Merge branch 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 bootup updates from Ingo Molnar:
 "The changes in this cycle were:

   - Fix rare SMP-boot hang (mostly in virtual environments)

   - Fix build warning with certain (rare) toolchains"

* 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/relocs: Make per_cpu_load_addr static
  x86/smpboot: Initialize secondary CPU only if master CPU will wait for it

4 files changed, 51 insertions, 80 deletions

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index c649f236e288..d8b1166c7888 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1266,6 +1266,19 @@ static void dbg_restore_debug_regs(void)
 #define dbg_restore_debug_regs()
 #endif /* ! CONFIG_KGDB */
 
+static void wait_for_master_cpu(int cpu)
+{
+#ifdef CONFIG_SMP
+        /*
+         * wait for ACK from master CPU before continuing
+         * with AP initialization
+         */
+        WARN_ON(cpumask_test_and_set_cpu(cpu, cpu_initialized_mask));
+        while (!cpumask_test_cpu(cpu, cpu_callout_mask))
+                cpu_relax();
+#endif
+}
+
 /*
  * cpu_init() initializes state that is per-CPU. Some data is already
  * initialized (naturally) in the bootstrap process, such as the GDT
@@ -1281,16 +1294,17 @@ void cpu_init(void)
         struct task_struct *me;
         struct tss_struct *t;
         unsigned long v;
-        int cpu;
+        int cpu = stack_smp_processor_id();
         int i;
 
+        wait_for_master_cpu(cpu);
+
         /*
          * Load microcode on this cpu if a valid microcode is available.
          * This is early microcode loading procedure.
          */
         load_ucode_ap();
 
-        cpu = stack_smp_processor_id();
         t = &per_cpu(init_tss, cpu);
         oist = &per_cpu(orig_ist, cpu);
 
@@ -1302,9 +1316,6 @@ void cpu_init(void)
 
         me = current;
 
-        if (cpumask_test_and_set_cpu(cpu, cpu_initialized_mask))
-                panic("CPU#%d already initialized!\n", cpu);
-
         pr_debug("Initializing CPU#%d\n", cpu);
 
         clear_in_cr4(X86_CR4_VME|X86_CR4_PVI|X86_CR4_TSD|X86_CR4_DE);
@@ -1381,13 +1392,9 @@ void cpu_init(void)
         struct tss_struct *t = &per_cpu(init_tss, cpu);
         struct thread_struct *thread = &curr->thread;
 
-        show_ucode_info_early();
+        wait_for_master_cpu(cpu);
 
-        if (cpumask_test_and_set_cpu(cpu, cpu_initialized_mask)) {
-                printk(KERN_WARNING "CPU#%d already initialized!\n", cpu);
-                for (;;)
-                        local_irq_enable();
-        }
+        show_ucode_info_early();
 
         printk(KERN_INFO "Initializing CPU#%d\n", cpu);
 
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 9b1c0f8f68e6..1c3443d98105 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -111,7 +111,6 @@ atomic_t init_deasserted;
 static void smp_callin(void)
 {
         int cpuid, phys_id;
-        unsigned long timeout;
 
         /*
          * If waken up by an INIT in an 82489DX configuration
@@ -130,37 +129,6 @@ static void smp_callin(void)
          * (This works even if the APIC is not enabled.)
          */
         phys_id = read_apic_id();
-        if (cpumask_test_cpu(cpuid, cpu_callin_mask)) {
-                panic("%s: phys CPU#%d, CPU#%d already present??\n", __func__,
-                                        phys_id, cpuid);
-        }
-        pr_debug("CPU#%d (phys ID: %d) waiting for CALLOUT\n", cpuid, phys_id);
-
-        /*
-         * STARTUP IPIs are fragile beasts as they might sometimes
-         * trigger some glue motherboard logic. Complete APIC bus
-         * silence for 1 second, this overestimates the time the
-         * boot CPU is spending to send the up to 2 STARTUP IPIs
-         * by a factor of two. This should be enough.
-         */
-
-        /*
-         * Waiting 2s total for startup (udelay is not yet working)
-         */
-        timeout = jiffies + 2*HZ;
-        while (time_before(jiffies, timeout)) {
-                /*
-                 * Has the boot CPU finished it's STARTUP sequence?
-                 */
-                if (cpumask_test_cpu(cpuid, cpu_callout_mask))
-                        break;
-                cpu_relax();
-        }
-
-        if (!time_before(jiffies, timeout)) {
-                panic("%s: CPU%d started up but did not get a callout!\n",
-                      __func__, cpuid);
-        }
 
