x86/resctrl: Prepare for new domain scope

Resctrl resources operate on subsets of CPUs in the system with the
defining attribute of each subset being an instance of a particular
level of cache. E.g. all CPUs sharing an L3 cache would be part of the
same domain.

In preparation for features that are scoped at the NUMA node level,
change the code from explicit references to "cache_level" to a more
generic scope. At this point the only options for this scope are groups
of CPUs that share an L2 cache or L3 cache.

Clean up the error handling when looking up domains. Report invalid ids
before calling rdt_find_domain() in preparation for better messages when
scope can be other than cache scope. This means that rdt_find_domain()
will never return an error. So remove checks for error from the call sites.
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20240628215619.76401-2-tony.luck@intel.com

arch/x86/kernel/cpu/resctrl/core.c

@@ -68,7 +68,7 @@ struct rdt_hw_resource rdt_resources_all[] = {
 		.r_resctrl = {
 			.rid			= RDT_RESOURCE_L3,
 			.name			= "L3",
-			.cache_level		= 3,
+			.scope			= RESCTRL_L3_CACHE,
 			.domains		= domain_init(RDT_RESOURCE_L3),
 			.parse_ctrlval		= parse_cbm,
 			.format_str		= "%d=%0*x",
@@ -82,7 +82,7 @@ struct rdt_hw_resource rdt_resources_all[] = {
 		.r_resctrl = {
 			.rid			= RDT_RESOURCE_L2,
 			.name			= "L2",
-			.cache_level		= 2,
+			.scope			= RESCTRL_L2_CACHE,
 			.domains		= domain_init(RDT_RESOURCE_L2),
 			.parse_ctrlval		= parse_cbm,
 			.format_str		= "%d=%0*x",
@@ -96,7 +96,7 @@ struct rdt_hw_resource rdt_resources_all[] = {
 		.r_resctrl = {
 			.rid			= RDT_RESOURCE_MBA,
 			.name			= "MB",
-			.cache_level		= 3,
+			.scope			= RESCTRL_L3_CACHE,
 			.domains		= domain_init(RDT_RESOURCE_MBA),
 			.parse_ctrlval		= parse_bw,
 			.format_str		= "%d=%*u",
@@ -108,7 +108,7 @@ struct rdt_hw_resource rdt_resources_all[] = {
 		.r_resctrl = {
 			.rid			= RDT_RESOURCE_SMBA,
 			.name			= "SMBA",
-			.cache_level		= 3,
+			.scope			= RESCTRL_L3_CACHE,
 			.domains		= domain_init(RDT_RESOURCE_SMBA),
 			.parse_ctrlval		= parse_bw,
 			.format_str		= "%d=%*u",
@@ -392,9 +392,6 @@ struct rdt_domain *rdt_find_domain(struct rdt_resource *r, int id,
 	struct rdt_domain *d;
 	struct list_head *l;
 
-	if (id < 0)
-		return ERR_PTR(-ENODEV);
-
 	list_for_each(l, &r->domains) {
 		d = list_entry(l, struct rdt_domain, list);
 		/* When id is found, return its domain. */
@@ -484,6 +481,19 @@ static int arch_domain_mbm_alloc(u32 num_rmid, struct rdt_hw_domain *hw_dom)
 	return 0;
 }
 
+static int get_domain_id_from_scope(int cpu, enum resctrl_scope scope)
+{
+	switch (scope) {
+	case RESCTRL_L2_CACHE:
+	case RESCTRL_L3_CACHE:
+		return get_cpu_cacheinfo_id(cpu, scope);
+	default:
+		break;
+	}
+
+	return -EINVAL;
+}
+
 /*
  * domain_add_cpu - Add a cpu to a resource's domain list.
  *
@@ -499,7 +509,7 @@ static int arch_domain_mbm_alloc(u32 num_rmid, struct rdt_hw_domain *hw_dom)
  */
 static void domain_add_cpu(int cpu, struct rdt_resource *r)
 {
-	int id = get_cpu_cacheinfo_id(cpu, r->cache_level);
+	int id = get_domain_id_from_scope(cpu, r->scope);
 	struct list_head *add_pos = NULL;
 	struct rdt_hw_domain *hw_dom;
 	struct rdt_domain *d;
@@ -507,12 +517,14 @@ static void domain_add_cpu(int cpu, struct rdt_resource *r)
 
 	lockdep_assert_held(&domain_list_lock);
 
-	d = rdt_find_domain(r, id, &add_pos);
-	if (IS_ERR(d)) {
-		pr_warn("Couldn't find cache id for CPU %d\n", cpu);
+	if (id < 0) {
+		pr_warn_once("Can't find domain id for CPU:%d scope:%d for resource %s\n",
+			     cpu, r->scope, r->name);
 		return;
 	}
 
