4 files changed, 363 insertions, 365 deletions

diff --git a/arch/x86_64/kernel/nmi.c b/arch/x86_64/kernel/nmi.c
index 6ec5217f4b73..72f40ca4f06b 100644
--- a/arch/x86_64/kernel/nmi.c
+++ b/arch/x86_64/kernel/nmi.c
@@ -130,12 +130,6 @@ int __init check_nmi_watchdog (void)
         mdelay((10*1000)/nmi_hz); // wait 10 ticks
 
         for (cpu = 0; cpu < NR_CPUS; cpu++) {
-#ifdef CONFIG_SMP
-                /* Check cpu_callin_map here because that is set
-                   after the timer is started. */
-                if (!cpu_isset(cpu, cpu_callin_map))
-                        continue;
-#endif
                 if (cpu_pda[cpu].__nmi_count - counts[cpu] <= 5) {
                         printk("CPU#%d: NMI appears to be stuck (%d)!\n", 
                                cpu,
diff --git a/arch/x86_64/kernel/smp.c b/arch/x86_64/kernel/smp.c
index e3cdbf9a88bd..1e379ed17b1d 100644
--- a/arch/x86_64/kernel/smp.c
+++ b/arch/x86_64/kernel/smp.c
@@ -27,6 +27,7 @@
 #include <asm/mach_apic.h>
 #include <asm/mmu_context.h>
 #include <asm/proto.h>
+#include <asm/apicdef.h>
 
 /*
  *      Smarter SMP flushing macros. 
@@ -413,3 +414,27 @@ asmlinkage void smp_call_function_interrupt(void)
                 atomic_inc(&call_data->finished);
         }
 }
+
+int safe_smp_processor_id(void)
+{
+        int apicid, i;
+
+        if (disable_apic)
+                return 0;
+
+        apicid = hard_smp_processor_id();
+        if (x86_cpu_to_apicid[apicid] == apicid)
+                return apicid;
+
+        for (i = 0; i < NR_CPUS; ++i) {
+                if (x86_cpu_to_apicid[i] == apicid)
+                        return i;
+        }
+
+        /* No entries in x86_cpu_to_apicid?  Either no MPS|ACPI,
+         * or called too early.  Either way, we must be CPU 0. */
+        if (x86_cpu_to_apicid[0] == BAD_APICID)
+                return 0;
+
+        return 0; /* Should not happen */
+}
diff --git a/arch/x86_64/kernel/smpboot.c b/arch/x86_64/kernel/smpboot.c
index 7e2de8925b0f..eca01e82d3c7 100644
--- a/arch/x86_64/kernel/smpboot.c
+++ b/arch/x86_64/kernel/smpboot.c
@@ -12,8 +12,7 @@
  *      Pentium Pro and Pentium-II/Xeon MP machines.
  *      Original development of Linux SMP code supported by Caldera.
  *
- *      This code is released under the GNU General Public License version 2 or
- *      later.
+ *      This code is released under the GNU General Public License version 2
  *
  *      Fixes
  *              Felix Koop      :       NR_CPUS used properly
@@ -31,9 +30,13 @@
  *              Tigran Aivazian :       fixed "0.00 in /proc/uptime on SMP" bug.
  *      Maciej W. Rozycki       :       Bits for genuine 82489DX APICs
  *      Andi Kleen              :       Changed for SMP boot into long mode.
- *              Rusty Russell   :       Hacked into shape for new "hotplug" boot process. 
+ *              Rusty Russell   :       Hacked into shape for new "hotplug" boot process.
+ *      Andi Kleen              :       Converted to new state machine.
+ *                                      Various cleanups.
+ *                                      Probably mostly hotplug CPU ready now.
  */
 
+
 #include <linux/config.h>
 #include <linux/init.h>
 
@@ -54,11 +57,15 @@
 #include <asm/tlbflush.h>
 #include <asm/proto.h>
 
+/* Change for real CPU hotplug. Note other files need to be fixed
+   first too. */
+#define __cpuinit __init
+#define __cpuinitdata __initdata
+
 /* Number of siblings per CPU package */
 int smp_num_siblings = 1;
 /* Package ID of each logical CPU */
 u8 phys_proc_id[NR_CPUS] = { [0 ... NR_CPUS-1] = BAD_APICID };
-/* Core ID of each logical CPU */
 u8 cpu_core_id[NR_CPUS] = { [0 ... NR_CPUS-1] = BAD_APICID };
 EXPORT_SYMBOL(phys_proc_id);
 EXPORT_SYMBOL(cpu_core_id);
@@ -66,13 +73,24 @@ EXPORT_SYMBOL(cpu_core_id);
 /* Bitmask of currently online CPUs */
 cpumask_t cpu_online_map;
 
