1 /*
2  * SMP support for pSeries machines.
3  *
4  * Dave Engebretsen, Peter Bergner, and
5  * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
6  *
7  * Plus various changes from other IBM teams...
8  *
9  *      This program is free software; you can redistribute it and/or
10  *      modify it under the terms of the GNU General Public License
11  *      as published by the Free Software Foundation; either version
12  *      2 of the License, or (at your option) any later version.
13  */
14 
15 
16 #include <linux/kernel.h>
17 #include <linux/sched.h>
18 #include <linux/smp.h>
19 #include <linux/interrupt.h>
20 #include <linux/delay.h>
21 #include <linux/init.h>
22 #include <linux/spinlock.h>
23 #include <linux/cache.h>
24 #include <linux/err.h>
25 #include <linux/device.h>
26 #include <linux/cpu.h>
27 
28 #include <asm/ptrace.h>
29 #include <linux/atomic.h>
30 #include <asm/irq.h>
31 #include <asm/page.h>
32 #include <asm/pgtable.h>
33 #include <asm/io.h>
34 #include <asm/prom.h>
35 #include <asm/smp.h>
36 #include <asm/paca.h>
37 #include <asm/machdep.h>
38 #include <asm/cputable.h>
39 #include <asm/firmware.h>
40 #include <asm/rtas.h>
41 #include <asm/vdso_datapage.h>
42 #include <asm/cputhreads.h>
43 #include <asm/xics.h>
44 #include <asm/xive.h>
45 #include <asm/dbell.h>
46 #include <asm/plpar_wrappers.h>
47 #include <asm/code-patching.h>
48 
49 #include "pseries.h"
50 #include "offline_states.h"
51 
52 
53 /*
54  * The Primary thread of each non-boot processor was started from the OF client
55  * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
56  */
57 static cpumask_var_t of_spin_mask;
58 
59 /* Query where a cpu is now.  Return codes #defined in plpar_wrappers.h */
60 int smp_query_cpu_stopped(unsigned int pcpu)
61 {
62 	int cpu_status, status;
63 	int qcss_tok = rtas_token("query-cpu-stopped-state");
64 
65 	if (qcss_tok == RTAS_UNKNOWN_SERVICE) {
66 		printk_once(KERN_INFO
67 			"Firmware doesn't support query-cpu-stopped-state\n");
68 		return QCSS_HARDWARE_ERROR;
69 	}
70 
71 	status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
72 	if (status != 0) {
73 		printk(KERN_ERR
74 		       "RTAS query-cpu-stopped-state failed: %i\n", status);
75 		return status;
76 	}
77 
78 	return cpu_status;
79 }
80 
81 /**
82  * smp_startup_cpu() - start the given cpu
83  *
84  * At boot time, there is nothing to do for primary threads which were
85  * started from Open Firmware.  For anything else, call RTAS with the
86  * appropriate start location.
87  *
88  * Returns:
89  *	0	- failure
90  *	1	- success
91  */
92 static inline int smp_startup_cpu(unsigned int lcpu)
93 {
94 	int status;
95 	unsigned long start_here =
96 			__pa(ppc_function_entry(generic_secondary_smp_init));
97 	unsigned int pcpu;
98 	int start_cpu;
99 
100 	if (cpumask_test_cpu(lcpu, of_spin_mask))
101 		/* Already started by OF and sitting in spin loop */
102 		return 1;
103 
104 	pcpu = get_hard_smp_processor_id(lcpu);
105 
106 	/* Check to see if the CPU out of FW already for kexec */
107 	if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){
108 		cpumask_set_cpu(lcpu, of_spin_mask);
109 		return 1;
110 	}
111 
112 	/* Fixup atomic count: it exited inside IRQ handler. */
113 	task_thread_info(paca[lcpu].__current)->preempt_count	= 0;
114 #ifdef CONFIG_HOTPLUG_CPU
115 	if (get_cpu_current_state(lcpu) == CPU_STATE_INACTIVE)
116 		goto out;
117 #endif
118 	/*
119 	 * If the RTAS start-cpu token does not exist then presume the
120 	 * cpu is already spinning.
