2 * pseries CPU Hotplug infrastructure.
4 * Split out from arch/powerpc/platforms/pseries/setup.c
5 * arch/powerpc/kernel/rtas.c, and arch/powerpc/platforms/pseries/smp.c
7 * Peter Bergner, IBM March 2001.
8 * Copyright (C) 2001 IBM.
9 * Dave Engebretsen, Peter Bergner, and
10 * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
11 * Plus various changes from other IBM teams...
13 * Copyright (C) 2006 Michael Ellerman, IBM Corporation
15 * This program is free software; you can redistribute it and/or
16 * modify it under the terms of the GNU General Public License
17 * as published by the Free Software Foundation; either version
18 * 2 of the License, or (at your option) any later version.
21 #include <linux/kernel.h>
22 #include <linux/interrupt.h>
23 #include <linux/delay.h>
24 #include <linux/sched.h> /* for idle_task_exit */
25 #include <linux/cpu.h>
29 #include <asm/firmware.h>
30 #include <asm/machdep.h>
31 #include <asm/vdso_datapage.h>
33 #include <asm/plpar_wrappers.h>
35 #include "offline_states.h"
37 /* This version can't take the spinlock, because it never returns */
38 static struct rtas_args rtas_stop_self_args
= {
39 .token
= RTAS_UNKNOWN_SERVICE
,
42 .rets
= &rtas_stop_self_args
.args
[0],
45 static DEFINE_PER_CPU(enum cpu_state_vals
, preferred_offline_state
) =
47 static DEFINE_PER_CPU(enum cpu_state_vals
, current_state
) = CPU_STATE_OFFLINE
;
49 static enum cpu_state_vals default_offline_state
= CPU_STATE_OFFLINE
;
51 static int cede_offline_enabled __read_mostly
= 1;
54 * Enable/disable cede_offline when available.
56 static int __init
setup_cede_offline(char *str
)
58 if (!strcmp(str
, "off"))
59 cede_offline_enabled
= 0;
60 else if (!strcmp(str
, "on"))
61 cede_offline_enabled
= 1;
67 __setup("cede_offline=", setup_cede_offline
);
69 enum cpu_state_vals
get_cpu_current_state(int cpu
)
71 return per_cpu(current_state
, cpu
);
74 void set_cpu_current_state(int cpu
, enum cpu_state_vals state
)
76 per_cpu(current_state
, cpu
) = state
;
79 enum cpu_state_vals
get_preferred_offline_state(int cpu
)
81 return per_cpu(preferred_offline_state
, cpu
);
84 void set_preferred_offline_state(int cpu
, enum cpu_state_vals state
)
86 per_cpu(preferred_offline_state
, cpu
) = state
;
89 void set_default_offline_state(int cpu
)
91 per_cpu(preferred_offline_state
, cpu
) = default_offline_state
;
94 static void rtas_stop_self(void)
96 struct rtas_args
*args
= &rtas_stop_self_args
;
100 BUG_ON(args
->token
== RTAS_UNKNOWN_SERVICE
);
102 printk("cpu %u (hwid %u) Ready to die...\n",
103 smp_processor_id(), hard_smp_processor_id());
104 enter_rtas(__pa(args
));
106 panic("Alas, I survived.\n");
109 static void pseries_mach_cpu_die(void)
111 unsigned int cpu
= smp_processor_id();
112 unsigned int hwcpu
= hard_smp_processor_id();
113 u8 cede_latency_hint
= 0;
119 if (get_preferred_offline_state(cpu
) == CPU_STATE_INACTIVE
) {
120 set_cpu_current_state(cpu
, CPU_STATE_INACTIVE
);
121 if (ppc_md
.suspend_disable_cpu
)
122 ppc_md
.suspend_disable_cpu();
124 cede_latency_hint
= 2;
126 get_lppaca()->idle
= 1;
127 if (!lppaca_shared_proc(get_lppaca()))
128 get_lppaca()->donate_dedicated_cpu
= 1;
130 while (get_preferred_offline_state(cpu
) == CPU_STATE_INACTIVE
) {
131 while (!prep_irq_for_idle()) {
136 extended_cede_processor(cede_latency_hint
);
141 if (!lppaca_shared_proc(get_lppaca()))
142 get_lppaca()->donate_dedicated_cpu
= 0;
143 get_lppaca()->idle
= 0;
145 if (get_preferred_offline_state(cpu
) == CPU_STATE_ONLINE
) {
146 unregister_slb_shadow(hwcpu
);
150 * Call to start_secondary_resume() will not return.
