x86: check bigsmp in smp_sanity_check instead of cpu_up

clear bits for cpu nr > 8.

This allows us to boot the full range of possible CPUs that the
supported APIC model will allow. Previously we'd hang or boot up
with less than 8 CPUs.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Tested-by: Jeff Chua <jeff.chua.linux@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 28 insertions, 10 deletions

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index e25287e4a85f..a8fb8a980fae 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -994,17 +994,7 @@ int __cpuinit native_cpu_up(unsigned int cpu)
         flush_tlb_all();
         low_mappings = 1;
 
-#ifdef CONFIG_X86_PC
-        if (def_to_bigsmp && apicid > 8) {
-                printk(KERN_WARNING
-                        "More than 8 CPUs detected - skipping them.\n"
-                        "Use CONFIG_X86_GENERICARCH and CONFIG_X86_BIGSMP.\n");
-                err = -1;
-        } else
-                err = do_boot_cpu(apicid, cpu);
-#else
         err = do_boot_cpu(apicid, cpu);
-#endif
 
         zap_low_mappings();
         low_mappings = 0;
@@ -1058,6 +1048,34 @@ static __init void disable_smp(void)
 static int __init smp_sanity_check(unsigned max_cpus)
 {
         preempt_disable();
+
+#if defined(CONFIG_X86_PC) && defined(CONFIG_X86_32)
+        if (def_to_bigsmp && nr_cpu_ids > 8) {
+                unsigned int cpu;
+                unsigned nr;
+
+                printk(KERN_WARNING
+                       "More than 8 CPUs detected - skipping them.\n"
+                       "Use CONFIG_X86_GENERICARCH and CONFIG_X86_BIGSMP.\n");
+
+                nr = 0;
+                for_each_present_cpu(cpu) {
+                        if (nr >= 8)
+                                cpu_clear(cpu, cpu_present_map);
+                        nr++;
+                }
+
+                nr = 0;
+                for_each_possible_cpu(cpu) {
+                        if (nr >= 8)
+                                cpu_clear(cpu, cpu_possible_map);
+                        nr++;
+                }
+
+                nr_cpu_ids = 8;
+        }
+#endif
+
         if (!physid_isset(hard_smp_processor_id(), phys_cpu_present_map)) {
                 printk(KERN_WARNING "weird, boot CPU (#%d) not listed"
                                     "by the BIOS.\n", hard_smp_processor_id());