Fedora kernel-2.6.17-1.2142_FC4 patched with stable patch-2.6.17.4-vs2.0.2-rc26.diff
[linux-2.6.git] / arch / x86_64 / kernel / smpboot.c
index f1ec0f3..28e351d 100644 (file)
@@ -34,6 +34,7 @@
  *      Andi Kleen              :       Converted to new state machine.
  *                                     Various cleanups.
  *                                     Probably mostly hotplug CPU ready now.
+ *     Ashok Raj                       : CPU hotplug support
  */
 
 
@@ -43,7 +44,6 @@
 #include <linux/mm.h>
 #include <linux/kernel_stat.h>
 #include <linux/smp_lock.h>
-#include <linux/irq.h>
 #include <linux/bootmem.h>
 #include <linux/thread_info.h>
 #include <linux/module.h>
 #include <asm/tlbflush.h>
 #include <asm/proto.h>
 #include <asm/nmi.h>
-
-/* Change for real CPU hotplug. Note other files need to be fixed
-   first too. */
-#define __cpuinit __init
-#define __cpuinitdata __initdata
+#include <asm/irq.h>
+#include <asm/hw_irq.h>
+#include <asm/numa.h>
 
 /* 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 };
-u8 cpu_core_id[NR_CPUS] = { [0 ... NR_CPUS-1] = BAD_APICID };
-EXPORT_SYMBOL(phys_proc_id);
-EXPORT_SYMBOL(cpu_core_id);
+u8 phys_proc_id[NR_CPUS] __read_mostly = { [0 ... NR_CPUS-1] = BAD_APICID };
+/* core ID of each logical CPU */
+u8 cpu_core_id[NR_CPUS] __read_mostly = { [0 ... NR_CPUS-1] = BAD_APICID };
+
+/* Last level cache ID of each logical CPU */
+u8 cpu_llc_id[NR_CPUS] __cpuinitdata  = {[0 ... NR_CPUS-1] = BAD_APICID};
 
 /* Bitmask of currently online CPUs */
-cpumask_t cpu_online_map;
+cpumask_t cpu_online_map __read_mostly;
 
 EXPORT_SYMBOL(cpu_online_map);
 
@@ -92,8 +92,11 @@ 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;
+/* representing HT siblings of each logical CPU */
+cpumask_t cpu_sibling_map[NR_CPUS] __read_mostly;
+
+/* representing HT and core siblings of each logical CPU */
+cpumask_t cpu_core_map[NR_CPUS] __read_mostly;
 EXPORT_SYMBOL(cpu_core_map);
 
 /*
@@ -103,6 +106,19 @@ EXPORT_SYMBOL(cpu_core_map);
 extern unsigned char trampoline_data[];
 extern unsigned char trampoline_end[];
 
+/* State of each CPU */
+DEFINE_PER_CPU(int, cpu_state) = { 0 };
+
+/*
+ * Store all idle threads, this can be reused instead of creating
+ * a new thread. Also avoids complicated thread destroy functionality
+ * for idle threads.
+ */
+struct task_struct *idle_thread_array[NR_CPUS] __cpuinitdata ;
+
+#define get_idle_for_cpu(x)     (idle_thread_array[(x)])
+#define set_idle_for_cpu(x,p)   (idle_thread_array[(x)] = (p))
+
 /*
  * Currently trivial. Write the real->protected mode
  * bootstrap into the page concerned. The caller
@@ -202,9 +218,6 @@ static __cpuinit void sync_master(void *arg)
 {
        unsigned long flags, i;
 
-       if (smp_processor_id() != boot_cpu_id)
-               return;
-
        go[MASTER] = 0;
 
        local_irq_save(flags);
@@ -253,12 +266,12 @@ get_delta(long *rt, long *master)
        return tcenter - best_tm;
 }
 
