x86, x2apic: Track the x2apic cluster sibling map

In the case of x2apic cluster mode, we can group IPI register
writes based on the cluster group instead of individual per-cpu
destination messages.

For this purpose, track the cpu's that belong to the same x2apic
cluster.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: steiner@sgi.com
Cc: yinghai@kernel.org
Link: http://lkml.kernel.org/r/20110519234637.421800999@sbsiddha-MOBL3.sc.intel.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/apic/x2apic_cluster.c b/arch/x86/kernel/apic/x2apic_cluster.c
index b261799..4b2bb13 100644 (file)
--- a/arch/x86/kernel/apic/x2apic_cluster.c
+++ b/arch/x86/kernel/apic/x2apic_cluster.c
@@ -11,6 +11,7 @@
 #include <asm/ipi.h>
 
 static DEFINE_PER_CPU(u32, x86_cpu_to_logical_apicid);
+static DEFINE_PER_CPU(cpumask_var_t, cpus_in_cluster);
 
 static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
 {
@@ -48,6 +49,11 @@ static void
        native_x2apic_icr_write(cfg, apicid);
 }
 
+static inline u32 x2apic_cluster(int cpu)
+{
+       return per_cpu(x86_cpu_to_logical_apicid, cpu) >> 16;
+}
+
 /*
  * for now, we send the IPI's one by one in the cpumask.
  * TBD: Based on the cpu mask, we can send the IPI's to the cluster group
@@ -162,15 +168,77 @@ static void x2apic_send_IPI_self(int vector)
 }
 
 static void init_x2apic_ldr(void)
+{
+       unsigned int this_cpu = smp_processor_id();
+       unsigned int cpu;
+
+       per_cpu(x86_cpu_to_logical_apicid, this_cpu) = apic_read(APIC_LDR);
+
+       __cpu_set(this_cpu, per_cpu(cpus_in_cluster, this_cpu));
+       for_each_online_cpu(cpu) {
+               if (x2apic_cluster(this_cpu) != x2apic_cluster(cpu))
+                       continue;
+               __cpu_set(this_cpu, per_cpu(cpus_in_cluster, cpu));
+               __cpu_set(cpu, per_cpu(cpus_in_cluster, this_cpu));
+       }
+}
+
+ /*
+  * At CPU state changes, update the x2apic cluster sibling info.
+  */
+static int __cpuinit
+update_clusterinfo(struct notifier_block *nfb, unsigned long action, void *hcpu)
+{
+       unsigned int this_cpu = (unsigned long)hcpu;
+       unsigned int cpu;
+       int err = 0;
+
+       switch (action) {
+       case CPU_UP_PREPARE:
+               if (!zalloc_cpumask_var(&per_cpu(cpus_in_cluster, this_cpu),
+                                       GFP_KERNEL)) {
+                       err = -ENOMEM;
+               }
+               break;
+       case CPU_UP_CANCELED:
+       case CPU_UP_CANCELED_FROZEN:
+       case CPU_DEAD:
+               for_each_online_cpu(cpu) {
+                       if (x2apic_cluster(this_cpu) != x2apic_cluster(cpu))
+                               continue;
+                       __cpu_clear(this_cpu, per_cpu(cpus_in_cluster, cpu));
+                       __cpu_clear(cpu, per_cpu(cpus_in_cluster, this_cpu));
+               }
+               free_cpumask_var(per_cpu(cpus_in_cluster, this_cpu));
+               break;
+       }
+
+       return notifier_from_errno(err);
+}
+
+static struct notifier_block __refdata x2apic_cpu_notifier = {
+       .notifier_call = update_clusterinfo,
+};
+
+static int x2apic_init_cpu_notifier(void)
 {
        int cpu = smp_processor_id();
 
-       per_cpu(x86_cpu_to_logical_apicid, cpu) = apic_read(APIC_LDR);
+       zalloc_cpumask_var(&per_cpu(cpus_in_cluster, cpu), GFP_KERNEL);
+
+       BUG_ON(!per_cpu(cpus_in_cluster, cpu));
+
+       __cpu_set(cpu, per_cpu(cpus_in_cluster, cpu));
+       register_hotcpu_notifier(&x2apic_cpu_notifier);
+       return 1;
 }
 
 static int x2apic_cluster_probe(void)
 {
-       return x2apic_mode;
+       if (x2apic_mode)
+               return x2apic_init_cpu_notifier();
+       else
+               return 0;
 }
 
 struct apic apic_x2apic_cluster = {