powerpc/powernv: Add CPU hotplug support

Unplugged CPU go into NAP mode in a loop until woken up Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/powernv: Add CPU hotplug support
Unplugged CPU go into NAP mode in a loop until woken up Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt
1 parent 78b782cb78
Showing 2 changed files with 78 additions and 2 deletions Side-by-side Diff
arch/powerpc/Kconfig
arch/powerpc/platforms/powernv/smp.c
@@ -323,7 +323,7 @@
  
 config HOTPLUG_CPU
 	bool "Support for enabling/disabling CPUs"
-	depends on SMP && HOTPLUG && EXPERIMENTAL && (PPC_PSERIES || PPC_PMAC)
+	depends on SMP && HOTPLUG && EXPERIMENTAL && (PPC_PSERIES || PPC_PMAC || PPC_POWERNV)
 	---help---
 	  Say Y here to be able to disable and re-enable individual
 	  CPUs at runtime on SMP machines.
@@ -33,7 +33,14 @@
  
 #include "powernv.h"
  
-static void __devinit pnv_smp_setup_cpu(int cpu)
+#ifdef DEBUG
+#include <asm/udbg.h>
+#define DBG(fmt...) udbg_printf(fmt)
+#else
+#define DBG(fmt...)
+#endif
+
+static void __cpuinit pnv_smp_setup_cpu(int cpu)
 {
 	if (cpu != boot_cpuid)
 		xics_setup_cpu();
@@ -55,6 +62,67 @@
 	return 1;
 }
  
+#ifdef CONFIG_HOTPLUG_CPU
+
+static int pnv_smp_cpu_disable(void)
+{
+	int cpu = smp_processor_id();
+
+	/* This is identical to pSeries... might consolidate by
+	 * moving migrate_irqs_away to a ppc_md with default to
+	 * the generic fixup_irqs. --BenH.
+	 */
+	set_cpu_online(cpu, false);
+	vdso_data->processorCount--;
+	if (cpu == boot_cpuid)
+		boot_cpuid = cpumask_any(cpu_online_mask);
+	xics_migrate_irqs_away();
+	return 0;
+}
+
+static void pnv_smp_cpu_kill_self(void)
+{
+	unsigned int cpu;
+
+	/* If powersave_nap is enabled, use NAP mode, else just
+	 * spin aimlessly
+	 */
+	if (!powersave_nap) {
+		generic_mach_cpu_die();
+		return;
+	}
+
+	/* Standard hot unplug procedure */
+	local_irq_disable();
+	idle_task_exit();
+	current->active_mm = NULL; /* for sanity */
+	cpu = smp_processor_id();
+	DBG("CPU%d offline\n", cpu);
+	generic_set_cpu_dead(cpu);
+	smp_wmb();
+
+	/* We don't want to take decrementer interrupts while we are offline,
+	 * so clear LPCR:PECE1. We keep PECE2 enabled.
+	 */
+	mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);
+	while (!generic_check_cpu_restart(cpu)) {
+		power7_idle();
+		if (!generic_check_cpu_restart(cpu)) {
+			DBG("CPU%d Unexpected exit while offline !\n", cpu);
+			/* We may be getting an IPI, so we re-enable
+			 * interrupts to process it, it will be ignored
+			 * since we aren't online (hopefully)
+			 */
+			local_irq_enable();
+			local_irq_disable();
+		}
+	}
+	mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1);
+	DBG("CPU%d coming online...\n", cpu);
+}
+
+#endif /* CONFIG_HOTPLUG_CPU */
+
 static struct smp_ops_t pnv_smp_ops = {
 	.message_pass	= smp_muxed_ipi_message_pass,
 	.cause_ipi	= NULL,	/* Filled at runtime by xics_smp_probe() */
@@ -62,6 +130,10 @@
 	.kick_cpu	= smp_generic_kick_cpu,
 	.setup_cpu	= pnv_smp_setup_cpu,
 	.cpu_bootable	= pnv_smp_cpu_bootable,
+#ifdef CONFIG_HOTPLUG_CPU
+	.cpu_disable	= pnv_smp_cpu_disable,
+	.cpu_die	= generic_cpu_die,
+#endif /* CONFIG_HOTPLUG_CPU */
 };
  