-static __cpuinit void sync_tsc(void)
+static __cpuinit void sync_tsc(unsigned int master)
 {
        int i, done = 0;
        long delta, adj, adjust_latency = 0;
        unsigned long flags, rt, master_time_stamp, bound;
-#if DEBUG_TSC_SYNC
+#ifdef DEBUG_TSC_SYNC
        static struct syncdebug {
                long rt;        /* roundtrip time */
                long master;    /* master's timestamp */
@@ -267,9 +280,17 @@ static __cpuinit void sync_tsc(void)
        } t[NUM_ROUNDS] __cpuinitdata;
 #endif
 
+       printk(KERN_INFO "CPU %d: Syncing TSC to CPU %u.\n",
+               smp_processor_id(), master);
+
        go[MASTER] = 1;
 
-       smp_call_function(sync_master, NULL, 1, 0);
+       /* It is dangerous to broadcast IPI as cpus are coming up,
+        * as they may not be ready to accept them.  So since
+        * we only need to send the ipi to the boot cpu direct
+        * the message, and avoid the race.
+        */
+       smp_call_function_single(master, sync_master, NULL, 1, 0);
 
        while (go[MASTER])      /* wait for master to be ready */
                no_cpu_relax();
@@ -294,7 +315,7 @@ static __cpuinit void sync_tsc(void)
                                rdtscll(t);
                                wrmsrl(MSR_IA32_TSC, t + adj);
                        }
-#if DEBUG_TSC_SYNC
+#ifdef DEBUG_TSC_SYNC
                        t[i].rt = rt;
                        t[i].master = master_time_stamp;
                        t[i].diff = delta;
@@ -304,7 +325,7 @@ static __cpuinit void sync_tsc(void)
        }
        spin_unlock_irqrestore(&tsc_sync_lock, flags);
 
-#if DEBUG_TSC_SYNC
+#ifdef DEBUG_TSC_SYNC
        for (i = 0; i < NUM_ROUNDS; ++i)
                printk("rt=%5ld master=%5ld diff=%5ld adjlat=%5ld\n",
                       t[i].rt, t[i].master, t[i].diff, t[i].lat);
@@ -313,22 +334,26 @@ static __cpuinit void sync_tsc(void)
        printk(KERN_INFO
               "CPU %d: synchronized TSC with CPU %u (last diff %ld cycles, "
               "maxerr %lu cycles)\n",
-              smp_processor_id(), boot_cpu_id, delta, rt);
+              smp_processor_id(), master, delta, rt);
 }
 
 static void __cpuinit tsc_sync_wait(void)
 {
-       if (notscsync || !cpu_has_tsc)
+       /*
+        * When the CPU has synchronized TSCs assume the BIOS
+        * or the hardware already synced.  Otherwise we could
+        * mess up a possible perfect synchronization with a
+        * not-quite-perfect algorithm.
+        */
+       if (notscsync || !cpu_has_tsc || !unsynchronized_tsc())
                return;
-       printk(KERN_INFO "CPU %d: Syncing TSC to CPU %u.\n", smp_processor_id(),
-                       boot_cpu_id);
-       sync_tsc();
+       sync_tsc(0);
 }
 
 static __init int notscsync_setup(char *s)
 {
        notscsync = 1;
-       return 0;
+       return 1;
 }
 __setup("notscsync", notscsync_setup);
 
@@ -401,8 +426,13 @@ void __cpuinit smp_callin(void)
 
        /*
         * Get our bogomips.
+        *
+        * Need to enable IRQs because it can take longer and then
+        * the NMI watchdog might kill us.
         */
+       local_irq_enable();
        calibrate_delay();
+       local_irq_disable();
        Dprintk("Stack at about %p\n",&cpuid);
 
        disable_APIC_timer();
@@ -418,6 +448,83 @@ void __cpuinit smp_callin(void)
        cpu_set(cpuid, cpu_callin_map);
 }
 
