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 #include <linux/pgtable.h>
24 
25 #include <asm/ptrace.h>
26 #include <linux/atomic.h>
27 #include <asm/irq.h>
28 #include <asm/page.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 #include <asm/svm.h>
45 
46 #include "pseries.h"
47 #include "offline_states.h"
48 
49 
50 /*
51  * The Primary thread of each non-boot processor was started from the OF client
52  * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
53  */
54 static cpumask_var_t of_spin_mask;
55 
56 /* Query where a cpu is now.  Return codes #defined in plpar_wrappers.h */
57 int smp_query_cpu_stopped(unsigned int pcpu)
58 {
59 	int cpu_status, status;
60 	int qcss_tok = rtas_token("query-cpu-stopped-state");
61 
62 	if (qcss_tok == RTAS_UNKNOWN_SERVICE) {
63 		printk_once(KERN_INFO
64 			"Firmware doesn't support query-cpu-stopped-state\n");
65 		return QCSS_HARDWARE_ERROR;
66 	}
67 
68 	status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
69 	if (status != 0) {
70 		printk(KERN_ERR
71 		       "RTAS query-cpu-stopped-state failed: %i\n", status);
72 		return status;
73 	}
74 
75 	return cpu_status;
76 }
77 
78 /**
79  * smp_startup_cpu() - start the given cpu
80  *
81  * At boot time, there is nothing to do for primary threads which were
82  * started from Open Firmware.  For anything else, call RTAS with the
83  * appropriate start location.
84  *
85  * Returns:
86  *	0	- failure
87  *	1	- success
88  */
89 static inline int smp_startup_cpu(unsigned int lcpu)
90 {
91 	int status;
92 	unsigned long start_here =
93 			__pa(ppc_function_entry(generic_secondary_smp_init));
94 	unsigned int pcpu;
95 	int start_cpu;
96 
97 	if (cpumask_test_cpu(lcpu, of_spin_mask))
98 		/* Already started by OF and sitting in spin loop */
99 		return 1;
100 
101 	pcpu = get_hard_smp_processor_id(lcpu);
102 
103 	/* Check to see if the CPU out of FW already for kexec */
104 	if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){
105 		cpumask_set_cpu(lcpu, of_spin_mask);
106 		return 1;
107 	}
108 
109 	/* Fixup atomic count: it exited inside IRQ handler. */
110 	task_thread_info(paca_ptrs[lcpu]->__current)->preempt_count	= 0;
111 #ifdef CONFIG_HOTPLUG_CPU
112 	if (get_cpu_current_state(lcpu) == CPU_STATE_INACTIVE)
113 		goto out;
114 #endif
115 	/*
116 	 * If the RTAS start-cpu token does not exist then presume the
117 	 * cpu is already spinning.
118 	 */
119 	start_cpu = rtas_token("start-cpu");
120 	if (start_cpu == RTAS_UNKNOWN_SERVICE)
121 		return 1;
122 
123 	status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
124 	if (status != 0) {
125 		printk(KERN_ERR "start-cpu failed: %i\n", status);
126 		return 0;
127 	}
128 
129 #ifdef CONFIG_HOTPLUG_CPU
130 out:
131 #endif
132 	return 1;
133 }
134 
135 static void smp_setup_cpu(int cpu)
136 {
137 	if (xive_enabled())
138 		xive_smp_setup_cpu();
139 	else 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 	if (nr < 0 || nr >= nr_cpu_ids)
155 		return -EINVAL;
156 
157 	if (!smp_startup_cpu(nr))
158 		return -ENOENT;
159 
160 	/*
161 	 * The processor is currently spinning, waiting for the
162 	 * cpu_start field to become non-zero After we set cpu_start,
163 	 * the processor will continue on to secondary_start
164 	 */
165 	paca_ptrs[nr]->cpu_start = 1;