+EXPORT_SYMBOL(cpu_online_map);
+
+/*
+ * Private maps to synchronize booting between AP and BP.
+ * Probably not needed anymore, but it makes for easier debugging. -AK
+ */
 cpumask_t cpu_callin_map;
 cpumask_t cpu_callout_map;
-static cpumask_t smp_commenced_mask;
+
+cpumask_t cpu_possible_map;
+EXPORT_SYMBOL(cpu_possible_map);
 
 /* Per CPU bogomips and other parameters */
 struct cpuinfo_x86 cpu_data[NR_CPUS] __cacheline_aligned;
 
+/* Set when the idlers are all forked */
+int smp_threads_ready;
+
 cpumask_t cpu_sibling_map[NR_CPUS] __cacheline_aligned;
 cpumask_t cpu_core_map[NR_CPUS] __cacheline_aligned;
 
@@ -80,8 +98,8 @@ cpumask_t cpu_core_map[NR_CPUS] __cacheline_aligned;
  * Trampoline 80x86 program as an array.
  */
 
-extern unsigned char trampoline_data [];
-extern unsigned char trampoline_end  [];
+extern unsigned char trampoline_data[];
+extern unsigned char trampoline_end[];
 
 /*
  * Currently trivial. Write the real->protected mode
@@ -89,7 +107,7 @@ extern unsigned char trampoline_end  [];
  * has made sure it's suitably aligned.
  */
 
-static unsigned long __init setup_trampoline(void)
+static unsigned long __cpuinit setup_trampoline(void)
 {
         void *tramp = __va(SMP_TRAMPOLINE_BASE); 
         memcpy(tramp, trampoline_data, trampoline_end - trampoline_data);
@@ -101,7 +119,7 @@ static unsigned long __init setup_trampoline(void)
  * a given CPU
  */
 
-static void __init smp_store_cpu_info(int id)
+static void __cpuinit smp_store_cpu_info(int id)
 {
         struct cpuinfo_x86 *c = cpu_data + id;
 
@@ -110,145 +128,101 @@ static void __init smp_store_cpu_info(int id)
 }
 
 /*
- * TSC synchronization.
+ * Synchronize TSCs of CPUs
  *
- * We first check whether all CPUs have their TSC's synchronized,
- * then we print a warning if not, and always resync.
+ * This new algorithm is less accurate than the old "zero TSCs"
+ * one, but we cannot zero TSCs anymore in the new hotplug CPU
+ * model.
  */
 
-static atomic_t tsc_start_flag = ATOMIC_INIT(0);
-static atomic_t tsc_count_start = ATOMIC_INIT(0);
-static atomic_t tsc_count_stop = ATOMIC_INIT(0);
-static unsigned long long tsc_values[NR_CPUS];
+static atomic_t __cpuinitdata tsc_flag;
+static __cpuinitdata DEFINE_SPINLOCK(tsc_sync_lock);
+static unsigned long long __cpuinitdata bp_tsc, ap_tsc;
 
 #define NR_LOOPS 5
 
-extern unsigned int fast_gettimeoffset_quotient;
-
-static void __init synchronize_tsc_bp (void)
+static void __cpuinit sync_tsc_bp_init(int init)
 {
-        int i;
-        unsigned long long t0;
-        unsigned long long sum, avg;
-        long long delta;
-        long one_usec;
-        int buggy = 0;
-
-        printk(KERN_INFO "checking TSC synchronization across %u CPUs: ",num_booting_cpus());
-
-        one_usec = cpu_khz; 
-
-        atomic_set(&tsc_start_flag, 1);
-        wmb();
-
-        /*
-         * We loop a few times to get a primed instruction cache,
-         * then the last pass is more or less synchronized and
-         * the BP and APs set their cycle counters to zero all at
-         * once. This reduces the chance of having random offsets
-         * between the processors, and guarantees that the maximum
-         * delay between the cycle counters is never bigger than
-         * the latency of information-passing (cachelines) between
-         * two CPUs.
-         */
-        for (i = 0; i < NR_LOOPS; i++) {
-                /*
-                 * all APs synchronize but they loop on '== num_cpus'
-                 */
-                while (atomic_read(&tsc_count_start) != num_booting_cpus()-1) mb();
-                atomic_set(&tsc_count_stop, 0);
-                wmb();
-                /*
-                 * this lets the APs save their current TSC:
-                 */
-                atomic_inc(&tsc_count_start);
-
-                sync_core();
-                rdtscll(tsc_values[smp_processor_id()]);
-                /*
-                 * We clear the TSC in the last loop:
-                 */
-                if (i == NR_LOOPS-1)
-                        write_tsc(0, 0);
-
-                /*
-                 * Wait for all APs to leave the synchronization point:
-                 */
-                while (atomic_read(&tsc_count_stop) != num_booting_cpus()-1) mb();
-                atomic_set(&tsc_count_start, 0);
-                wmb();
-                atomic_inc(&tsc_count_stop);
-        }
-
-        sum = 0;
-        for (i = 0; i < NR_CPUS; i++) {
-                if (cpu_isset(i, cpu_callout_map)) {
-                t0 = tsc_values[i];
-                sum += t0;
-        }
-        }
-        avg = sum / num_booting_cpus();
-
-        sum = 0;
-        for (i = 0; i < NR_CPUS; i++) {
-                if (!cpu_isset(i, cpu_callout_map))
-                        continue;
-
-                delta = tsc_values[i] - avg;
-                if (delta < 0)
-                        delta = -delta;
-                /*
-                 * We report bigger than 2 microseconds clock differences.
-                 */
-                if (delta > 2*one_usec) {
-                        long realdelta;
-                        if (!buggy) {
-                                buggy = 1;
-                                printk("\n");
-                        }
-                        realdelta = delta / one_usec;
-                        if (tsc_values[i] < avg)
-                                realdelta = -realdelta;
-
-                        printk("BIOS BUG: CPU#%d improperly initialized, has %ld usecs TSC skew! FIXED.\n",
-                                i, realdelta);
-                }
+        if (init)
+                _raw_spin_lock(&tsc_sync_lock);
+        else
+                _raw_spin_unlock(&tsc_sync_lock);
+        atomic_set(&tsc_flag, 0);
+}
 
