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/dbell.h>
45 #include <asm/plpar_wrappers.h>
46 #include <asm/code-patching.h>
47 
48 #include "pseries.h"
49 #include "offline_states.h"
50 
51 
52 /*
53  * The Primary thread of each non-boot processor was started from the OF client
54  * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
55  */
56 static cpumask_var_t of_spin_mask;
57 
58 /* Query where a cpu is now.  Return codes #defined in plpar_wrappers.h */
59 int smp_query_cpu_stopped(unsigned int pcpu)
60 {
61 	int cpu_status, status;
62 	int qcss_tok = rtas_token("query-cpu-stopped-state");
63 
64 	if (qcss_tok == RTAS_UNKNOWN_SERVICE) {
65 		printk_once(KERN_INFO
66 			"Firmware doesn't support query-cpu-stopped-state\n");
67 		return QCSS_HARDWARE_ERROR;
68 	}
69 
70 	status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
71 	if (status != 0) {
72 		printk(KERN_ERR
73 		       "RTAS query-cpu-stopped-state failed: %i\n", status);
74 		return status;
75 	}
76 
77 	return cpu_status;
78 }
79 
80 /**
81  * smp_startup_cpu() - start the given cpu
82  *
83  * At boot time, there is nothing to do for primary threads which were
84  * started from Open Firmware.  For anything else, call RTAS with the
85  * appropriate start location.
86  *
87  * Returns:
88  *	0	- failure
89  *	1	- success
90  */
91 static inline int smp_startup_cpu(unsigned int lcpu)
92 {
93 	int status;
94 	unsigned long start_here =
95 			__pa(ppc_function_entry(generic_secondary_smp_init));
96 	unsigned int pcpu;
97 	int start_cpu;
98 
99 	if (cpumask_test_cpu(lcpu, of_spin_mask))
100 		/* Already started by OF and sitting in spin loop */
101 		return 1;
102 
103 	pcpu = get_hard_smp_processor_id(lcpu);
104 
105 	/* Check to see if the CPU out of FW already for kexec */
106 	if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){
107 		cpumask_set_cpu(lcpu, of_spin_mask);
108 		return 1;
109 	}
110 
111 	/* Fixup atomic count: it exited inside IRQ handler. */
112 	task_thread_info(paca[lcpu].__current)->preempt_count	= 0;
113 #ifdef CONFIG_HOTPLUG_CPU
114 	if (get_cpu_current_state(lcpu) == CPU_STATE_INACTIVE)
115 		goto out;
116 #endif
117 	/*
118 	 * If the RTAS start-cpu token does not exist then presume the
119 	 * cpu is already spinning.
120 	 */
121 	start_cpu = rtas_token("start-cpu");
122 	if (start_cpu == RTAS_UNKNOWN_SERVICE)
123 		return 1;
124 
125 	status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
126 	if (status != 0) {
127 		printk(KERN_ERR "start-cpu failed: %i\n", status);
128 		return 0;
129 	}
130 
131 #ifdef CONFIG_HOTPLUG_CPU
132 out:
133 #endif
134 	return 1;
135 }
136 
137 static void smp_setup_cpu(int cpu)
138 {
139 	if (cpu != boot_cpuid)
140 		xics_setup_cpu();
141 
142 	if (firmware_has_feature(FW_FEATURE_SPLPAR))
143 		vpa_init(cpu);
144 
145 	cpumask_clear_cpu(cpu, of_spin_mask);
146 #ifdef CONFIG_HOTPLUG_CPU
147 	set_cpu_current_state(cpu, CPU_STATE_ONLINE);
148 	set_default_offline_state(cpu);
149 #endif
150 }
151 
152 static int smp_pSeries_kick_cpu(int nr)
153 {
154 	BUG_ON(nr < 0 || nr >= NR_CPUS);
155 
