kernel - Try to idle cpus when in panic()

[dragonfly.git] / sys / platform / pc64 / x86_64 / mp_machdep.c

/*
 * Copyright (c) 1996, by Steve Passe
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. The name of the developer may NOT be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: src/sys/i386/i386/mp_machdep.c,v 1.115.2.15 2003/03/14 21:22:35 jhb Exp $
 */

#include "opt_cpu.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/malloc.h>
#include <sys/memrange.h>
#include <sys/cons.h>   /* cngetc() */
#include <sys/machintr.h>
#include <sys/cpu_topology.h>

#include <sys/mplock2.h>

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>
#include <sys/lock.h>
#include <vm/vm_map.h>
#include <sys/user.h>
#ifdef GPROF 
#include <sys/gmon.h>
#endif

#include <machine/smp.h>
#include <machine_base/apic/apicreg.h>
#include <machine/atomic.h>
#include <machine/cpufunc.h>
#include <machine/cputypes.h>
#include <machine_base/apic/lapic.h>
#include <machine_base/apic/ioapic.h>
#include <machine_base/acpica/acpi_md_cpu.h>
#include <machine/psl.h>
#include <machine/segments.h>
#include <machine/tss.h>
#include <machine/specialreg.h>
#include <machine/globaldata.h>
#include <machine/pmap_inval.h>
#include <machine/clock.h>

#include <machine/md_var.h>             /* setidt() */
#include <machine_base/icu/icu.h>       /* IPIs */
#include <machine_base/icu/icu_var.h>
#include <machine_base/apic/ioapic_abi.h>
#include <machine/intr_machdep.h>       /* IPIs */

#define WARMBOOT_TARGET         0
#define WARMBOOT_OFF            (KERNBASE + 0x0467)
#define WARMBOOT_SEG            (KERNBASE + 0x0469)

#define CMOS_REG                (0x70)
#define CMOS_DATA               (0x71)
#define BIOS_RESET              (0x0f)
#define BIOS_WARM               (0x0a)

/*
 * this code MUST be enabled here and in mpboot.s.
 * it follows the very early stages of AP boot by placing values in CMOS ram.
 * it NORMALLY will never be needed and thus the primitive method for enabling.
 *
 */
#if defined(CHECK_POINTS)
#define CHECK_READ(A)    (outb(CMOS_REG, (A)), inb(CMOS_DATA))
#define CHECK_WRITE(A,D) (outb(CMOS_REG, (A)), outb(CMOS_DATA, (D)))

#define CHECK_INIT(D);                          \
        CHECK_WRITE(0x34, (D));                 \
        CHECK_WRITE(0x35, (D));                 \
        CHECK_WRITE(0x36, (D));                 \
        CHECK_WRITE(0x37, (D));                 \
        CHECK_WRITE(0x38, (D));                 \
        CHECK_WRITE(0x39, (D));

#define CHECK_PRINT(S);                         \
        kprintf("%s: %d, %d, %d, %d, %d, %d\n", \
           (S),                                 \
           CHECK_READ(0x34),                    \
           CHECK_READ(0x35),                    \
           CHECK_READ(0x36),                    \
           CHECK_READ(0x37),                    \
           CHECK_READ(0x38),                    \
           CHECK_READ(0x39));

#else                           /* CHECK_POINTS */

#define CHECK_INIT(D)
#define CHECK_PRINT(S)

#endif                          /* CHECK_POINTS */

/*
 * Values to send to the POST hardware.
 */
#define MP_BOOTADDRESS_POST     0x10
#define MP_PROBE_POST           0x11
#define MPTABLE_PASS1_POST      0x12

#define MP_START_POST           0x13
#define MP_ENABLE_POST          0x14
#define MPTABLE_PASS2_POST      0x15

#define START_ALL_APS_POST      0x16
#define INSTALL_AP_TRAMP_POST   0x17
#define START_AP_POST           0x18

#define MP_ANNOUNCE_POST        0x19

/** XXX FIXME: where does this really belong, isa.h/isa.c perhaps? */
int     current_postcode;

/** XXX FIXME: what system files declare these??? */
extern struct region_descriptor r_gdt;

extern int nkpt;
extern int naps;

int64_t tsc0_offset;
extern int64_t tsc_offsets[];

/* AP uses this during bootstrap.  Do not staticize.  */
char *bootSTK;
static int bootAP;

struct pcb stoppcbs[MAXCPU];

extern inthand_t IDTVEC(fast_syscall), IDTVEC(fast_syscall32);

/*
 * Local data and functions.
 */

static u_int    boot_address;
static int      mp_finish;
static int      mp_finish_lapic;

static int      start_all_aps(u_int boot_addr);
#if 0
static void     install_ap_tramp(u_int boot_addr);
#endif
static int      start_ap(struct mdglobaldata *gd, u_int boot_addr, int smibest);
static int      smitest(void);
static void     mp_bsp_simple_setup(void);

/* which cpus have been started */
static cpumask_t smp_startup_mask = CPUMASK_INITIALIZER_ONLYONE;
/* which cpus have lapic been inited */
static cpumask_t smp_lapic_mask = CPUMASK_INITIALIZER_ONLYONE;
/* which cpus are ready for IPIs etc? */
cpumask_t smp_active_mask = CPUMASK_INITIALIZER_ONLYONE;
cpumask_t smp_finalize_mask = CPUMASK_INITIALIZER_ONLYONE;

SYSCTL_INT(_machdep, OID_AUTO, smp_active, CTLFLAG_RD, &smp_active_mask, 0, "");
static u_int    bootMP_size;
static u_int    report_invlpg_src;
SYSCTL_INT(_machdep, OID_AUTO, report_invlpg_src, CTLFLAG_RW,
        &report_invlpg_src, 0, "");
static u_int    report_invltlb_src;
SYSCTL_INT(_machdep, OID_AUTO, report_invltlb_src, CTLFLAG_RW,
        &report_invltlb_src, 0, "");
static int      optimized_invltlb;
SYSCTL_INT(_machdep, OID_AUTO, optimized_invltlb, CTLFLAG_RW,
        &optimized_invltlb, 0, "");
static int      all_but_self_ipi_enable = 1;
SYSCTL_INT(_machdep, OID_AUTO, all_but_self_ipi_enable, CTLFLAG_RW,
        &all_but_self_ipi_enable, 0, "");

/* Local data for detecting CPU TOPOLOGY */
static int core_bits = 0;
static int logical_CPU_bits = 0;


/*
 * Calculate usable address in base memory for AP trampoline code.
 */
u_int
mp_bootaddress(u_int basemem)
{
        POSTCODE(MP_BOOTADDRESS_POST);

        bootMP_size = mptramp_end - mptramp_start;
        boot_address = trunc_page(basemem * 1024); /* round down to 4k boundary */
        if (((basemem * 1024) - boot_address) < bootMP_size)
                boot_address -= PAGE_SIZE;      /* not enough, lower by 4k */
        /* 3 levels of page table pages */
        mptramp_pagetables = boot_address - (PAGE_SIZE * 3);

        return mptramp_pagetables;
}

/*
 * Print various information about the SMP system hardware and setup.
 */
void
mp_announce(void)
{
        int     x;

