1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * SMP support for PowerNV machines.
4  *
5  * Copyright 2011 IBM Corp.
6  */
7 
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/sched.h>
11 #include <linux/sched/hotplug.h>
12 #include <linux/smp.h>
13 #include <linux/interrupt.h>
14 #include <linux/delay.h>
15 #include <linux/init.h>
16 #include <linux/spinlock.h>
17 #include <linux/cpu.h>
18 
19 #include <asm/irq.h>
20 #include <asm/smp.h>
21 #include <asm/paca.h>
22 #include <asm/machdep.h>
23 #include <asm/cputable.h>
24 #include <asm/firmware.h>
25 #include <asm/vdso_datapage.h>
26 #include <asm/cputhreads.h>
27 #include <asm/xics.h>
28 #include <asm/xive.h>
29 #include <asm/opal.h>
30 #include <asm/runlatch.h>
31 #include <asm/code-patching.h>
32 #include <asm/dbell.h>
33 #include <asm/kvm_ppc.h>
34 #include <asm/ppc-opcode.h>
35 #include <asm/cpuidle.h>
36 #include <asm/kexec.h>
37 #include <asm/reg.h>
38 #include <asm/powernv.h>
39 
40 #include "powernv.h"
41 
42 #ifdef DEBUG
43 #include <asm/udbg.h>
44 #define DBG(fmt...) udbg_printf(fmt)
45 #else
46 #define DBG(fmt...)
47 #endif
48 
49 static void pnv_smp_setup_cpu(int cpu)
50 {
51 	/*
52 	 * P9 workaround for CI vector load (see traps.c),
53 	 * enable the corresponding HMI interrupt
54 	 */
55 	if (pvr_version_is(PVR_POWER9))
56 		mtspr(SPRN_HMEER, mfspr(SPRN_HMEER) | PPC_BIT(17));
57 
58 	if (xive_enabled())
59 		xive_smp_setup_cpu();
60 	else if (cpu != boot_cpuid)
61 		xics_setup_cpu();
62 }
63 
64 static int pnv_smp_kick_cpu(int nr)
65 {
66 	unsigned int pcpu;
67 	unsigned long start_here =
68 			__pa(ppc_function_entry(generic_secondary_smp_init));
69 	long rc;
70 	uint8_t status;
71 
72 	if (nr < 0 || nr >= nr_cpu_ids)
73 		return -EINVAL;
74 
75 	pcpu = get_hard_smp_processor_id(nr);
76 	/*
77 	 * If we already started or OPAL is not supported, we just
78 	 * kick the CPU via the PACA
79 	 */
80 	if (paca_ptrs[nr]->cpu_start || !firmware_has_feature(FW_FEATURE_OPAL))
81 		goto kick;
82 
83 	/*
84 	 * At this point, the CPU can either be spinning on the way in
85 	 * from kexec or be inside OPAL waiting to be started for the
86 	 * first time. OPAL v3 allows us to query OPAL to know if it
87 	 * has the CPUs, so we do that
88 	 */
89 	rc = opal_query_cpu_status(pcpu, &status);
90 	if (rc != OPAL_SUCCESS) {
91 		pr_warn("OPAL Error %ld querying CPU %d state\n", rc, nr);
92 		return -ENODEV;
93 	}
94 
95 	/*
96 	 * Already started, just kick it, probably coming from
97 	 * kexec and spinning
98 	 */
99 	if (status == OPAL_THREAD_STARTED)
100 		goto kick;
101 
102 	/*
103 	 * Available/inactive, let's kick it
104 	 */
105 	if (status == OPAL_THREAD_INACTIVE) {
106 		pr_devel("OPAL: Starting CPU %d (HW 0x%x)...\n", nr, pcpu);
107 		rc = opal_start_cpu(pcpu, start_here);
108 		if (rc != OPAL_SUCCESS) {
109 			pr_warn("OPAL Error %ld starting CPU %d\n", rc, nr);
110 			return -ENODEV;
111 		}
112 	} else {
113 		/*
114 		 * An unavailable CPU (or any other unknown status)
115 		 * shouldn't be started. It should also
116 		 * not be in the possible map but currently it can
117 		 * happen
118 		 */
119 		pr_devel("OPAL: CPU %d (HW 0x%x) is unavailable"
120 			 " (status %d)...\n", nr, pcpu, status);
121 		return -ENODEV;
122 	}
123 
124 kick:
125 	return smp_generic_kick_cpu(nr);
126 }
127 
128 #ifdef CONFIG_HOTPLUG_CPU
129 
130 static int pnv_smp_cpu_disable(void)
131 {
132 	int cpu = smp_processor_id();
133 
134 	/* This is identical to pSeries... might consolidate by
135 	 * moving migrate_irqs_away to a ppc_md with default to
136 	 * the generic fixup_irqs. --BenH.
