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Linux/arch/powerpc/platforms/powernv/smp.c

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  1 /*
  2  * SMP support for PowerNV machines.
  3  *
  4  * Copyright 2011 IBM Corp.
  5  *
  6  * This program is free software; you can redistribute it and/or
  7  * modify it under the terms of the GNU General Public License
  8  * as published by the Free Software Foundation; either version
  9  * 2 of the License, or (at your option) any later version.
 10  */
 11 
 12 #include <linux/kernel.h>
 13 #include <linux/module.h>
 14 #include <linux/sched.h>
 15 #include <linux/smp.h>
 16 #include <linux/interrupt.h>
 17 #include <linux/delay.h>
 18 #include <linux/init.h>
 19 #include <linux/spinlock.h>
 20 #include <linux/cpu.h>
 21 
 22 #include <asm/irq.h>
 23 #include <asm/smp.h>
 24 #include <asm/paca.h>
 25 #include <asm/machdep.h>
 26 #include <asm/cputable.h>
 27 #include <asm/firmware.h>
 28 #include <asm/vdso_datapage.h>
 29 #include <asm/cputhreads.h>
 30 #include <asm/xics.h>
 31 #include <asm/opal.h>
 32 #include <asm/runlatch.h>
 33 #include <asm/code-patching.h>
 34 #include <asm/dbell.h>
 35 #include <asm/kvm_ppc.h>
 36 #include <asm/ppc-opcode.h>
 37 
 38 #include "powernv.h"
 39 
 40 #ifdef DEBUG
 41 #include <asm/udbg.h>
 42 #define DBG(fmt...) udbg_printf(fmt)
 43 #else
 44 #define DBG(fmt...)
 45 #endif
 46 
 47 static void pnv_smp_setup_cpu(int cpu)
 48 {
 49         if (cpu != boot_cpuid)
 50                 xics_setup_cpu();
 51 
 52 #ifdef CONFIG_PPC_DOORBELL
 53         if (cpu_has_feature(CPU_FTR_DBELL))
 54                 doorbell_setup_this_cpu();
 55 #endif
 56 }
 57 
 58 static int pnv_smp_kick_cpu(int nr)
 59 {
 60         unsigned int pcpu = get_hard_smp_processor_id(nr);
 61         unsigned long start_here =
 62                         __pa(ppc_function_entry(generic_secondary_smp_init));
 63         long rc;
 64         uint8_t status;
 65 
 66         BUG_ON(nr < 0 || nr >= NR_CPUS);
 67 
 68         /*
 69          * If we already started or OPAL is not supported, we just
 70          * kick the CPU via the PACA
 71          */
 72         if (paca[nr].cpu_start || !firmware_has_feature(FW_FEATURE_OPAL))
 73                 goto kick;
 74 
 75         /*
 76          * At this point, the CPU can either be spinning on the way in
 77          * from kexec or be inside OPAL waiting to be started for the
 78          * first time. OPAL v3 allows us to query OPAL to know if it
 79          * has the CPUs, so we do that
 80          */
 81         rc = opal_query_cpu_status(pcpu, &status);
 82         if (rc != OPAL_SUCCESS) {
 83                 pr_warn("OPAL Error %ld querying CPU %d state\n", rc, nr);
 84                 return -ENODEV;
 85         }
 86 
 87         /*
 88          * Already started, just kick it, probably coming from
 89          * kexec and spinning
 90          */
 91         if (status == OPAL_THREAD_STARTED)
 92                 goto kick;
 93 
 94         /*
 95          * Available/inactive, let's kick it
 96          */
 97         if (status == OPAL_THREAD_INACTIVE) {
 98                 pr_devel("OPAL: Starting CPU %d (HW 0x%x)...\n", nr, pcpu);
 99                 rc = opal_start_cpu(pcpu, start_here);
100                 if (rc != OPAL_SUCCESS) {
101                         pr_warn("OPAL Error %ld starting CPU %d\n", rc, nr);
102                         return -ENODEV;
103                 }
104         } else {
105                 /*
106                  * An unavailable CPU (or any other unknown status)
107                  * shouldn't be started. It should also
108                  * not be in the possible map but currently it can
109                  * happen
110                  */
111                 pr_devel("OPAL: CPU %d (HW 0x%x) is unavailable"
112                          " (status %d)...\n", nr, pcpu, status);
113                 return -ENODEV;
114         }
115 
116 kick:
117         return smp_generic_kick_cpu(nr);
118 }
119 
120 #ifdef CONFIG_HOTPLUG_CPU
121 
122 static int pnv_smp_cpu_disable(void)
123 {
124         int cpu = smp_processor_id();
125 
126         /* This is identical to pSeries... might consolidate by
127          * moving migrate_irqs_away to a ppc_md with default to
128          * the generic fixup_irqs. --BenH.
