linux-kernel - [PATCH v3 06/26] fs-x86/rectrl: Improve domain type checking

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Message-ID: <20250407234032.241215-7-tony.luck@intel.com>
Date: Mon,  7 Apr 2025 16:40:08 -0700
From: Tony Luck <tony.luck@...el.com>
To: Fenghua Yu <fenghuay@...dia.com>,
	Reinette Chatre <reinette.chatre@...el.com>,
	Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>,
	Peter Newman <peternewman@...gle.com>,
	James Morse <james.morse@....com>,
	Babu Moger <babu.moger@....com>,
	Drew Fustini <dfustini@...libre.com>,
	Dave Martin <Dave.Martin@....com>,
	Anil Keshavamurthy <anil.s.keshavamurthy@...el.com>
Cc: linux-kernel@...r.kernel.org,
	patches@...ts.linux.dev,
	Tony Luck <tony.luck@...el.com>
Subject: [PATCH v3 06/26] fs-x86/rectrl: Improve domain type checking

The rdt_domain_hdr structure is used in both control and monitor
domain structures to provide common methods for operations such as
adding a CPU to a domain, removing a CPU from a domain, accessing
the mask of all CPUs in a domain.

The "type" field provides a simple check whether a domain is a
control or monitor domain so that programming errors operating
on domains will be quickly caught.

To prepare for additional domain types that depend on the rdt_resource
to which they are connected add the resource id into the type.

Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 include/linux/resctrl.h            | 19 ++++++++++---------
 arch/x86/kernel/cpu/resctrl/core.c | 12 ++++++------
 fs/resctrl/ctrlmondata.c           |  2 +-
 3 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index d6a926b6fc0e..177f9879bae1 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -111,11 +111,6 @@ struct resctrl_staged_config {
 	bool			have_new_ctrl;
 };
 
-enum resctrl_domain_type {
-	RESCTRL_CTRL_DOMAIN,
-	RESCTRL_MON_DOMAIN,
-};
-
 /**
  * struct rdt_domain_hdr - common header for different domain types
  * @list:		all instances of this resource
@@ -124,12 +119,18 @@ enum resctrl_domain_type {
  * @cpu_mask:		which CPUs share this resource
  */
 struct rdt_domain_hdr {
-	struct list_head		list;
-	int				id;
-	enum resctrl_domain_type	type;
-	struct cpumask			cpu_mask;
+	struct list_head	list;
+	int			id;
+	u32			type;
+	struct cpumask		cpu_mask;
 };
 
+/* Bitfields in rdt_domain_hdr.type */
+#define	DOMTYPE_RID		GENMASK(8, 0)
+#define DOMTYPE_CTRL		BIT(9)
+#define DOMTYPE_MON		BIT(10)
+#define DOMTYPE(rid, type)	(((rid) & DOMTYPE_RID) | (type))
+
 /**
  * struct rdt_ctrl_domain - group of CPUs sharing a resctrl control resource
  * @hdr:		common header for different domain types
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 6f4a3bd02a42..d82a4a2db699 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -457,7 +457,7 @@ static void domain_add_cpu_ctrl(int cpu, struct rdt_resource *r)
 
 	hdr = resctrl_find_domain(&r->ctrl_domains, id, &add_pos);
 	if (hdr) {
-		if (WARN_ON_ONCE(hdr->type != RESCTRL_CTRL_DOMAIN))
+		if (WARN_ON_ONCE(hdr->type != DOMTYPE(r->rid, DOMTYPE_CTRL)))
 			return;
 		d = container_of(hdr, struct rdt_ctrl_domain, hdr);
 
@@ -473,7 +473,7 @@ static void domain_add_cpu_ctrl(int cpu, struct rdt_resource *r)
 
 	d = &hw_dom->d_resctrl;
 	d->hdr.id = id;
-	d->hdr.type = RESCTRL_CTRL_DOMAIN;
+	d->hdr.type = DOMTYPE(r->rid, DOMTYPE_CTRL);
 	cpumask_set_cpu(cpu, &d->hdr.cpu_mask);
 
 	rdt_domain_reconfigure_cdp(r);
@@ -512,7 +512,7 @@ static void domain_add_cpu_mon(int cpu, struct rdt_resource *r)
 
 	hdr = resctrl_find_domain(&r->mon_domains, id, &add_pos);
 	if (hdr) {
-		if (WARN_ON_ONCE(hdr->type != RESCTRL_MON_DOMAIN))
+		if (WARN_ON_ONCE(hdr->type != DOMTYPE(r->rid, DOMTYPE_MON)))
 			return;
 		d = container_of(hdr, struct rdt_mon_domain, hdr);
 
@@ -526,7 +526,7 @@ static void domain_add_cpu_mon(int cpu, struct rdt_resource *r)
 
 	d = &hw_dom->d_resctrl;
 	d->hdr.id = id;
-	d->hdr.type = RESCTRL_MON_DOMAIN;
+	d->hdr.type = DOMTYPE(r->rid, DOMTYPE_MON);
 	d->ci = get_cpu_cacheinfo_level(cpu, RESCTRL_L3_CACHE);
 	if (!d->ci) {
 		pr_warn_once("Can't find L3 cache for CPU:%d resource %s\n", cpu, r->name);
@@ -582,7 +582,7 @@ static void domain_remove_cpu_ctrl(int cpu, struct rdt_resource *r)
 		return;
 	}
 
-	if (WARN_ON_ONCE(hdr->type != RESCTRL_CTRL_DOMAIN))
+	if (WARN_ON_ONCE(hdr->type != DOMTYPE(r->rid, DOMTYPE_CTRL)))
 		return;
 
 	d = container_of(hdr, struct rdt_ctrl_domain, hdr);
@@ -628,7 +628,7 @@ static void domain_remove_cpu_mon(int cpu, struct rdt_resource *r)
 		return;
 	}
 
-	if (WARN_ON_ONCE(hdr->type != RESCTRL_MON_DOMAIN))
+	if (WARN_ON_ONCE(hdr->type != DOMTYPE(r->rid, DOMTYPE_MON)))
 		return;
 
 	d = container_of(hdr, struct rdt_mon_domain, hdr);
diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
index ce02e961a6c3..0c245af0ff42 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -614,7 +614,7 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
 		 * the resource to find the domain with "domid".
 		 */
 		hdr = resctrl_find_domain(&r->mon_domains, domid, NULL);
-		if (!hdr || WARN_ON_ONCE(hdr->type != RESCTRL_MON_DOMAIN)) {
+		if (!hdr || WARN_ON_ONCE(hdr->type != DOMTYPE(r->rid, DOMTYPE_MON))) {
 			ret = -ENOENT;
 			goto out;
 		}
-- 
2.48.1