[PATCH v3 15/19] x86/resctrl: Add helpers for system wide mon/alloc capable

James Morse
2023-03-20T17:48:10Z

resctrl reads rdt_alloc_capable or rdt_mon_capable to determine
whether any of the resources support the corresponding features.
resctrl also uses the static-keys that affect the architecture's
context-switch code to determine the same thing.

This forces another architecture to have the same static-keys.

As the static-key is enabled based on the capable flag, and none of
the filesystem uses of these are in the scheduler path, move the
capable flags behind helpers, and use these in the filesystem
code instead of the static-key.

After this change, only the architecture code manages and uses
the static-keys to ensure __resctrl_sched_in() does not need
runtime checks.

This avoids multiple architectures having to define the same
static-keys.

Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Signed-off-by: James Morse <james.morse@arm.com>

---
Changes since v1:
* Added missing conversion in mkdir_rdt_prepare_rmid_free()
---
arch/x86/include/asm/resctrl.h | 13 +++++++++
arch/x86/kernel/cpu/resctrl/internal.h | 2 --
arch/x86/kernel/cpu/resctrl/monitor.c | 4 +--
arch/x86/kernel/cpu/resctrl/pseudo_lock.c | 6 ++--
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 34 +++++++++++------------
5 files changed, 35 insertions(+), 24 deletions(-)

diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h
index 147af2b43385..4355245652c9 100644
--- a/arch/x86/include/asm/resctrl.h
+++ b/arch/x86/include/asm/resctrl.h
@@ -38,10 +38,18 @@ struct resctrl_pqr_state {

DECLARE_PER_CPU(struct resctrl_pqr_state, pqr_state);

+extern bool rdt_alloc_capable;
+extern bool rdt_mon_capable;
+
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);
@@ -54,6 +62,11 @@ 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/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index c83bd581c1d5..3eb5b307b809 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -135,8 +135,6 @@ struct rmid_read {
int arch_mon_ctx;
};

-extern bool rdt_alloc_capable;
-extern bool rdt_mon_capable;
extern unsigned int rdt_mon_features;
extern struct list_head resctrl_schema_all;
extern bool resctrl_mounted;
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 6279f5c98b39..f0f2e61b15d5 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -834,7 +834,7 @@ void mbm_handle_overflow(struct work_struct *work)

mutex_lock(&rdtgroup_mutex);

- if (!resctrl_mounted || !static_branch_likely(&rdt_mon_enable_key))
+ if (!resctrl_mounted || !resctrl_arch_mon_capable())
goto out_unlock;

r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
@@ -867,7 +867,7 @@ void mbm_setup_overflow_handler(struct rdt_domain *dom, unsigned long delay_ms)
unsigned long delay = msecs_to_jiffies(delay_ms);
int cpu;

- if (!resctrl_mounted || !static_branch_likely(&rdt_mon_enable_key))
+ if (!resctrl_mounted || !resctrl_arch_mon_capable())
return;

cpu = cpumask_any_housekeeping(&dom->cpu_mask);
diff --git a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
index 3b724a40d3a2..0b4fdb118643 100644
--- a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
+++ b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
@@ -567,7 +567,7 @@ static int rdtgroup_locksetup_user_restrict(struct rdtgroup *rdtgrp)
if (ret)
goto err_cpus;

- if (rdt_mon_capable) {
+ if (resctrl_arch_mon_capable()) {
ret = rdtgroup_kn_mode_restrict(rdtgrp, "mon_groups");
if (ret)
goto err_cpus_list;
@@ -614,7 +614,7 @@ static int rdtgroup_locksetup_user_restore(struct rdtgroup *rdtgrp)
if (ret)
goto err_cpus;

- if (rdt_mon_capable) {
+ if (resctrl_arch_mon_capable()) {
ret = rdtgroup_kn_mode_restore(rdtgrp, "mon_groups", 0777);
if (ret)
goto err_cpus_list;
@@ -762,7 +762,7 @@ int rdtgroup_locksetup_exit(struct rdtgroup *rdtgrp)
{
int ret;

- if (rdt_mon_capable) {
+ if (resctrl_arch_mon_capable()) {
ret = alloc_rmid(rdtgrp->closid);
if (ret < 0) {
rdt_last_cmd_puts("Out of RMIDs\n");
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 2ca8981c7d0d..8f319e03b449 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -611,13 +611,13 @@ static int __rdtgroup_move_task(struct task_struct *tsk,

static bool is_closid_match(struct task_struct *t, struct rdtgroup *r)
{
- return (rdt_alloc_capable && (r->type == RDTCTRL_GROUP) &&
+ return (resctrl_arch_alloc_capable() && (r->type == RDTCTRL_GROUP) &&
resctrl_arch_match_closid(t, r->closid));
}

static bool is_rmid_match(struct task_struct *t, struct rdtgroup *r)
{
- return (rdt_mon_capable && (r->type == RDTMON_GROUP) &&
+ return (resctrl_arch_mon_capable() && (r->type == RDTMON_GROUP) &&
resctrl_arch_match_rmid(t, r->mon.parent->closid,
r->mon.rmid));
}
@@ -2487,7 +2487,7 @@ static int rdt_get_tree(struct fs_context *fc)
if (ret < 0)
goto out_schemata_free;