        POSTCODE(MP_ANNOUNCE_POST);

        kprintf("DragonFly/MP: Multiprocessor motherboard\n");
        kprintf(" cpu0 (BSP): apic id: %2d\n", CPUID_TO_APICID(0));
        for (x = 1; x <= naps; ++x)
                kprintf(" cpu%d (AP):  apic id: %2d\n", x, CPUID_TO_APICID(x));

        if (!ioapic_enable)
                kprintf(" Warning: APIC I/O disabled\n");
}

/*
 * AP cpu's call this to sync up protected mode.
 *
 * WARNING! %gs is not set up on entry.  This routine sets up %gs.
 */
void
init_secondary(void)
{
        int     gsel_tss;
        int     x, myid = bootAP;
        u_int64_t msr, cr0;
        struct mdglobaldata *md;
        struct privatespace *ps;

        ps = CPU_prvspace[myid];

        gdt_segs[GPROC0_SEL].ssd_base =
                (long) &ps->mdglobaldata.gd_common_tss;
        ps->mdglobaldata.mi.gd_prvspace = ps;

        /* We fill the 32-bit segment descriptors */
        for (x = 0; x < NGDT; x++) {
                if (x != GPROC0_SEL && x != (GPROC0_SEL + 1))
                        ssdtosd(&gdt_segs[x], &gdt[myid * NGDT + x]);
        }
        /* And now a 64-bit one */
        ssdtosyssd(&gdt_segs[GPROC0_SEL],
            (struct system_segment_descriptor *)&gdt[myid * NGDT + GPROC0_SEL]);

        r_gdt.rd_limit = NGDT * sizeof(gdt[0]) - 1;
        r_gdt.rd_base = (long) &gdt[myid * NGDT];
        lgdt(&r_gdt);                   /* does magic intra-segment return */

        /* lgdt() destroys the GSBASE value, so we load GSBASE after lgdt() */
        wrmsr(MSR_FSBASE, 0);           /* User value */
        wrmsr(MSR_GSBASE, (u_int64_t)ps);
        wrmsr(MSR_KGSBASE, 0);          /* XXX User value while we're in the kernel */

        lidt(&r_idt_arr[mdcpu->mi.gd_cpuid]);

#if 0
        lldt(_default_ldt);
        mdcpu->gd_currentldt = _default_ldt;
#endif

        gsel_tss = GSEL(GPROC0_SEL, SEL_KPL);
        gdt[myid * NGDT + GPROC0_SEL].sd_type = SDT_SYSTSS;

        md = mdcpu;     /* loaded through %gs:0 (mdglobaldata.mi.gd_prvspace)*/

        md->gd_common_tss.tss_rsp0 = 0; /* not used until after switch */
#if 0 /* JG XXX */
        md->gd_common_tss.tss_ioopt = (sizeof md->gd_common_tss) << 16;
#endif
        md->gd_tss_gdt = &gdt[myid * NGDT + GPROC0_SEL];
        md->gd_common_tssd = *md->gd_tss_gdt;

        /* double fault stack */
        md->gd_common_tss.tss_ist1 =
                (long)&md->mi.gd_prvspace->idlestack[
                        sizeof(md->mi.gd_prvspace->idlestack)];

        ltr(gsel_tss);

        /*
         * Set to a known state:
         * Set by mpboot.s: CR0_PG, CR0_PE
         * Set by cpu_setregs: CR0_NE, CR0_MP, CR0_TS, CR0_WP, CR0_AM
         */
        cr0 = rcr0();
        cr0 &= ~(CR0_CD | CR0_NW | CR0_EM);
        load_cr0(cr0);

        /* Set up the fast syscall stuff */
        msr = rdmsr(MSR_EFER) | EFER_SCE;
        wrmsr(MSR_EFER, msr);
        wrmsr(MSR_LSTAR, (u_int64_t)IDTVEC(fast_syscall));
        wrmsr(MSR_CSTAR, (u_int64_t)IDTVEC(fast_syscall32));
        msr = ((u_int64_t)GSEL(GCODE_SEL, SEL_KPL) << 32) |
              ((u_int64_t)GSEL(GUCODE32_SEL, SEL_UPL) << 48);
        wrmsr(MSR_STAR, msr);
        wrmsr(MSR_SF_MASK, PSL_NT|PSL_T|PSL_I|PSL_C|PSL_D|PSL_IOPL);

        pmap_set_opt();         /* PSE/4MB pages, etc */
        pmap_init_pat();        /* Page Attribute Table */

        /* set up CPU registers and state */
        cpu_setregs();

        /* set up SSE/NX registers */
        initializecpu(myid);

        /* set up FPU state on the AP */
        npxinit();

        /* disable the APIC, just to be SURE */
        lapic->svr &= ~APIC_SVR_ENABLE;
}

/*******************************************************************
 * local functions and data
 */

/*
 * Start the SMP system
 */
static void
mp_start_aps(void *dummy __unused)
{
        if (lapic_enable) {
                /* start each Application Processor */
                start_all_aps(boot_address);
        } else {
                mp_bsp_simple_setup();
        }
}
SYSINIT(startaps, SI_BOOT2_START_APS, SI_ORDER_FIRST, mp_start_aps, NULL);

/*
 * start each AP in our list
 */
static int
start_all_aps(u_int boot_addr)
{
        vm_offset_t va = boot_address + KERNBASE;
        u_int64_t *pt4, *pt3, *pt2;
        int     pssize;
        int     x, i;
        int     shift;
        int     smicount;
        int     smibest;
        int     smilast;
        u_char  mpbiosreason;
        u_long  mpbioswarmvec;
        struct mdglobaldata *gd;
        struct privatespace *ps;
        size_t ipiq_size;

        POSTCODE(START_ALL_APS_POST);

        /* install the AP 1st level boot code */
        pmap_kenter(va, boot_address);
        cpu_invlpg((void *)va);         /* JG XXX */
        bcopy(mptramp_start, (void *)va, bootMP_size);

        /* Locate the page tables, they'll be below the trampoline */
        pt4 = (u_int64_t *)(uintptr_t)(mptramp_pagetables + KERNBASE);
        pt3 = pt4 + (PAGE_SIZE) / sizeof(u_int64_t);
        pt2 = pt3 + (PAGE_SIZE) / sizeof(u_int64_t);

        /* Create the initial 1GB replicated page tables */
        for (i = 0; i < 512; i++) {
                /* Each slot of the level 4 pages points to the same level 3 page */
                pt4[i] = (u_int64_t)(uintptr_t)(mptramp_pagetables + PAGE_SIZE);
                pt4[i] |= kernel_pmap.pmap_bits[PG_V_IDX] |
                    kernel_pmap.pmap_bits[PG_RW_IDX] |
                    kernel_pmap.pmap_bits[PG_U_IDX];

                /* Each slot of the level 3 pages points to the same level 2 page */
                pt3[i] = (u_int64_t)(uintptr_t)(mptramp_pagetables + (2 * PAGE_SIZE));
                pt3[i] |= kernel_pmap.pmap_bits[PG_V_IDX] |
                    kernel_pmap.pmap_bits[PG_RW_IDX] |
                    kernel_pmap.pmap_bits[PG_U_IDX];

                /* The level 2 page slots are mapped with 2MB pages for 1GB. */
                pt2[i] = i * (2 * 1024 * 1024);
                pt2[i] |= kernel_pmap.pmap_bits[PG_V_IDX] |
                    kernel_pmap.pmap_bits[PG_RW_IDX] |
                    kernel_pmap.pmap_bits[PG_PS_IDX] |
                    kernel_pmap.pmap_bits[PG_U_IDX];
        }

        /* save the current value of the warm-start vector */
        mpbioswarmvec = *((u_int32_t *) WARMBOOT_OFF);
        outb(CMOS_REG, BIOS_RESET);
        mpbiosreason = inb(CMOS_DATA);

        /* setup a vector to our boot code */
        *((volatile u_short *) WARMBOOT_OFF) = WARMBOOT_TARGET;
        *((volatile u_short *) WARMBOOT_SEG) = (boot_address >> 4);
        outb(CMOS_REG, BIOS_RESET);
        outb(CMOS_DATA, BIOS_WARM);     /* 'warm-start' */