-                sum += delta;
-        }
-        if (!buggy)
-                printk("passed.\n");
+/*
+ * Synchronize TSC on AP with BP.
+ */
+static void __cpuinit __sync_tsc_ap(void)
+{
+        if (!cpu_has_tsc)
+                return;
+        Dprintk("AP %d syncing TSC\n", smp_processor_id());
+
+        while (atomic_read(&tsc_flag) != 0)
+                cpu_relax();
+        atomic_inc(&tsc_flag);
+        mb();
+        _raw_spin_lock(&tsc_sync_lock);
+        wrmsrl(MSR_IA32_TSC, bp_tsc);
+        _raw_spin_unlock(&tsc_sync_lock);
+        rdtscll(ap_tsc);
+        mb();
+        atomic_inc(&tsc_flag);
+        mb();
 }
 
-static void __init synchronize_tsc_ap (void)
+static void __cpuinit sync_tsc_ap(void)
 {
         int i;
+        for (i = 0; i < NR_LOOPS; i++)
+                __sync_tsc_ap();
+}
 
-        /*
-         * Not every cpu is online at the time
-         * this gets called, so we first wait for the BP to
-         * finish SMP initialization:
-         */
-        while (!atomic_read(&tsc_start_flag)) mb();
-
-        for (i = 0; i < NR_LOOPS; i++) {
-                atomic_inc(&tsc_count_start);
-                while (atomic_read(&tsc_count_start) != num_booting_cpus()) mb();
+/*
+ * Synchronize TSC from BP to AP.
+ */
+static void __cpuinit __sync_tsc_bp(int cpu)
+{
+        if (!cpu_has_tsc)
+                return;
 
-                sync_core();
-                rdtscll(tsc_values[smp_processor_id()]);
-                if (i == NR_LOOPS-1)
-                        write_tsc(0, 0);
+        /* Wait for AP */
+        while (atomic_read(&tsc_flag) == 0)
+                cpu_relax();
+        /* Save BPs TSC */
+        sync_core();
+        rdtscll(bp_tsc);
+        /* Don't do the sync core here to avoid too much latency. */
+        mb();
+        /* Start the AP */
+        _raw_spin_unlock(&tsc_sync_lock);
+        /* Wait for AP again */
+        while (atomic_read(&tsc_flag) < 2)
+                cpu_relax();
+        rdtscl(bp_tsc);
+        barrier();
+}
 
-                atomic_inc(&tsc_count_stop);
-                while (atomic_read(&tsc_count_stop) != num_booting_cpus()) mb();
+static void __cpuinit sync_tsc_bp(int cpu)
+{
+        int i;
+        for (i = 0; i < NR_LOOPS - 1; i++) {
+                __sync_tsc_bp(cpu);
+                sync_tsc_bp_init(1);
         }
+        __sync_tsc_bp(cpu);
+        printk(KERN_INFO "Synced TSC of CPU %d difference %Ld\n",
+               cpu, ap_tsc - bp_tsc);
 }
-#undef NR_LOOPS
 
-static atomic_t init_deasserted;
+static atomic_t init_deasserted __cpuinitdata;
 
