powerpc/perf: Unregister thread-imc if core-imc not supported

Since thread-imc internally use the core-imc hardware infrastructure
and is depended on it, having thread-imc in the kernel in the
absence of core-imc is trivial. Patch disables thread-imc, if
core-imc is not registered.

Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/imc-pmu.h

@@ -128,4 +128,5 @@ extern int init_imc_pmu(struct device_node *parent,
 				struct imc_pmu *pmu_ptr, int pmu_id);
 extern void thread_imc_disable(void);
 extern int get_max_nest_dev(void);
+extern void unregister_thread_imc(void);
 #endif /* __ASM_POWERPC_IMC_PMU_H */

arch/powerpc/perf/imc-pmu.c

@@ -40,6 +40,7 @@ static struct imc_pmu *core_imc_pmu;
 /* Thread IMC data structures and variables */
 
 static DEFINE_PER_CPU(u64 *, thread_imc_mem);
+static struct imc_pmu *thread_imc_pmu;
 static int thread_imc_mem_size;
 
 struct imc_pmu *imc_event_to_pmu(struct perf_event *event)
@@ -1228,6 +1229,16 @@ static void imc_common_cpuhp_mem_free(struct imc_pmu *pmu_ptr)
 	}
 }
 
+/*
+ * Function to unregister thread-imc if core-imc
+ * is not registered.
+ */
+void unregister_thread_imc(void)
+{
+	imc_common_cpuhp_mem_free(thread_imc_pmu);
+	imc_common_mem_free(thread_imc_pmu);
+	perf_pmu_unregister(&thread_imc_pmu->pmu);
+}
 
 /*
  * imc_mem_init : Function to support memory allocation for core imc.
@@ -1296,6 +1307,7 @@ static int imc_mem_init(struct imc_pmu *pmu_ptr, struct device_node *parent,
 			}
 		}
 
+		thread_imc_pmu = pmu_ptr;
 		break;
 	default:
 		return -EINVAL;

arch/powerpc/platforms/powernv/opal-imc.c

@@ -255,6 +255,7 @@ static int opal_imc_counters_probe(struct platform_device *pdev)
 {
 	struct device_node *imc_dev = pdev->dev.of_node;
 	int pmu_count = 0, domain;
+	bool core_imc_reg = false, thread_imc_reg = false;
 	u32 type;
 
 	/*
@@ -292,13 +293,21 @@ static int opal_imc_counters_probe(struct platform_device *pdev)
 		if (!imc_pmu_create(imc_dev, pmu_count, domain)) {
 			if (domain == IMC_DOMAIN_NEST)
 				pmu_count++;
+			if (domain == IMC_DOMAIN_CORE)
+				core_imc_reg = true;
+			if (domain == IMC_DOMAIN_THREAD)
+				thread_imc_reg = true;
 		}
 	}
 
 	/* If none of the nest units are registered, remove debugfs interface */
 	if (pmu_count == 0)
 		debugfs_remove_recursive(imc_debugfs_parent);
 
+	/* If core imc is not registered, unregister thread-imc */
+	if (!core_imc_reg && thread_imc_reg)
+		unregister_thread_imc();
+
 	return 0;
 }