[PATCH 5/6] pseries: Add CPU dlpar add functionality

[Nathan Fontenot <nfont@linux.vnet.ibm.com>]

Add the ability to hotplug add cpus via rtas hotplug events by either
specifying the drc index of the CPU to add, or providing a count of the
number of CPUs to add.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
---
 arch/powerpc/platforms/pseries/hotplug-cpu.c |   76 ++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index 49b7196..a5d4c89 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -673,6 +673,74 @@ static int dlpar_cpu_remove_by_count(struct device_node *parent,
 	return rc;
 }
 
+static int dlpar_cpu_add_by_count(struct device_node *parent, u32 cpus_to_add)
+{
+	struct dr_cpu *dr_cpus;
+	int dr_cpus_added = 0;
+	int dr_cpus_available = 0;
+	int dr_cpus_possible;
+	int i, rc;
+
+	pr_info("Attempting to hot-add %d CPUs\n", cpus_to_add);
+
+	dr_cpus = get_dlpar_cpus(parent);
+	if (!dr_cpus) {
+		pr_info("Could not gather dr CPU info\n");
+		return -EINVAL;
+	}
+
+	dr_cpus_possible = dlpar_cpus_possible(parent);
+
+	for (i = 0; i < dr_cpus_possible; i++) {
+		if (!dr_cpus[i].present)
+			dr_cpus_available++;
+	}
+
+	/* Validate the available CPUs to add. */
+	if (cpus_to_add > dr_cpus_available) {
+		pr_err("Insufficient CPUs (%d) to satisfy add request\n",
+		       dr_cpus_available);
+		kfree(dr_cpus);
+		return -EINVAL;
+	}
+
+	for (i = 0; i < dr_cpus_possible; i++) {
+		if (dr_cpus_added == cpus_to_add)
+			break;
+
+		if (dr_cpus[i].present)
+			continue;
+
+		rc = dlpar_cpu_add(parent, dr_cpus[i].drc_index);
+		if (!rc) {
+			dr_cpus_added++;
+			dr_cpus[i].modified = true;
+		}
+	}
+
+	if (dr_cpus_added < cpus_to_add) {
+		pr_err("CPU hot-add failed, removing any added CPUs\n");
+
+		for (i = 0; i < dr_cpus_possible; i++) {
+			if (!dr_cpus[i].modified)
+				continue;
+
+			rc = dlpar_cpu_remove_by_index(parent,
+						       dr_cpus[i].drc_index);
+			if (rc)
+				pr_info("Failed to remove added CPU (%x)\n",
+					dr_cpus[i].drc_index);
+		}
+
+		rc = -EINVAL;
+	} else {
+		rc = 0;
+	}
+
+	kfree(dr_cpus);
+	return rc;
+}
+
 int dlpar_cpu(struct pseries_hp_errorlog *hp_elog)
 {
 	struct device_node *parent;
@@ -697,6 +765,14 @@ int dlpar_cpu(struct pseries_hp_errorlog *hp_elog)
 		else
 			rc = -EINVAL;
 		break;
+	case PSERIES_HP_ELOG_ACTION_ADD:
+		if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT)
+			rc = dlpar_cpu_add_by_count(parent, count);
+		else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX)
+			rc = dlpar_cpu_add(parent, drc_index);
+		else
+			rc = -EINVAL;
+		break;
 	default:
 		pr_err("Invalid action (%d) specified\n", hp_elog->action);
 		rc = -EINVAL;