-static void __init smp_callin(void)
+/*
+ * Report back to the Boot Processor.
+ * Running on AP.
+ */
+void __cpuinit smp_callin(void)
 {
         int cpuid, phys_id;
         unsigned long timeout;
@@ -259,7 +233,8 @@ static void __init smp_callin(void)
          * our local APIC.  We have to wait for the IPI or we'll
          * lock up on an APIC access.
          */
-        while (!atomic_read(&init_deasserted));
+        while (!atomic_read(&init_deasserted))
+                cpu_relax();
 
         /*
          * (This works even if the APIC is not enabled.)
@@ -290,7 +265,7 @@ static void __init smp_callin(void)
                  */
                 if (cpu_isset(cpuid, cpu_callout_map))
                         break;
-                rep_nop();
+                cpu_relax();
         }
 
         if (!time_before(jiffies, timeout)) {
@@ -325,20 +300,12 @@ static void __init smp_callin(void)
          * Allow the master to continue.
          */
         cpu_set(cpuid, cpu_callin_map);
-
-        /*
-         *      Synchronize the TSC with the BP
-         */
-        if (cpu_has_tsc)
-                synchronize_tsc_ap();
 }
 
-static int cpucount;
-
 /*
- * Activate a secondary processor.
+ * Setup code on secondary processor (after comming out of the trampoline)
  */
-void __init start_secondary(void)
+void __cpuinit start_secondary(void)
 {
         /*
          * Dont put anything before smp_callin(), SMP
@@ -348,17 +315,18 @@ void __init start_secondary(void)
         cpu_init();
         smp_callin();
 
+        /*
+         * Synchronize the TSC with the BP
+         */
+        sync_tsc_ap();
+
         /* otherwise gcc will move up the smp_processor_id before the cpu_init */
         barrier();
 
-        Dprintk("cpu %d: waiting for commence\n", smp_processor_id()); 
-        while (!cpu_isset(smp_processor_id(), smp_commenced_mask))
-                rep_nop();
-
         Dprintk("cpu %d: setting up apic clock\n", smp_processor_id());         
         setup_secondary_APIC_clock();
 
-        Dprintk("cpu %d: enabling apic timer\n", smp_processor_id()); 
+        Dprintk("cpu %d: enabling apic timer\n", smp_processor_id());
 
         if (nmi_watchdog == NMI_IO_APIC) {
                 disable_8259A_irq(0);
@@ -367,26 +335,22 @@ void __init start_secondary(void)
         }
 
 
-        enable_APIC_timer(); 
+        enable_APIC_timer();
 
         /*
-         * low-memory mappings have been cleared, flush them from
-         * the local TLBs too.
+         * Allow the master to continue.
          */
-        local_flush_tlb();
-
-        Dprintk("cpu %d eSetting cpu_online_map\n", smp_processor_id()); 
         cpu_set(smp_processor_id(), cpu_online_map);
-        wmb();
-        
+        mb();
+
         cpu_idle();
 }
 
-extern volatile unsigned long init_rsp; 
+extern volatile unsigned long init_rsp;
 extern void (*initial_code)(void);
 
 #if APIC_DEBUG
-static inline void inquire_remote_apic(int apicid)
+static void inquire_remote_apic(int apicid)
 {
         unsigned i, regs[] = { APIC_ID >> 4, APIC_LVR >> 4, APIC_SPIV >> 4 };
         char *names[] = { "ID", "VERSION", "SPIV" };
@@ -423,7 +387,10 @@ static inline void inquire_remote_apic(int apicid)
 }
 #endif
 
-static int __init wakeup_secondary_via_INIT(int phys_apicid, unsigned int start_rip)
+/*
+ * Kick the secondary to wake up.
+ */
+static int __cpuinit wakeup_secondary_via_INIT(int phys_apicid, unsigned int start_rip)
 {
         unsigned long send_status = 0, accept_status = 0;
         int maxlvt, timeout, num_starts, j;
@@ -546,33 +513,36 @@ static int __init wakeup_secondary_via_INIT(int phys_apicid, unsigned int start_
         return (send_status | accept_status);
 }
 
-static void __init do_boot_cpu (int apicid)
+/*
+ * Boot one CPU.
+ */
+static int __cpuinit do_boot_cpu(int cpu, int apicid)
 {
         struct task_struct *idle;
         unsigned long boot_error;
-        int timeout, cpu;
+        int timeout;
         unsigned long start_rip;
-
-        cpu = ++cpucount;
         /*
          * We can't use kernel_thread since we must avoid to
          * reschedule the child.
          */
         idle = fork_idle(cpu);
-        if (IS_ERR(idle))
-                panic("failed fork for CPU %d", cpu);
+        if (IS_ERR(idle)) {
+                printk("failed fork for CPU %d\n", cpu);
+                return PTR_ERR(idle);
+        }
         x86_cpu_to_apicid[cpu] = apicid;
 
         cpu_pda[cpu].pcurrent = idle;
 
         start_rip = setup_trampoline();
 
