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

[James Morse]

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@xxxxxxxxxxx>
Signed-off-by: James Morse <james.morse@xxxxxxx>
---
 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