[PATCH v10 10/10] powerpc/perf: Thread imc cpuhotplug support

[Madhavan Srinivasan]

From: Anju T Sudhakar <anju at linux.vnet.ibm.com>

Code to add support for thread IMC on cpuhotplug.
When a cpu goes offline, the LDBAR for that cpu is disabled, and when it comes
back online the previous ldbar value is written back to the LDBAR for that cpu.

To register the hotplug functions for thread_imc, a new state
CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE is added to the list of existing
states.

Signed-off-by: Anju T Sudhakar <anju at linux.vnet.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy at linux.vnet.ibm.com>
---
 arch/powerpc/perf/imc-pmu.c | 42 +++++++++++++++++++++++++++++++++++++++---
 include/linux/cpuhotplug.h  |  1 +
 2 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
index ca8c0b8e157a..69bc411a82af 100644
--- a/arch/powerpc/perf/imc-pmu.c
+++ b/arch/powerpc/perf/imc-pmu.c
@@ -377,6 +377,37 @@ static int imc_mem_init(struct imc_pmu *pmu_ptr)
 	return 0;
 }
 
+static int ppc_thread_imc_cpu_online(unsigned int cpu)
+{
+	int rc = 0;
+	u64 ldbar_value;
+
+	if (per_cpu(thread_imc_mem, cpu) == NULL)
+		rc = thread_imc_mem_alloc(cpu, thread_imc_mem_size);
+
+	if (rc)
+		mtspr(SPRN_LDBAR, 0);
+
+	ldbar_value = ((u64)per_cpu(thread_imc_mem, cpu) & (u64)THREAD_IMC_LDBAR_MASK) |
+							(u64)THREAD_IMC_ENABLE;
+	mtspr(SPRN_LDBAR, ldbar_value);
+	return 0;
+}
+
+static int ppc_thread_imc_cpu_offline(unsigned int cpu)
+{
+	mtspr(SPRN_LDBAR, 0);
+	return 0;
+}
+
+void thread_imc_cpu_init(void)
+{
+	cpuhp_setup_state(CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE,
+			  "perf/powerpc/imc_thread:online",
+			  ppc_thread_imc_cpu_online,
+			  ppc_thread_imc_cpu_offline);
+}
+
 static int ppc_core_imc_cpu_online(unsigned int cpu)
 {
 	const struct cpumask *l_cpumask;
@@ -860,8 +891,8 @@ static void cleanup_all_thread_imc_memory(void)
 	int i;
 
 	for_each_online_cpu(i) {
-		if (per_cpu(thread_imc_mem, cpu))
-			free_pages(per_cpu(thread_imc_mem, cpu), 0);
+		if (per_cpu(thread_imc_mem, i))
+			free_pages((u64)per_cpu(thread_imc_mem, i), 0);
 	}
 }
 
@@ -899,6 +930,9 @@ int __init init_imc_pmu(struct imc_events *events, int idx,
 		if (ret)
 			return ret;
 		break;
+	case IMC_DOMAIN_THREAD:
+		thread_imc_cpu_init();
+		break;
 	default:
 		return -1;  /* Unknown domain */
 	}
@@ -933,8 +967,10 @@ int __init init_imc_pmu(struct imc_events *events, int idx,
 	}
 
 	/* For thread_imc, we have allocated memory, we need to free it */
-	if (pmu_ptr->domain == IMC_DOMAIN_THREAD)
+	if (pmu_ptr->domain == IMC_DOMAIN_THREAD) {
 		cleanup_all_thread_imc_memory();
+		cpuhp_remove_state(CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE);
+	}
 
 	return ret;
 }
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index e145fffec093..937d1ec8c3e9 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -141,6 +141,7 @@ enum cpuhp_state {
 	CPUHP_AP_PERF_ARM_QCOM_L3_ONLINE,
 	CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE,
 	CPUHP_AP_PERF_POWERPC_CORE_IMC_ONLINE,
+	CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE,
 	CPUHP_AP_WORKQUEUE_ONLINE,
 	CPUHP_AP_RCUTREE_ONLINE,
 	CPUHP_AP_ONLINE_DYN,
-- 
2.7.4