151 * Kernel stack will be reset and start_secondary()
152 * will be called to continue the online operation.
154 start_secondary_resume();
158 /* Requested state is CPU_STATE_OFFLINE at this point */
159 WARN_ON(get_preferred_offline_state(cpu
) != CPU_STATE_OFFLINE
);
161 set_cpu_current_state(cpu
, CPU_STATE_OFFLINE
);
162 unregister_slb_shadow(hwcpu
);
165 /* Should never get here... */
170 static int pseries_cpu_disable(void)
172 int cpu
= smp_processor_id();
174 set_cpu_online(cpu
, false);
175 vdso_data
->processorCount
--;
177 /*fix boot_cpuid here*/
178 if (cpu
== boot_cpuid
)
179 boot_cpuid
= cpumask_any(cpu_online_mask
);
181 /* FIXME: abstract this to not be platform specific later on */
182 xics_migrate_irqs_away();
187 * pseries_cpu_die: Wait for the cpu to die.
188 * @cpu: logical processor id of the CPU whose death we're awaiting.
190 * This function is called from the context of the thread which is performing
191 * the cpu-offline. Here we wait for long enough to allow the cpu in question
192 * to self-destroy so that the cpu-offline thread can send the CPU_DEAD
195 * OTOH, pseries_mach_cpu_die() is called by the @cpu when it wants to
198 static void pseries_cpu_die(unsigned int cpu
)
202 unsigned int pcpu
= get_hard_smp_processor_id(cpu
);
204 if (get_preferred_offline_state(cpu
) == CPU_STATE_INACTIVE
) {
206 for (tries
= 0; tries
< 5000; tries
++) {
207 if (get_cpu_current_state(cpu
) == CPU_STATE_INACTIVE
) {
213 } else if (get_preferred_offline_state(cpu
) == CPU_STATE_OFFLINE
) {
215 for (tries
= 0; tries
< 25; tries
++) {
216 cpu_status
= smp_query_cpu_stopped(pcpu
);
217 if (cpu_status
== QCSS_STOPPED
||
218 cpu_status
== QCSS_HARDWARE_ERROR
)
224 if (cpu_status
!= 0) {
225 printk("Querying DEAD? cpu %i (%i) shows %i\n",
226 cpu
, pcpu
, cpu_status
);
229 /* Isolation and deallocation are definitely done by
230 * drslot_chrp_cpu. If they were not they would be
231 * done here. Change isolate state to Isolate and
232 * change allocation-state to Unusable.
234 paca
[cpu
].cpu_start
= 0;
238 * Update cpu_present_mask and paca(s) for a new cpu node. The wrinkle
239 * here is that a cpu device node may represent up to two logical cpus
240 * in the SMT case. We must honor the assumption in other code that
241 * the logical ids for sibling SMT threads x and y are adjacent, such
242 * that x^1 == y and y^1 == x.
244 static int pseries_add_processor(struct device_node
*np
)
247 cpumask_var_t candidate_mask
, tmp
;
248 int err
= -ENOSPC
, len
, nthreads
, i
;
251 intserv
= of_get_property(np
, "ibm,ppc-interrupt-server#s", &len
);
255 zalloc_cpumask_var(&candidate_mask
, GFP_KERNEL
);
256 zalloc_cpumask_var(&tmp
, GFP_KERNEL
);
258 nthreads
= len
/ sizeof(u32
);
259 for (i
= 0; i
< nthreads
; i
++)
260 cpumask_set_cpu(i
, tmp
);
262 cpu_maps_update_begin();
264 BUG_ON(!cpumask_subset(cpu_present_mask
, cpu_possible_mask
));
266 /* Get a bitmap of unoccupied slots. */
267 cpumask_xor(candidate_mask
, cpu_possible_mask
, cpu_present_mask
);
268 if (cpumask_empty(candidate_mask
)) {
269 /* If we get here, it most likely means that NR_CPUS is
270 * less than the partition's max processors setting.
