blob: ec1de97600e70638bcfdcb53da52a83bc1288829 [file] [log] [blame]
* Intel SMP support routines.
* (c) 1995 Alan Cox, Building #3 <>
* (c) 1998-99, 2000, 2009 Ingo Molnar <>
* (c) 2002,2003 Andi Kleen, SuSE Labs.
* i386 and x86_64 integration by Glauber Costa <>
* This code is released under the GNU General Public License version 2 or
* later.
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/kernel_stat.h>
#include <linux/mc146818rtc.h>
#include <linux/cache.h>
#include <linux/interrupt.h>
#include <linux/cpu.h>
#include <asm/mtrr.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/proto.h>
#include <asm/apic.h>
* Some notes on x86 processor bugs affecting SMP operation:
* Pentium, Pentium Pro, II, III (and all CPUs) have bugs.
* The Linux implications for SMP are handled as follows:
* Pentium III / [Xeon]
* None of the E1AP-E3AP errata are visible to the user.
* E1AP. see PII A1AP
* E2AP. see PII A2AP
* E3AP. see PII A3AP
* Pentium II / [Xeon]
* None of the A1AP-A3AP errata are visible to the user.
* A1AP. see PPro 1AP
* A2AP. see PPro 2AP
* A3AP. see PPro 7AP
* Pentium Pro
* None of 1AP-9AP errata are visible to the normal user,
* except occasional delivery of 'spurious interrupt' as trap #15.
* This is very rare and a non-problem.
* 1AP. Linux maps APIC as non-cacheable
* 2AP. worked around in hardware
* 3AP. fixed in C0 and above steppings microcode update.
* Linux does not use excessive STARTUP_IPIs.
* 4AP. worked around in hardware
* 5AP. symmetric IO mode (normal Linux operation) not affected.
* 'noapic' mode has vector 0xf filled out properly.
* 6AP. 'noapic' mode might be affected - fixed in later steppings
* 7AP. We do not assume writes to the LVT deassering IRQs
* 8AP. We do not enable low power mode (deep sleep) during MP bootup
* 9AP. We do not use mixed mode
* Pentium
* There is a marginal case where REP MOVS on 100MHz SMP
* machines with B stepping processors can fail. XXX should provide
* an L1cache=Writethrough or L1cache=off option.
* B stepping CPUs may hang. There are hardware work arounds
* for this. We warn about it in case your board doesn't have the work
* arounds. Basically that's so I can tell anyone with a B stepping
* CPU and SMP problems "tough".
* Specific items [From Pentium Processor Specification Update]
* 1AP. Linux doesn't use remote read
* 2AP. Linux doesn't trust APIC errors
* 3AP. We work around this
* 4AP. Linux never generated 3 interrupts of the same priority
* to cause a lost local interrupt.
* 5AP. Remote read is never used
* 6AP. not affected - worked around in hardware
* 7AP. not affected - worked around in hardware
* 8AP. worked around in hardware - we get explicit CS errors if not
* 9AP. only 'noapic' mode affected. Might generate spurious
* interrupts, we log only the first one and count the
* rest silently.
* 10AP. not affected - worked around in hardware
* 11AP. Linux reads the APIC between writes to avoid this, as per
* the documentation. Make sure you preserve this as it affects
* the C stepping chips too.
* 12AP. not affected - worked around in hardware
* 13AP. not affected - worked around in hardware
* 14AP. we always deassert INIT during bootup
* 15AP. not affected - worked around in hardware
* 16AP. not affected - worked around in hardware
* 17AP. not affected - worked around in hardware
* 18AP. not affected - worked around in hardware
* 19AP. not affected - worked around in BIOS
* If this sounds worrying believe me these bugs are either ___RARE___,
* or are signal timing bugs worked around in hardware and there's
* about nothing of note with C stepping upwards.
* this function sends a 'reschedule' IPI to another CPU.
* it goes straight through and wastes no time serializing
* anything. Worst case is that we lose a reschedule ...
static void native_smp_send_reschedule(int cpu)
if (unlikely(cpu_is_offline(cpu))) {
apic->send_IPI_mask(cpumask_of(cpu), RESCHEDULE_VECTOR);
void native_send_call_func_single_ipi(int cpu)
apic->send_IPI_mask(cpumask_of(cpu), CALL_FUNCTION_SINGLE_VECTOR);
void native_send_call_func_ipi(const struct cpumask *mask)
cpumask_var_t allbutself;
if (!alloc_cpumask_var(&allbutself, GFP_ATOMIC)) {
apic->send_IPI_mask(mask, CALL_FUNCTION_VECTOR);
cpumask_copy(allbutself, cpu_online_mask);
cpumask_clear_cpu(smp_processor_id(), allbutself);
if (cpumask_equal(mask, allbutself) &&
cpumask_equal(cpu_online_mask, cpu_callout_mask))
apic->send_IPI_mask(mask, CALL_FUNCTION_VECTOR);
* this function calls the 'stop' function on all other CPUs in the system.
asmlinkage void smp_reboot_interrupt(void)
static void native_smp_send_stop(void)
unsigned long flags;
unsigned long wait;
if (reboot_force)
* Use an own vector here because smp_call_function
* does lots of things not suitable in a panic situation.
* On most systems we could also use an NMI here,
* but there are a few systems around where NMI
* is problematic so stay with an non NMI for now
* (this implies we cannot stop CPUs spinning with irq off
* currently)
if (num_online_cpus() > 1) {
/* Don't wait longer than a second */
wait = USEC_PER_SEC;
while (num_online_cpus() > 1 && wait--)
* Reschedule call back. Nothing to do,
* all the work is done automatically when
* we return from the interrupt.
void smp_reschedule_interrupt(struct pt_regs *regs)
* KVM uses this interrupt to force a cpu out of guest mode
void smp_call_function_interrupt(struct pt_regs *regs)
void smp_call_function_single_interrupt(struct pt_regs *regs)
struct smp_ops smp_ops = {
.smp_prepare_boot_cpu = native_smp_prepare_boot_cpu,
.smp_prepare_cpus = native_smp_prepare_cpus,
.smp_cpus_done = native_smp_cpus_done,
.smp_send_stop = native_smp_send_stop,
.smp_send_reschedule = native_smp_send_reschedule,
.cpu_up = native_cpu_up,
.cpu_die = native_cpu_die,
.cpu_disable = native_cpu_disable,
.play_dead = native_play_dead,
.send_call_func_ipi = native_send_call_func_ipi,
.send_call_func_single_ipi = native_send_call_func_single_ipi,