137 	 */
138 	set_cpu_online(cpu, false);
139 	vdso_data->processorCount--;
140 	if (cpu == boot_cpuid)
141 		boot_cpuid = cpumask_any(cpu_online_mask);
142 	if (xive_enabled())
143 		xive_smp_disable_cpu();
144 	else
145 		xics_migrate_irqs_away();
146 	return 0;
147 }
148 
149 static void pnv_smp_cpu_kill_self(void)
150 {
151 	unsigned int cpu;
152 	unsigned long srr1, wmask;
153 	u64 lpcr_val;
154 
155 	/* Standard hot unplug procedure */
156 	/*
157 	 * This hard disables local interurpts, ensuring we have no lazy
158 	 * irqs pending.
159 	 */
160 	WARN_ON(irqs_disabled());
161 	hard_irq_disable();
162 	WARN_ON(lazy_irq_pending());
163 
164 	idle_task_exit();
165 	current->active_mm = NULL; /* for sanity */
166 	cpu = smp_processor_id();
167 	DBG("CPU%d offline\n", cpu);
168 	generic_set_cpu_dead(cpu);
169 	smp_wmb();
170 
171 	wmask = SRR1_WAKEMASK;
172 	if (cpu_has_feature(CPU_FTR_ARCH_207S))
173 		wmask = SRR1_WAKEMASK_P8;
174 
175 	/*
176 	 * We don't want to take decrementer interrupts while we are
177 	 * offline, so clear LPCR:PECE1. We keep PECE2 (and
178 	 * LPCR_PECE_HVEE on P9) enabled so as to let IPIs in.
179 	 *
180 	 * If the CPU gets woken up by a special wakeup, ensure that
181 	 * the SLW engine sets LPCR with decrementer bit cleared, else
182 	 * the CPU will come back to the kernel due to a spurious
183 	 * wakeup.
184 	 */
185 	lpcr_val = mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1;
186 	pnv_program_cpu_hotplug_lpcr(cpu, lpcr_val);
187 
188 	while (!generic_check_cpu_restart(cpu)) {
189 		/*
190 		 * Clear IPI flag, since we don't handle IPIs while
191 		 * offline, except for those when changing micro-threading
192 		 * mode, which are handled explicitly below, and those
193 		 * for coming online, which are handled via
194 		 * generic_check_cpu_restart() calls.
195 		 */
196 		kvmppc_set_host_ipi(cpu, 0);
197 
198 		srr1 = pnv_cpu_offline(cpu);
199 
200 		WARN_ON(lazy_irq_pending());
201 
202 		/*
203 		 * If the SRR1 value indicates that we woke up due to
204 		 * an external interrupt, then clear the interrupt.
205 		 * We clear the interrupt before checking for the
206 		 * reason, so as to avoid a race where we wake up for
207 		 * some other reason, find nothing and clear the interrupt
208 		 * just as some other cpu is sending us an interrupt.
