pseries/pseries: Add code to online/offline CPUs of a DLPAR node

Currently the cpu-allocation/deallocation on pSeries is a
two step process from the Userspace.

- Set the indicators and update the device tree by writing to the sysfs
  tunable "probe" during allocation and "release" during deallocation.
- Online / Offline the CPUs of the allocated/would_be_deallocated node by
  writing to the sysfs tunable "online".

This patch adds kernel code to online/offline the CPUs soon_after/just_before
they have been allocated/would_be_deallocated. This way, the userspace tool
that performs DLPAR operations would only have to deal with one set of sysfs
tunables namely "probe" and release".

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
Acked-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/platforms/pseries/dlpar.c

@@ -16,6 +16,7 @@
 #include <linux/proc_fs.h>
 #include <linux/spinlock.h>
 #include <linux/cpu.h>
+#include "offline_states.h"
 
 #include <asm/prom.h>
 #include <asm/machdep.h>
@@ -287,6 +288,98 @@ int dlpar_detach_node(struct device_node *dn)
 	return 0;
 }
 
+int online_node_cpus(struct device_node *dn)
+{
+	int rc = 0;
+	unsigned int cpu;
+	int len, nthreads, i;
+	const u32 *intserv;
+
+	intserv = of_get_property(dn, "ibm,ppc-interrupt-server#s", &len);
+	if (!intserv)
+		return -EINVAL;
+
+	nthreads = len / sizeof(u32);
+
+	cpu_maps_update_begin();
+	for (i = 0; i < nthreads; i++) {
+		for_each_present_cpu(cpu) {
+			if (get_hard_smp_processor_id(cpu) != intserv[i])
+				continue;
+			BUG_ON(get_cpu_current_state(cpu)
+					!= CPU_STATE_OFFLINE);
+			cpu_maps_update_done();
+			rc = cpu_up(cpu);
+			if (rc)
+				goto out;
+			cpu_maps_update_begin();
+
+			break;
+		}
+		if (cpu == num_possible_cpus())
+			printk(KERN_WARNING "Could not find cpu to online "
+			       "with physical id 0x%x\n", intserv[i]);
+	}
+	cpu_maps_update_done();
+
+out:
+	return rc;
+
+}
+
+int offline_node_cpus(struct device_node *dn)
+{
+	int rc = 0;
+	unsigned int cpu;
+	int len, nthreads, i;
+	const u32 *intserv;
+
+	intserv = of_get_property(dn, "ibm,ppc-interrupt-server#s", &len);
+	if (!intserv)
+		return -EINVAL;
+
+	nthreads = len / sizeof(u32);
+
+	cpu_maps_update_begin();
+	for (i = 0; i < nthreads; i++) {
+		for_each_present_cpu(cpu) {
+			if (get_hard_smp_processor_id(cpu) != intserv[i])
+				continue;
+
+			if (get_cpu_current_state(cpu) == CPU_STATE_OFFLINE)
+				break;
+
+			if (get_cpu_current_state(cpu) == CPU_STATE_ONLINE) {
+				cpu_maps_update_done();
+				rc = cpu_down(cpu);
+				if (rc)
+					goto out;
+				cpu_maps_update_begin();
+				break;
+
+			}
+
+			/*
+			 * The cpu is in CPU_STATE_INACTIVE.
+			 * Upgrade it's state to CPU_STATE_OFFLINE.
+			 */
+			set_preferred_offline_state(cpu, CPU_STATE_OFFLINE);
+			BUG_ON(plpar_hcall_norets(H_PROD, intserv[i])
+								!= H_SUCCESS);
+			__cpu_die(cpu);
+			break;
+		}
+		if (cpu == num_possible_cpus())
+			printk(KERN_WARNING "Could not find cpu to offline "
+			       "with physical id 0x%x\n", intserv[i]);
+	}
+	cpu_maps_update_done();
+
+out:
+	return rc;
+
+}
+
 #define DR_ENTITY_SENSE		9003
 #define DR_ENTITY_PRESENT	1
 #define DR_ENTITY_UNUSABLE	2
@@ -385,6 +478,8 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
 		dlpar_free_cc_nodes(dn);
 	}
 
+	rc = online_node_cpus(dn);
+
 	return rc ? rc : count;
 }
 
@@ -404,6 +499,12 @@ static ssize_t dlpar_cpu_release(const char *buf, size_t count)
 		return -EINVAL;
 	}
 
+	rc = offline_node_cpus(dn);
+	if (rc) {
+		of_node_put(dn);
+		return -EINVAL;
+	}
+
 	rc = dlpar_release_drc(*drc_index);
 	if (rc) {
 		of_node_put(dn);