-        init_rsp = idle->thread.rsp; 
+        init_rsp = idle->thread.rsp;
         per_cpu(init_tss,cpu).rsp0 = init_rsp;
         initial_code = start_secondary;
         clear_ti_thread_flag(idle->thread_info, TIF_FORK);
 
-        printk(KERN_INFO "Booting processor %d/%d rip %lx rsp %lx\n", cpu, apicid, 
+        printk(KERN_INFO "Booting processor %d/%d rip %lx rsp %lx\n", cpu, apicid,
                start_rip, init_rsp);
 
         /*
@@ -609,7 +579,7 @@ static void __init do_boot_cpu (int apicid)
         /*
          * Starting actual IPI sequence...
          */
-        boot_error = wakeup_secondary_via_INIT(apicid, start_rip); 
+        boot_error = wakeup_secondary_via_INIT(apicid, start_rip);
 
         if (!boot_error) {
                 /*
@@ -650,58 +620,131 @@ static void __init do_boot_cpu (int apicid)
         if (boot_error) {
                 cpu_clear(cpu, cpu_callout_map); /* was set here (do_boot_cpu()) */
                 clear_bit(cpu, &cpu_initialized); /* was set by cpu_init() */
-                cpucount--;
+                cpu_clear(cpu, cpu_present_map);
+                cpu_clear(cpu, cpu_possible_map);
                 x86_cpu_to_apicid[cpu] = BAD_APICID;
                 x86_cpu_to_log_apicid[cpu] = BAD_APICID;
+                return -EIO;
         }
+
+        return 0;
 }
 
-static void smp_tune_scheduling (void)
+cycles_t cacheflush_time;
+unsigned long cache_decay_ticks;
+
+/*
+ * Construct cpu_sibling_map[], so that we can tell the sibling CPU
+ * on SMT systems efficiently.
+ */
+static __cpuinit void detect_siblings(void)
 {
-        int cachesize;       /* kB   */
-        unsigned long bandwidth = 1000; /* MB/s */
-        /*
-         * Rough estimation for SMP scheduling, this is the number of
-         * cycles it takes for a fully memory-limited process to flush
-         * the SMP-local cache.
-         *
-         * (For a P5 this pretty much means we will choose another idle
-         *  CPU almost always at wakeup time (this is due to the small
-         *  L1 cache), on PIIs it's around 50-100 usecs, depending on
-         *  the cache size)
-         */
+        int cpu;
 
-        if (!cpu_khz) {
-                return;
-        } else {
-                cachesize = boot_cpu_data.x86_cache_size;
-                if (cachesize == -1) {
-                        cachesize = 16; /* Pentiums, 2x8kB cache */
-                        bandwidth = 100;
+        for (cpu = 0; cpu < NR_CPUS; cpu++) {
+                cpus_clear(cpu_sibling_map[cpu]);
+                cpus_clear(cpu_core_map[cpu]);
+        }
+
+        for_each_online_cpu (cpu) {
+                struct cpuinfo_x86 *c = cpu_data + cpu;
+                int siblings = 0;
+                int i;
+                if (smp_num_siblings > 1) {
+                        for_each_online_cpu (i) {
+                                if (cpu_core_id[cpu] == phys_proc_id[i]) {
+                                        siblings++;
+                                        cpu_set(i, cpu_sibling_map[cpu]);
+                                }
+                        }
+                } else {
+                        siblings++;
+                        cpu_set(cpu, cpu_sibling_map[cpu]);
+                }
+
+                if (siblings != smp_num_siblings) {
+                        printk(KERN_WARNING
+               "WARNING: %d siblings found for CPU%d, should be %d\n",
+                               siblings, cpu, smp_num_siblings);
+                        smp_num_siblings = siblings;
                 }
+                if (c->x86_num_cores > 1) {
+                        for_each_online_cpu(i) {
+                                if (phys_proc_id[cpu] == phys_proc_id[i])
+                                        cpu_set(i, cpu_core_map[cpu]);
+                        }
+                } else
+                        cpu_core_map[cpu] = cpu_sibling_map[cpu];
         }
 }
 
 /*
- * Cycle through the processors sending APIC IPIs to boot each.
+ * Cleanup possible dangling ends...
  */
-
-static void __init smp_boot_cpus(unsigned int max_cpus)
+static __cpuinit void smp_cleanup_boot(void)
 {
-        unsigned apicid, cpu, bit, kicked;
+        /*
+         * Paranoid:  Set warm reset code and vector here back
+         * to default values.
+         */
+        CMOS_WRITE(0, 0xf);
 
-        nmi_watchdog_default();
+        /*
+         * Reset trampoline flag
+         */
+        *((volatile int *) phys_to_virt(0x467)) = 0;
 