209 		 * If we returned from power7_nap as a result of
210 		 * having finished executing in a KVM guest, then srr1
211 		 * contains 0.
212 		 */
213 		if (((srr1 & wmask) == SRR1_WAKEEE) ||
214 		    ((srr1 & wmask) == SRR1_WAKEHVI)) {
215 			if (cpu_has_feature(CPU_FTR_ARCH_300)) {
216 				if (xive_enabled())
217 					xive_flush_interrupt();
218 				else
219 					icp_opal_flush_interrupt();
220 			} else
221 				icp_native_flush_interrupt();
222 		} else if ((srr1 & wmask) == SRR1_WAKEHDBELL) {
223 			unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);
224 			asm volatile(PPC_MSGCLR(%0) : : "r" (msg));
225 		} else if ((srr1 & wmask) == SRR1_WAKERESET) {
226 			irq_set_pending_from_srr1(srr1);
227 			/* Does not return */
228 		}
229 
230 		smp_mb();
231 
232 		/*
233 		 * For kdump kernels, we process the ipi and jump to
234 		 * crash_ipi_callback
235 		 */
236 		if (kdump_in_progress()) {
237 			/*
238 			 * If we got to this point, we've not used
239 			 * NMI's, otherwise we would have gone
240 			 * via the SRR1_WAKERESET path. We are
241 			 * using regular IPI's for waking up offline
242 			 * threads.
243 			 */
244 			struct pt_regs regs;
245 
246 			ppc_save_regs(&regs);
247 			crash_ipi_callback(&regs);
248 			/* Does not return */
249 		}
250 
251 		if (cpu_core_split_required())
252 			continue;
253 
254 		if (srr1 && !generic_check_cpu_restart(cpu))
255 			DBG("CPU%d Unexpected exit while offline srr1=%lx!\n",
256 					cpu, srr1);
257 
258 	}
259 
260 	/*
261 	 * Re-enable decrementer interrupts in LPCR.
262 	 *
263 	 * Further, we want stop states to be woken up by decrementer
264 	 * for non-hotplug cases. So program the LPCR via stop api as
265 	 * well.
266 	 */
267 	lpcr_val = mfspr(SPRN_LPCR) | (u64)LPCR_PECE1;
268 	pnv_program_cpu_hotplug_lpcr(cpu, lpcr_val);
269 
270 	DBG("CPU%d coming online...\n", cpu);
271 }
272 
273 #endif /* CONFIG_HOTPLUG_CPU */
274 
275 static int pnv_cpu_bootable(unsigned int nr)
276 {
277 	/*
278 	 * Starting with POWER8, the subcore logic relies on all threads of a
279 	 * core being booted so that they can participate in split mode
280 	 * switches. So on those machines we ignore the smt_enabled_at_boot
281 	 * setting (smt-enabled on the kernel command line).
