Re: [PATCH v14 06/24] arm,x86,fs/resctrl: Replace architecture capability helpers with generic versions

[Ben Horgan]

Hi Tony,

On 19/10/2026 21:50, Tony Luck wrote:
> resctrl supports allocation or monitoring if any resource is capable of
> it. Each architecture answers this via resctrl_arch_alloc_capable() and
> resctrl_arch_mon_capable(). x86 maintains global flags for this in
> addition to the per-resource flags and must keep both in sync. MPAM
> derives the answer from its per-resource flags.
> 
> The per-resource flags are part of the resource description that the file
> system already has, so the architecture helpers duplicate information
> available to the file system.
> 
> Define resctrl_alloc_capable() and resctrl_mon_capable() in the file system
> based on the per-resource flags and remove the architecture helpers, in
> preparation for removing the x86 global flags. The result is unchanged for
> MPAM, which presents all monitors on the L3 resource.
> 
> Suggested-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
> Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>

Looks good to me. For the MPAM parts:

Acked-by: Ben Horgan <ben.horgan@xxxxxxx>

Thanks,

Ben

> ---
> v14:
> 	New Subject: without {alloc,mon}
> 	New commit message in context, problem, solution format
> 	Did not apply Reinette RB tag because of commit message rewrite.
> ---
>  include/linux/arm_mpam.h       |  3 ---
>  include/linux/resctrl.h        | 30 ++++++++++++++++++++++++++++
>  arch/x86/include/asm/resctrl.h | 10 ----------
>  drivers/resctrl/mpam_resctrl.c | 26 ++----------------------
>  fs/resctrl/monitor.c           | 10 +++++-----
>  fs/resctrl/pseudo_lock.c       |  6 +++---
>  fs/resctrl/rdtgroup.c          | 36 +++++++++++++++++-----------------
>  7 files changed, 58 insertions(+), 63 deletions(-)
> 
> diff --git a/include/linux/arm_mpam.h b/include/linux/arm_mpam.h
> index f92a36187a52..ba4131048260 100644
> --- a/include/linux/arm_mpam.h
> +++ b/include/linux/arm_mpam.h
> @@ -50,9 +50,6 @@ static inline int mpam_ris_create(struct mpam_msc *msc, u8 ris_idx,
>  }
>  #endif
>  
> -bool resctrl_arch_alloc_capable(void);
> -bool resctrl_arch_mon_capable(void);
> -
>  void resctrl_arch_set_cpu_default_closid(int cpu, u32 closid);
>  void resctrl_arch_set_closid_rmid(struct task_struct *tsk, u32 closid, u32 rmid);
>  void resctrl_arch_set_cpu_default_closid_rmid(int cpu, u32 closid, u32 rmid);
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index 10dfdca7f4bf..0e7fce070fde 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -346,6 +346,36 @@ struct rdt_resource {
>   */
>  struct rdt_resource *resctrl_arch_get_resource(enum resctrl_res_level l);
>  
> +/*
> + * resctrl_alloc_capable - Are any allocation resources enabled?
> + */
> +static inline bool resctrl_alloc_capable(void)
> +{
> +	struct rdt_resource *r;
> +
> +	for_each_rdt_resource(r) {
> +		if (r->alloc_capable)
> +			return true;
> +	}
> +
> +	return false;
> +}
> +
> +/*
> + * resctrl_mon_capable - Are any monitor resources enabled?
> + */
> +static inline bool resctrl_mon_capable(void)
> +{
> +	struct rdt_resource *r;
> +
> +	for_each_rdt_resource(r) {
> +		if (r->mon_capable)
> +			return true;
> +	}
> +
> +	return false;
> +}
> +
>  /**
>   * struct resctrl_schema - configuration abilities of a resource presented to
>   *			   user-space
> diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h
> index 2031b30ff25b..9c44a7766631 100644
> --- a/arch/x86/include/asm/resctrl.h
> +++ b/arch/x86/include/asm/resctrl.h
> @@ -50,11 +50,6 @@ DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
>  DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key);
>  DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);
>  
> -static inline bool resctrl_arch_alloc_capable(void)
> -{
> -	return rdt_alloc_capable;
> -}
> -
>  static inline void resctrl_arch_enable_alloc(void)
>  {
>  	static_branch_enable_cpuslocked(&rdt_alloc_enable_key);
> @@ -67,11 +62,6 @@ static inline void resctrl_arch_disable_alloc(void)
>  	static_branch_dec_cpuslocked(&rdt_enable_key);
>  }
>  
> -static inline bool resctrl_arch_mon_capable(void)
> -{
> -	return rdt_mon_capable;
> -}
> -
>  static inline void resctrl_arch_enable_mon(void)
>  {
>  	static_branch_enable_cpuslocked(&rdt_mon_enable_key);
> diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
> index f2c651e9f6ea..7ddee8f5162f 100644
> --- a/drivers/resctrl/mpam_resctrl.c
> +++ b/drivers/resctrl/mpam_resctrl.c
> @@ -75,28 +75,6 @@ static DECLARE_WAIT_QUEUE_HEAD(wait_cacheinfo_ready);
>   */
>  static bool resctrl_enabled;
>  
> -bool resctrl_arch_alloc_capable(void)
> -{
> -	struct mpam_resctrl_res *res;
> -	enum resctrl_res_level rid;
> -
> -	for_each_mpam_resctrl_control(res, rid) {
> -		if (res->resctrl_res.alloc_capable)
> -			return true;
> -	}
> -
> -	return false;
> -}
> -
> -bool resctrl_arch_mon_capable(void)
> -{
> -	struct mpam_resctrl_res *res = &mpam_resctrl_controls[RDT_RESOURCE_L3];
> -	struct rdt_resource *l3 = &res->resctrl_res;
> -
> -	/* All monitors are presented as being on the L3 cache */
> -	return l3->mon_capable;
> -}
> -
>  bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt)
>  {
>  	return false;
> @@ -1902,9 +1880,9 @@ int mpam_resctrl_setup(void)
>  
>  	cpus_read_unlock();
>  
> -	if (!resctrl_arch_alloc_capable() && !resctrl_arch_mon_capable()) {
> +	if (!resctrl_alloc_capable() && !resctrl_mon_capable()) {
>  		pr_debug("No alloc(%u) or monitor(%u) found - resctrl not supported\n",
> -			 resctrl_arch_alloc_capable(), resctrl_arch_mon_capable());
> +			 resctrl_alloc_capable(), resctrl_mon_capable());
>  		return -EOPNOTSUPP;
>  	}
>  
> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
> index 04e4ea612b7c..cb34d3637ee5 100644
> --- a/fs/resctrl/monitor.c
> +++ b/fs/resctrl/monitor.c
> @@ -338,7 +338,7 @@ void free_rmid(u32 closid, u32 rmid)
>  	 * allows architectures that ignore the closid parameter to avoid an
>  	 * unnecessary check.
>  	 */
> -	if (!resctrl_arch_mon_capable() ||
> +	if (!resctrl_mon_capable() ||
>  	    idx == resctrl_arch_rmid_idx_encode(RESCTRL_RESERVED_CLOSID,
>  						RESCTRL_RESERVED_RMID))
>  		return;
> @@ -888,7 +888,7 @@ void mbm_handle_overflow(struct work_struct *work)
>  	 * If the filesystem has been unmounted this work no longer needs to
>  	 * run.
>  	 */
> -	if (!resctrl_mounted || !resctrl_arch_mon_capable())
> +	if (!resctrl_mounted || !resctrl_mon_capable())
>  		goto out_unlock;
>  
>  	/*
> @@ -950,7 +950,7 @@ void mbm_setup_overflow_handler(struct rdt_l3_mon_domain *dom, unsigned long del
>  	 * When a domain comes online there is no guarantee the filesystem is
>  	 * mounted. If not, there is no need to catch counter overflow.
