---
> Change since v5:
>  * Ensure rdt_resources_all[] is always padded to RDT_NUM_RESOURCES
> 
> Changes since v1:
>  * Backed out non-functional renaming of "r" to "l3" in rdt_get_tree(),
>    and unhoisted the assignment of r (as now is) back into the if ()
>    where it started out.  There seem to be no uses of this variable
>    outside this if().
>  * [Commit message only] Typo fix:
>    s/resctrl_hw_resource/rdt_hw_resource/g
> ---
>  arch/x86/kernel/cpu/resctrl/core.c        | 12 ++++++++++--
>  arch/x86/kernel/cpu/resctrl/ctrlmondata.c |  2 +-
>  arch/x86/kernel/cpu/resctrl/internal.h    | 10 ----------
>  arch/x86/kernel/cpu/resctrl/monitor.c     |  8 ++++----
>  arch/x86/kernel/cpu/resctrl/rdtgroup.c    | 14 +++++++-------
>  include/linux/resctrl.h                   | 17 +++++++++++++++++
>  6 files changed, 39 insertions(+), 24 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
> index 3d1735ed8d1f..12b41316d8f7 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -62,7 +62,7 @@ static void mba_wrmsr_amd(struct msr_param *m);
>  #define ctrl_domain_init(id) LIST_HEAD_INIT(rdt_resources_all[id].r_resctrl.ctrl_domains)
>  #define mon_domain_init(id) LIST_HEAD_INIT(rdt_resources_all[id].r_resctrl.mon_domains)
>  
> -struct rdt_hw_resource rdt_resources_all[] = {
> +struct rdt_hw_resource rdt_resources_all[RDT_NUM_RESOURCES] = {
>  	[RDT_RESOURCE_L3] =
>  	{
>  		.r_resctrl = {
> @@ -127,6 +127,14 @@ u32 resctrl_arch_system_num_rmid_idx(void)
>  	return r->num_rmid;
>  }
>  
> +struct rdt_resource *resctrl_arch_get_resource(enum resctrl_res_level l)
> +{
> +	if (l >= RDT_NUM_RESOURCES)
> +		return NULL;
> +
> +	return &rdt_resources_all[l].r_resctrl;
> +}
> +
>  /*
>   * cache_alloc_hsw_probe() - Have to probe for Intel haswell server CPUs
>   * as they do not have CPUID enumeration support for Cache allocation.
> @@ -174,7 +182,7 @@ static inline void cache_alloc_hsw_probe(void)
>  bool is_mba_sc(struct rdt_resource *r)
>  {
>  	if (!r)
> -		return rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl.membw.mba_sc;
> +		r = resctrl_arch_get_resource(RDT_RESOURCE_MBA);
>  
>  	/*
>  	 * The software controller support is only applicable to MBA resource.
> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> index 536351159cc2..4af27ef5a8a1 100644
> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> @@ -649,7 +649,7 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
>  	resid = md.u.rid;
>  	domid = md.u.domid;
>  	evtid = md.u.evtid;
> -	r = &rdt_resources_all[resid].r_resctrl;
> +	r = resctrl_arch_get_resource(resid);
>  
>  	if (md.u.sum) {
>  		/*
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 20c898f09b7e..75252a7e1ebc 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -512,16 +512,6 @@ extern struct rdtgroup rdtgroup_default;
>  extern struct dentry *debugfs_resctrl;
>  extern enum resctrl_event_id mba_mbps_default_event;
>  
> -enum resctrl_res_level {
> -	RDT_RESOURCE_L3,
> -	RDT_RESOURCE_L2,
> -	RDT_RESOURCE_MBA,
> -	RDT_RESOURCE_SMBA,
> -
> -	/* Must be the last */
> -	RDT_NUM_RESOURCES,
> -};
> -
>  static inline struct rdt_resource *resctrl_inc(struct rdt_resource *res)
>  {
>  	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(res);
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
> index 94a1d9780461..58b5b21349a8 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -365,7 +365,7 @@ static void limbo_release_entry(struct rmid_entry *entry)
>   */
>  void __check_limbo(struct rdt_mon_domain *d, bool force_free)
>  {
> -	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> +	struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
>  	u32 idx_limit = resctrl_arch_system_num_rmid_idx();
>  	struct rmid_entry *entry;
>  	u32 idx, cur_idx = 1;
> @@ -521,7 +521,7 @@ int alloc_rmid(u32 closid)
>  
>  static void add_rmid_to_limbo(struct rmid_entry *entry)
>  {
> -	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> +	struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
>  	struct rdt_mon_domain *d;
>  	u32 idx;
>  