166 #ifdef CONFIG_HOTPLUG_CPU
167 	set_preferred_offline_state(nr, CPU_STATE_ONLINE);
168 
169 	if (get_cpu_current_state(nr) == CPU_STATE_INACTIVE) {
170 		long rc;
171 		unsigned long hcpuid;
172 
173 		hcpuid = get_hard_smp_processor_id(nr);
174 		rc = plpar_hcall_norets(H_PROD, hcpuid);
175 		if (rc != H_SUCCESS)
176 			printk(KERN_ERR "Error: Prod to wake up processor %d "
177 						"Ret= %ld\n", nr, rc);
178 	}
179 #endif
180 
181 	return 0;
182 }
183 
184 static int pseries_smp_prepare_cpu(int cpu)
185 {
186 	if (xive_enabled())
187 		return xive_smp_prepare_cpu(cpu);
188 	return 0;
189 }
190 
191 static void smp_pseries_cause_ipi(int cpu)
192 {
193 	/* POWER9 should not use this handler */
194 	if (doorbell_try_core_ipi(cpu))
195 		return;
196 
197 	icp_ops->cause_ipi(cpu);
198 }
199 
200 static int pseries_cause_nmi_ipi(int cpu)
201 {
202 	int hwcpu;
203 
204 	if (cpu == NMI_IPI_ALL_OTHERS) {
205 		hwcpu = H_SIGNAL_SYS_RESET_ALL_OTHERS;
206 	} else {
207 		if (cpu < 0) {
208 			WARN_ONCE(true, "incorrect cpu parameter %d", cpu);
209 			return 0;
210 		}
211 
212 		hwcpu = get_hard_smp_processor_id(cpu);
213 	}
214 
215 	if (plpar_signal_sys_reset(hwcpu) == H_SUCCESS)
216 		return 1;
217 
218 	return 0;
219 }
220 
221 static __init void pSeries_smp_probe_xics(void)
222 {
223 	xics_smp_probe();
224 
225 	if (cpu_has_feature(CPU_FTR_DBELL) && !is_secure_guest())
226 		smp_ops->cause_ipi = smp_pseries_cause_ipi;
227 	else
228 		smp_ops->cause_ipi = icp_ops->cause_ipi;
229 }
230 
231 static __init void pSeries_smp_probe(void)
232 {
233 	if (xive_enabled())
234 		/*
235 		 * Don't use P9 doorbells when XIVE is enabled. IPIs
236 		 * using MMIOs should be faster
237 		 */
238 		xive_smp_probe();
239 	else
240 		pSeries_smp_probe_xics();
241 }
242 
243 static struct smp_ops_t pseries_smp_ops = {
244 	.message_pass	= NULL,	/* Use smp_muxed_ipi_message_pass */
245 	.cause_ipi	= NULL,	/* Filled at runtime by pSeries_smp_probe() */
246 	.cause_nmi_ipi	= pseries_cause_nmi_ipi,
247 	.probe		= pSeries_smp_probe,
248 	.prepare_cpu	= pseries_smp_prepare_cpu,
249 	.kick_cpu	= smp_pSeries_kick_cpu,
250 	.setup_cpu	= smp_setup_cpu,
251 	.cpu_bootable	= smp_generic_cpu_bootable,
252 };
253 
254 /* This is called very early */
255 void __init smp_init_pseries(void)
256 {
257 	int i;
258 
259 	pr_debug(" -> smp_init_pSeries()\n");
260 	smp_ops = &pseries_smp_ops;
261 
262 	alloc_bootmem_cpumask_var(&of_spin_mask);
263 
264 	/*
265 	 * Mark threads which are still spinning in hold loops
266 	 *
267 	 * We know prom_init will not have started them if RTAS supports
268 	 * query-cpu-stopped-state.
269 	 */
270 	if (rtas_token("query-cpu-stopped-state") == RTAS_UNKNOWN_SERVICE) {
271 		if (cpu_has_feature(CPU_FTR_SMT)) {
272 			for_each_present_cpu(i) {
273 				if (cpu_thread_in_core(i) == 0)
274 					cpumask_set_cpu(i, of_spin_mask);
275 			}
276 		} else
277 			cpumask_copy(of_spin_mask, cpu_present_mask);
278 
279 		cpumask_clear_cpu(boot_cpuid, of_spin_mask);
280 	}
281 
282 	/* Non-lpar has additional take/give timebase */
283 	if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
284 		smp_ops->give_timebase = rtas_give_timebase;
285 		smp_ops->take_timebase = rtas_take_timebase;
286 	}
287 
288 	pr_debug(" <- smp_init_pSeries()\n");
289 }
290