[PATCH v4 03/24] x86/resctrl: Add a separate schema list for resctrl

From: James Morse
Date: Mon Jun 14 2021 - 16:10:18 EST


Resctrl exposes schemata to user-space, which allow the control values
to be specified for a group of tasks.

User-visible properties of the interface, (such as the schemata names
and how the values are parsed) are rooted in a struct provided by the
architecture code. (struct rdt_hw_resource). Once a second architecture
uses resctrl, this would allow user-visible properties to diverge
between architectures.

These properties should come from the resctrl code that will be common
to all architectures. Resctrl has no per-schema structure, only struct
rdt_{hw_,}resource. Create a struct resctrl_schema to hold the
rdt_resource. Before a second architecture can be supported, this
structure will also need to hold the schema name visible to user-space
and the type of configuration values for resctrl.

Reviewed-by: Jamie Iles <jamie@xxxxxxxxxxxx>
Signed-off-by: James Morse <james.morse@xxxxxxx>
---
Changes since v3:
* Fixed a spelling mistake, removed a space.

Changes since v2:
* Expanded comments.
* Shuffled commit message,

Changes since v1:
* Renamed resctrl_all_schema list
* Used schemata_list as a prefix to make these easier to search for
* Added kerneldoc string
* Removed 'pending configuration' reference in commit message
---
arch/x86/kernel/cpu/resctrl/internal.h | 1 +
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 43 +++++++++++++++++++++++++-
include/linux/resctrl.h | 11 +++++++
3 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 235cf621c878..f6790d03f056 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -106,6 +106,7 @@ extern unsigned int resctrl_cqm_threshold;
extern bool rdt_alloc_capable;
extern bool rdt_mon_capable;
extern unsigned int rdt_mon_features;
+extern struct list_head resctrl_schema_all;

enum rdt_group_type {
RDTCTRL_GROUP = 0,
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 9a8665c8ab89..14ea1212f476 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -39,6 +39,9 @@ static struct kernfs_root *rdt_root;
struct rdtgroup rdtgroup_default;
LIST_HEAD(rdt_all_groups);

+/* list of entries for the schemata file */
+LIST_HEAD(resctrl_schema_all);
+
/* Kernel fs node for "info" directory under root */
static struct kernfs_node *kn_info;

@@ -2109,6 +2112,35 @@ static int rdt_enable_ctx(struct rdt_fs_context *ctx)
return ret;
}

+static int schemata_list_create(void)
+{
+ struct resctrl_schema *s;
+ struct rdt_resource *r;
+
+ for_each_alloc_enabled_rdt_resource(r) {
+ s = kzalloc(sizeof(*s), GFP_KERNEL);
+ if (!s)
+ return -ENOMEM;
+
+ s->res = r;
+
+ INIT_LIST_HEAD(&s->list);
+ list_add(&s->list, &resctrl_schema_all);
+ }
+
+ return 0;
+}
+
+static void schemata_list_destroy(void)
+{
+ struct resctrl_schema *s, *tmp;
+
+ list_for_each_entry_safe(s, tmp, &resctrl_schema_all, list) {
+ list_del(&s->list);
+ kfree(s);
+ }
+}
+
static int rdt_get_tree(struct fs_context *fc)
{
struct rdt_fs_context *ctx = rdt_fc2context(fc);
@@ -2130,11 +2162,17 @@ static int rdt_get_tree(struct fs_context *fc)
if (ret < 0)
goto out_cdp;

+ ret = schemata_list_create();
+ if (ret) {
+ schemata_list_destroy();
+ goto out_mba;
+ }
+
closid_init();

ret = rdtgroup_create_info_dir(rdtgroup_default.kn);
if (ret < 0)
- goto out_mba;
+ goto out_schemata_free;

if (rdt_mon_capable) {
ret = mongroup_create_dir(rdtgroup_default.kn,
@@ -2184,6 +2222,8 @@ static int rdt_get_tree(struct fs_context *fc)
kernfs_remove(kn_mongrp);
out_info:
kernfs_remove(kn_info);
+out_schemata_free:
+ schemata_list_destroy();
out_mba:
if (ctx->enable_mba_mbps)
set_mba_sc(false);
@@ -2425,6 +2465,7 @@ static void rdt_kill_sb(struct super_block *sb)
rmdir_all_sub();
rdt_pseudo_lock_release();
rdtgroup_default.mode = RDT_MODE_SHAREABLE;
+ schemata_list_destroy();
static_branch_disable_cpuslocked(&rdt_alloc_enable_key);
static_branch_disable_cpuslocked(&rdt_mon_enable_key);
static_branch_disable_cpuslocked(&rdt_enable_key);
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index be6f5df78e31..425e7913dc8d 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -154,4 +154,15 @@ struct rdt_resource {

};

+/**
+ * struct resctrl_schema - configuration abilities of a resource presented to
+ * user-space
+ * @list: Member of resctrl_schema_all.
+ * @res: The resource structure exported by the architecture to describe
+ * the hardware that is configured by this schema.
+ */
+struct resctrl_schema {
+ struct list_head list;
+ struct rdt_resource *res;
+};
#endif /* _RESCTRL_H */
--
2.30.2