minix/kernel/smp.c

   1 #include <assert.h>
   2
   3 #include "smp.h"
   4 #include "interrupt.h"
   5 #include "clock.h"
   6
   7 unsigned ncpus;
   8 unsigned ht_per_core;
   9 unsigned bsp_cpu_id;
  10
  11 struct cpu cpus[CONFIG_MAX_CPUS];
  12
  13 /* info passed to another cpu along with a sched ipi */
  14 struct sched_ipi_data {
  15         volatile u32_t  flags;
  16         volatile u32_t  data;
  17 };
  18
  19 static struct sched_ipi_data  sched_ipi_data[CONFIG_MAX_CPUS];
  20
  21 #define SCHED_IPI_STOP_PROC     1
  22 #define SCHED_IPI_VM_INHIBIT    2
  23 #define SCHED_IPI_SAVE_CTX      4
  24
  25 static volatile unsigned ap_cpus_booted;
  26
  27 SPINLOCK_DEFINE(big_kernel_lock)
  28 SPINLOCK_DEFINE(boot_lock)
  29
  30 void wait_for_APs_to_finish_booting(void)
  31 {
  32         unsigned n = 0;
  33         int i;
  34
  35         /* check how many cpus are actually alive */
  36         for (i = 0 ; i < ncpus ; i++) {
  37                 if (cpu_test_flag(i, CPU_IS_READY))
  38                         n++;
  39         }
  40         if (n != ncpus)
  41                 printf("WARNING only %d out of %d cpus booted\n", n, ncpus);
  42
  43         /* we must let the other CPUs to run in kernel mode first */
  44         BKL_UNLOCK();
  45         while (ap_cpus_booted != (n - 1))
  46                 arch_pause();
  47         /* now we have to take the lock again as we continue execution */
  48         BKL_LOCK();
  49 }
  50
  51 void ap_boot_finished(unsigned cpu)
  52 {
  53         ap_cpus_booted++;
  54 }
  55
  56 void smp_ipi_halt_handler(void)
  57 {
  58         ipi_ack();
  59         stop_local_timer();
  60         arch_smp_halt_cpu();
  61 }
  62
  63 void smp_schedule(unsigned cpu)
  64 {
  65         arch_send_smp_schedule_ipi(cpu);
  66 }
  67
  68 void smp_sched_handler(void);
  69
  70 /*
  71  * tell another cpu about a task to do and return only after the cpu acks that
  72  * the task is finished. Also wait before it finishes task sent by another cpu
  73  * to the same one.
  74  */
  75 static void smp_schedule_sync(struct proc * p, unsigned task)
  76 {
  77         unsigned cpu = p->p_cpu;
  78         unsigned mycpu = cpuid;
  79
  80         assert(cpu != mycpu);
  81         /*
  82          * if some other cpu made a request to the same cpu, wait until it is
  83          * done before proceeding
  84          */
  85         if (sched_ipi_data[cpu].flags != 0) {
  86                 BKL_UNLOCK();
  87                 while (sched_ipi_data[cpu].flags != 0) {
  88                         if (sched_ipi_data[mycpu].flags) {
  89                                 BKL_LOCK();
  90                                 smp_sched_handler();
  91                                 BKL_UNLOCK();
  92                         }
  93                 }
  94                 BKL_LOCK();
  95         }
  96
  97         sched_ipi_data[cpu].data = (u32_t) p;
  98         sched_ipi_data[cpu].flags |= task;
  99         __insn_barrier();
 100         arch_send_smp_schedule_ipi(cpu);
 101
 102         /* wait until the destination cpu finishes its job */
 103         BKL_UNLOCK();
 104         while (sched_ipi_data[cpu].flags != 0) {
 105                 if (sched_ipi_data[mycpu].flags) {
 106                         BKL_LOCK();
 107                         smp_sched_handler();
 108                         BKL_UNLOCK();
 109                 }
 110         }
 111         BKL_LOCK();
 112 }
 113
 114 void smp_schedule_stop_proc(struct proc * p)
 115 {
 116         if (proc_is_runnable(p))
 117                 smp_schedule_sync(p, SCHED_IPI_STOP_PROC);
 118         else
 119                 RTS_SET(p, RTS_PROC_STOP);
 120         assert(RTS_ISSET(p, RTS_PROC_STOP));
 121 }
 122
 123 void smp_schedule_vminhibit(struct proc * p)
 124 {
 125         if (proc_is_runnable(p))
 126                 smp_schedule_sync(p, SCHED_IPI_VM_INHIBIT);
 127         else
 128                 RTS_SET(p, RTS_VMINHIBIT);
 129         assert(RTS_ISSET(p, RTS_VMINHIBIT));
 130 }
 131
 132 void smp_schedule_stop_proc_save_ctx(struct proc * p)
 133 {
 134         /*
 135          * stop the processes and force the complete context of the process to
 136          * be saved (i.e. including FPU state and such)
 137          */
 138         smp_schedule_sync(p, SCHED_IPI_STOP_PROC | SCHED_IPI_SAVE_CTX);
 139         assert(RTS_ISSET(p, RTS_PROC_STOP));
 140 }
 141
 142 void smp_schedule_migrate_proc(struct proc * p, unsigned dest_cpu)
 143 {
 144         /*
 145          * stop the processes and force the complete context of the process to
 146          * be saved (i.e. including FPU state and such)
 147          */
 148         smp_schedule_sync(p, SCHED_IPI_STOP_PROC | SCHED_IPI_SAVE_CTX);
 149         assert(RTS_ISSET(p, RTS_PROC_STOP));
 150
 151         /* assign the new cpu and let the process run again */
 152         p->p_cpu = dest_cpu;
 153         RTS_UNSET(p, RTS_PROC_STOP);
 154 }
 155
 156 void smp_sched_handler(void)
 157 {
 158         unsigned flgs;
 159         unsigned cpu = cpuid;
 160
 161         flgs = sched_ipi_data[cpu].flags;
 162
 163         if (flgs) {
 164                 struct proc * p;
 165                 p = (struct proc *)sched_ipi_data[cpu].data;
 166
 167                 if (flgs & SCHED_IPI_STOP_PROC) {
 168                         RTS_SET(p, RTS_PROC_STOP);
 169                 }
 170                 if (flgs & SCHED_IPI_SAVE_CTX) {
 171                         /* all context has been saved already, FPU remains */
 172                         if (proc_used_fpu(p) &&
 173                                         get_cpulocal_var(fpu_owner) == p) {
 174                                 disable_fpu_exception();
 175                                 save_local_fpu(p, FALSE /*retain*/);
 176                                 /* we're preparing to migrate somewhere else */
 177                                 release_fpu(p);
 178                         }
 179                 }
 180                 if (flgs & SCHED_IPI_VM_INHIBIT) {
 181                         RTS_SET(p, RTS_VMINHIBIT);
 182                 }
 183         }
 184
 185         __insn_barrier();
 186         sched_ipi_data[cpu].flags = 0;
 187 }
 188
 189 /*
 190  * This function gets always called only after smp_sched_handler() has been
 191  * already called. It only serves the purpose of acknowledging the IPI and
 192  * preempting the current process if the CPU was not idle.
 193  */
 194 void smp_ipi_sched_handler(void)
 195 {
 196         struct proc * curr;
 197
 198         ipi_ack();
 199
 200         curr = get_cpulocal_var(proc_ptr);
 201         if (curr->p_endpoint != IDLE) {
 202                 RTS_SET(curr, RTS_PREEMPTED);
 203         }
 204 }
 205