- if (rdt_mon_capable) {
+ if (resctrl_arch_mon_capable()) {
ret = mongroup_create_dir(rdtgroup_default.kn,
&rdtgroup_default, "mon_groups",
&kn_mongrp);
@@ -2509,12 +2509,12 @@ static int rdt_get_tree(struct fs_context *fc)
if (ret < 0)
goto out_psl;

- if (rdt_alloc_capable)
+ if (resctrl_arch_alloc_capable())
resctrl_arch_enable_alloc();
- if (rdt_mon_capable)
+ if (resctrl_arch_mon_capable())
resctrl_arch_enable_mon();

- if (rdt_alloc_capable || rdt_mon_capable)
+ if (resctrl_arch_alloc_capable() || resctrl_arch_mon_capable())
resctrl_mounted = true;

if (is_mbm_enabled()) {
@@ -2528,10 +2528,10 @@ static int rdt_get_tree(struct fs_context *fc)
out_psl:
rdt_pseudo_lock_release();
out_mondata:
- if (rdt_mon_capable)
+ if (resctrl_arch_mon_capable())
kernfs_remove(kn_mondata);
out_mongrp:
- if (rdt_mon_capable)
+ if (resctrl_arch_mon_capable())
kernfs_remove(kn_mongrp);
out_info:
kernfs_remove(kn_info);
@@ -2783,9 +2783,9 @@ static void rdt_kill_sb(struct super_block *sb)
rdt_pseudo_lock_release();
rdtgroup_default.mode = RDT_MODE_SHAREABLE;
schemata_list_destroy();
- if (rdt_alloc_capable)
+ if (resctrl_arch_alloc_capable())
resctrl_arch_disable_alloc();
- if (rdt_mon_capable)
+ if (resctrl_arch_mon_capable())
resctrl_arch_disable_mon();
resctrl_mounted = false;
kernfs_kill_sb(sb);
@@ -3161,7 +3161,7 @@ static int mkdir_rdt_prepare_rmid_alloc(struct rdtgroup *rdtgrp)
{
int ret;

- if (!rdt_mon_capable)
+ if (!resctrl_arch_mon_capable())
return 0;

ret = alloc_rmid(rdtgrp->closid);
@@ -3183,7 +3183,7 @@ static int mkdir_rdt_prepare_rmid_alloc(struct rdtgroup *rdtgrp)

static void mkdir_rdt_prepare_rmid_free(struct rdtgroup *rgrp)
{
- if (rdt_mon_capable)
+ if (resctrl_arch_mon_capable())
free_rmid(rgrp->closid, rgrp->mon.rmid);
}

@@ -3349,7 +3349,7 @@ static int rdtgroup_mkdir_ctrl_mon(struct kernfs_node *parent_kn,

list_add(&rdtgrp->rdtgroup_list, &rdt_all_groups);

- if (rdt_mon_capable) {
+ if (resctrl_arch_mon_capable()) {
/*
* Create an empty mon_groups directory to hold the subset
* of tasks and cpus to monitor.
@@ -3404,14 +3404,14 @@ static int rdtgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
* allocation is supported, add a control and monitoring
* subdirectory
*/
- if (rdt_alloc_capable && parent_kn == rdtgroup_default.kn)
+ if (resctrl_arch_alloc_capable() && parent_kn == rdtgroup_default.kn)
return rdtgroup_mkdir_ctrl_mon(parent_kn, name, mode);

/*
* If RDT monitoring is supported and the parent directory is a valid
* "mon_groups" directory, add a monitoring subdirectory.
*/
- if (rdt_mon_capable && is_mon_groups(parent_kn, name))
+ if (resctrl_arch_mon_capable() && is_mon_groups(parent_kn, name))
return rdtgroup_mkdir_mon(parent_kn, name, mode);

return -EPERM;
@@ -3615,7 +3615,7 @@ void resctrl_offline_domain(struct rdt_resource *r, struct rdt_domain *d)
* If resctrl is mounted, remove all the
* per domain monitor data directories.
*/
- if (resctrl_mounted && static_branch_unlikely(&rdt_mon_enable_key))
+ if (resctrl_mounted && resctrl_arch_mon_capable())
rmdir_mondata_subdir_allrdtgrp(r, d->id);

if (is_mbm_enabled())
@@ -3692,7 +3692,7 @@ int resctrl_online_domain(struct rdt_resource *r, struct rdt_domain *d)
if (is_llc_occupancy_enabled())
INIT_DELAYED_WORK(&d->cqm_limbo, cqm_handle_limbo);

- if (resctrl_mounted && static_branch_unlikely(&rdt_mon_enable_key))
+ if (resctrl_mounted && resctrl_arch_mon_capable())
mkdir_mondata_subdir_allrdtgrp(r, d);

return 0;
--
2.39.2