[PATCH v3 18/19] x86/resctrl: Add cpu offline callback for resctrl work

James Morse
2023-03-20T17:47:53Z

The resctrl architecture specific code may need to free a domain when
a CPU goes offline, it also needs to reset the CPUs PQR_ASSOC register.
The resctrl filesystem code needs to move the overflow and limbo work
to run on a different CPU, and clear this CPU from the cpu_mask of
control and monitor groups.

Currently this is all done in core.c and called from
resctrl_offline_cpu(), making the split between architecture and
filesystem code unclear.

Move the filesystem work into a filesystem helper called
resctrl_offline_cpu(), and rename the one in core.c
resctrl_arch_offline_cpu().

The rdtgroup_mutex is unlocked and locked again in the call in
preparation for changing the locking rules for the architecture
code.

resctrl_offline_cpu() is called before any of the resource/domains
are updated, and makes use of the exclude_cpu feature that was
previously added.

Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Signed-off-by: James Morse <james.morse@arm.com>
---
arch/x86/kernel/cpu/resctrl/core.c | 41 ++++----------------------
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 39 ++++++++++++++++++++++++
include/linux/resctrl.h | 1 +
3 files changed, 45 insertions(+), 36 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index aafe4b74587c..4e5fc89dab6d 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -578,22 +578,6 @@ static void domain_remove_cpu(int cpu, struct rdt_resource *r)

return;
}
-
- if (r == &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl) {
- if (is_mbm_enabled() && cpu == d->mbm_work_cpu) {
- cancel_delayed_work(&d->mbm_over);
- /*
- * exclude_cpu=-1 as this CPU has already been removed
- * by cpumask_clear_cpu()d
- */
- mbm_setup_overflow_handler(d, 0, RESCTRL_PICK_ANY_CPU);
- }
- if (is_llc_occupancy_enabled() && cpu == d->cqm_work_cpu &&
- has_busy_rmid(r, d)) {
- cancel_delayed_work(&d->cqm_limbo);
- cqm_setup_limbo_handler(d, 0, RESCTRL_PICK_ANY_CPU);
- }
- }
}

static void clear_closid_rmid(int cpu)
@@ -623,31 +607,15 @@ static int resctrl_arch_online_cpu(unsigned int cpu)
return err;
}

-static void clear_childcpus(struct rdtgroup *r, unsigned int cpu)
+static int resctrl_arch_offline_cpu(unsigned int cpu)
{
- struct rdtgroup *cr;
-
- list_for_each_entry(cr, &r->mon.crdtgrp_list, mon.crdtgrp_list) {
- if (cpumask_test_and_clear_cpu(cpu, &cr->cpu_mask)) {
- break;
- }
- }
-}
-
-static int resctrl_offline_cpu(unsigned int cpu)
-{
- struct rdtgroup *rdtgrp;
struct rdt_resource *r;

mutex_lock(&rdtgroup_mutex);
+ resctrl_offline_cpu(cpu);
+
for_each_capable_rdt_resource(r)
domain_remove_cpu(cpu, r);
- list_for_each_entry(rdtgrp, &rdt_all_groups, rdtgroup_list) {
- if (cpumask_test_and_clear_cpu(cpu, &rdtgrp->cpu_mask)) {
- clear_childcpus(rdtgrp, cpu);
- break;
- }
- }
clear_closid_rmid(cpu);
mutex_unlock(&rdtgroup_mutex);

@@ -970,7 +938,8 @@ static int __init resctrl_late_init(void)

state = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
"x86/resctrl/cat:online:",
- resctrl_arch_online_cpu, resctrl_offline_cpu);
+ resctrl_arch_online_cpu,
+ resctrl_arch_offline_cpu);
if (state < 0)
return state;

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index bf206bdb21ee..c27ec56c6c60 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -3710,6 +3710,45 @@ int resctrl_online_cpu(unsigned int cpu)
return 0;
}

+static void clear_childcpus(struct rdtgroup *r, unsigned int cpu)
+{
+ struct rdtgroup *cr;
+
+ list_for_each_entry(cr, &r->mon.crdtgrp_list, mon.crdtgrp_list) {
+ if (cpumask_test_and_clear_cpu(cpu, &cr->cpu_mask))
+ break;
+ }
+}
+
+void resctrl_offline_cpu(unsigned int cpu)
+{
+ struct rdt_domain *d;
+ struct rdtgroup *rdtgrp;
+ struct rdt_resource *l3 = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
+
+ lockdep_assert_held(&rdtgroup_mutex);
+
+ list_for_each_entry(rdtgrp, &rdt_all_groups, rdtgroup_list) {
+ if (cpumask_test_and_clear_cpu(cpu, &rdtgrp->cpu_mask)) {
+ clear_childcpus(rdtgrp, cpu);
+ break;
+ }
+ }
+
+ d = get_domain_from_cpu(cpu, l3);
+ if (d) {
+ if (is_mbm_enabled() && cpu == d->mbm_work_cpu) {
+ cancel_delayed_work(&d->mbm_over);
+ mbm_setup_overflow_handler(d, 0, cpu);
+ }
+ if (is_llc_occupancy_enabled() && cpu == d->cqm_work_cpu &&
+ has_busy_rmid(l3, d)) {
+ cancel_delayed_work(&d->cqm_limbo);
+ cqm_setup_limbo_handler(d, 0, cpu);
+ }
+ }
+}
+
/*
* rdtgroup_init - rdtgroup initialization
*
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 3ea7d618f33f..f053527aaa5b 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -226,6 +226,7 @@ u32 resctrl_arch_get_config(struct rdt_resource *r, struct rdt_domain *d,
int resctrl_online_domain(struct rdt_resource *r, struct rdt_domain *d);
void resctrl_offline_domain(struct rdt_resource *r, struct rdt_domain *d);
int resctrl_online_cpu(unsigned int cpu);
+void resctrl_offline_cpu(unsigned int cpu);

/**
* resctrl_arch_rmid_read() - Read the eventid counter corresponding to rmid
--
2.39.2