        /*
         * If we have a TSC we can figure out the SMI interrupt rate.
         * The SMI does not necessarily use a constant rate.  Spend
         * up to 250ms trying to figure it out.
         */
        smibest = 0;
        if (cpu_feature & CPUID_TSC) {
                set_apic_timer(275000);
                smilast = read_apic_timer();
                for (x = 0; x < 20 && read_apic_timer(); ++x) {
                        smicount = smitest();
                        if (smibest == 0 || smilast - smicount < smibest)
                                smibest = smilast - smicount;
                        smilast = smicount;
                }
                if (smibest > 250000)
                        smibest = 0;
                if (smibest) {
                        smibest = smibest * (int64_t)1000000 /
                                  get_apic_timer_frequency();
                }
        }
        if (smibest)
                kprintf("SMI Frequency (worst case): %d Hz (%d us)\n",
                        1000000 / smibest, smibest);

        /* start each AP */
        for (x = 1; x <= naps; ++x) {
                /* This is a bit verbose, it will go away soon.  */

                pssize = sizeof(struct privatespace);
                ps = (void *)kmem_alloc(&kernel_map, pssize);
                CPU_prvspace[x] = ps;
#if 0
                kprintf("ps %d %p %d\n", x, ps, pssize);
#endif
                bzero(ps, pssize);
                gd = &ps->mdglobaldata;
                gd->mi.gd_prvspace = ps;

                /* prime data page for it to use */
                mi_gdinit(&gd->mi, x);
                cpu_gdinit(gd, x);
                ipiq_size = sizeof(struct lwkt_ipiq) * (naps + 1);
                gd->mi.gd_ipiq = (void *)kmem_alloc(&kernel_map, ipiq_size);
                bzero(gd->mi.gd_ipiq, ipiq_size);

                gd->gd_acpi_id = CPUID_TO_ACPIID(gd->mi.gd_cpuid);

                /* setup a vector to our boot code */
                *((volatile u_short *) WARMBOOT_OFF) = WARMBOOT_TARGET;
                *((volatile u_short *) WARMBOOT_SEG) = (boot_addr >> 4);
                outb(CMOS_REG, BIOS_RESET);
                outb(CMOS_DATA, BIOS_WARM);     /* 'warm-start' */

                /*
                 * Setup the AP boot stack
                 */
                bootSTK = &ps->idlestack[UPAGES * PAGE_SIZE - PAGE_SIZE];
                bootAP = x;

                /* attempt to start the Application Processor */
                CHECK_INIT(99); /* setup checkpoints */
                if (!start_ap(gd, boot_addr, smibest)) {
                        kprintf("\nAP #%d (PHY# %d) failed!\n",
                                x, CPUID_TO_APICID(x));
                        CHECK_PRINT("trace");   /* show checkpoints */
                        /* better panic as the AP may be running loose */
                        kprintf("panic y/n? [y] ");
                        cnpoll(TRUE);
                        if (cngetc() != 'n')
                                panic("bye-bye");
                        cnpoll(FALSE);
                }
                CHECK_PRINT("trace");           /* show checkpoints */
        }

        /* set ncpus to 1 + highest logical cpu.  Not all may have come up */
        ncpus = x;

        /* ncpus2 -- ncpus rounded down to the nearest power of 2 */
        for (shift = 0; (1 << shift) <= ncpus; ++shift)
                ;
        --shift;
        ncpus2_shift = shift;
        ncpus2 = 1 << shift;
        ncpus2_mask = ncpus2 - 1;

        /* ncpus_fit -- ncpus rounded up to the nearest power of 2 */
        if ((1 << shift) < ncpus)
                ++shift;
        ncpus_fit = 1 << shift;
        ncpus_fit_mask = ncpus_fit - 1;

        /* build our map of 'other' CPUs */
        mycpu->gd_other_cpus = smp_startup_mask;
        CPUMASK_NANDBIT(mycpu->gd_other_cpus, mycpu->gd_cpuid);

        gd = (struct mdglobaldata *)mycpu;
        gd->gd_acpi_id = CPUID_TO_ACPIID(mycpu->gd_cpuid);

        ipiq_size = sizeof(struct lwkt_ipiq) * ncpus;
        mycpu->gd_ipiq = (void *)kmem_alloc(&kernel_map, ipiq_size);
        bzero(mycpu->gd_ipiq, ipiq_size);

        /* restore the warmstart vector */
        *(u_long *) WARMBOOT_OFF = mpbioswarmvec;
        outb(CMOS_REG, BIOS_RESET);
        outb(CMOS_DATA, mpbiosreason);

        /*
         * NOTE!  The idlestack for the BSP was setup by locore.  Finish
         * up, clean out the P==V mapping we did earlier.
         */
        pmap_set_opt();

        /*
         * Wait all APs to finish initializing LAPIC
         */
        if (bootverbose)
                kprintf("SMP: Waiting APs LAPIC initialization\n");
        if (cpu_feature & CPUID_TSC)
                tsc0_offset = rdtsc();
        tsc_offsets[0] = 0;
        mp_finish_lapic = 1;
        rel_mplock();

        while (CPUMASK_CMPMASKNEQ(smp_lapic_mask, smp_startup_mask)) {
                cpu_pause();
                cpu_lfence();
                if (cpu_feature & CPUID_TSC)
                        tsc0_offset = rdtsc();
        }
        while (try_mplock() == 0) {
                cpu_pause();
                cpu_lfence();
        }

        /* number of APs actually started */
        return ncpus - 1;
}


/*
 * load the 1st level AP boot code into base memory.
 */

/* targets for relocation */
extern void bigJump(void);
extern void bootCodeSeg(void);
extern void bootDataSeg(void);
extern void MPentry(void);
extern u_int MP_GDT;
extern u_int mp_gdtbase;

#if 0

static void
install_ap_tramp(u_int boot_addr)
{
        int     x;
        int     size = *(int *) ((u_long) & bootMP_size);
        u_char *src = (u_char *) ((u_long) bootMP);
        u_char *dst = (u_char *) boot_addr + KERNBASE;
        u_int   boot_base = (u_int) bootMP;
        u_int8_t *dst8;
        u_int16_t *dst16;
        u_int32_t *dst32;

        POSTCODE(INSTALL_AP_TRAMP_POST);

        for (x = 0; x < size; ++x)
                *dst++ = *src++;

        /*
         * modify addresses in code we just moved to basemem. unfortunately we
         * need fairly detailed info about mpboot.s for this to work.  changes
         * to mpboot.s might require changes here.
         */

        /* boot code is located in KERNEL space */
        dst = (u_char *) boot_addr + KERNBASE;

        /* modify the lgdt arg */
        dst32 = (u_int32_t *) (dst + ((u_int) & mp_gdtbase - boot_base));
        *dst32 = boot_addr + ((u_int) & MP_GDT - boot_base);

        /* modify the ljmp target for MPentry() */
        dst32 = (u_int32_t *) (dst + ((u_int) bigJump - boot_base) + 1);
        *dst32 = ((u_int) MPentry - KERNBASE);

        /* modify the target for boot code segment */
        dst16 = (u_int16_t *) (dst + ((u_int) bootCodeSeg - boot_base));
        dst8 = (u_int8_t *) (dst16 + 1);
        *dst16 = (u_int) boot_addr & 0xffff;
        *dst8 = ((u_int) boot_addr >> 16) & 0xff;