129          */
130         set_cpu_online(cpu, false);
131         vdso_data->processorCount--;
132         if (cpu == boot_cpuid)
133                 boot_cpuid = cpumask_any(cpu_online_mask);
134         xics_migrate_irqs_away();
135         return 0;
136 }
137 
138 static void pnv_smp_cpu_kill_self(void)
139 {
140         unsigned int cpu;
141         unsigned long srr1, wmask;
142         u32 idle_states;
143 
144         /* Standard hot unplug procedure */
145         local_irq_disable();
146         idle_task_exit();
147         current->active_mm = NULL; /* for sanity */
148         cpu = smp_processor_id();
149         DBG("CPU%d offline\n", cpu);
150         generic_set_cpu_dead(cpu);
151         smp_wmb();
152 
153         wmask = SRR1_WAKEMASK;
154         if (cpu_has_feature(CPU_FTR_ARCH_207S))
155                 wmask = SRR1_WAKEMASK_P8;
156 
157         idle_states = pnv_get_supported_cpuidle_states();
158         /* We don't want to take decrementer interrupts while we are offline,
159          * so clear LPCR:PECE1. We keep PECE2 enabled.
160          */
161         mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);
162 
163         /*
164          * Hard-disable interrupts, and then clear irq_happened flags
165          * that we can safely ignore while off-line, since they
166          * are for things for which we do no processing when off-line
167          * (or in the case of HMI, all the processing we need to do
168          * is done in lower-level real-mode code).
169          */
170         hard_irq_disable();
171         local_paca->irq_happened &= ~(PACA_IRQ_DEC | PACA_IRQ_HMI);
172 
173         while (!generic_check_cpu_restart(cpu)) {
174                 /*
175                  * Clear IPI flag, since we don't handle IPIs while
176                  * offline, except for those when changing micro-threading
177                  * mode, which are handled explicitly below, and those
178                  * for coming online, which are handled via
179                  * generic_check_cpu_restart() calls.
180                  */
181                 kvmppc_set_host_ipi(cpu, 0);
182 
183                 ppc64_runlatch_off();
184 
185                 if (cpu_has_feature(CPU_FTR_ARCH_300))
186                         srr1 = power9_idle_stop(pnv_deepest_stop_state);
187                 else if (idle_states & OPAL_PM_WINKLE_ENABLED)
188                         srr1 = power7_winkle();
189                 else if ((idle_states & OPAL_PM_SLEEP_ENABLED) ||
190                                 (idle_states & OPAL_PM_SLEEP_ENABLED_ER1))
191                         srr1 = power7_sleep();
192                 else
193                         srr1 = power7_nap(1);
194 
195                 ppc64_runlatch_on();
196 
197                 /*
198                  * If the SRR1 value indicates that we woke up due to
199                  * an external interrupt, then clear the interrupt.
200                  * We clear the interrupt before checking for the
201                  * reason, so as to avoid a race where we wake up for
202                  * some other reason, find nothing and clear the interrupt
203                  * just as some other cpu is sending us an interrupt.
204                  * If we returned from power7_nap as a result of
205                  * having finished executing in a KVM guest, then srr1
206                  * contains 0.
207                  */
208                 if (((srr1 & wmask) == SRR1_WAKEEE) ||
209                     (local_paca->irq_happened & PACA_IRQ_EE)) {
210                         icp_native_flush_interrupt();
211                 } else if ((srr1 & wmask) == SRR1_WAKEHDBELL) {
212                         unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);
213                         asm volatile(PPC_MSGCLR(%0) : : "r" (msg));
214                 }
215                 local_paca->irq_happened &= ~(PACA_IRQ_EE | PACA_IRQ_DBELL);
216                 smp_mb();
217 
218                 if (cpu_core_split_required())
219                         continue;
220 
221                 if (srr1 && !generic_check_cpu_restart(cpu))
222                         DBG("CPU%d Unexpected exit while offline !\n", cpu);
223         }
224         mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1);
225         DBG("CPU%d coming online...\n", cpu);
226 }
227 
228 #endif /* CONFIG_HOTPLUG_CPU */
229 
230 static int pnv_cpu_bootable(unsigned int nr)
231 {
232         /*
233          * Starting with POWER8, the subcore logic relies on all threads of a
234          * core being booted so that they can participate in split mode
235          * switches. So on those machines we ignore the smt_enabled_at_boot
236          * setting (smt-enabled on the kernel command line).
237          */
238         if (cpu_has_feature(CPU_FTR_ARCH_207S))
239                 return 1;
240 
241         return smp_generic_cpu_bootable(nr);
242 }
243 
244 static struct smp_ops_t pnv_smp_ops = {
245         .message_pass   = smp_muxed_ipi_message_pass,
246         .cause_ipi      = NULL, /* Filled at runtime by xics_smp_probe() */
247         .probe          = xics_smp_probe,
248         .kick_cpu       = pnv_smp_kick_cpu,
249         .setup_cpu      = pnv_smp_setup_cpu,
250         .cpu_bootable   = pnv_cpu_bootable,
251 #ifdef CONFIG_HOTPLUG_CPU
252         .cpu_disable    = pnv_smp_cpu_disable,
253         .cpu_die        = generic_cpu_die,
254 #endif /* CONFIG_HOTPLUG_CPU */
255 };
256 
257 /* This is called very early during platform setup_arch */
258 void __init pnv_smp_init(void)
259 {
260         smp_ops = &pnv_smp_ops;
261 
262 #ifdef CONFIG_HOTPLUG_CPU
263         ppc_md.cpu_die  = pnv_smp_cpu_kill_self;
264 #endif
265 }
266 

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