 /* This is called very early during platform setup_arch */
@@ -80,5 +152,9 @@
 		smp_ops->take_timebase = rtas_take_timebase;
 	}
 #endif /* CONFIG_PPC_RTAS */
+
+#ifdef CONFIG_HOTPLUG_CPU
+	ppc_md.cpu_die	= pnv_smp_cpu_kill_self;
+#endif
 }
...	...	@@ -323,7 +323,7 @@
323	323
324	324	config HOTPLUG_CPU
325	325	bool "Support for enabling/disabling CPUs"
326		- depends on SMP && HOTPLUG && EXPERIMENTAL && (PPC_PSERIES \|\| PPC_PMAC)
	326	+ depends on SMP && HOTPLUG && EXPERIMENTAL && (PPC_PSERIES \|\| PPC_PMAC \|\| PPC_POWERNV)
327	327	---help---
328	328	Say Y here to be able to disable and re-enable individual
329	329	CPUs at runtime on SMP machines.
...	...	@@ -33,7 +33,14 @@
33	33
34	34	#include "powernv.h"
35	35
36		-static void __devinit pnv_smp_setup_cpu(int cpu)
	36	+#ifdef DEBUG
	37	+#include <asm/udbg.h>
	38	+#define DBG(fmt...) udbg_printf(fmt)
	39	+#else
	40	+#define DBG(fmt...)
	41	+#endif
	42	+
	43	+static void __cpuinit pnv_smp_setup_cpu(int cpu)
37	44	{
38	45	if (cpu != boot_cpuid)
39	46	xics_setup_cpu();
...	...	@@ -55,6 +62,67 @@
55	62	return 1;
56	63	}
57	64
	65	+#ifdef CONFIG_HOTPLUG_CPU
	66	+
	67	+static int pnv_smp_cpu_disable(void)
	68	+{
	69	+ int cpu = smp_processor_id();
	70	+
	71	+ /* This is identical to pSeries... might consolidate by
	72	+ * moving migrate_irqs_away to a ppc_md with default to
	73	+ * the generic fixup_irqs. --BenH.
	74	+ */
	75	+ set_cpu_online(cpu, false);
	76	+ vdso_data->processorCount--;
	77	+ if (cpu == boot_cpuid)
	78	+ boot_cpuid = cpumask_any(cpu_online_mask);
	79	+ xics_migrate_irqs_away();
	80	+ return 0;
	81	+}
	82	+
	83	+static void pnv_smp_cpu_kill_self(void)
	84	+{
	85	+ unsigned int cpu;
	86	+
	87	+ /* If powersave_nap is enabled, use NAP mode, else just
	88	+ * spin aimlessly
	89	+ */
	90	+ if (!powersave_nap) {
	91	+ generic_mach_cpu_die();
	92	+ return;
	93	+ }
	94	+
	95	+ /* Standard hot unplug procedure */
	96	+ local_irq_disable();
	97	+ idle_task_exit();
	98	+ current->active_mm = NULL; /* for sanity */
	99	+ cpu = smp_processor_id();
	100	+ DBG("CPU%d offline\n", cpu);
	101	+ generic_set_cpu_dead(cpu);
	102	+ smp_wmb();
	103	+
	104	+ /* We don't want to take decrementer interrupts while we are offline,
	105	+ * so clear LPCR:PECE1. We keep PECE2 enabled.
	106	+ */
	107	+ mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);
	108	+ while (!generic_check_cpu_restart(cpu)) {
	109	+ power7_idle();
	110	+ if (!generic_check_cpu_restart(cpu)) {
	111	+ DBG("CPU%d Unexpected exit while offline !\n", cpu);
	112	+ /* We may be getting an IPI, so we re-enable
	113	+ * interrupts to process it, it will be ignored
	114	+ * since we aren't online (hopefully)
	115	+ */
	116	+ local_irq_enable();
	117	+ local_irq_disable();
	118	+ }
	119	+ }
	120	+ mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) \| LPCR_PECE1);
	121	+ DBG("CPU%d coming online...\n", cpu);
	122	+}
	123	+
	124	+#endif /* CONFIG_HOTPLUG_CPU */
	125	+
58	126	static struct smp_ops_t pnv_smp_ops = {
59	127	.message_pass = smp_muxed_ipi_message_pass,
60	128	.cause_ipi = NULL, /* Filled at runtime by xics_smp_probe() */
...	...	@@ -62,6 +130,10 @@
62	130	.kick_cpu = smp_generic_kick_cpu,
63	131	.setup_cpu = pnv_smp_setup_cpu,
64	132	.cpu_bootable = pnv_smp_cpu_bootable,
	133	+#ifdef CONFIG_HOTPLUG_CPU
	134	+ .cpu_disable = pnv_smp_cpu_disable,
	135	+ .cpu_die = generic_cpu_die,
	136	+#endif /* CONFIG_HOTPLUG_CPU */
65	137	};
66	138
67	139	/* This is called very early during platform setup_arch */
...	...	@@ -80,5 +152,9 @@
80	152	smp_ops->take_timebase = rtas_take_timebase;
81	153	}
82	154	#endif /* CONFIG_PPC_RTAS */
	155	+
	156	+#ifdef CONFIG_HOTPLUG_CPU
	157	+ ppc_md.cpu_die = pnv_smp_cpu_kill_self;
	158	+#endif
83	159	}