>  	 */
> -	if (!resctrl_mounted || !resctrl_arch_mon_capable())
> +	if (!resctrl_mounted || !resctrl_mon_capable())
>  		return;
>  	cpu = cpumask_any_housekeeping(&dom->hdr.cpu_mask, exclude_cpu);
>  	dom->mbm_work_cpu = cpu;
> @@ -966,7 +966,7 @@ int setup_rmid_lru_list(void)
>  	u32 idx;
>  	int i;
>  
> -	if (!resctrl_arch_mon_capable())
> +	if (!resctrl_mon_capable())
>  		return 0;
>  
>  	/*
> @@ -1006,7 +1006,7 @@ int setup_rmid_lru_list(void)
>  
>  void free_rmid_lru_list(void)
>  {
> -	if (!resctrl_arch_mon_capable())
> +	if (!resctrl_mon_capable())
>  		return;
>  
>  	mutex_lock(&rdtgroup_mutex);
> diff --git a/fs/resctrl/pseudo_lock.c b/fs/resctrl/pseudo_lock.c
> index 56ab63f19bad..3d831227a42f 100644
> --- a/fs/resctrl/pseudo_lock.c
> +++ b/fs/resctrl/pseudo_lock.c
> @@ -383,7 +383,7 @@ static int rdtgroup_locksetup_user_restrict(struct rdtgroup *rdtgrp)
>  	if (ret)
>  		goto err_cpus;
>  
> -	if (resctrl_arch_mon_capable()) {
> +	if (resctrl_mon_capable()) {
>  		ret = rdtgroup_kn_mode_restrict(rdtgrp, "mon_groups");
>  		if (ret)
>  			goto err_cpus_list;
> @@ -430,7 +430,7 @@ static int rdtgroup_locksetup_user_restore(struct rdtgroup *rdtgrp)
>  	if (ret)
>  		goto err_cpus;
>  
> -	if (resctrl_arch_mon_capable()) {
> +	if (resctrl_mon_capable()) {
>  		ret = rdtgroup_kn_mode_restore(rdtgrp, "mon_groups", 0777);
>  		if (ret)
>  			goto err_cpus_list;
> @@ -577,7 +577,7 @@ int rdtgroup_locksetup_exit(struct rdtgroup *rdtgrp)
>  {
>  	int ret;
>  
> -	if (resctrl_arch_mon_capable()) {
> +	if (resctrl_mon_capable()) {
>  		ret = alloc_rmid(rdtgrp->closid);
>  		if (ret < 0) {
>  			rdt_last_cmd_puts("Out of RMIDs\n");
> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
> index 57ab090072c2..96a4978ce6b6 100644
> --- a/fs/resctrl/rdtgroup.c
> +++ b/fs/resctrl/rdtgroup.c
> @@ -691,7 +691,7 @@ static bool is_closid_match(struct task_struct *t, struct rdtgroup *r)
>  
>  static bool is_rmid_match(struct task_struct *t, struct rdtgroup *r)
>  {
> -	return (resctrl_arch_mon_capable() && (r->type == RDTMON_GROUP) &&
> +	return (resctrl_mon_capable() && (r->type == RDTMON_GROUP) &&
>  		resctrl_arch_match_rmid(t, r->mon.parent->closid,
>  					r->mon.rmid));
>  }
> @@ -3157,9 +3157,9 @@ static void resctrl_unmount(void)
>  		resctrl_arch_reset_all_ctrls(r);
>  
>  	resctrl_fs_teardown();
> -	if (resctrl_arch_alloc_capable())
> +	if (resctrl_alloc_capable())
>  		resctrl_arch_disable_alloc();
> -	if (resctrl_arch_mon_capable())
> +	if (resctrl_mon_capable())
>  		resctrl_arch_disable_mon();
>  	resctrl_mounted = false;
>  	mutex_unlock(&rdtgroup_mutex);
> @@ -3213,7 +3213,7 @@ static int rdt_get_tree(struct fs_context *fc)
>  	if (ret)
>  		goto out_schemata_free;
>  
> -	if (resctrl_arch_mon_capable())
> +	if (resctrl_mon_capable())
>  		flags |= RFTYPE_MON;
>  
>  	ret = rdtgroup_add_files(rdtgroup_default.kn, flags);
> @@ -3226,7 +3226,7 @@ static int rdt_get_tree(struct fs_context *fc)
>  	if (ret < 0)
>  		goto out_closid_exit;
>  
> -	if (resctrl_arch_mon_capable()) {
> +	if (resctrl_mon_capable()) {
>  		ret = mongroup_create_dir(rdtgroup_default.kn,
>  					  &rdtgroup_default, "mon_groups",
>  					  &kn_mongrp);
> @@ -3246,12 +3246,12 @@ static int rdt_get_tree(struct fs_context *fc)
>  	if (ret)
>  		goto out_mondata;
>  
> -	if (resctrl_arch_alloc_capable())
