powerpc/pseries: Add CPU dlpar add functionality

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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index 86c7ae3..32274f7 100644 (file)
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -405,6 +405,27 @@ static bool dlpar_cpu_exists(struct device_node *parent, u32 drc_index)
        return found;
 }
 
+static bool valid_cpu_drc_index(struct device_node *parent, u32 drc_index)
+{
+       bool found = false;
+       int rc, index;
+
+       index = 0;
+       while (!found) {
+               u32 drc;
+
+               rc = of_property_read_u32_index(parent, "ibm,drc-indexes",
+                                               index++, &drc);
+               if (rc)
+                       break;
+
+               if (drc == drc_index)
+                       found = true;
+       }
+
+       return found;
+}
+
 static ssize_t dlpar_cpu_add(u32 drc_index)
 {
        struct device_node *dn, *parent;
@@ -424,6 +445,12 @@ static ssize_t dlpar_cpu_add(u32 drc_index)
                return -EINVAL;
        }
 
+       if (!valid_cpu_drc_index(parent, drc_index)) {
+               of_node_put(parent);
+               pr_warn("Cannot find CPU (drc index %x) to add.\n", drc_index);
+               return -EINVAL;
+       }
+
        rc = dlpar_acquire_drc(drc_index);
        if (rc) {
                pr_warn("Failed to acquire DRC, rc: %d, drc index: %x\n",
@@ -683,6 +710,87 @@ static int dlpar_cpu_remove_by_count(u32 cpus_to_remove)
        return rc;
 }
 
+static int find_dlpar_cpus_to_add(u32 *cpu_drcs, u32 cpus_to_add)
+{
+       struct device_node *parent;
+       int cpus_found = 0;
+       int index, rc;
+
+       parent = of_find_node_by_path("/cpus");
+       if (!parent) {
+               pr_warn("Could not find CPU root node in device tree\n");
+               kfree(cpu_drcs);
+               return -1;
+       }
+
+       /* Search the ibm,drc-indexes array for possible CPU drcs to
+        * add. Note that the format of the ibm,drc-indexes array is
+        * the number of entries in the array followed by the array
+        * of drc values so we start looking at index = 1.
+        */
+       index = 1;
+       while (cpus_found < cpus_to_add) {
+               u32 drc;
+
+               rc = of_property_read_u32_index(parent, "ibm,drc-indexes",
+                                               index++, &drc);
+               if (rc)
+                       break;
+
+               if (dlpar_cpu_exists(parent, drc))
+                       continue;
+
+               cpu_drcs[cpus_found++] = drc;
+       }
+
+       of_node_put(parent);
+       return cpus_found;
+}
+
+static int dlpar_cpu_add_by_count(u32 cpus_to_add)
+{
+       u32 *cpu_drcs;
+       int cpus_added = 0;
+       int cpus_found;
+       int i, rc;
+
+       pr_debug("Attempting to hot-add %d CPUs\n", cpus_to_add);
+
+       cpu_drcs = kcalloc(cpus_to_add, sizeof(*cpu_drcs), GFP_KERNEL);
+       if (!cpu_drcs)
+               return -EINVAL;
+
+       cpus_found = find_dlpar_cpus_to_add(cpu_drcs, cpus_to_add);
+       if (cpus_found < cpus_to_add) {
+               pr_warn("Failed to find enough CPUs (%d of %d) to add\n",
+                       cpus_found, cpus_to_add);
+               kfree(cpu_drcs);
+               return -EINVAL;
+       }
+
+       for (i = 0; i < cpus_to_add; i++) {
+               rc = dlpar_cpu_add(cpu_drcs[i]);
+               if (rc)
+                       break;
+
+               cpus_added++;
+       }
+
+       if (cpus_added < cpus_to_add) {
+               pr_warn("CPU hot-add failed, removing any added CPUs\n");
+
+               for (i = 0; i < cpus_added; i++)
+                       dlpar_cpu_remove_by_index(cpu_drcs[i]);
+
+               rc = -EINVAL;
+       } else {
+               rc = 0;
+       }
+
+       kfree(cpu_drcs);
+       return rc;
+}
+
 int dlpar_cpu(struct pseries_hp_errorlog *hp_elog)
 {
        u32 count, drc_index;
@@ -702,6 +810,14 @@ 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(count);
+               else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX)
+                       rc = dlpar_cpu_add(drc_index);
+               else
+                       rc = -EINVAL;
+               break;
        default:
                pr_err("Invalid action (%d) specified\n", hp_elog->action);
                rc = -EINVAL;