121 	 */
122 	start_cpu = rtas_token("start-cpu");
123 	if (start_cpu == RTAS_UNKNOWN_SERVICE)
124 		return 1;
125 
126 	status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
127 	if (status != 0) {
128 		printk(KERN_ERR "start-cpu failed: %i\n", status);
129 		return 0;
130 	}
131 
132 #ifdef CONFIG_HOTPLUG_CPU
133 out:
134 #endif
135 	return 1;
136 }
137 
138 static void smp_setup_cpu(int cpu)
139 {
140 	if (xive_enabled())
141 		xive_smp_setup_cpu();
142 	else if (cpu != boot_cpuid)
143 		xics_setup_cpu();
144 
145 	if (firmware_has_feature(FW_FEATURE_SPLPAR))
146 		vpa_init(cpu);
147 
148 	cpumask_clear_cpu(cpu, of_spin_mask);
149 #ifdef CONFIG_HOTPLUG_CPU
150 	set_cpu_current_state(cpu, CPU_STATE_ONLINE);
151 	set_default_offline_state(cpu);
152 #endif
153 }
154 
155 static int smp_pSeries_kick_cpu(int nr)
156 {
157 	if (nr < 0 || nr >= nr_cpu_ids)
158 		return -EINVAL;
159 
160 	if (!smp_startup_cpu(nr))
161 		return -ENOENT;
162 
163 	/*
164 	 * The processor is currently spinning, waiting for the
165 	 * cpu_start field to become non-zero After we set cpu_start,
166 	 * the processor will continue on to secondary_start
167 	 */
168 	paca[nr].cpu_start = 1;
169 #ifdef CONFIG_HOTPLUG_CPU
170 	set_preferred_offline_state(nr, CPU_STATE_ONLINE);
171 
172 	if (get_cpu_current_state(nr) == CPU_STATE_INACTIVE) {
173 		long rc;
174 		unsigned long hcpuid;
175 
176 		hcpuid = get_hard_smp_processor_id(nr);
177 		rc = plpar_hcall_norets(H_PROD, hcpuid);
178 		if (rc != H_SUCCESS)
179 			printk(KERN_ERR "Error: Prod to wake up processor %d "
180 						"Ret= %ld\n", nr, rc);
181 	}
182 #endif
183 
184 	return 0;
185 }
186 
187 static int pseries_smp_prepare_cpu(int cpu)
188 {
189 	if (xive_enabled())
190 		return xive_smp_prepare_cpu(cpu);
191 	return 0;
192 }
193 
194 static void smp_pseries_cause_ipi(int cpu)
195 {
196 	/* POWER9 should not use this handler */
197 	if (doorbell_try_core_ipi(cpu))
198 		return;
199 
200 	icp_ops->cause_ipi(cpu);
201 }
202 
203 static int pseries_cause_nmi_ipi(int cpu)
204 {
205 	int hwcpu;
206 
207 	if (cpu == NMI_IPI_ALL_OTHERS) {
208 		hwcpu = H_SIGNAL_SYS_RESET_ALL_OTHERS;
209 	} else {
210 		if (cpu < 0) {
211 			WARN_ONCE(true, "incorrect cpu parameter %d", cpu);
212 			return 0;
213 		}
214 
215 		hwcpu = get_hard_smp_processor_id(cpu);
216 	}
217 
218 	if (plapr_signal_sys_reset(hwcpu) == H_SUCCESS)
219 		return 1;
220 
221 	return 0;
222 }
223 
224 static __init void pSeries_smp_probe_xics(void)
225 {
226 	xics_smp_probe();
227 
228 	if (cpu_has_feature(CPU_FTR_DBELL))
229 		smp_ops->cause_ipi = smp_pseries_cause_ipi;
230 	else
231 		smp_ops->cause_ipi = icp_ops->cause_ipi;
232 }
233 
234 static __init void pSeries_smp_probe(void)
235 {
236 	if (xive_enabled())
237 		/*
238 		 * Don't use P9 doorbells when XIVE is enabled. IPIs
239 		 * using MMIOs should be faster
240 		 */
241 		xive_smp_probe();
242 	else
243 		pSeries_smp_probe_xics();
244 }
245 
246 static struct smp_ops_t pseries_smp_ops = {
247 	.message_pass	= NULL,	/* Use smp_muxed_ipi_message_pass */
248 	.cause_ipi	= NULL,	/* Filled at runtime by pSeries_smp_probe() */
249 	.cause_nmi_ipi	= pseries_cause_nmi_ipi,
250 	.probe		= pSeries_smp_probe,
251 	.prepare_cpu	= pseries_smp_prepare_cpu,
252 	.kick_cpu	= smp_pSeries_kick_cpu,
253 	.setup_cpu	= smp_setup_cpu,
254 	.cpu_bootable	= smp_generic_cpu_bootable,
255 };
256 
257 /* This is called very early */
258 void __init smp_init_pseries(void)
259 {
260 	int i;
261 
262 	pr_debug(" -> smp_init_pSeries()\n");
263 	smp_ops = &pseries_smp_ops;
264 
265 	alloc_bootmem_cpumask_var(&of_spin_mask);
266 
267 	/*
268 	 * Mark threads which are still spinning in hold loops
269 	 *
270 	 * We know prom_init will not have started them if RTAS supports
271 	 * query-cpu-stopped-state.
272 	 */
273 	if (rtas_token("query-cpu-stopped-state") == RTAS_UNKNOWN_SERVICE) {
274 		if (cpu_has_feature(CPU_FTR_SMT)) {
275 			for_each_present_cpu(i) {
276 				if (cpu_thread_in_core(i) == 0)
277 					cpumask_set_cpu(i, of_spin_mask);
278 			}
279 		} else
280 			cpumask_copy(of_spin_mask, cpu_present_mask);
281 
282 		cpumask_clear_cpu(boot_cpuid, of_spin_mask);
283 	}
284 
285 	/* Non-lpar has additional take/give timebase */
286 	if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
287 		smp_ops->give_timebase = rtas_give_timebase;
288 		smp_ops->take_timebase = rtas_take_timebase;
289 	}
290 
291 	pr_debug(" <- smp_init_pSeries()\n");
292 }
293