1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * SMP support for pSeries machines.
4  *
5  * Dave Engebretsen, Peter Bergner, and
6  * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
7  *
8  * Plus various changes from other IBM teams...
9  */
10 
11 
12 #include <linux/kernel.h>
13 #include <linux/sched.h>
14 #include <linux/smp.h>
15 #include <linux/interrupt.h>
16 #include <linux/delay.h>
17 #include <linux/init.h>
18 #include <linux/spinlock.h>
19 #include <linux/cache.h>
20 #include <linux/err.h>
21 #include <linux/device.h>
22 #include <linux/cpu.h>
23 
24 #include <asm/ptrace.h>
25 #include <linux/atomic.h>
26 #include <asm/irq.h>
27 #include <asm/page.h>
28 #include <asm/pgtable.h>
29 #include <asm/io.h>
30 #include <asm/prom.h>
31 #include <asm/smp.h>
32 #include <asm/paca.h>
33 #include <asm/machdep.h>
34 #include <asm/cputable.h>
35 #include <asm/firmware.h>
36 #include <asm/rtas.h>
37 #include <asm/vdso_datapage.h>
38 #include <asm/cputhreads.h>
39 #include <asm/xics.h>
40 #include <asm/xive.h>
41 #include <asm/dbell.h>
42 #include <asm/plpar_wrappers.h>
43 #include <asm/code-patching.h>
44 
45 #include "pseries.h"
46 #include "offline_states.h"
47 
48 
49 /*
50  * The Primary thread of each non-boot processor was started from the OF client
51  * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
52  */
53 static cpumask_var_t of_spin_mask;
54 
55 /* Query where a cpu is now.  Return codes #defined in plpar_wrappers.h */
56 int smp_query_cpu_stopped(unsigned int pcpu)
57 {
58 	int cpu_status, status;
59 	int qcss_tok = rtas_token("query-cpu-stopped-state");
60 
61 	if (qcss_tok == RTAS_UNKNOWN_SERVICE) {
62 		printk_once(KERN_INFO
63 			"Firmware doesn't support query-cpu-stopped-state\n");
64 		return QCSS_HARDWARE_ERROR;
65 	}
66 
67 	status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
68 	if (status != 0) {
69 		printk(KERN_ERR
70 		       "RTAS query-cpu-stopped-state failed: %i\n", status);
71 		return status;
72 	}
73 
74 	return cpu_status;
75 }
76 
77 /**
78  * smp_startup_cpu() - start the given cpu
79  *
80  * At boot time, there is nothing to do for primary threads which were
81  * started from Open Firmware.  For anything else, call RTAS with the
82  * appropriate start location.
83  *
84  * Returns:
85  *	0	- failure
86  *	1	- success
87  */
88 static inline int smp_startup_cpu(unsigned int lcpu)
89 {
90 	int status;
91 	unsigned long start_here =
92 			__pa(ppc_function_entry(generic_secondary_smp_init));
93 	unsigned int pcpu;
94 	int start_cpu;
95 
96 	if (cpumask_test_cpu(lcpu, of_spin_mask))
97 		/* Already started by OF and sitting in spin loop */
98 		return 1;
99 
100 	pcpu = get_hard_smp_processor_id(lcpu);
101 
102 	/* Check to see if the CPU out of FW already for kexec */
103 	if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){
104 		cpumask_set_cpu(lcpu, of_spin_mask);
105 		return 1;
106 	}
107 
108 	/* Fixup atomic count: it exited inside IRQ handler. */
109 	task_thread_info(paca_ptrs[lcpu]->__current)->preempt_count	= 0;
110 #ifdef CONFIG_HOTPLUG_CPU
111 	if (get_cpu_current_state(lcpu) == CPU_STATE_INACTIVE)
112 		goto out;
113 #endif
114 	/*
115 	 * If the RTAS start-cpu token does not exist then presume the
116 	 * cpu is already spinning.