272 printk(KERN_ERR
"Cannot add cpu %s; this system configuration"
273 " supports %d logical cpus.\n", np
->full_name
,
274 cpumask_weight(cpu_possible_mask
));
278 while (!cpumask_empty(tmp
))
279 if (cpumask_subset(tmp
, candidate_mask
))
280 /* Found a range where we can insert the new cpu(s) */
283 cpumask_shift_left(tmp
, tmp
, nthreads
);
285 if (cpumask_empty(tmp
)) {
286 printk(KERN_ERR
"Unable to find space in cpu_present_mask for"
287 " processor %s with %d thread(s)\n", np
->name
,
292 for_each_cpu(cpu
, tmp
) {
293 BUG_ON(cpu_present(cpu
));
294 set_cpu_present(cpu
, true);
295 set_hard_smp_processor_id(cpu
, *intserv
++);
299 cpu_maps_update_done();
300 free_cpumask_var(candidate_mask
);
301 free_cpumask_var(tmp
);
306 * Update the present map for a cpu node which is going away, and set
307 * the hard id in the paca(s) to -1 to be consistent with boot time
308 * convention for non-present cpus.
310 static void pseries_remove_processor(struct device_node
*np
)
313 int len
, nthreads
, i
;
316 intserv
= of_get_property(np
, "ibm,ppc-interrupt-server#s", &len
);
320 nthreads
= len
/ sizeof(u32
);
322 cpu_maps_update_begin();
323 for (i
= 0; i
< nthreads
; i
++) {
324 for_each_present_cpu(cpu
) {
325 if (get_hard_smp_processor_id(cpu
) != intserv
[i
])
327 BUG_ON(cpu_online(cpu
));
328 set_cpu_present(cpu
, false);
329 set_hard_smp_processor_id(cpu
, -1);
332 if (cpu
>= nr_cpu_ids
)
333 printk(KERN_WARNING
"Could not find cpu to remove "
334 "with physical id 0x%x\n", intserv
[i
]);
336 cpu_maps_update_done();
339 static int pseries_smp_notifier(struct notifier_block
*nb
,
340 unsigned long action
, void *node
)
345 case OF_RECONFIG_ATTACH_NODE
:
346 err
= pseries_add_processor(node
);
348 case OF_RECONFIG_DETACH_NODE
:
349 pseries_remove_processor(node
);
352 return notifier_from_errno(err
);
355 static struct notifier_block pseries_smp_nb
= {
356 .notifier_call
= pseries_smp_notifier
,
359 #define MAX_CEDE_LATENCY_LEVELS 4
360 #define CEDE_LATENCY_PARAM_LENGTH 10
361 #define CEDE_LATENCY_PARAM_MAX_LENGTH \
362 (MAX_CEDE_LATENCY_LEVELS * CEDE_LATENCY_PARAM_LENGTH * sizeof(char))
363 #define CEDE_LATENCY_TOKEN 45
365 static char cede_parameters
[CEDE_LATENCY_PARAM_MAX_LENGTH
];
367 static int parse_cede_parameters(void)
369 memset(cede_parameters
, 0, CEDE_LATENCY_PARAM_MAX_LENGTH
);
370 return rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,
373 __pa(cede_parameters
),
374 CEDE_LATENCY_PARAM_MAX_LENGTH
);
377 static int __init
pseries_cpu_hotplug_init(void)
379 struct device_node
*np
;
384 for_each_node_by_name(np
, "interrupt-controller") {
385 typep
= of_get_property(np
, "compatible", NULL
);
386 if (strstr(typep
, "open-pic")) {
389 printk(KERN_INFO
"CPU Hotplug not supported on "
390 "systems using MPIC\n");
395 rtas_stop_self_args
.token
= rtas_token("stop-self");
396 qcss_tok
= rtas_token("query-cpu-stopped-state");
398 if (rtas_stop_self_args
.token
== RTAS_UNKNOWN_SERVICE
||
399 qcss_tok
== RTAS_UNKNOWN_SERVICE
) {
400 printk(KERN_INFO
"CPU Hotplug not supported by firmware "
405 ppc_md
.cpu_die
= pseries_mach_cpu_die
;
406 smp_ops
->cpu_disable
= pseries_cpu_disable
;
407 smp_ops
->cpu_die
= pseries_cpu_die
;
409 /* Processors can be added/removed only on LPAR */
410 if (firmware_has_feature(FW_FEATURE_LPAR
)) {
411 of_reconfig_notifier_register(&pseries_smp_nb
);
412 cpu_maps_update_begin();
413 if (cede_offline_enabled
&& parse_cede_parameters() == 0) {
414 default_offline_state
= CPU_STATE_INACTIVE
;
415 for_each_online_cpu(cpu
)
416 set_default_offline_state(cpu
);
418 cpu_maps_update_done();
423 arch_initcall(pseries_cpu_hotplug_init
);