> +	if (resctrl_alloc_capable())
>  		resctrl_arch_enable_alloc();
> -	if (resctrl_arch_mon_capable())
> +	if (resctrl_mon_capable())
>  		resctrl_arch_enable_mon();
>  
> -	if (resctrl_arch_alloc_capable() || resctrl_arch_mon_capable())
> +	if (resctrl_alloc_capable() || resctrl_mon_capable())
>  		resctrl_mounted = true;
>  
>  	if (resctrl_is_mbm_enabled()) {
> @@ -3294,10 +3294,10 @@ static int rdt_get_tree(struct fs_context *fc)
>  	return ret;
>  
>  out_mondata:
> -	if (resctrl_arch_mon_capable())
> +	if (resctrl_mon_capable())
>  		kernfs_remove(kn_mondata);
>  out_mongrp:
> -	if (resctrl_arch_mon_capable()) {
> +	if (resctrl_mon_capable()) {
>  		mon_put_kn_priv();
>  		rdtgroup_unassign_cntrs(&rdtgroup_default);
>  		kernfs_remove(kn_mongrp);
> @@ -3886,7 +3886,7 @@ static int mkdir_rdt_prepare_rmid_alloc(struct rdtgroup *rdtgrp)
>  {
>  	int ret;
>  
> -	if (!resctrl_arch_mon_capable())
> +	if (!resctrl_mon_capable())
>  		return 0;
>  
>  	ret = alloc_rmid(rdtgrp->closid);
> @@ -3911,7 +3911,7 @@ static int mkdir_rdt_prepare_rmid_alloc(struct rdtgroup *rdtgrp)
>  
>  static void mkdir_rdt_prepare_rmid_free(struct rdtgroup *rgrp)
>  {
> -	if (resctrl_arch_mon_capable()) {
> +	if (resctrl_mon_capable()) {
>  		rdtgroup_unassign_cntrs(rgrp);
>  		free_rmid(rgrp->closid, rgrp->mon.rmid);
>  	}
> @@ -4002,7 +4002,7 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
>  
>  	if (rtype == RDTCTRL_GROUP) {
>  		files = RFTYPE_BASE | RFTYPE_CTRL;
> -		if (resctrl_arch_mon_capable())
> +		if (resctrl_mon_capable())
>  			files |= RFTYPE_MON;
>  	} else {
>  		files = RFTYPE_BASE | RFTYPE_MON;
> @@ -4111,7 +4111,7 @@ static int rdtgroup_mkdir_ctrl_mon(struct kernfs_node *parent_kn,
>  
>  	list_add(&rdtgrp->rdtgroup_list, &rdt_all_groups);
>  
> -	if (resctrl_arch_mon_capable()) {
> +	if (resctrl_mon_capable()) {
>  		/*
>  		 * Create an empty mon_groups directory to hold the subset
>  		 * of tasks and cpus to monitor.
> @@ -4152,11 +4152,11 @@ static int rdtgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
>  	 * allocation is supported, add a control and monitoring
>  	 * subdirectory
>  	 */
> -	if (resctrl_arch_alloc_capable() && parent_kn == rdtgroup_default.kn)
> +	if (resctrl_alloc_capable() && parent_kn == rdtgroup_default.kn)
>  		return rdtgroup_mkdir_ctrl_mon(parent_kn, name, mode);
>  
>  	/* Else, attempt to add a monitoring subdirectory. */
> -	if (resctrl_arch_mon_capable())
> +	if (resctrl_mon_capable())
>  		return rdtgroup_mkdir_mon(parent_kn, name, mode);
>  
>  	return -EPERM;
> @@ -4571,7 +4571,7 @@ void resctrl_offline_mon_domain(struct rdt_resource *r, struct rdt_domain_hdr *h
>  	 * If resctrl is mounted, remove all the
>  	 * per domain monitor data directories.
>  	 */
> -	if (resctrl_mounted && resctrl_arch_mon_capable())
> +	if (resctrl_mounted && resctrl_mon_capable())
>  		rmdir_mondata_subdir_allrdtgrp(r, hdr);
>  
>  	if (r->rid != RDT_RESOURCE_L3)
> @@ -4708,7 +4708,7 @@ int resctrl_online_mon_domain(struct rdt_resource *r, struct rdt_domain_hdr *hdr
>  	 * by rdt_get_tree() calling mkdir_mondata_all().
>  	 * If resctrl is mounted, add per domain monitor data directories.
>  	 */
> -	if (resctrl_mounted && resctrl_arch_mon_capable())
> +	if (resctrl_mounted && resctrl_mon_capable())
>  		mkdir_mondata_subdir_allrdtgrp(r, hdr);
>  
>  out_unlock: