arch/x86/kernel/smp.c

   1 /*
   2  *      Intel SMP support routines.
   3  *
   4  *      (c) 1995 Alan Cox, Building #3 <alan@lxorguk.ukuu.org.uk>
   5  *      (c) 1998-99, 2000, 2009 Ingo Molnar <mingo@redhat.com>
   6  *      (c) 2002,2003 Andi Kleen, SuSE Labs.
   7  *
   8  *      i386 and x86_64 integration by Glauber Costa <gcosta@redhat.com>
   9  *
  10  *      This code is released under the GNU General Public License version 2 or
  11  *      later.
  12  */
  13
  14 #include <linux/init.h>
  15
  16 #include <linux/mm.h>
  17 #include <linux/delay.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/kernel_stat.h>
  20 #include <linux/mc146818rtc.h>
  21 #include <linux/cache.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/cpu.h>
  24 #include <linux/gfp.h>
  25
  26 #include <asm/mtrr.h>
  27 #include <asm/tlbflush.h>
  28 #include <asm/mmu_context.h>
  29 #include <asm/proto.h>
  30 #include <asm/apic.h>
  31 /*
  32  *      Some notes on x86 processor bugs affecting SMP operation:
  33  *
  34  *      Pentium, Pentium Pro, II, III (and all CPUs) have bugs.
  35  *      The Linux implications for SMP are handled as follows:
  36  *
  37  *      Pentium III / [Xeon]
  38  *              None of the E1AP-E3AP errata are visible to the user.
  39  *
  40  *      E1AP.   see PII A1AP
  41  *      E2AP.   see PII A2AP
  42  *      E3AP.   see PII A3AP
  43  *
  44  *      Pentium II / [Xeon]
  45  *              None of the A1AP-A3AP errata are visible to the user.
  46  *
  47  *      A1AP.   see PPro 1AP
  48  *      A2AP.   see PPro 2AP
  49  *      A3AP.   see PPro 7AP
  50  *
  51  *      Pentium Pro
  52  *              None of 1AP-9AP errata are visible to the normal user,
  53  *      except occasional delivery of 'spurious interrupt' as trap #15.
  54  *      This is very rare and a non-problem.
  55  *
  56  *      1AP.    Linux maps APIC as non-cacheable
  57  *      2AP.    worked around in hardware
  58  *      3AP.    fixed in C0 and above steppings microcode update.
  59  *              Linux does not use excessive STARTUP_IPIs.
  60  *      4AP.    worked around in hardware
  61  *      5AP.    symmetric IO mode (normal Linux operation) not affected.
  62  *              'noapic' mode has vector 0xf filled out properly.
  63  *      6AP.    'noapic' mode might be affected - fixed in later steppings
  64  *      7AP.    We do not assume writes to the LVT deassering IRQs
  65  *      8AP.    We do not enable low power mode (deep sleep) during MP bootup
  66  *      9AP.    We do not use mixed mode
  67  *
  68  *      Pentium
  69  *              There is a marginal case where REP MOVS on 100MHz SMP
  70  *      machines with B stepping processors can fail. XXX should provide
  71  *      an L1cache=Writethrough or L1cache=off option.
  72  *
  73  *              B stepping CPUs may hang. There are hardware work arounds
  74  *      for this. We warn about it in case your board doesn't have the work
  75  *      arounds. Basically that's so I can tell anyone with a B stepping
  76  *      CPU and SMP problems "tough".
  77  *
  78  *      Specific items [From Pentium Processor Specification Update]
  79  *
  80  *      1AP.    Linux doesn't use remote read
  81  *      2AP.    Linux doesn't trust APIC errors
  82  *      3AP.    We work around this
  83  *      4AP.    Linux never generated 3 interrupts of the same priority
  84  *              to cause a lost local interrupt.
  85  *      5AP.    Remote read is never used
  86  *      6AP.    not affected - worked around in hardware
  87  *      7AP.    not affected - worked around in hardware
  88  *      8AP.    worked around in hardware - we get explicit CS errors if not
  89  *      9AP.    only 'noapic' mode affected. Might generate spurious
  90  *              interrupts, we log only the first one and count the
  91  *              rest silently.
  92  *      10AP.   not affected - worked around in hardware
  93  *      11AP.   Linux reads the APIC between writes to avoid this, as per
  94  *              the documentation. Make sure you preserve this as it affects
  95  *              the C stepping chips too.
  96  *      12AP.   not affected - worked around in hardware
  97  *      13AP.   not affected - worked around in hardware
  98  *      14AP.   we always deassert INIT during bootup
  99  *      15AP.   not affected - worked around in hardware
 100  *      16AP.   not affected - worked around in hardware
 101  *      17AP.   not affected - worked around in hardware
 102  *      18AP.   not affected - worked around in hardware
 103  *      19AP.   not affected - worked around in BIOS
 104  *
 105  *      If this sounds worrying believe me these bugs are either ___RARE___,
 106  *      or are signal timing bugs worked around in hardware and there's
 107  *      about nothing of note with C stepping upwards.