+/* maps the cpu to the sched domain representing multi-core */
+cpumask_t cpu_coregroup_map(int cpu)
+{
+       struct cpuinfo_x86 *c = cpu_data + cpu;
+       /*
+        * For perf, we return last level cache shared map.
+        * TBD: when power saving sched policy is added, we will return
+        *      cpu_core_map when power saving policy is enabled
+        */
+       return c->llc_shared_map;
+}
+
+/* representing cpus for which sibling maps can be computed */
+static cpumask_t cpu_sibling_setup_map;
+
+static inline void set_cpu_sibling_map(int cpu)
+{
+       int i;
+       struct cpuinfo_x86 *c = cpu_data;
+
+       cpu_set(cpu, cpu_sibling_setup_map);
+
+       if (smp_num_siblings > 1) {
+               for_each_cpu_mask(i, cpu_sibling_setup_map) {
+                       if (phys_proc_id[cpu] == phys_proc_id[i] &&
+                           cpu_core_id[cpu] == cpu_core_id[i]) {
+                               cpu_set(i, cpu_sibling_map[cpu]);
+                               cpu_set(cpu, cpu_sibling_map[i]);
+                               cpu_set(i, cpu_core_map[cpu]);
+                               cpu_set(cpu, cpu_core_map[i]);
+                               cpu_set(i, c[cpu].llc_shared_map);
+                               cpu_set(cpu, c[i].llc_shared_map);
+                       }
+               }
+       } else {
+               cpu_set(cpu, cpu_sibling_map[cpu]);
+       }
+
+       cpu_set(cpu, c[cpu].llc_shared_map);
+
+       if (current_cpu_data.x86_max_cores == 1) {
+               cpu_core_map[cpu] = cpu_sibling_map[cpu];
+               c[cpu].booted_cores = 1;
+               return;
+       }
+
+       for_each_cpu_mask(i, cpu_sibling_setup_map) {
+               if (cpu_llc_id[cpu] != BAD_APICID &&
+                   cpu_llc_id[cpu] == cpu_llc_id[i]) {
+                       cpu_set(i, c[cpu].llc_shared_map);
+                       cpu_set(cpu, c[i].llc_shared_map);
+               }
+               if (phys_proc_id[cpu] == phys_proc_id[i]) {
+                       cpu_set(i, cpu_core_map[cpu]);
+                       cpu_set(cpu, cpu_core_map[i]);
+                       /*
+                        *  Does this new cpu bringup a new core?
+                        */
+                       if (cpus_weight(cpu_sibling_map[cpu]) == 1) {
+                               /*
+                                * for each core in package, increment
+                                * the booted_cores for this new cpu
+                                */
+                               if (first_cpu(cpu_sibling_map[i]) == i)
+                                       c[cpu].booted_cores++;
+                               /*
+                                * increment the core count for all
+                                * the other cpus in this package
+                                */
+                               if (i != cpu)
+                                       c[i].booted_cores++;
+                       } else if (i != cpu && !c[cpu].booted_cores)
+                               c[cpu].booted_cores = c[i].booted_cores;
+               }
+       }
+}
+
 /*
  * Setup code on secondary processor (after comming out of the trampoline)
  */
@@ -429,6 +536,7 @@ void __cpuinit start_secondary(void)
         * things done here to the most necessary things.
         */
        cpu_init();
+       preempt_disable();
        smp_callin();
 
        /* otherwise gcc will move up the smp_processor_id before the cpu_init */
@@ -447,16 +555,36 @@ void __cpuinit start_secondary(void)
 
        enable_APIC_timer();
 
+       /*
+        * The sibling maps must be set before turing the online map on for
+        * this cpu
+        */
+       set_cpu_sibling_map(smp_processor_id());
+
+       /* 
+        * Wait for TSC sync to not schedule things before.
+        * We still process interrupts, which could see an inconsistent
+        * time in that window unfortunately. 
+        * Do this here because TSC sync has global unprotected state.
+        */
+       tsc_sync_wait();
+
+       /*
+        * We need to hold call_lock, so there is no inconsistency
+        * between the time smp_call_function() determines number of
+        * IPI receipients, and the time when the determination is made
+        * for which cpus receive the IPI in genapic_flat.c. Holding this
+        * lock helps us to not include this cpu in a currently in progress
+        * smp_call_function().
+        */
+       lock_ipi_call_lock();
+
        /*
         * Allow the master to continue.
         */
        cpu_set(smp_processor_id(), cpu_online_map);
-       mb();
-
-       /* Wait for TSC sync to not schedule things before.
-          We still process interrupts, which could see an inconsistent
-          time in that window unfortunately. */
-       tsc_sync_wait();
+       per_cpu(cpu_state, smp_processor_id()) = CPU_ONLINE;
+       unlock_ipi_call_lock();
 
        cpu_idle();
 }
@@ -464,7 +592,7 @@ void __cpuinit start_secondary(void)
 extern volatile unsigned long init_rsp;
 extern void (*initial_code)(void);
 