+#ifndef CONFIG_HOTPLUG_CPU
         /*
-         * Setup boot CPU information
+         * Free pages reserved for SMP bootup.
+         * When you add hotplug CPU support later remove this
+         * Note there is more work to be done for later CPU bootup.
          */
-        smp_store_cpu_info(0); /* Final full version of the data */
-        printk(KERN_INFO "CPU%d: ", 0);
-        print_cpu_info(&cpu_data[0]);
 
-        current_thread_info()->cpu = 0;
-        smp_tune_scheduling();
+        free_page((unsigned long) __va(PAGE_SIZE));
+        free_page((unsigned long) __va(SMP_TRAMPOLINE_BASE));
+#endif
+}
+
+/*
+ * Fall back to non SMP mode after errors.
+ *
+ * RED-PEN audit/test this more. I bet there is more state messed up here.
+ */
+static __cpuinit void disable_smp(void)
+{
+        cpu_present_map = cpumask_of_cpu(0);
+        cpu_possible_map = cpumask_of_cpu(0);
+        if (smp_found_config)
+                phys_cpu_present_map = physid_mask_of_physid(boot_cpu_id);
+        else
+                phys_cpu_present_map = physid_mask_of_physid(0);
+        cpu_set(0, cpu_sibling_map[0]);
+        cpu_set(0, cpu_core_map[0]);
+}
+
+/*
+ * Handle user cpus=... parameter.
+ */
+static __cpuinit void enforce_max_cpus(unsigned max_cpus)
+{
+        int i, k;
+        k = 0;
+        for (i = 0; i < NR_CPUS; i++) {
+                if (!cpu_possible(i))
+                        continue;
+                if (++k > max_cpus) {
+                        cpu_clear(i, cpu_possible_map);
+                        cpu_clear(i, cpu_present_map);
+                }
+        }
+}
 
+/*
+ * Various sanity checks.
+ */
+static int __cpuinit smp_sanity_check(unsigned max_cpus)
+{
         if (!physid_isset(hard_smp_processor_id(), phys_cpu_present_map)) {
                 printk("weird, boot CPU (#%d) not listed by the BIOS.\n",
                        hard_smp_processor_id());
@@ -714,15 +757,11 @@ static void __init smp_boot_cpus(unsigned int max_cpus)
          */
         if (!smp_found_config) {
                 printk(KERN_NOTICE "SMP motherboard not detected.\n");
-                io_apic_irqs = 0;
-                cpu_online_map = cpumask_of_cpu(0);
-                cpu_set(0, cpu_sibling_map[0]);
-                cpu_set(0, cpu_core_map[0]);
-                phys_cpu_present_map = physid_mask_of_physid(0);
+                disable_smp();
                 if (APIC_init_uniprocessor())
                         printk(KERN_NOTICE "Local APIC not detected."
                                            " Using dummy APIC emulation.\n");
-                goto smp_done;
+                return -1;
         }
 
         /*
@@ -742,213 +781,146 @@ static void __init smp_boot_cpus(unsigned int max_cpus)
                 printk(KERN_ERR "BIOS bug, local APIC #%d not detected!...\n",
                         boot_cpu_id);
                 printk(KERN_ERR "... forcing use of dummy APIC emulation. (tell your hw vendor)\n");
-                io_apic_irqs = 0;
-                cpu_online_map = cpumask_of_cpu(0);
-                cpu_set(0, cpu_sibling_map[0]);
-                cpu_set(0, cpu_core_map[0]);
-                phys_cpu_present_map = physid_mask_of_physid(0);
-                disable_apic = 1;
-                goto smp_done;
+                nr_ioapics = 0;
+                return -1;
         }
 
-        verify_local_APIC();
-
         /*
          * If SMP should be disabled, then really disable it!
          */
         if (!max_cpus) {
-                smp_found_config = 0;
                 printk(KERN_INFO "SMP mode deactivated, forcing use of dummy APIC emulation.\n");
-                io_apic_irqs = 0;
-                cpu_online_map = cpumask_of_cpu(0);
-                cpu_set(0, cpu_sibling_map[0]);
-                cpu_set(0, cpu_core_map[0]);
-                phys_cpu_present_map = physid_mask_of_physid(0);
-                disable_apic = 1;
-                goto smp_done;
+                nr_ioapics = 0;
+                return -1;
         }
 
-        connect_bsp_APIC();
-        setup_local_APIC();
-
-        if (GET_APIC_ID(apic_read(APIC_ID)) != boot_cpu_id)
-                BUG();
-
-        x86_cpu_to_apicid[0] = boot_cpu_id;
-
-        /*
-         * Now scan the CPU present map and fire up the other CPUs.
-         */
-        Dprintk("CPU present map: %lx\n", physids_coerce(phys_cpu_present_map));
+        return 0;
+}
 
-        kicked = 1;
-        for (bit = 0; kicked < NR_CPUS && bit < MAX_APICS; bit++) {
-                apicid = cpu_present_to_apicid(bit);
-                /*
-                 * Don't even attempt to start the boot CPU!
-                 */
-                if (apicid == boot_cpu_id || (apicid == BAD_APICID))
-                        continue;
+/*
+ * Prepare for SMP bootup.  The MP table or ACPI has been read
+ * earlier.  Just do some sanity checking here and enable APIC mode.
+ */
+void __cpuinit smp_prepare_cpus(unsigned int max_cpus)
+{
+        int i;
 
-                if (!physid_isset(apicid, phys_cpu_present_map))
-                        continue;
-                if ((max_cpus >= 0) && (max_cpus <= cpucount+1))
-                        continue;
+        nmi_watchdog_default();
+        current_cpu_data = boot_cpu_data;
+        current_thread_info()->cpu = 0;  /* needed? */
 
-                do_boot_cpu(apicid);
-                ++kicked;
-        }
+        enforce_max_cpus(max_cpus);
 
         /*
-         * Cleanup possible dangling ends...
+         * Fill in cpu_present_mask
          */
-        {
-                /*
-                 * Install writable page 0 entry to set BIOS data area.
-                 */
-                local_flush_tlb();
-
-                /*
-                 * Paranoid:  Set warm reset code and vector here back
-                 * to default values.
-                 */
-                CMOS_WRITE(0, 0xf);
-
-                *((volatile int *) phys_to_virt(0x467)) = 0;
+        for (i = 0; i < NR_CPUS; i++) {
+                int apicid = cpu_present_to_apicid(i);
+                if (physid_isset(apicid, phys_cpu_present_map)) {
+                        cpu_set(i, cpu_present_map);
+                        /* possible map would be different if we supported real
+                           CPU hotplug. */
+                        cpu_set(i, cpu_possible_map);
+                }
         }
 
-        /*
-         * Allow the user to impress friends.
-         */
-
-        Dprintk("Before bogomips.\n");
-        if (!cpucount) {
-                printk(KERN_INFO "Only one processor found.\n");
-        } else {
-                unsigned long bogosum = 0;
-                for (cpu = 0; cpu < NR_CPUS; cpu++)
-                        if (cpu_isset(cpu, cpu_callout_map))
-                                bogosum += cpu_data[cpu].loops_per_jiffy;
-                printk(KERN_INFO "Total of %d processors activated (%lu.%02lu BogoMIPS).\n",
-                        cpucount+1,
-                        bogosum/(500000/HZ),
-                        (bogosum/(5000/HZ))%100);
-                Dprintk("Before bogocount - setting activated=1.\n");
+        if (smp_sanity_check(max_cpus) < 0) {
+                printk(KERN_INFO "SMP disabled\n");
+                disable_smp();
+                return;
         }
 
+
         /*
-         * Construct cpu_sibling_map[], so that we can tell the
-         * sibling CPU efficiently.
+         * Switch from PIC to APIC mode.
          */
-        for (cpu = 0; cpu < NR_CPUS; cpu++) {
-                cpus_clear(cpu_sibling_map[cpu]);
-                cpus_clear(cpu_core_map[cpu]);
-        }
-
-        for (cpu = 0; cpu < NR_CPUS; cpu++) {
-                struct cpuinfo_x86 *c = cpu_data + cpu;
-                int siblings = 0;
-                int i;
-                if (!cpu_isset(cpu, cpu_callout_map))
-                        continue;
-
-                if (smp_num_siblings > 1) {
-                        for (i = 0; i < NR_CPUS; i++) {
-                                if (!cpu_isset(i, cpu_callout_map))
-                                        continue;
-                                if (phys_proc_id[cpu] == cpu_core_id[i]) {
-                                        siblings++;
-                                        cpu_set(i, cpu_sibling_map[cpu]);
-                                }
-                        }
-                } else { 
-                        siblings++;
-                        cpu_set(cpu, cpu_sibling_map[cpu]);
-                }
+        connect_bsp_APIC();
+        setup_local_APIC();
 
-                if (siblings != smp_num_siblings) {
-                        printk(KERN_WARNING 
-               "WARNING: %d siblings found for CPU%d, should be %d\n", 
-                               siblings, cpu, smp_num_siblings);
-                        smp_num_siblings = siblings;
-                }       
-                if (c->x86_num_cores > 1) {
-                        for (i = 0; i < NR_CPUS; i++) {
-                                if (!cpu_isset(i, cpu_callout_map))
-                                        continue;
-                                if (phys_proc_id[cpu] == phys_proc_id[i]) {
-                                        cpu_set(i, cpu_core_map[cpu]);
-                                }
-                        }
-                } else
-                        cpu_core_map[cpu] = cpu_sibling_map[cpu];
+        if (GET_APIC_ID(apic_read(APIC_ID)) != boot_cpu_id) {
+                panic("Boot APIC ID in local APIC unexpected (%d vs %d)",
+                      GET_APIC_ID(apic_read(APIC_ID)), boot_cpu_id);
+                /* Or can we switch back to PIC here? */
         }
-
-        Dprintk("Boot done.\n");
+        x86_cpu_to_apicid[0] = boot_cpu_id;
 
         /*
-         * Here we can be sure that there is an IO-APIC in the system. Let's
-         * go and set it up:
+         * Now start the IO-APICs
          */
         if (!skip_ioapic_setup && nr_ioapics)
                 setup_IO_APIC();
         else
                 nr_ioapics = 0;
 
-        setup_boot_APIC_clock();
-
         /*
-         * Synchronize the TSC with the AP
+         * Set up local APIC timer on boot CPU.
          */
-        if (cpu_has_tsc && cpucount)
-                synchronize_tsc_bp();
 
- smp_done:
-        time_init_smp();
+        setup_boot_APIC_clock();
 }
 
-/* These are wrappers to interface to the new boot process.  Someone
-   who understands all this stuff should rewrite it properly. --RR 15/Jul/02 */
-void __init smp_prepare_cpus(unsigned int max_cpus)
+/*
+ * Early setup to make printk work.
+ */
+void __init smp_prepare_boot_cpu(void)
 {
-        smp_boot_cpus(max_cpus);
+        int me = smp_processor_id();
+        cpu_set(me, cpu_online_map);
+        cpu_set(me, cpu_callout_map);
 }
 
-void __devinit smp_prepare_boot_cpu(void)
+/*
+ * Entry point to boot a CPU.
+ *
+ * This is all __cpuinit, not __devinit for now because we don't support
+ * CPU hotplug (yet).
+ */
+int __cpuinit __cpu_up(unsigned int cpu)
 {
-        cpu_set(smp_processor_id(), cpu_online_map);
-        cpu_set(smp_processor_id(), cpu_callout_map);
-}
+        int err;
+        int apicid = cpu_present_to_apicid(cpu);
 
-int __devinit __cpu_up(unsigned int cpu)
-{
-        /* This only works at boot for x86.  See "rewrite" above. */
-        if (cpu_isset(cpu, smp_commenced_mask)) {
-                local_irq_enable();
-                return -ENOSYS;
-        }
+        WARN_ON(irqs_disabled());
 
-        /* In case one didn't come up */
-        if (!cpu_isset(cpu, cpu_callin_map)) {
-                local_irq_enable();
-                return -EIO;
+        Dprintk("++++++++++++++++++++=_---CPU UP  %u\n", cpu);
+
+        if (apicid == BAD_APICID || apicid == boot_cpu_id ||
+            !physid_isset(apicid, phys_cpu_present_map)) {
+                printk("__cpu_up: bad cpu %d\n", cpu);
+                return -EINVAL;
+        }
+        sync_tsc_bp_init(1);
+
+        /* Boot it! */
+        err = do_boot_cpu(cpu, apicid);
+        if (err < 0) {
+                sync_tsc_bp_init(0);
+                Dprintk("do_boot_cpu failed %d\n", err);
+                return err;
         }
-        local_irq_enable();
+
+        sync_tsc_bp(cpu);
 
         /* Unleash the CPU! */
         Dprintk("waiting for cpu %d\n", cpu);
 
-        cpu_set(cpu, smp_commenced_mask);
         while (!cpu_isset(cpu, cpu_online_map))
-                mb();
+                cpu_relax();
         return 0;
 }
 
-void __init smp_cpus_done(unsigned int max_cpus)
+/*
+ * Finish the SMP boot.
+ */
+void __cpuinit smp_cpus_done(unsigned int max_cpus)
 {
+        zap_low_mappings();
+        smp_cleanup_boot();
+
 #ifdef CONFIG_X86_IO_APIC
         setup_ioapic_dest();
 #endif
-        zap_low_mappings();
-}
 
+        detect_siblings();
+        time_init_gtod();
+}
diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index c7a1b50b4af3..943a9bfba209 100644
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -916,9 +916,16 @@ void __init time_init(void)
         setup_irq(0, &irq0);
 
         set_cyc2ns_scale(cpu_khz / 1000);
+
+#ifndef CONFIG_SMP
+        time_init_gtod();
+#endif
 }
 
-void __init time_init_smp(void)
+/*
+ * Decide after all CPUs are booted what mode gettimeofday should use.
+ */
+void __init time_init_gtod(void)
 {
         char *timetype;