156 	if (!smp_startup_cpu(nr))
157 		return -ENOENT;
158 
159 	/*
160 	 * The processor is currently spinning, waiting for the
161 	 * cpu_start field to become non-zero After we set cpu_start,
162 	 * the processor will continue on to secondary_start
163 	 */
164 	paca[nr].cpu_start = 1;
165 #ifdef CONFIG_HOTPLUG_CPU
166 	set_preferred_offline_state(nr, CPU_STATE_ONLINE);
167 
168 	if (get_cpu_current_state(nr) == CPU_STATE_INACTIVE) {
169 		long rc;
170 		unsigned long hcpuid;
171 
172 		hcpuid = get_hard_smp_processor_id(nr);
173 		rc = plpar_hcall_norets(H_PROD, hcpuid);
174 		if (rc != H_SUCCESS)
175 			printk(KERN_ERR "Error: Prod to wake up processor %d "
176 						"Ret= %ld\n", nr, rc);
177 	}
178 #endif
179 
180 	return 0;
181 }
182 
183 static void smp_pseries_cause_ipi(int cpu)
184 {
185 	/* POWER9 should not use this handler */
186 	if (doorbell_try_core_ipi(cpu))
187 		return;
188 
189 	icp_ops->cause_ipi(cpu);
190 }
191 
192 static int pseries_cause_nmi_ipi(int cpu)
193 {
194 	int hwcpu;
195 
196 	if (cpu == NMI_IPI_ALL_OTHERS) {
197 		hwcpu = H_SIGNAL_SYS_RESET_ALL_OTHERS;
198 	} else {
199 		if (cpu < 0) {
200 			WARN_ONCE(true, "incorrect cpu parameter %d", cpu);
201 			return 0;
202 		}
203 
204 		hwcpu = get_hard_smp_processor_id(cpu);
205 	}
206 
207 	if (plapr_signal_sys_reset(hwcpu) == H_SUCCESS)
208 		return 1;
209 
210 	return 0;
211 }
212 
213 static __init void pSeries_smp_probe(void)
214 {
215 	xics_smp_probe();
216 
217 	if (cpu_has_feature(CPU_FTR_DBELL))
218 		smp_ops->cause_ipi = smp_pseries_cause_ipi;
219 	else
220 		smp_ops->cause_ipi = icp_ops->cause_ipi;
221 }
222 
223 static struct smp_ops_t pseries_smp_ops = {
224 	.message_pass	= NULL,	/* Use smp_muxed_ipi_message_pass */
225 	.cause_ipi	= NULL,	/* Filled at runtime by pSeries_smp_probe() */
226 	.cause_nmi_ipi	= pseries_cause_nmi_ipi,
227 	.probe		= pSeries_smp_probe,
228 	.kick_cpu	= smp_pSeries_kick_cpu,
229 	.setup_cpu	= smp_setup_cpu,
230 	.cpu_bootable	= smp_generic_cpu_bootable,
231 };
232 
233 /* This is called very early */
234 void __init smp_init_pseries(void)
235 {
236 	int i;
237 
238 	pr_debug(" -> smp_init_pSeries()\n");
239 	smp_ops = &pseries_smp_ops;
240 
241 	alloc_bootmem_cpumask_var(&of_spin_mask);
242 
243 	/*
244 	 * Mark threads which are still spinning in hold loops
245 	 *
246 	 * We know prom_init will not have started them if RTAS supports
247 	 * query-cpu-stopped-state.
248 	 */
249 	if (rtas_token("query-cpu-stopped-state") == RTAS_UNKNOWN_SERVICE) {
250 		if (cpu_has_feature(CPU_FTR_SMT)) {
251 			for_each_present_cpu(i) {
252 				if (cpu_thread_in_core(i) == 0)
253 					cpumask_set_cpu(i, of_spin_mask);
254 			}
255 		} else
256 			cpumask_copy(of_spin_mask, cpu_present_mask);
257 
258 		cpumask_clear_cpu(boot_cpuid, of_spin_mask);
259 	}
260 
261 	/* Non-lpar has additional take/give timebase */
262 	if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
263 		smp_ops->give_timebase = rtas_give_timebase;
264 		smp_ops->take_timebase = rtas_take_timebase;
265 	}
266 
267 	pr_debug(" <- smp_init_pSeries()\n");
268 }
269