-#if APIC_DEBUG
+#ifdef APIC_DEBUG
 static void inquire_remote_apic(int apicid)
 {
        unsigned i, regs[] = { APIC_ID >> 4, APIC_LVR >> 4, APIC_SPIV >> 4 };
@@ -481,8 +609,8 @@ static void inquire_remote_apic(int apicid)
                 */
                apic_wait_icr_idle();
 
-               apic_write_around(APIC_ICR2, SET_APIC_DEST_FIELD(apicid));
-               apic_write_around(APIC_ICR, APIC_DM_REMRD | regs[i]);
+               apic_write(APIC_ICR2, SET_APIC_DEST_FIELD(apicid));
+               apic_write(APIC_ICR, APIC_DM_REMRD | regs[i]);
 
                timeout = 0;
                do {
@@ -515,12 +643,12 @@ static int __cpuinit wakeup_secondary_via_INIT(int phys_apicid, unsigned int sta
        /*
         * Turn INIT on target chip
         */
-       apic_write_around(APIC_ICR2, SET_APIC_DEST_FIELD(phys_apicid));
+       apic_write(APIC_ICR2, SET_APIC_DEST_FIELD(phys_apicid));
 
        /*
         * Send IPI
         */
-       apic_write_around(APIC_ICR, APIC_INT_LEVELTRIG | APIC_INT_ASSERT
+       apic_write(APIC_ICR, APIC_INT_LEVELTRIG | APIC_INT_ASSERT
                                | APIC_DM_INIT);
 
        Dprintk("Waiting for send to finish...\n");
@@ -536,10 +664,10 @@ static int __cpuinit wakeup_secondary_via_INIT(int phys_apicid, unsigned int sta
        Dprintk("Deasserting INIT.\n");
 
        /* Target chip */
-       apic_write_around(APIC_ICR2, SET_APIC_DEST_FIELD(phys_apicid));
+       apic_write(APIC_ICR2, SET_APIC_DEST_FIELD(phys_apicid));
 
        /* Send IPI */
-       apic_write_around(APIC_ICR, APIC_INT_LEVELTRIG | APIC_DM_INIT);
+       apic_write(APIC_ICR, APIC_INT_LEVELTRIG | APIC_DM_INIT);
 
        Dprintk("Waiting for send to finish...\n");
        timeout = 0;
@@ -549,18 +677,10 @@ static int __cpuinit wakeup_secondary_via_INIT(int phys_apicid, unsigned int sta
                send_status = apic_read(APIC_ICR) & APIC_ICR_BUSY;
        } while (send_status && (timeout++ < 1000));
 
+       mb();
        atomic_set(&init_deasserted, 1);
 
-       /*
-        * Should we send STARTUP IPIs ?
-        *
-        * Determine this based on the APIC version.
-        * If we don't have an integrated APIC, don't send the STARTUP IPIs.
-        */
-       if (APIC_INTEGRATED(apic_version[phys_apicid]))
-               num_starts = 2;
-       else
-               num_starts = 0;
+       num_starts = 2;
 
        /*
         * Run STARTUP IPI loop.
@@ -571,7 +691,6 @@ static int __cpuinit wakeup_secondary_via_INIT(int phys_apicid, unsigned int sta
 
        for (j = 1; j <= num_starts; j++) {
                Dprintk("Sending STARTUP #%d.\n",j);
-               apic_read_around(APIC_SPIV);
                apic_write(APIC_ESR, 0);
                apic_read(APIC_ESR);
                Dprintk("After apic_write.\n");
@@ -581,12 +700,11 @@ static int __cpuinit wakeup_secondary_via_INIT(int phys_apicid, unsigned int sta
                 */
 