        /* modify the target for boot data segment */
        dst16 = (u_int16_t *) (dst + ((u_int) bootDataSeg - boot_base));
        dst8 = (u_int8_t *) (dst16 + 1);
        *dst16 = (u_int) boot_addr & 0xffff;
        *dst8 = ((u_int) boot_addr >> 16) & 0xff;
}

#endif

/*
 * This function starts the AP (application processor) identified
 * by the APIC ID 'physicalCpu'.  It does quite a "song and dance"
 * to accomplish this.  This is necessary because of the nuances
 * of the different hardware we might encounter.  It ain't pretty,
 * but it seems to work.
 *
 * NOTE: eventually an AP gets to ap_init(), which is called just 
 * before the AP goes into the LWKT scheduler's idle loop.
 */
static int
start_ap(struct mdglobaldata *gd, u_int boot_addr, int smibest)
{
        int     physical_cpu;
        int     vector;
        u_long  icr_lo, icr_hi;

        POSTCODE(START_AP_POST);

        /* get the PHYSICAL APIC ID# */
        physical_cpu = CPUID_TO_APICID(gd->mi.gd_cpuid);

        /* calculate the vector */
        vector = (boot_addr >> 12) & 0xff;

        /* We don't want anything interfering */
        cpu_disable_intr();

        /* Make sure the target cpu sees everything */
        wbinvd();

        /*
         * Try to detect when a SMI has occurred, wait up to 200ms.
         *
         * If a SMI occurs during an AP reset but before we issue
         * the STARTUP command, the AP may brick.  To work around
         * this problem we hold off doing the AP startup until
         * after we have detected the SMI.  Hopefully another SMI
         * will not occur before we finish the AP startup.
         *
         * Retries don't seem to help.  SMIs have a window of opportunity
         * and if USB->legacy keyboard emulation is enabled in the BIOS
         * the interrupt rate can be quite high.
         *
         * NOTE: Don't worry about the L1 cache load, it might bloat
         *       ldelta a little but ndelta will be so huge when the SMI
         *       occurs the detection logic will still work fine.
         */
        if (smibest) {
                set_apic_timer(200000);
                smitest();
        }

        /*
         * first we do an INIT/RESET IPI this INIT IPI might be run, reseting
         * and running the target CPU. OR this INIT IPI might be latched (P5
         * bug), CPU waiting for STARTUP IPI. OR this INIT IPI might be
         * ignored.
         *
         * see apic/apicreg.h for icr bit definitions.
         *
         * TIME CRITICAL CODE, DO NOT DO ANY KPRINTFS IN THE HOT PATH.
         */

        /*
         * Setup the address for the target AP.  We can setup
         * icr_hi once and then just trigger operations with
         * icr_lo.
         */
        icr_hi = lapic->icr_hi & ~APIC_ID_MASK;
        icr_hi |= (physical_cpu << 24);
        icr_lo = lapic->icr_lo & 0xfff00000;
        lapic->icr_hi = icr_hi;

        /*
         * Do an INIT IPI: assert RESET
         *
         * Use edge triggered mode to assert INIT
         */
        lapic->icr_lo = icr_lo | 0x00004500;
        while (lapic->icr_lo & APIC_DELSTAT_MASK)
                 /* spin */ ;

        /*
         * The spec calls for a 10ms delay but we may have to use a
         * MUCH lower delay to avoid bricking an AP due to a fast SMI
         * interrupt.  We have other loops here too and dividing by 2
         * doesn't seem to be enough even after subtracting 350us,
         * so we divide by 4.
         *
         * Our minimum delay is 150uS, maximum is 10ms.  If no SMI
         * interrupt was detected we use the full 10ms.
         */
        if (smibest == 0)
                u_sleep(10000);
        else if (smibest < 150 * 4 + 350)
                u_sleep(150);
        else if ((smibest - 350) / 4 < 10000)
                u_sleep((smibest - 350) / 4);
        else
                u_sleep(10000);

        /*
         * Do an INIT IPI: deassert RESET
         *
         * Use level triggered mode to deassert.  It is unclear
         * why we need to do this.
         */
        lapic->icr_lo = icr_lo | 0x00008500;
        while (lapic->icr_lo & APIC_DELSTAT_MASK)
                 /* spin */ ;
        u_sleep(150);                           /* wait 150us */

        /*
         * Next we do a STARTUP IPI: the previous INIT IPI might still be
         * latched, (P5 bug) this 1st STARTUP would then terminate
         * immediately, and the previously started INIT IPI would continue. OR
         * the previous INIT IPI has already run. and this STARTUP IPI will
         * run. OR the previous INIT IPI was ignored. and this STARTUP IPI
         * will run.
         */
        lapic->icr_lo = icr_lo | 0x00000600 | vector;
        while (lapic->icr_lo & APIC_DELSTAT_MASK)
                 /* spin */ ;
        u_sleep(200);           /* wait ~200uS */

        /*
         * Finally we do a 2nd STARTUP IPI: this 2nd STARTUP IPI should run IF
         * the previous STARTUP IPI was cancelled by a latched INIT IPI. OR
         * this STARTUP IPI will be ignored, as only ONE STARTUP IPI is
         * recognized after hardware RESET or INIT IPI.
         */
        lapic->icr_lo = icr_lo | 0x00000600 | vector;
        while (lapic->icr_lo & APIC_DELSTAT_MASK)
                 /* spin */ ;

        /* Resume normal operation */
        cpu_enable_intr();

        /* wait for it to start, see ap_init() */
        set_apic_timer(5000000);/* == 5 seconds */
        while (read_apic_timer()) {
                if (CPUMASK_TESTBIT(smp_startup_mask, gd->mi.gd_cpuid))
                        return 1;       /* return SUCCESS */
        }

        return 0;               /* return FAILURE */
}

static
int
smitest(void)
{
        int64_t ltsc;
        int64_t ntsc;
        int64_t ldelta;
        int64_t ndelta;
        int count;

        ldelta = 0;
        ndelta = 0;
        while (read_apic_timer()) {
                ltsc = rdtsc();
                for (count = 0; count < 100; ++count)
                        ntsc = rdtsc(); /* force loop to occur */
                if (ldelta) {
                        ndelta = ntsc - ltsc;
                        if (ldelta > ndelta)
                                ldelta = ndelta;
                        if (ndelta > ldelta * 2)
                                break;
                } else {
                        ldelta = ntsc - ltsc;
                }
        }
        return(read_apic_timer());
}

/*
 * Synchronously flush the TLB on all other CPU's.  The current cpu's
 * TLB is not flushed.  If the caller wishes to flush the current cpu's
 * TLB the caller must call cpu_invltlb() in addition to smp_invltlb().
 *
 * This routine may be called concurrently from multiple cpus.  When this
 * happens, smp_invltlb() can wind up sticking around in the confirmation
 * while() loop at the end as additional cpus are added to the global
 * cpumask, until they are acknowledged by another IPI.
 *
 * NOTE: If for some reason we were unable to start all cpus we cannot
 *       safely use broadcast IPIs.
 */

cpumask_t smp_smurf_mask;
static cpumask_t smp_invltlb_mask;
#define LOOPRECOVER
#ifdef LOOPMASK_IN
cpumask_t smp_in_mask;
#endif
cpumask_t smp_invmask;
extern cpumask_t smp_idleinvl_mask;
extern cpumask_t smp_idleinvl_reqs;