+	d = rdt_find_domain(r, id, &add_pos);
+
 	if (d) {
 		cpumask_set_cpu(cpu, &d->cpu_mask);
 		if (r->cache.arch_has_per_cpu_cfg)
@@ -552,15 +564,21 @@ static void domain_add_cpu(int cpu, struct rdt_resource *r)
 
 static void domain_remove_cpu(int cpu, struct rdt_resource *r)
 {
-	int id = get_cpu_cacheinfo_id(cpu, r->cache_level);
+	int id = get_domain_id_from_scope(cpu, r->scope);
 	struct rdt_hw_domain *hw_dom;
 	struct rdt_domain *d;
 
 	lockdep_assert_held(&domain_list_lock);
 
+	if (id < 0) {
+		pr_warn_once("Can't find domain id for CPU:%d scope:%d for resource %s\n",
+			     cpu, r->scope, r->name);
+		return;
+	}
+
 	d = rdt_find_domain(r, id, NULL);
-	if (IS_ERR_OR_NULL(d)) {
-		pr_warn("Couldn't find cache id for CPU %d\n", cpu);
+	if (!d) {
+		pr_warn("Couldn't find domain with id=%d for CPU %d\n", id, cpu);
 		return;
 	}
 	hw_dom = resctrl_to_arch_dom(d);

arch/x86/kernel/cpu/resctrl/ctrlmondata.c

@@ -577,7 +577,7 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
 
 	r = &rdt_resources_all[resid].r_resctrl;
 	d = rdt_find_domain(r, domid, NULL);
-	if (IS_ERR_OR_NULL(d)) {
+	if (!d) {
 		ret = -ENOENT;
 		goto out;
 	}

arch/x86/kernel/cpu/resctrl/pseudo_lock.c

@@ -292,9 +292,13 @@ static void pseudo_lock_region_clear(struct pseudo_lock_region *plr)
  */
 static int pseudo_lock_region_init(struct pseudo_lock_region *plr)
 {
+	enum resctrl_scope scope = plr->s->res->scope;
 	struct cacheinfo *ci;
 	int ret;
 
+	if (WARN_ON_ONCE(scope != RESCTRL_L2_CACHE && scope != RESCTRL_L3_CACHE))
+		return -ENODEV;
+
 	/* Pick the first cpu we find that is associated with the cache. */
 	plr->cpu = cpumask_first(&plr->d->cpu_mask);
 
@@ -305,7 +309,7 @@ static int pseudo_lock_region_init(struct pseudo_lock_region *plr)
 		goto out_region;
 	}
 
-	ci = get_cpu_cacheinfo_level(plr->cpu, plr->s->res->cache_level);
+	ci = get_cpu_cacheinfo_level(plr->cpu, scope);
 	if (ci) {
 		plr->line_size = ci->coherency_line_size;
 		plr->size = rdtgroup_cbm_to_size(plr->s->res, plr->d, plr->cbm);

arch/x86/kernel/cpu/resctrl/rdtgroup.c

@@ -1454,8 +1454,11 @@ unsigned int rdtgroup_cbm_to_size(struct rdt_resource *r,
 	struct cacheinfo *ci;
 	int num_b;
 
+	if (WARN_ON_ONCE(r->scope != RESCTRL_L2_CACHE && r->scope != RESCTRL_L3_CACHE))
+		return size;
+
 	num_b = bitmap_weight(&cbm, r->cache.cbm_len);
-	ci = get_cpu_cacheinfo_level(cpumask_any(&d->cpu_mask), r->cache_level);
+	ci = get_cpu_cacheinfo_level(cpumask_any(&d->cpu_mask), r->scope);
 	if (ci)
 		size = ci->size / r->cache.cbm_len * num_b;
 

include/linux/resctrl.h

@@ -150,13 +150,18 @@ struct resctrl_membw {
 struct rdt_parse_data;
 struct resctrl_schema;
 
+enum resctrl_scope {
+	RESCTRL_L2_CACHE = 2,
+	RESCTRL_L3_CACHE = 3,
+};
+
 /**
  * struct rdt_resource - attributes of a resctrl resource
  * @rid:		The index of the resource
  * @alloc_capable:	Is allocation available on this machine
  * @mon_capable:	Is monitor feature available on this machine
  * @num_rmid:		Number of RMIDs available
- * @cache_level:	Which cache level defines scope of this resource
+ * @scope:		Scope of this resource
  * @cache:		Cache allocation related data
  * @membw:		If the component has bandwidth controls, their properties.
  * @domains:		RCU list of all domains for this resource
@@ -174,7 +179,7 @@ struct rdt_resource {
 	bool			alloc_capable;
 	bool			mon_capable;
 	int			num_rmid;
-	int			cache_level;
+	enum resctrl_scope	scope;
 	struct resctrl_cache	cache;
 	struct resctrl_membw	membw;
 	struct list_head	domains;