                /* Target chip */
-               apic_write_around(APIC_ICR2, SET_APIC_DEST_FIELD(phys_apicid));
+               apic_write(APIC_ICR2, SET_APIC_DEST_FIELD(phys_apicid));
 
                /* Boot on the stack */
                /* Kick the second */
-               apic_write_around(APIC_ICR, APIC_DM_STARTUP
-                                       | (start_rip >> 12));
+               apic_write(APIC_ICR, APIC_DM_STARTUP | (start_rip >> 12));
 
                /*
                 * Give the other CPU some time to accept the IPI.
@@ -611,7 +729,6 @@ static int __cpuinit wakeup_secondary_via_INIT(int phys_apicid, unsigned int sta
                 * Due to the Pentium erratum 3AP.
                 */
                if (maxlvt > 3) {
-                       apic_read_around(APIC_SPIV);
                        apic_write(APIC_ESR, 0);
                }
                accept_status = (apic_read(APIC_ESR) & 0xEF);
@@ -628,36 +745,105 @@ static int __cpuinit wakeup_secondary_via_INIT(int phys_apicid, unsigned int sta
        return (send_status | accept_status);
 }
 
+struct create_idle {
+       struct task_struct *idle;
+       struct completion done;
+       int cpu;
+};
+
+void do_fork_idle(void *_c_idle)
+{
+       struct create_idle *c_idle = _c_idle;
+
+       c_idle->idle = fork_idle(c_idle->cpu);
+       complete(&c_idle->done);
+}
+
 /*
  * Boot one CPU.
  */
 static int __cpuinit do_boot_cpu(int cpu, int apicid)
 {
-       struct task_struct *idle;
        unsigned long boot_error;
        int timeout;
        unsigned long start_rip;
+       struct create_idle c_idle = {
+               .cpu = cpu,
+               .done = COMPLETION_INITIALIZER(c_idle.done),
+       };
+       DECLARE_WORK(work, do_fork_idle, &c_idle);
+
+       /* allocate memory for gdts of secondary cpus. Hotplug is considered */
+       if (!cpu_gdt_descr[cpu].address &&
+               !(cpu_gdt_descr[cpu].address = get_zeroed_page(GFP_KERNEL))) {
+               printk(KERN_ERR "Failed to allocate GDT for CPU %d\n", cpu);
+               return -1;
+       }
+
+       /* Allocate node local memory for AP pdas */
+       if (cpu_pda(cpu) == &boot_cpu_pda[cpu]) {
+               struct x8664_pda *newpda, *pda;
+               int node = cpu_to_node(cpu);
+               pda = cpu_pda(cpu);
+               newpda = kmalloc_node(sizeof (struct x8664_pda), GFP_ATOMIC,
+                                     node);
+               if (newpda) {
+                       memcpy(newpda, pda, sizeof (struct x8664_pda));
+                       cpu_pda(cpu) = newpda;
+               } else
+                       printk(KERN_ERR
+               "Could not allocate node local PDA for CPU %d on node %d\n",
+                               cpu, node);
+       }
+
+
+       c_idle.idle = get_idle_for_cpu(cpu);
+
+       if (c_idle.idle) {
+               c_idle.idle->thread.rsp = (unsigned long) (((struct pt_regs *)
+                       (THREAD_SIZE +  task_stack_page(c_idle.idle))) - 1);
+               init_idle(c_idle.idle, cpu);
+               goto do_rest;
+       }
+
        /*
-        * We can't use kernel_thread since we must avoid to
-        * reschedule the child.
+        * During cold boot process, keventd thread is not spun up yet.
+        * When we do cpu hot-add, we create idle threads on the fly, we should
+        * not acquire any attributes from the calling context. Hence the clean
+        * way to create kernel_threads() is to do that from keventd().
+        * We do the current_is_keventd() due to the fact that ACPI notifier
+        * was also queuing to keventd() and when the caller is already running
+        * in context of keventd(), we would end up with locking up the keventd
+        * thread.
         */
-       idle = fork_idle(cpu);
-       if (IS_ERR(idle)) {
+       if (!keventd_up() || current_is_keventd())
+               work.func(work.data);
+       else {
+               schedule_work(&work);
+               wait_for_completion(&c_idle.done);
+       }
+
+       if (IS_ERR(c_idle.idle)) {
                printk("failed fork for CPU %d\n", cpu);
-               return PTR_ERR(idle);
+               return PTR_ERR(c_idle.idle);
        }
 
