arm: Add simple cpu_{sibling, core}_mask

This needs to be done for all cpus. The allocations require smp_prepare_cpus
to be called a bit later on.

In a previous version of this patch these maps were being zeroed (instead of
setting the CPU itself in them). This in turn causes cpumask_first to return
NR_CPUS, which in turn was causing default_vcpu0_location to misbehave and
read off the end of its cnt array.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Tim Deegan <tim@xen.org>
Committed-by: Ian Campbell <ian.campbell@citrix.com>

xen/arch/arm/dummy.S

@@ -7,8 +7,6 @@ x:	.word 0xe7f000f0 /* Undefined instruction */
 x:	mov pc, lr
 	
 /* SMP support */
-DUMMY(per_cpu__cpu_core_mask);
-DUMMY(per_cpu__cpu_sibling_mask);
 DUMMY(node_online_map);
 DUMMY(smp_send_state_dump);
 

xen/arch/arm/setup.c

@@ -173,8 +173,6 @@ void __init start_xen(unsigned long boot_phys_offset,
     set_current((struct vcpu *)0xfffff000); /* debug sanity */
     idle_vcpu[0] = current;
 
-    smp_prepare_cpus(cpus);
-
     init_xen_time();
 
     setup_mm(atag_paddr, fdt_size);
@@ -214,6 +212,8 @@ void __init start_xen(unsigned long boot_phys_offset,
 
     local_irq_enable();
 
+    smp_prepare_cpus(cpus);
+
     initialize_keytable();
 
     console_init_postirq();

xen/arch/arm/smpboot.c

@@ -52,6 +52,23 @@ unsigned long __initdata ready_cpus = 0;
 
 /* ID of the PCPU we're running on */
 DEFINE_PER_CPU(unsigned int, cpu_id);
+/* XXX these seem awfully x86ish... */
+/* representing HT siblings of each logical CPU */
+DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_sibling_mask);
+/* representing HT and core siblings of each logical CPU */
+DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_core_mask);
+
+static void setup_cpu_sibling_map(int cpu)
+{
+    if ( !zalloc_cpumask_var(&per_cpu(cpu_sibling_mask, cpu)) ||
+         !zalloc_cpumask_var(&per_cpu(cpu_core_mask, cpu)) )
+        panic("No memory for CPU sibling/core maps\n");
+
+    /* A CPU is a sibling with itself and is always on its own core. */
+    cpumask_set_cpu(cpu, per_cpu(cpu_sibling_mask, cpu));
+    cpumask_set_cpu(cpu, per_cpu(cpu_core_mask, cpu));
+}
+
 
 void __init
 smp_prepare_cpus (unsigned int max_cpus)
@@ -65,6 +82,8 @@ smp_prepare_cpus (unsigned int max_cpus)
     for ( i = 0; i < max_cpus; i++ )
         cpumask_set_cpu(i, &cpu_possible_map);
     cpumask_copy(&cpu_present_map, &cpu_possible_map);
+
+    setup_cpu_sibling_map(0);
 }
 
 void __init
@@ -115,6 +134,8 @@ void __cpuinit start_secondary(unsigned long boot_phys_offset,
 
     set_current(idle_vcpu[cpuid]);
 
+    setup_cpu_sibling_map(cpuid);
+
     /* Run local notifiers */
     notify_cpu_starting(cpuid);
     wmb();