282 	 */
283 	if (cpu_has_feature(CPU_FTR_ARCH_207S))
284 		return 1;
285 
286 	return smp_generic_cpu_bootable(nr);
287 }
288 
289 static int pnv_smp_prepare_cpu(int cpu)
290 {
291 	if (xive_enabled())
292 		return xive_smp_prepare_cpu(cpu);
293 	return 0;
294 }
295 
296 /* Cause IPI as setup by the interrupt controller (xics or xive) */
297 static void (*ic_cause_ipi)(int cpu);
298 
299 static void pnv_cause_ipi(int cpu)
300 {
301 	if (doorbell_try_core_ipi(cpu))
302 		return;
303 
304 	ic_cause_ipi(cpu);
305 }
306 
307 static void __init pnv_smp_probe(void)
308 {
309 	if (xive_enabled())
310 		xive_smp_probe();
311 	else
312 		xics_smp_probe();
313 
314 	if (cpu_has_feature(CPU_FTR_DBELL)) {
315 		ic_cause_ipi = smp_ops->cause_ipi;
316 		WARN_ON(!ic_cause_ipi);
317 
318 		if (cpu_has_feature(CPU_FTR_ARCH_300))
319 			smp_ops->cause_ipi = doorbell_global_ipi;
320 		else
321 			smp_ops->cause_ipi = pnv_cause_ipi;
322 	}
323 }
324 
325 static int pnv_system_reset_exception(struct pt_regs *regs)
326 {
327 	if (smp_handle_nmi_ipi(regs))
328 		return 1;
329 	return 0;
330 }
331 
332 static int pnv_cause_nmi_ipi(int cpu)
333 {
334 	int64_t rc;
335 
336 	if (cpu >= 0) {
337 		int h = get_hard_smp_processor_id(cpu);
338 
339 		if (opal_check_token(OPAL_QUIESCE))
340 			opal_quiesce(QUIESCE_HOLD, h);
341 
342 		rc = opal_signal_system_reset(h);
343 
344 		if (opal_check_token(OPAL_QUIESCE))
345 			opal_quiesce(QUIESCE_RESUME, h);
346 
347 		if (rc != OPAL_SUCCESS)
348 			return 0;
349 		return 1;
350 
351 	} else if (cpu == NMI_IPI_ALL_OTHERS) {
352 		bool success = true;
353 		int c;
354 
355 		if (opal_check_token(OPAL_QUIESCE))
356 			opal_quiesce(QUIESCE_HOLD, -1);
357 
358 		/*
359 		 * We do not use broadcasts (yet), because it's not clear
360 		 * exactly what semantics Linux wants or the firmware should
361 		 * provide.
362 		 */
363 		for_each_online_cpu(c) {
364 			if (c == smp_processor_id())
365 				continue;
366 
367 			rc = opal_signal_system_reset(
368 						get_hard_smp_processor_id(c));
369 			if (rc != OPAL_SUCCESS)
370 				success = false;
371 		}
372 
373 		if (opal_check_token(OPAL_QUIESCE))
374 			opal_quiesce(QUIESCE_RESUME, -1);
375 
376 		if (success)
377 			return 1;
378 
379 		/*
380 		 * Caller will fall back to doorbells, which may pick
381 		 * up the remainders.
382 		 */
383 	}
384 
385 	return 0;
386 }
387 
388 static struct smp_ops_t pnv_smp_ops = {
389 	.message_pass	= NULL, /* Use smp_muxed_ipi_message_pass */
390 	.cause_ipi	= NULL,	/* Filled at runtime by pnv_smp_probe() */
391 	.cause_nmi_ipi	= NULL,
392 	.probe		= pnv_smp_probe,
393 	.prepare_cpu	= pnv_smp_prepare_cpu,
394 	.kick_cpu	= pnv_smp_kick_cpu,
395 	.setup_cpu	= pnv_smp_setup_cpu,
396 	.cpu_bootable	= pnv_cpu_bootable,
397 #ifdef CONFIG_HOTPLUG_CPU
398 	.cpu_disable	= pnv_smp_cpu_disable,
399 	.cpu_die	= generic_cpu_die,
400 #endif /* CONFIG_HOTPLUG_CPU */
401 };
402 
403 /* This is called very early during platform setup_arch */
404 void __init pnv_smp_init(void)
405 {
406 	if (opal_check_token(OPAL_SIGNAL_SYSTEM_RESET)) {
407 		ppc_md.system_reset_exception = pnv_system_reset_exception;
408 		pnv_smp_ops.cause_nmi_ipi = pnv_cause_nmi_ipi;
409 	}
410 	smp_ops = &pnv_smp_ops;
411 
412 #ifdef CONFIG_HOTPLUG_CPU
413 	ppc_md.cpu_die	= pnv_smp_cpu_kill_self;
414 #ifdef CONFIG_KEXEC_CORE
415 	crash_wake_offline = 1;
416 #endif
417 #endif
418 }
419