117 	 */
118 	start_cpu = rtas_token("start-cpu");
119 	if (start_cpu == RTAS_UNKNOWN_SERVICE)
120 		return 1;
121 
122 	status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
123 	if (status != 0) {
124 		printk(KERN_ERR "start-cpu failed: %i\n", status);
125 		return 0;
126 	}
127 
128 #ifdef CONFIG_HOTPLUG_CPU
129 out:
130 #endif
131 	return 1;
132 }
133 
134 static void smp_setup_cpu(int cpu)
135 {
136 	if (xive_enabled())
137 		xive_smp_setup_cpu();
138 	else if (cpu != boot_cpuid)
139 		xics_setup_cpu();
140 
141 	if (firmware_has_feature(FW_FEATURE_SPLPAR))
142 		vpa_init(cpu);
143 
144 	cpumask_clear_cpu(cpu, of_spin_mask);
145 #ifdef CONFIG_HOTPLUG_CPU
146 	set_cpu_current_state(cpu, CPU_STATE_ONLINE);
147 	set_default_offline_state(cpu);
148 #endif
149 }
150 
151 static int smp_pSeries_kick_cpu(int nr)
152 {
153 	if (nr < 0 || nr >= nr_cpu_ids)
154 		return -EINVAL;
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_ptrs[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 int pseries_smp_prepare_cpu(int cpu)
184 {
185 	if (xive_enabled())
186 		return xive_smp_prepare_cpu(cpu);
187 	return 0;
188 }
189 
190 static void smp_pseries_cause_ipi(int cpu)
191 {
192 	/* POWER9 should not use this handler */
193 	if (doorbell_try_core_ipi(cpu))
194 		return;
195 
196 	icp_ops->cause_ipi(cpu);
197 }
198 
199 static int pseries_cause_nmi_ipi(int cpu)
200 {
201 	int hwcpu;
202 
203 	if (cpu == NMI_IPI_ALL_OTHERS) {
204 		hwcpu = H_SIGNAL_SYS_RESET_ALL_OTHERS;
205 	} else {
206 		if (cpu < 0) {
207 			WARN_ONCE(true, "incorrect cpu parameter %d", cpu);
208 			return 0;
209 		}
210 
211 		hwcpu = get_hard_smp_processor_id(cpu);
212 	}
213 
214 	if (plpar_signal_sys_reset(hwcpu) == H_SUCCESS)
215 		return 1;
216 
217 	return 0;
218 }
219 
220 static __init void pSeries_smp_probe_xics(void)
221 {
222 	xics_smp_probe();
223 
224 	if (cpu_has_feature(CPU_FTR_DBELL))
225 		smp_ops->cause_ipi = smp_pseries_cause_ipi;
226 	else
227 		smp_ops->cause_ipi = icp_ops->cause_ipi;
228 }
229 
230 static __init void pSeries_smp_probe(void)
231 {
232 	if (xive_enabled())
233 		/*
234 		 * Don't use P9 doorbells when XIVE is enabled. IPIs
235 		 * using MMIOs should be faster
236 		 */
237 		xive_smp_probe();
238 	else
239 		pSeries_smp_probe_xics();
240 }
241 
242 static struct smp_ops_t pseries_smp_ops = {
243 	.message_pass	= NULL,	/* Use smp_muxed_ipi_message_pass */
244 	.cause_ipi	= NULL,	/* Filled at runtime by pSeries_smp_probe() */
245 	.cause_nmi_ipi	= pseries_cause_nmi_ipi,
246 	.probe		= pSeries_smp_probe,
247 	.prepare_cpu	= pseries_smp_prepare_cpu,
248 	.kick_cpu	= smp_pSeries_kick_cpu,
249 	.setup_cpu	= smp_setup_cpu,
250 	.cpu_bootable	= smp_generic_cpu_bootable,
251 };
252 
253 /* This is called very early */
254 void __init smp_init_pseries(void)
255 {
256 	int i;
257 
258 	pr_debug(" -> smp_init_pSeries()\n");
259 	smp_ops = &pseries_smp_ops;
260 
261 	alloc_bootmem_cpumask_var(&of_spin_mask);
262 
263 	/*
264 	 * Mark threads which are still spinning in hold loops
265 	 *
266 	 * We know prom_init will not have started them if RTAS supports
267 	 * query-cpu-stopped-state.
268 	 */
269 	if (rtas_token("query-cpu-stopped-state") == RTAS_UNKNOWN_SERVICE) {
270 		if (cpu_has_feature(CPU_FTR_SMT)) {
271 			for_each_present_cpu(i) {
272 				if (cpu_thread_in_core(i) == 0)
273 					cpumask_set_cpu(i, of_spin_mask);
274 			}
275 		} else
276 			cpumask_copy(of_spin_mask, cpu_present_mask);
277 
278 		cpumask_clear_cpu(boot_cpuid, of_spin_mask);
279 	}
280 
281 	/* Non-lpar has additional take/give timebase */
282 	if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
283 		smp_ops->give_timebase = rtas_give_timebase;
284 		smp_ops->take_timebase = rtas_take_timebase;
285 	}
286 
287 	pr_debug(" <- smp_init_pSeries()\n");
288 }
289