[PATCH] x86-64/i386: Intel HT, Multi core detection fixes

Fields obtained through cpuid vector 0x1(ebx[16:23]) and
vector 0x4(eax[14:25], eax[26:31]) indicate the maximum values and might not
always be the same as what is available and what OS sees.  So make sure
"siblings" and "cpu cores" values in /proc/cpuinfo reflect the values as seen
by OS instead of what cpuid instruction says. This will also fix the buggy BIOS
cases (for example where cpuid on a single core cpu says there are "2" siblings,
even when HT is disabled in the BIOS.
http://bugzilla.kernel.org/show_bug.cgi?id=4359)

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 55 insertions, 14 deletions

diff --git a/arch/x86_64/kernel/smpboot.c b/arch/x86_64/kernel/smpboot.c
index f74319a80659..2b9ddba61b37 100644
--- a/arch/x86_64/kernel/smpboot.c
+++ b/arch/x86_64/kernel/smpboot.c
@@ -64,6 +64,7 @@
 int smp_num_siblings = 1;
 /* Package ID of each logical CPU */
 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 };
 EXPORT_SYMBOL(phys_proc_id);
 EXPORT_SYMBOL(cpu_core_id);
@@ -89,7 +90,10 @@ struct cpuinfo_x86 cpu_data[NR_CPUS] __cacheline_aligned;
 /* Set when the idlers are all forked */
 int smp_threads_ready;
 
+/* 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);
 
@@ -436,30 +440,59 @@ void __cpuinit smp_callin(void)
         cpu_set(cpuid, cpu_callin_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(i) {
-                        if (cpu_core_id[cpu] == cpu_core_id[i]) {
+                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]);
                         }
                 }
         } else {
                 cpu_set(cpu, cpu_sibling_map[cpu]);
         }
 
-        if (current_cpu_data.x86_num_cores > 1) {
-                for_each_cpu(i) {
-                        if (phys_proc_id[cpu] == phys_proc_id[i]) {
-                                cpu_set(i, cpu_core_map[cpu]);
-                                cpu_set(cpu, cpu_core_map[i]);
-                        }
-                }
-        } else {
+        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 (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;
+                }
         }
 }
 
@@ -993,6 +1026,7 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
         nmi_watchdog_default();
         current_cpu_data = boot_cpu_data;
         current_thread_info()->cpu = 0;  /* needed? */
+        set_cpu_sibling_map(0);
 
         if (smp_sanity_check(max_cpus) < 0) {
                 printk(KERN_INFO "SMP disabled\n");
@@ -1036,8 +1070,6 @@ void __init smp_prepare_boot_cpu(void)
         int me = smp_processor_id();
         cpu_set(me, cpu_online_map);
         cpu_set(me, cpu_callout_map);
-        cpu_set(0, cpu_sibling_map[0]);
-        cpu_set(0, cpu_core_map[0]);
         per_cpu(cpu_state, me) = CPU_ONLINE;
 }
 
@@ -1106,15 +1138,24 @@ void __init smp_cpus_done(unsigned int max_cpus)
 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]);
-        for_each_cpu_mask(sibling, cpu_core_map[cpu])
-                cpu_clear(cpu, cpu_core_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)