> @@ -761,7 +761,7 @@ static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_mon_domain *dom_mbm)
>  	struct rdtgroup *entry;
>  	u32 cur_bw, user_bw;
>  
> -	r_mba = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
> +	r_mba = resctrl_arch_get_resource(RDT_RESOURCE_MBA);
>  	evt_id = rgrp->mba_mbps_event;
>  
>  	closid = rgrp->closid;
> @@ -925,7 +925,7 @@ void mbm_handle_overflow(struct work_struct *work)
>  	if (!resctrl_mounted || !resctrl_arch_mon_capable())
>  		goto out_unlock;
>  
> -	r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> +	r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
>  	d = container_of(work, struct rdt_mon_domain, mbm_over.work);
>  
>  	list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 04b653d613e8..45093b9e8e63 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -2256,7 +2256,7 @@ static void l2_qos_cfg_update(void *arg)
>  
>  static inline bool is_mba_linear(void)
>  {
> -	return rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl.membw.delay_linear;
> +	return resctrl_arch_get_resource(RDT_RESOURCE_MBA)->membw.delay_linear;
>  }
>  
>  static int set_cache_qos_cfg(int level, bool enable)
> @@ -2346,8 +2346,8 @@ static void mba_sc_domain_destroy(struct rdt_resource *r,
>   */
>  static bool supports_mba_mbps(void)
>  {
> -	struct rdt_resource *rmbm = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> -	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
> +	struct rdt_resource *rmbm = resctrl_arch_get_resource(RDT_RESOURCE_L3);
> +	struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_MBA);
>  
>  	return (is_mbm_enabled() &&
>  		r->alloc_capable && is_mba_linear() &&
> @@ -2360,7 +2360,7 @@ static bool supports_mba_mbps(void)
>   */
>  static int set_mba_sc(bool mba_sc)
>  {
> -	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
> +	struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_MBA);
>  	u32 num_closid = resctrl_arch_get_num_closid(r);
>  	struct rdt_ctrl_domain *d;
>  	unsigned long fflags;
> @@ -2714,7 +2714,7 @@ static int rdt_get_tree(struct fs_context *fc)
>  		resctrl_mounted = true;
>  
>  	if (is_mbm_enabled()) {
> -		r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> +		r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
>  		list_for_each_entry(dom, &r->mon_domains, hdr.list)
>  			mbm_setup_overflow_handler(dom, MBM_OVERFLOW_INTERVAL,
>  						   RESCTRL_PICK_ANY_CPU);
> @@ -3951,7 +3951,7 @@ static int rdtgroup_show_options(struct seq_file *seq, struct kernfs_root *kf)
>  	if (resctrl_arch_get_cdp_enabled(RDT_RESOURCE_L2))
>  		seq_puts(seq, ",cdpl2");
>  
> -	if (is_mba_sc(&rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl))
> +	if (is_mba_sc(resctrl_arch_get_resource(RDT_RESOURCE_MBA)))
>  		seq_puts(seq, ",mba_MBps");
>  
>  	if (resctrl_debug)
> @@ -4151,7 +4151,7 @@ static void clear_childcpus(struct rdtgroup *r, unsigned int cpu)
>  
>  void resctrl_offline_cpu(unsigned int cpu)
>  {
> -	struct rdt_resource *l3 = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> +	struct rdt_resource *l3 = resctrl_arch_get_resource(RDT_RESOURCE_L3);
>  	struct rdt_mon_domain *d;
>  	struct rdtgroup *rdtgrp;
>  
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index d94abba1c716..37279e2a89da 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -37,6 +37,16 @@ enum resctrl_conf_type {
>  	CDP_DATA,
>  };
>  
> +enum resctrl_res_level {
> +	RDT_RESOURCE_L3,
> +	RDT_RESOURCE_L2,
> +	RDT_RESOURCE_MBA,
> +	RDT_RESOURCE_SMBA,
> +
> +	/* Must be the last */
> +	RDT_NUM_RESOURCES,
> +};
> +
>  #define CDP_NUM_TYPES	(CDP_DATA + 1)
>  
>  /*
> @@ -226,6 +236,13 @@ struct rdt_resource {
>  	bool			cdp_capable;
>  };
>  
> +/*
> + * Get the resource that exists at this level. If the level is not supported
> + * a dummy/not-capable resource can be returned. Levels >= RDT_NUM_RESOURCES
> + * will return NULL.
> + */
> +struct rdt_resource *resctrl_arch_get_resource(enum resctrl_res_level l);
> +
>  /**
>   * struct resctrl_schema - configuration abilities of a resource presented to
>   *			   user-space

-- 
Thanks
Babu Moger