         /*
          * the boot CPU has finished the init stage and is spinning
@@ -790,8 +758,8 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle)
         unsigned long start_ip = real_mode_header->trampoline_start;
 
         unsigned long boot_error = 0;
-        int timeout;
         int cpu0_nmi_registered = 0;
+        unsigned long timeout;
 
         /* Just in case we booted with a single CPU. */
         alternatives_enable_smp();
@@ -839,6 +807,15 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle)
         }
 
         /*
+         * AP might wait on cpu_callout_mask in cpu_init() with
+         * cpu_initialized_mask set if previous attempt to online
+         * it timed-out. Clear cpu_initialized_mask so that after
+         * INIT/SIPI it could start with a clean state.
+         */
+        cpumask_clear_cpu(cpu, cpu_initialized_mask);
+        smp_mb();
+
+        /*
          * Wake up a CPU in difference cases:
          * - Use the method in the APIC driver if it's defined
          * Otherwise,
@@ -852,53 +829,38 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle)
 
         if (!boot_error) {
                 /*
-                 * allow APs to start initializing.
+                 * Wait 10s total for a response from AP
                  */
-                pr_debug("Before Callout %d\n", cpu);
-                cpumask_set_cpu(cpu, cpu_callout_mask);
-                pr_debug("After Callout %d\n", cpu);
+                boot_error = -1;
+                timeout = jiffies + 10*HZ;
+                while (time_before(jiffies, timeout)) {
+                        if (cpumask_test_cpu(cpu, cpu_initialized_mask)) {
+                                /*
+                                 * Tell AP to proceed with initialization
+                                 */
+                                cpumask_set_cpu(cpu, cpu_callout_mask);
+                                boot_error = 0;
+                                break;
+                        }
+                        udelay(100);
+                        schedule();
+                }
+        }
 
+        if (!boot_error) {
                 /*
-                 * Wait 5s total for a response
+                 * Wait till AP completes initial initialization
                  */
-                for (timeout = 0; timeout < 50000; timeout++) {
-                        if (cpumask_test_cpu(cpu, cpu_callin_mask))
-                                break;  /* It has booted */
-                        udelay(100);
+                while (!cpumask_test_cpu(cpu, cpu_callin_mask)) {
                         /*
                          * Allow other tasks to run while we wait for the
                          * AP to come online. This also gives a chance
                          * for the MTRR work(triggered by the AP coming online)
                          * to be completed in the stop machine context.
                          */
+                        udelay(100);
                         schedule();
                 }
-
-                if (cpumask_test_cpu(cpu, cpu_callin_mask)) {
-                        print_cpu_msr(&cpu_data(cpu));
-                        pr_debug("CPU%d: has booted.\n", cpu);
-                } else {
-                        boot_error = 1;
-                        if (*trampoline_status == 0xA5A5A5A5)
-                                /* trampoline started but...? */
-                                pr_err("CPU%d: Stuck ??\n", cpu);
-                        else
-                                /* trampoline code not run */
-                                pr_err("CPU%d: Not responding\n", cpu);
-                        if (apic->inquire_remote_apic)
-                                apic->inquire_remote_apic(apicid);
-                }
-        }
-
-        if (boot_error) {
-                /* Try to put things back the way they were before ... */
-                numa_remove_cpu(cpu); /* was set by numa_add_cpu */
-
-                /* was set by do_boot_cpu() */
-                cpumask_clear_cpu(cpu, cpu_callout_mask);
-
-                /* was set by cpu_init() */
-                cpumask_clear_cpu(cpu, cpu_initialized_mask);
         }
 
         /* mark "stuck" area as not stuck */
diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c
index bbb1d2259ecf..a5efb21d5228 100644
--- a/arch/x86/tools/relocs.c
+++ b/arch/x86/tools/relocs.c
@@ -695,7 +695,7 @@ static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
  *
  */
 static int per_cpu_shndx        = -1;
-Elf_Addr per_cpu_load_addr;
+static Elf_Addr per_cpu_load_addr;
 
 static void percpu_init(void)
 {
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index c670d7518cf4..8650cdb53209 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -365,6 +365,8 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
         struct desc_struct *gdt;
         unsigned long gdt_mfn;
 
+        /* used to tell cpu_init() that it can proceed with initialization */
+        cpumask_set_cpu(cpu, cpu_callout_mask);
         if (cpumask_test_and_set_cpu(cpu, xen_cpu_initialized_map))
                 return 0;