/*
 * Atomically OR bits in *mask to smp_smurf_mask.  Adjust *mask to remove
 * bits that do not need to be IPId.  These bits are still part of the command,
 * but the target cpus have already been signalled and do not need to be
 * sigalled again.
 */
#include <sys/spinlock.h>
#include <sys/spinlock2.h>

static __noinline
void
smp_smurf_fetchset(cpumask_t *mask)
{
        cpumask_t omask;
        int i;
        __uint64_t obits;
        __uint64_t nbits;

        i = 0;
        while (i < CPUMASK_ELEMENTS) {
                obits = smp_smurf_mask.ary[i];
                cpu_ccfence();
                nbits = obits | mask->ary[i];
                if (atomic_cmpset_long(&smp_smurf_mask.ary[i], obits, nbits)) {
                        omask.ary[i] = obits;
                        ++i;
                }
        }
        CPUMASK_NANDMASK(*mask, omask);
}

/*
 * This is a mechanism which guarantees that cpu_invltlb() will be executed
 * on idle cpus without having to signal or wake them up.  The invltlb will be
 * executed when they wake up, prior to any scheduling or interrupt thread.
 *
 * (*mask) is modified to remove the cpus we successfully negotiate this
 * function with.  This function may only be used with semi-synchronous
 * commands (typically invltlb's or semi-synchronous invalidations which
 * are usually associated only with kernel memory).
 */
void
smp_smurf_idleinvlclr(cpumask_t *mask)
{
        if (optimized_invltlb) {
                ATOMIC_CPUMASK_ORMASK(smp_idleinvl_reqs, *mask);
                /* cpu_lfence() not needed */
                CPUMASK_NANDMASK(*mask, smp_idleinvl_mask);
        }
}

/*
 * Issue cpu_invltlb() across all cpus except the current cpu.
 *
 * This function will arrange to avoid idle cpus, but still gurantee that
 * invltlb is run on them when they wake up prior to any scheduling or
 * nominal interrupt.
 */
void
smp_invltlb(void)
{
        struct mdglobaldata *md = mdcpu;
        cpumask_t mask;
        unsigned long rflags;
#ifdef LOOPRECOVER
        uint64_t tsc_base = rdtsc();
        int repeats = 0;
#endif

        if (report_invltlb_src > 0) {
                if (--report_invltlb_src <= 0)
                        print_backtrace(8);
        }

        /*
         * Disallow normal interrupts, set all active cpus except our own
         * in the global smp_invltlb_mask.
         */
        ++md->mi.gd_cnt.v_smpinvltlb;
        crit_enter_gd(&md->mi);

        /*
         * Bits we want to set in smp_invltlb_mask.  We do not want to signal
         * our own cpu.  Also try to remove bits associated with idle cpus
         * that we can flag for auto-invltlb.
         */
        mask = smp_active_mask;
        CPUMASK_NANDBIT(mask, md->mi.gd_cpuid);
        smp_smurf_idleinvlclr(&mask);

        rflags = read_rflags();
        cpu_disable_intr();
        ATOMIC_CPUMASK_ORMASK(smp_invltlb_mask, mask);

        /*
         * IPI non-idle cpus represented by mask.  The omask calculation
         * removes cpus from the mask which already have a Xinvltlb IPI
         * pending (avoid double-queueing the IPI).
         *
         * We must disable real interrupts when setting the smurf flags or
         * we might race a XINVLTLB before we manage to send the ipi's for
         * the bits we set.
         *
         * NOTE: We are not signalling ourselves, mask already does NOT
         * include our own cpu.
         */
        smp_smurf_fetchset(&mask);

        /*
         * Issue the IPI.  Note that the XINVLTLB IPI runs regardless of
         * the critical section count on the target cpus.
         */
        CPUMASK_ORMASK(mask, md->mi.gd_cpumask);
        if (all_but_self_ipi_enable &&
            CPUMASK_CMPMASKEQ(smp_startup_mask, mask)) {
                all_but_self_ipi(XINVLTLB_OFFSET);
        } else {
                CPUMASK_NANDMASK(mask, md->mi.gd_cpumask);
                selected_apic_ipi(mask, XINVLTLB_OFFSET, APIC_DELMODE_FIXED);
        }

        /*
         * Wait for acknowledgement by all cpus.  smp_inval_intr() will
         * temporarily enable interrupts to avoid deadlocking the lapic,
         * and will also handle running cpu_invltlb() and remote invlpg
         * command son our cpu if some other cpu requests it of us.
         *
         * WARNING! I originally tried to implement this as a hard loop
         *          checking only smp_invltlb_mask (and issuing a local
         *          cpu_invltlb() if requested), with interrupts enabled
         *          and without calling smp_inval_intr().  This DID NOT WORK.
         *          It resulted in weird races where smurf bits would get
         *          cleared without any action being taken.
         */
        smp_inval_intr();
        CPUMASK_ASSZERO(mask);
        while (CPUMASK_CMPMASKNEQ(smp_invltlb_mask, mask)) {
                smp_inval_intr();
                cpu_pause();
#ifdef LOOPRECOVER
                if (tsc_frequency && rdtsc() - tsc_base > tsc_frequency) {
                        kprintf("smp_invltlb %d: waited too long %08jx "
                                "dbg=%08jx %08jx\n",
                                md->mi.gd_cpuid,
                                smp_invltlb_mask.ary[0],
                                smp_idleinvl_mask.ary[0],
                                smp_idleinvl_reqs.ary[0]);
                        mdcpu->gd_xinvaltlb = 0;
                        ATOMIC_CPUMASK_NANDMASK(smp_smurf_mask,
                                                smp_invltlb_mask);
                        smp_invlpg(&smp_active_mask);
                        tsc_base = rdtsc();
                        if (++repeats > 10) {
                                kprintf("smp_invltlb: giving up\n");
                                CPUMASK_ASSZERO(smp_invltlb_mask);
                        }
                }
#endif
        }
        write_rflags(rflags);
        crit_exit_gd(&md->mi);
}

/*
 * Called from a critical section with interrupts hard-disabled.
 * This function issues an XINVLTLB IPI and then executes any pending
 * command on the current cpu before returning.
 */
void
smp_invlpg(cpumask_t *cmdmask)
{
        struct mdglobaldata *md = mdcpu;
        cpumask_t mask;

        if (report_invlpg_src > 0) {
                if (--report_invlpg_src <= 0)
                        print_backtrace(8);
        }

        /*
         * Disallow normal interrupts, set all active cpus in the pmap,
         * plus our own for completion processing (it might or might not
         * be part of the set).
         */
        mask = smp_active_mask;
        CPUMASK_ANDMASK(mask, *cmdmask);
        CPUMASK_ORMASK(mask, md->mi.gd_cpumask);

        /*
         * Avoid double-queuing IPIs, which can deadlock us.  We must disable
         * real interrupts when setting the smurf flags or we might race a
         * XINVLTLB before we manage to send the ipi's for the bits we set.
         *
         * NOTE: We might be including our own cpu in the smurf mask.
         */
        smp_smurf_fetchset(&mask);

        /*
         * Issue the IPI.  Note that the XINVLTLB IPI runs regardless of
         * the critical section count on the target cpus.
         *
         * We do not include our own cpu when issuing the IPI.
         */
        if (all_but_self_ipi_enable &&
            CPUMASK_CMPMASKEQ(smp_startup_mask, mask)) {
                all_but_self_ipi(XINVLTLB_OFFSET);
        } else {
                CPUMASK_NANDMASK(mask, md->mi.gd_cpumask);
                selected_apic_ipi(mask, XINVLTLB_OFFSET, APIC_DELMODE_FIXED);
        }

        /*
         * This will synchronously wait for our command to complete,
         * as well as process commands from other cpus.  It also handles
         * reentrancy.
         *
         * (interrupts are disabled and we are in a critical section here)
         */
        smp_inval_intr();
}

void
smp_sniff(void)
{
        globaldata_t gd = mycpu;
        int dummy;