 108  */
 109
 110 /*
 111  * this function sends a 'reschedule' IPI to another CPU.
 112  * it goes straight through and wastes no time serializing
 113  * anything. Worst case is that we lose a reschedule ...
 114  */
 115 static void native_smp_send_reschedule(int cpu)
 116 {
 117         if (unlikely(cpu_is_offline(cpu))) {
 118                 WARN_ON(1);
 119                 return;
 120         }
 121         apic->send_IPI_mask(cpumask_of(cpu), RESCHEDULE_VECTOR);
 122 }
 123
 124 void native_send_call_func_single_ipi(int cpu)
 125 {
 126         apic->send_IPI_mask(cpumask_of(cpu), CALL_FUNCTION_SINGLE_VECTOR);
 127 }
 128
 129 void native_send_call_func_ipi(const struct cpumask *mask)
 130 {
 131         cpumask_var_t allbutself;
 132
 133         if (!alloc_cpumask_var(&allbutself, GFP_ATOMIC)) {
 134                 apic->send_IPI_mask(mask, CALL_FUNCTION_VECTOR);
 135                 return;
 136         }
 137
 138         cpumask_copy(allbutself, cpu_online_mask);
 139         cpumask_clear_cpu(smp_processor_id(), allbutself);
 140
 141         if (cpumask_equal(mask, allbutself) &&
 142             cpumask_equal(cpu_online_mask, cpu_callout_mask))
 143                 apic->send_IPI_allbutself(CALL_FUNCTION_VECTOR);
 144         else
 145                 apic->send_IPI_mask(mask, CALL_FUNCTION_VECTOR);
 146
 147         free_cpumask_var(allbutself);
 148 }
 149
 150 /*
 151  * this function calls the 'stop' function on all other CPUs in the system.
 152  */
 153
 154 asmlinkage void smp_reboot_interrupt(void)
 155 {
 156         ack_APIC_irq();
 157         irq_enter();
 158         stop_this_cpu(NULL);
 159         irq_exit();
 160 }
 161
 162 static void native_stop_other_cpus(int wait)
 163 {
 164         unsigned long flags;
 165         unsigned long timeout;
 166
 167         if (reboot_force)
 168                 return;
 169
 170         /*
 171          * Use an own vector here because smp_call_function
 172          * does lots of things not suitable in a panic situation.
 173          * On most systems we could also use an NMI here,
 174          * but there are a few systems around where NMI
 175          * is problematic so stay with an non NMI for now
 176          * (this implies we cannot stop CPUs spinning with irq off
 177          * currently)
 178          */
 179         if (num_online_cpus() > 1) {
 180                 apic->send_IPI_allbutself(REBOOT_VECTOR);
 181
 182                 /*
 183                  * Don't wait longer than a second if the caller
 184                  * didn't ask us to wait.
 185                  */
 186                 timeout = USEC_PER_SEC;
 187                 while (num_online_cpus() > 1 && (wait || timeout--))
 188                         udelay(1);
 189         }
 190
 191         local_irq_save(flags);
 192         disable_local_APIC();
 193         local_irq_restore(flags);
 194 }
 195
 196 /*
 197  * Reschedule call back. Nothing to do,
 198  * all the work is done automatically when
 199  * we return from the interrupt.
 200  */
 201 void smp_reschedule_interrupt(struct pt_regs *regs)
 202 {
 203         ack_APIC_irq();
 204         inc_irq_stat(irq_resched_count);
 205         /*
 206          * KVM uses this interrupt to force a cpu out of guest mode
 207          */
 208 }
 209
 210 void smp_call_function_interrupt(struct pt_regs *regs)
 211 {
 212         ack_APIC_irq();
 213         irq_enter();
 214         generic_smp_call_function_interrupt();
 215         inc_irq_stat(irq_call_count);
 216         irq_exit();
 217 }
 218
 219 void smp_call_function_single_interrupt(struct pt_regs *regs)
 220 {
 221         ack_APIC_irq();
 222         irq_enter();
 223         generic_smp_call_function_single_interrupt();
 224         inc_irq_stat(irq_call_count);
 225         irq_exit();
 226 }
 227
 228 struct smp_ops smp_ops = {
 229         .smp_prepare_boot_cpu   = native_smp_prepare_boot_cpu,
 230         .smp_prepare_cpus       = native_smp_prepare_cpus,
 231         .smp_cpus_done          = native_smp_cpus_done,
 232
 233         .stop_other_cpus        = native_stop_other_cpus,
 234         .smp_send_reschedule    = native_smp_send_reschedule,
 235
 236         .cpu_up                 = native_cpu_up,
 237         .cpu_die                = native_cpu_die,
 238         .cpu_disable            = native_cpu_disable,
 239         .play_dead              = native_play_dead,
 240
 241         .send_call_func_ipi     = native_send_call_func_ipi,
 242         .send_call_func_single_ipi = native_send_call_func_single_ipi,
 243 };
 244 EXPORT_SYMBOL_GPL(smp_ops);