-       cpu_pda[cpu].pcurrent = idle;
+       set_idle_for_cpu(cpu, c_idle.idle);
+
+do_rest:
+
+       cpu_pda(cpu)->pcurrent = c_idle.idle;
 
        start_rip = setup_trampoline();
 
-       init_rsp = idle->thread.rsp;
+       init_rsp = c_idle.idle->thread.rsp;
        per_cpu(init_tss,cpu).rsp0 = init_rsp;
        initial_code = start_secondary;
-       clear_ti_thread_flag(idle->thread_info, TIF_FORK);
+       clear_tsk_thread_flag(c_idle.idle, TIF_FORK);
 
-       printk(KERN_INFO "Booting processor %d/%d rip %lx rsp %lx\n", cpu, apicid,
-              start_rip, init_rsp);
+       printk(KERN_INFO "Booting processor %d/%d APIC 0x%x\n", cpu,
+               cpus_weight(cpu_present_map),
+               apicid);
 
        /*
         * This grunge runs the startup process for
@@ -679,11 +865,8 @@ static int __cpuinit do_boot_cpu(int cpu, int apicid)
        /*
         * Be paranoid about clearing APIC errors.
         */
-       if (APIC_INTEGRATED(apic_version[apicid])) {
-               apic_read_around(APIC_SPIV);
-               apic_write(APIC_ESR, 0);
-               apic_read(APIC_ESR);
-       }
+       apic_write(APIC_ESR, 0);
+       apic_read(APIC_ESR);
 
        /*
         * Status is now clean
@@ -724,7 +907,7 @@ static int __cpuinit do_boot_cpu(int cpu, int apicid)
                        else
                                /* trampoline code not run */
                                printk("Not responding.\n");
-#if APIC_DEBUG
+#ifdef APIC_DEBUG
                        inquire_remote_apic(apicid);
 #endif
                }
@@ -732,6 +915,7 @@ static int __cpuinit do_boot_cpu(int 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() */
+               clear_node_cpumask(cpu); /* was set by numa_add_cpu */
                cpu_clear(cpu, cpu_present_map);
                cpu_clear(cpu, cpu_possible_map);
                x86_cpu_to_apicid[cpu] = BAD_APICID;
@@ -745,51 +929,6 @@ static int __cpuinit do_boot_cpu(int cpu, int apicid)
 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 cpu;
-
-       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] == cpu_core_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];
-       }
-}
-
 /*
  * Cleanup possible dangling ends...
  */
@@ -805,17 +944,6 @@ static __cpuinit void smp_cleanup_boot(void)
         * Reset trampoline flag
         */
        *((volatile int *) phys_to_virt(0x467)) = 0;
-
-#ifndef CONFIG_HOTPLUG_CPU
-       /*
-        * 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.
-        */
-
-       free_page((unsigned long) __va(PAGE_SIZE));
-       free_page((unsigned long) __va(SMP_TRAMPOLINE_BASE));
-#endif
 }
 
 /*
@@ -823,7 +951,7 @@ static __cpuinit void smp_cleanup_boot(void)
  *
  * RED-PEN audit/test this more. I bet there is more state messed up here.
  */
-static __cpuinit void disable_smp(void)
+static __init void disable_smp(void)
 {
        cpu_present_map = cpumask_of_cpu(0);
        cpu_possible_map = cpumask_of_cpu(0);
@@ -835,27 +963,60 @@ static __cpuinit void disable_smp(void)
        cpu_set(0, cpu_core_map[0]);
 }
 
+#ifdef CONFIG_HOTPLUG_CPU
+
+int additional_cpus __initdata = -1;
+
 /*
- * Handle user cpus=... parameter.
+ * cpu_possible_map should be static, it cannot change as cpu's
+ * are onlined, or offlined. The reason is per-cpu data-structures
+ * are allocated by some modules at init time, and dont expect to
+ * do this dynamically on cpu arrival/departure.
+ * cpu_present_map on the other hand can change dynamically.
+ * In case when cpu_hotplug is not compiled, then we resort to current
+ * behaviour, which is cpu_possible == cpu_present.
+ * - Ashok Raj
+ *
+ * Three ways to find out the number of additional hotplug CPUs:
+ * - If the BIOS specified disabled CPUs in ACPI/mptables use that.
+ * - The user can overwrite it with additional_cpus=NUM
+ * - Otherwise don't reserve additional CPUs.
+ * We do this because additional CPUs waste a lot of memory.
+ * -AK
  */
-static __cpuinit void enforce_max_cpus(unsigned max_cpus)
+__init void prefill_possible_map(void)
 {
-       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);
-               }
+       int i;
+       int possible;
+
+       if (additional_cpus == -1) {
+               if (disabled_cpus > 0)
+                       additional_cpus = disabled_cpus;
+               else
+                       additional_cpus = 0;
+       }
+       possible = num_processors + additional_cpus;
+       if (possible > NR_CPUS) 
+               possible = NR_CPUS;
+
+       if (possible == 0) {    /* Could be SMP kernel on UP hw with broken BIOS */
+               possible = 1;
+               printk (KERN_DEBUG "BIOS never enumerated boot CPU, fixing.\n");
        }
+
+       printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n",
+               possible,
+               max_t(int, possible - num_processors, 0));
+
+       for (i = 0; i < possible; i++)
+               cpu_set(i, cpu_possible_map);
 }
+#endif
 
 /*
  * Various sanity checks.
  */
-static int __cpuinit smp_sanity_check(unsigned max_cpus)
+static int __init 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",
@@ -889,7 +1050,7 @@ static int __cpuinit smp_sanity_check(unsigned max_cpus)
        /*
         * If we couldn't find a local APIC, then get out of here now!
         */
-       if (APIC_INTEGRATED(apic_version[boot_cpu_id]) && !cpu_has_apic) {
+       if (!cpu_has_apic) {
                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");
@@ -913,28 +1074,12 @@ static int __cpuinit smp_sanity_check(unsigned max_cpus)
  * 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)
+void __init smp_prepare_cpus(unsigned int max_cpus)
 {
-       int i;
-
        nmi_watchdog_default();
        current_cpu_data = boot_cpu_data;
        current_thread_info()->cpu = 0;  /* needed? */
-
-       enforce_max_cpus(max_cpus);
-
-       /*
-        * Fill in cpu_present_mask
-        */
-       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);
-               }
-       }
+       set_cpu_sibling_map(0);
 
        if (smp_sanity_check(max_cpus) < 0) {
                printk(KERN_INFO "SMP disabled\n");
@@ -978,13 +1123,11 @@ void __init smp_prepare_boot_cpu(void)
        int me = smp_processor_id();
        cpu_set(me, cpu_online_map);
        cpu_set(me, cpu_callout_map);
+       per_cpu(cpu_state, me) = CPU_ONLINE;
 }
 
 /*
  * 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)
 {
@@ -1001,6 +1144,15 @@ int __cpuinit __cpu_up(unsigned int cpu)
                return -EINVAL;
        }
 
+       /*
+        * Already booted CPU?
+        */
+       if (cpu_isset(cpu, cpu_callin_map)) {
+               Dprintk("do_boot_cpu %d Already started\n", cpu);
+               return -ENOSYS;
+       }
+
+       per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
        /* Boot it! */
        err = do_boot_cpu(cpu, apicid);
        if (err < 0) {
@@ -1013,23 +1165,128 @@ int __cpuinit __cpu_up(unsigned int cpu)
 
        while (!cpu_isset(cpu, cpu_online_map))
                cpu_relax();
-       return 0;
+       err = 0;
+
+       return err;
 }
 
 /*
  * Finish the SMP boot.
  */
-void __cpuinit smp_cpus_done(unsigned int max_cpus)
+void __init smp_cpus_done(unsigned int max_cpus)
 {
-       zap_low_mappings();
        smp_cleanup_boot();
 
 #ifdef CONFIG_X86_IO_APIC
        setup_ioapic_dest();
 #endif
 
-       detect_siblings();
-       time_init_gtod();
-
        check_nmi_watchdog();
 }
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+static void remove_siblinginfo(int cpu)
+{
+       int sibling;
+       struct cpuinfo_x86 *c = cpu_data;
+
+       for_each_cpu_mask(sibling, cpu_core_map[cpu]) {
+               cpu_clear(cpu, cpu_core_map[sibling]);
+               /*
+                * last thread sibling in this cpu core going down
+                */
+               if (cpus_weight(cpu_sibling_map[cpu]) == 1)
+                       c[sibling].booted_cores--;
+       }
+                       
+       for_each_cpu_mask(sibling, cpu_sibling_map[cpu])
+               cpu_clear(cpu, cpu_sibling_map[sibling]);
+       cpus_clear(cpu_sibling_map[cpu]);
+       cpus_clear(cpu_core_map[cpu]);
+       phys_proc_id[cpu] = BAD_APICID;
+       cpu_core_id[cpu] = BAD_APICID;
+       cpu_clear(cpu, cpu_sibling_setup_map);
+}
+
+void remove_cpu_from_maps(void)
+{
+       int cpu = smp_processor_id();
+
+       cpu_clear(cpu, cpu_callout_map);
+       cpu_clear(cpu, cpu_callin_map);
+       clear_bit(cpu, &cpu_initialized); /* was set by cpu_init() */
+       clear_node_cpumask(cpu);
+}
+
+int __cpu_disable(void)
+{
+       int cpu = smp_processor_id();
+
+       /*
+        * Perhaps use cpufreq to drop frequency, but that could go
+        * into generic code.
+        *
+        * We won't take down the boot processor on i386 due to some
+        * interrupts only being able to be serviced by the BSP.
+        * Especially so if we're not using an IOAPIC   -zwane
+        */
+       if (cpu == 0)
+               return -EBUSY;
+
+       clear_local_APIC();
+
+       /*
+        * HACK:
+        * Allow any queued timer interrupts to get serviced
+        * This is only a temporary solution until we cleanup
+        * fixup_irqs as we do for IA64.
+        */
+       local_irq_enable();
+       mdelay(1);
+
+       local_irq_disable();
+       remove_siblinginfo(cpu);
+
+       /* It's now safe to remove this processor from the online map */
+       cpu_clear(cpu, cpu_online_map);
+       remove_cpu_from_maps();
+       fixup_irqs(cpu_online_map);
+       return 0;
+}
+
+void __cpu_die(unsigned int cpu)
+{
+       /* We don't do anything here: idle task is faking death itself. */
+       unsigned int i;
+
+       for (i = 0; i < 10; i++) {
+               /* They ack this in play_dead by setting CPU_DEAD */
+               if (per_cpu(cpu_state, cpu) == CPU_DEAD) {
+                       printk ("CPU %d is now offline\n", cpu);
+                       return;
+               }
+               msleep(100);
+       }
+       printk(KERN_ERR "CPU %u didn't die...\n", cpu);
+}
+
+__init int setup_additional_cpus(char *s)
+{
+       return get_option(&s, &additional_cpus);
+}
+__setup("additional_cpus=", setup_additional_cpus);
+
+#else /* ... !CONFIG_HOTPLUG_CPU */
+
+int __cpu_disable(void)
+{
+       return -ENOSYS;
+}
+
+void __cpu_die(unsigned int cpu)
+{
+       /* We said "no" in __cpu_disable */
+       BUG();
+}
+#endif /* CONFIG_HOTPLUG_CPU */