        /*
         * Ignore all_but_self_ipi_enable here and just use it.
         */
        all_but_self_ipi(XSNIFF_OFFSET);
        gd->gd_sample_pc = smp_sniff;
        gd->gd_sample_sp = &dummy;
}

/*
 * Called from Xinvltlb assembly with interrupts hard-disabled and in a
 * critical section.  gd_intr_nesting_level may or may not be bumped
 * depending on entry.
 *
 * THIS CODE IS INTENDED TO EXPLICITLY IGNORE THE CRITICAL SECTION COUNT.
 * THAT IS, THE INTERRUPT IS INTENDED TO FUNCTION EVEN WHEN MAINLINE CODE
 * IS IN A CRITICAL SECTION.
 */
void
smp_inval_intr(void)
{
        struct mdglobaldata *md = mdcpu;
        cpumask_t cpumask;
#ifdef LOOPRECOVER
        uint64_t tsc_base = rdtsc();
#endif

#if 0
        /*
         * The idle code is in a critical section, but that doesn't stop
         * Xinvltlb from executing, so deal with the race which can occur
         * in that situation.  Otherwise r-m-w operations by pmap_inval_intr()
         * may have problems.
         */
        if (ATOMIC_CPUMASK_TESTANDCLR(smp_idleinvl_reqs, md->mi.gd_cpuid)) {
                ATOMIC_CPUMASK_NANDBIT(smp_invltlb_mask, md->mi.gd_cpuid);
                cpu_invltlb();
                cpu_mfence();
        }
#endif

        /*
         * This is a real mess.  I'd like to just leave interrupts disabled
         * but it can cause the lapic to deadlock if too many interrupts queue
         * to it, due to the idiotic design of the lapic.  So instead we have
         * to enter a critical section so normal interrupts are made pending
         * and track whether this one was reentered.
         */
        if (md->gd_xinvaltlb) {         /* reentrant on cpu */
                md->gd_xinvaltlb = 2;
                return;
        }
        md->gd_xinvaltlb = 1;

        /*
         * Check only those cpus with active Xinvl* commands pending.
         *
         * We are going to enable interrupts so make sure we are in a
         * critical section.  This is necessary to avoid deadlocking
         * the lapic and to ensure that we execute our commands prior to
         * any nominal interrupt or preemption.
         *
         * WARNING! It is very important that we only clear out but in
         *          smp_smurf_mask once for each interrupt we take.  In
         *          this case, we clear it on initial entry and only loop
         *          on the reentrancy detect (caused by another interrupt).
         */
        cpumask = smp_invmask;
loop:
        cpu_enable_intr();
#ifdef LOOPMASK_IN
        ATOMIC_CPUMASK_ORBIT(smp_in_mask, md->mi.gd_cpuid);
#endif
        ATOMIC_CPUMASK_NANDBIT(smp_smurf_mask, md->mi.gd_cpuid);

        /*
         * Specific page request(s), and we can't return until all bits
         * are zero.
         */
        for (;;) {
                int toolong;

                /*
                 * Also execute any pending full invalidation request in
                 * this loop.
                 */
                if (CPUMASK_TESTBIT(smp_invltlb_mask, md->mi.gd_cpuid)) {
                        ATOMIC_CPUMASK_NANDBIT(smp_invltlb_mask,
                                               md->mi.gd_cpuid);
                        cpu_invltlb();
                        cpu_mfence();
                }

#ifdef LOOPRECOVER
                if (tsc_frequency && rdtsc() - tsc_base > tsc_frequency) {
                        kprintf("smp_inval_intr %d inv=%08jx tlbm=%08jx "
                                "idle=%08jx/%08jx\n",
                                md->mi.gd_cpuid,
                                smp_invmask.ary[0],
                                smp_invltlb_mask.ary[0],
                                smp_idleinvl_mask.ary[0],
                                smp_idleinvl_reqs.ary[0]);
                        tsc_base = rdtsc();
                        toolong = 1;
                } else {
                        toolong = 0;
                }
#else
                toolong = 0;
#endif

                /*
                 * We can only add bits to the cpumask to test during the
                 * loop because the smp_invmask bit is cleared once the
                 * originator completes the command (the targets may still
                 * be cycling their own completions in this loop, afterwords).
                 *
                 * lfence required prior to all tests as this Xinvltlb
                 * interrupt could race the originator (already be in progress
                 * wnen the originator decides to issue, due to an issue by
                 * another cpu).
                 */
                cpu_lfence();
                CPUMASK_ORMASK(cpumask, smp_invmask);
                /*cpumask = smp_active_mask;*/  /* XXX */

                if (pmap_inval_intr(&cpumask, toolong) == 0) {
                        /*
                         * Clear our smurf mask to allow new IPIs, but deal
                         * with potential races.
                         */
                        break;
                }

                /*
                 * Test if someone sent us another invalidation IPI, break
                 * out so we can take it to avoid deadlocking the lapic
                 * interrupt queue (? stupid intel, amd).
                 */
                if (md->gd_xinvaltlb == 2)
                        break;
                /*
                if (CPUMASK_TESTBIT(smp_smurf_mask, md->mi.gd_cpuid))
                        break;
                */
        }

        /*
         * Full invalidation request
         */
        if (CPUMASK_TESTBIT(smp_invltlb_mask, md->mi.gd_cpuid)) {
                ATOMIC_CPUMASK_NANDBIT(smp_invltlb_mask,
                                       md->mi.gd_cpuid);
                cpu_invltlb();
                cpu_mfence();
        }

#ifdef LOOPMASK_IN
        ATOMIC_CPUMASK_NANDBIT(smp_in_mask, md->mi.gd_cpuid);
#endif
        /*
         * Check to see if another Xinvltlb interrupt occurred and loop up
         * if it did.
         */
        cpu_disable_intr();
        if (md->gd_xinvaltlb == 2) {
                md->gd_xinvaltlb = 1;
                goto loop;
        }
        md->gd_xinvaltlb = 0;
}

void
cpu_wbinvd_on_all_cpus_callback(void *arg)
{
        wbinvd();
}

/*
 * When called the executing CPU will send an IPI to all other CPUs
 *  requesting that they halt execution.
 *
 * Usually (but not necessarily) called with 'other_cpus' as its arg.
 *
 *  - Signals all CPUs in map to stop.
 *  - Waits for each to stop.
 *
 * Returns:
 *  -1: error
 *   0: NA
 *   1: ok
 *
 * XXX FIXME: this is not MP-safe, needs a lock to prevent multiple CPUs
 *            from executing at same time.
 */
int
stop_cpus(cpumask_t map)
{
        cpumask_t mask;

        CPUMASK_ANDMASK(map, smp_active_mask);

        /* send the Xcpustop IPI to all CPUs in map */
        selected_apic_ipi(map, XCPUSTOP_OFFSET, APIC_DELMODE_FIXED);

        do {
                mask = stopped_cpus;
                CPUMASK_ANDMASK(mask, map);
                /* spin */
        } while (CPUMASK_CMPMASKNEQ(mask, map));

        return 1;
}


/*
 * Called by a CPU to restart stopped CPUs. 
 *
 * Usually (but not necessarily) called with 'stopped_cpus' as its arg.
 *
 *  - Signals all CPUs in map to restart.
 *  - Waits for each to restart.
 *
 * Returns:
 *  -1: error
 *   0: NA
 *   1: ok
 */
int
restart_cpus(cpumask_t map)
{
        cpumask_t mask;

        /* signal other cpus to restart */
        mask = map;
        CPUMASK_ANDMASK(mask, smp_active_mask);
        cpu_ccfence();
        started_cpus = mask;
        cpu_ccfence();

        /* wait for each to clear its bit */
        while (CPUMASK_CMPMASKNEQ(stopped_cpus, map))
                cpu_pause();

        return 1;
}

/*
 * This is called once the mpboot code has gotten us properly relocated
 * and the MMU turned on, etc.   ap_init() is actually the idle thread,
 * and when it returns the scheduler will call the real cpu_idle() main
 * loop for the idlethread.  Interrupts are disabled on entry and should
 * remain disabled at return.
 */
void
ap_init(void)
{
        int     cpu_id;

        /*
         * Adjust smp_startup_mask to signal the BSP that we have started
         * up successfully.  Note that we do not yet hold the BGL.  The BSP
         * is waiting for our signal.
         *
         * We can't set our bit in smp_active_mask yet because we are holding
         * interrupts physically disabled and remote cpus could deadlock
         * trying to send us an IPI.
         */
        ATOMIC_CPUMASK_ORBIT(smp_startup_mask, mycpu->gd_cpuid);
        cpu_mfence();

        /*
         * Interlock for LAPIC initialization.  Wait until mp_finish_lapic is
         * non-zero, then get the MP lock.
         *
         * Note: We are in a critical section.
         *
         * Note: we are the idle thread, we can only spin.
         *
         * Note: The load fence is memory volatile and prevents the compiler
         * from improperly caching mp_finish_lapic, and the cpu from improperly
         * caching it.
         */
        while (mp_finish_lapic == 0) {
                cpu_pause();
                cpu_lfence();
        }
#if 0
        while (try_mplock() == 0) {
                cpu_pause();
                cpu_lfence();
        }
#endif

        if (cpu_feature & CPUID_TSC) {
                /*
                 * The BSP is constantly updating tsc0_offset, figure out
                 * the relative difference to synchronize ktrdump.
                 */
                tsc_offsets[mycpu->gd_cpuid] = rdtsc() - tsc0_offset;
        }

        /* BSP may have changed PTD while we're waiting for the lock */
        cpu_invltlb();

        /* Build our map of 'other' CPUs. */
        mycpu->gd_other_cpus = smp_startup_mask;
        ATOMIC_CPUMASK_NANDBIT(mycpu->gd_other_cpus, mycpu->gd_cpuid);

        /* A quick check from sanity claus */
        cpu_id = APICID_TO_CPUID((lapic->id & 0xff000000) >> 24);
        if (mycpu->gd_cpuid != cpu_id) {
                kprintf("SMP: assigned cpuid = %d\n", mycpu->gd_cpuid);
                kprintf("SMP: actual cpuid = %d lapicid %d\n",
                        cpu_id, (lapic->id & 0xff000000) >> 24);
#if 0 /* JGXXX */
                kprintf("PTD[MPPTDI] = %p\n", (void *)PTD[MPPTDI]);
#endif
                panic("cpuid mismatch! boom!!");
        }

        /* Initialize AP's local APIC for irq's */
        lapic_init(FALSE);

        /* LAPIC initialization is done */
        ATOMIC_CPUMASK_ORBIT(smp_lapic_mask, mycpu->gd_cpuid);
        cpu_mfence();

#if 0
        /* Let BSP move onto the next initialization stage */
        rel_mplock();
#endif

        /*
         * Interlock for finalization.  Wait until mp_finish is non-zero,
         * then get the MP lock.
         *
         * Note: We are in a critical section.
         *
         * Note: we are the idle thread, we can only spin.
         *
         * Note: The load fence is memory volatile and prevents the compiler
         * from improperly caching mp_finish, and the cpu from improperly
         * caching it.
         */
        while (mp_finish == 0) {
                cpu_pause();
                cpu_lfence();
        }

        /* BSP may have changed PTD while we're waiting for the lock */
        cpu_invltlb();

        /* Set memory range attributes for this CPU to match the BSP */
        mem_range_AP_init();

        /*
         * Once we go active we must process any IPIQ messages that may
         * have been queued, because no actual IPI will occur until we
         * set our bit in the smp_active_mask.  If we don't the IPI
         * message interlock could be left set which would also prevent
         * further IPIs.
         *
         * The idle loop doesn't expect the BGL to be held and while
         * lwkt_switch() normally cleans things up this is a special case
         * because we returning almost directly into the idle loop.
         *
         * The idle thread is never placed on the runq, make sure
         * nothing we've done put it there.
         */

        /*
         * Hold a critical section and allow real interrupts to occur.  Zero
         * any spurious interrupts which have accumulated, then set our
         * smp_active_mask indicating that we are fully operational.
         */
        crit_enter();
        __asm __volatile("sti; pause; pause"::);
        bzero(mdcpu->gd_ipending, sizeof(mdcpu->gd_ipending));
        ATOMIC_CPUMASK_ORBIT(smp_active_mask, mycpu->gd_cpuid);

        /*
         * Wait until all cpus have set their smp_active_mask and have fully
         * operational interrupts before proceeding.
         *
         * We need a final cpu_invltlb() because we would not have received
         * any until we set our bit in smp_active_mask.
         */
        while (mp_finish == 1) {
                cpu_pause();
                cpu_lfence();
        }
        cpu_invltlb();

        /*
         * Initialize per-cpu clocks and do other per-cpu initialization.
         * At this point code is expected to be able to use the full kernel
         * API.
         */
        initclocks_pcpu();      /* clock interrupts (via IPIs) */

        /*
         * Since we may have cleaned up the interrupt triggers, manually
         * process any pending IPIs before exiting our critical section.
         * Once the critical section has exited, normal interrupt processing
         * may occur.
         */
        atomic_swap_int(&mycpu->gd_npoll, 0);
        lwkt_process_ipiq();
        crit_exit();

        /*
         * Final final, allow the waiting BSP to resume the boot process,
         * return 'into' the idle thread bootstrap.
         */
        ATOMIC_CPUMASK_ORBIT(smp_finalize_mask, mycpu->gd_cpuid);
        KKASSERT((curthread->td_flags & TDF_RUNQ) == 0);
}

/*
 * Get SMP fully working before we start initializing devices.
 */
static
void
ap_finish(void)
{
        if (bootverbose)
                kprintf("Finish MP startup\n");
        rel_mplock();

        /*
         * Wait for the active mask to complete, after which all cpus will
         * be accepting interrupts.
         */
        mp_finish = 1;
        while (CPUMASK_CMPMASKNEQ(smp_active_mask, smp_startup_mask)) {
                cpu_pause();
                cpu_lfence();
        }

        /*
         * Wait for the finalization mask to complete, after which all cpus
         * have completely finished initializing and are entering or are in
         * their idle thread.
         *
         * BSP should have received all required invltlbs but do another
         * one just in case.
         */
        cpu_invltlb();
        mp_finish = 2;
        while (CPUMASK_CMPMASKNEQ(smp_finalize_mask, smp_startup_mask)) {
                cpu_pause();
                cpu_lfence();
        }

        while (try_mplock() == 0) {
                cpu_pause();
                cpu_lfence();
        }

        if (bootverbose) {
                kprintf("Active CPU Mask: %016jx\n",
                        (uintmax_t)CPUMASK_LOWMASK(smp_active_mask));
        }
}

SYSINIT(finishsmp, SI_BOOT2_FINISH_SMP, SI_ORDER_FIRST, ap_finish, NULL);

void
cpu_send_ipiq(int dcpu)
{
        if (CPUMASK_TESTBIT(smp_active_mask, dcpu))
                single_apic_ipi(dcpu, XIPIQ_OFFSET, APIC_DELMODE_FIXED);
}

#if 0   /* single_apic_ipi_passive() not working yet */
/*
 * Returns 0 on failure, 1 on success
 */
int
cpu_send_ipiq_passive(int dcpu)
{
        int r = 0;
        if (CPUMASK_TESTBIT(smp_active_mask, dcpu)) {
                r = single_apic_ipi_passive(dcpu, XIPIQ_OFFSET,
                                        APIC_DELMODE_FIXED);
        }
        return(r);
}
#endif

static void
mp_bsp_simple_setup(void)
{
        struct mdglobaldata *gd;
        size_t ipiq_size;

        /* build our map of 'other' CPUs */
        mycpu->gd_other_cpus = smp_startup_mask;
        CPUMASK_NANDBIT(mycpu->gd_other_cpus, mycpu->gd_cpuid);

        gd = (struct mdglobaldata *)mycpu;
        gd->gd_acpi_id = CPUID_TO_ACPIID(mycpu->gd_cpuid);

        ipiq_size = sizeof(struct lwkt_ipiq) * ncpus;
        mycpu->gd_ipiq = (void *)kmem_alloc(&kernel_map, ipiq_size);
        bzero(mycpu->gd_ipiq, ipiq_size);

        pmap_set_opt();

        if (cpu_feature & CPUID_TSC)
                tsc0_offset = rdtsc();
}


/*
 * CPU TOPOLOGY DETECTION FUNCTIONS
 */

/* Detect intel topology using CPUID 
 * Ref: http://www.intel.com/Assets/PDF/appnote/241618.pdf, pg 41
 */
static void
detect_intel_topology(int count_htt_cores)
{
        int shift = 0;
        int ecx_index = 0;
        int core_plus_logical_bits = 0;
        int cores_per_package;
        int logical_per_package;
        int logical_per_core;
        unsigned int p[4];

        if (cpu_high >= 0xb) {
                goto FUNC_B;

        } else if (cpu_high >= 0x4) {
                goto FUNC_4;

        } else {
                core_bits = 0;
                for (shift = 0; (1 << shift) < count_htt_cores; ++shift)
                        ;
                logical_CPU_bits = 1 << shift;
                return;
        }

FUNC_B:
        cpuid_count(0xb, FUNC_B_THREAD_LEVEL, p);

        /* if 0xb not supported - fallback to 0x4 */
        if (p[1] == 0 || (FUNC_B_TYPE(p[2]) != FUNC_B_THREAD_TYPE)) {
                goto FUNC_4;
        }

        logical_CPU_bits = FUNC_B_BITS_SHIFT_NEXT_LEVEL(p[0]);

        ecx_index = FUNC_B_THREAD_LEVEL + 1;
        do {
                cpuid_count(0xb, ecx_index, p);

                /* Check for the Core type in the implemented sub leaves. */
                if (FUNC_B_TYPE(p[2]) == FUNC_B_CORE_TYPE) {
                        core_plus_logical_bits = FUNC_B_BITS_SHIFT_NEXT_LEVEL(p[0]);
                        break;
                }

                ecx_index++;

        } while (FUNC_B_TYPE(p[2]) != FUNC_B_INVALID_TYPE);

        core_bits = core_plus_logical_bits - logical_CPU_bits;

        return;

FUNC_4:
        cpuid_count(0x4, 0, p);
        cores_per_package = FUNC_4_MAX_CORE_NO(p[0]) + 1;

        logical_per_package = count_htt_cores;
        logical_per_core = logical_per_package / cores_per_package;
        
        for (shift = 0; (1 << shift) < logical_per_core; ++shift)
                ;
        logical_CPU_bits = shift;

        for (shift = 0; (1 << shift) < cores_per_package; ++shift)
                ;
        core_bits = shift;

        return;
}

/* Detect AMD topology using CPUID
 * Ref: http://support.amd.com/us/Embedded_TechDocs/25481.pdf, last page
 */
static void
detect_amd_topology(int count_htt_cores)
{
        int shift = 0;
        if ((cpu_feature & CPUID_HTT)
                        && (amd_feature2 & AMDID2_CMP)) {
                
                if (cpu_procinfo2 & AMDID_COREID_SIZE) {
                        core_bits = (cpu_procinfo2 & AMDID_COREID_SIZE)
                            >> AMDID_COREID_SIZE_SHIFT;
                } else {
                        core_bits = (cpu_procinfo2 & AMDID_CMP_CORES) + 1;
                        for (shift = 0; (1 << shift) < core_bits; ++shift)
                                ;
                        core_bits = shift;
                }

                logical_CPU_bits = count_htt_cores >> core_bits;
                for (shift = 0; (1 << shift) < logical_CPU_bits; ++shift)
                        ;
                logical_CPU_bits = shift;
        } else {
                for (shift = 0; (1 << shift) < count_htt_cores; ++shift)
                        ;
                core_bits = shift;
                logical_CPU_bits = 0;
        }
}

static void
amd_get_compute_unit_id(void *arg)
{
        u_int regs[4];

        do_cpuid(0x8000001e, regs);
        cpu_node_t * mynode = get_cpu_node_by_cpuid(mycpuid);
        /* 
         * AMD - CPUID Specification September 2010
         * page 34 - //ComputeUnitID = ebx[0:7]//
         */
        mynode->compute_unit_id = regs[1] & 0xff;
}

int
fix_amd_topology(void)
{
        cpumask_t mask;

        if (cpu_vendor_id != CPU_VENDOR_AMD)
                return -1;
        if ((amd_feature2 & AMDID2_TOPOEXT) == 0)
                return -1;

        CPUMASK_ASSALLONES(mask);
        lwkt_cpusync_simple(mask, amd_get_compute_unit_id, NULL);

        kprintf("Compute unit iDS:\n");
        int i;
        for (i = 0; i < ncpus; i++) {
                kprintf("%d-%d; \n",
                        i, get_cpu_node_by_cpuid(i)->compute_unit_id);
        }

        return 0;
}

/* Calculate
 * - logical_CPU_bits
 * - core_bits
 * With the values above (for AMD or INTEL) we are able to generally
 * detect the CPU topology (number of cores for each level):
 * Ref: http://wiki.osdev.org/Detecting_CPU_Topology_(80x86)
 * Ref: http://www.multicoreinfo.com/research/papers/whitepapers/Intel-detect-topology.pdf
 */
void
detect_cpu_topology(void)
{
        static int topology_detected = 0;
        int count = 0;
        
        if (topology_detected)
                goto OUT;
        if ((cpu_feature & CPUID_HTT) == 0) {
                core_bits = 0;
                logical_CPU_bits = 0;
                goto OUT;
        }
        count = (cpu_procinfo & CPUID_HTT_CORES) >> CPUID_HTT_CORE_SHIFT;

        if (cpu_vendor_id == CPU_VENDOR_INTEL)
                detect_intel_topology(count);   
        else if (cpu_vendor_id == CPU_VENDOR_AMD)
                detect_amd_topology(count);
        topology_detected = 1;

OUT:
        if (bootverbose)
                kprintf("Bits within APICID: logical_CPU_bits: %d; core_bits: %d\n",
                    logical_CPU_bits, core_bits);
}

/* Interface functions to calculate chip_ID,
 * core_number and logical_number
 * Ref: http://wiki.osdev.org/Detecting_CPU_Topology_(80x86)
 */
int
get_chip_ID(int cpuid)
{
        return get_apicid_from_cpuid(cpuid) >>
            (logical_CPU_bits + core_bits);
}

int
get_core_number_within_chip(int cpuid)
{
        return (get_apicid_from_cpuid(cpuid) >> logical_CPU_bits) &
            ( (1 << core_bits) -1);
}

int
get_logical_CPU_number_within_core(int cpuid)
{
        return get_apicid_from_cpuid(cpuid) &
            ( (1 << logical_CPU_bits) -1);
}