[PATCH v2 2/3] xen/sched: Link CPU topology to scheduler

[Hirokazu Takahashi <taka@xxxxxxxxxxxxx>]

Make CPU topology information available to the Xen scheduler.
Additionally, ensure that this topology information is displayed
when executing the 'xl info -n' command.

Signed-off-by: Hirokazu Takahashi <taka@xxxxxxxxxxxxx>
---
 xen/arch/arm/include/asm/processor.h  |  4 ---
 xen/arch/arm/smpboot.c                | 10 ++++--
 xen/common/device-tree/cpu-topology.c | 51 +++++++++++++++++++++++++++
 xen/common/sched/credit2.c            |  3 ++
 xen/common/sysctl.c                   |  1 +
 xen/drivers/acpi/topology.c           |  3 ++
 xen/include/xen/cpu-topology.h        | 10 ++++++
 7 files changed, 75 insertions(+), 7 deletions(-)

diff --git a/xen/arch/arm/include/asm/processor.h 
b/xen/arch/arm/include/asm/processor.h
index a3753c317f..41fa73cfc4 100644
--- a/xen/arch/arm/include/asm/processor.h
+++ b/xen/arch/arm/include/asm/processor.h
@@ -613,10 +613,6 @@ void show_stack(const struct cpu_user_regs *regs);
 
 #define cpu_relax() barrier() /* Could yield? */
 
-/* All a bit UP for the moment */
-#define cpu_to_core(_cpu)   (0)
-#define cpu_to_socket(_cpu) (0)
-
 struct vcpu;
 void vcpu_regs_hyp_to_user(const struct vcpu *vcpu,
                            struct vcpu_guest_core_regs *regs);
diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c
index fb2cf26424..4a3f1149f6 100644
--- a/xen/arch/arm/smpboot.c
+++ b/xen/arch/arm/smpboot.c
@@ -91,13 +91,17 @@ static int setup_cpu_sibling_map(int cpu)
          !zalloc_cpumask_var(&per_cpu(cpu_core_mask, cpu)) )
         return -ENOMEM;
 
+#ifdef CONFIG_CPU_TOPOLOGY
+    cpumask_copy(per_cpu(cpu_sibling_mask, cpu), 
&cpu_topology[cpu].thread_sibling);
+    cpumask_copy(per_cpu(cpu_core_mask, cpu), &cpu_topology[cpu].core_sibling);
+#else /* CONFIG_CPU_TOPOLOGY */
     /*
-     * Currently we assume there is no multithread and NUMA, so
-     * a CPU is a sibling with itself, and the all possible CPUs
-     * are supposed to belong to the same socket (NUMA node).
+     * If CONFIG_CPU_TOPOLOGY is disabled, it is assumed that
+     * all CPUs reside in the same socket and that SMT is not used.
      */
     cpumask_set_cpu(cpu, per_cpu(cpu_sibling_mask, cpu));
     cpumask_copy(per_cpu(cpu_core_mask, cpu), &cpu_possible_map);
+#endif /* CONFIG_CPU_TOPOLOGY */
 
     return 0;
 }
diff --git a/xen/common/device-tree/cpu-topology.c 
b/xen/common/device-tree/cpu-topology.c
index af8417b478..39c11ad5c6 100644
--- a/xen/common/device-tree/cpu-topology.c
+++ b/xen/common/device-tree/cpu-topology.c
@@ -319,6 +319,55 @@ int __init parse_dt_topology(void)
     return parse_socket(map);
 }
 
+static void __init setup_cpu_topology_ids(void)
+{
+    unsigned int cpu;
+    unsigned int next_core_id = 0U;
+    unsigned int next_cluster_id = 0U;
+    unsigned int next_socket_id = 0U;
+
+    for_each_possible_cpu(cpu)
+    {
+        unsigned int first_cpu;
+        struct cpu_topology *topo = &cpu_topology[cpu];
+
+        first_cpu = cpumask_first(&topo->thread_sibling);
+        if ( first_cpu == cpu )
+        {
+            topo->phys_core_id = next_core_id;
+            next_core_id++;
+        }
+        else
+            topo->phys_core_id = cpu_topology[first_cpu].phys_core_id;
+
+        /* Reuse the calculated core id if clustering is not supported */
+        if ( cpumask_empty(&topo->cluster_sibling) )
+            topo->phys_cluster_id = topo->phys_core_id;
+        else
+        {
+            first_cpu = cpumask_first(&topo->cluster_sibling);
+            if ( first_cpu == cpu )
+            {
+                topo->phys_cluster_id = next_cluster_id;
+                next_cluster_id++;
+            }
+            else
+                topo->phys_cluster_id = 
cpu_topology[first_cpu].phys_cluster_id;
+        }
+
+        first_cpu = cpumask_first(&topo->core_sibling);
+        if ( first_cpu == cpu )
+        {
+            topo->phys_socket_id = next_socket_id;
+            next_socket_id++;
+        }
+        else
+            topo->phys_socket_id = cpu_topology[first_cpu].phys_socket_id;
+
+        topo->num_siblings = cpumask_weight(&topo->thread_sibling);
+    }
+}
+
 void __init dt_init_cpu_topology(void)
 {
     unsigned int cpu;
@@ -330,6 +379,8 @@ void __init dt_init_cpu_topology(void)
 
     for_each_possible_cpu(cpu)
         setup_siblings_masks(cpu);
+
+    setup_cpu_topology_ids();
 }
 
 /*
diff --git a/xen/common/sched/credit2.c b/xen/common/sched/credit2.c
index 77475ee363..cd8b7212bc 100644
--- a/xen/common/sched/credit2.c
+++ b/xen/common/sched/credit2.c
@@ -19,6 +19,7 @@
 #include <xen/softirq.h>
 #include <xen/time.h>
 #include <xen/trace.h>
+#include <xen/cpu-topology.h>
 
 #include <asm/div64.h>
 
@@ -37,6 +38,8 @@ static unsigned int cpu_nr_siblings(unsigned int cpu)
 {
 #ifdef CONFIG_X86
     return cpu_data[cpu].x86_num_siblings;
+#elif defined(CONFIG_CPU_TOPOLOGY)
+    return cpu_topology[cpu].num_siblings;
 #else
     return 1;
 #endif
diff --git a/xen/common/sysctl.c b/xen/common/sysctl.c
index 5207664252..81a68fe24c 100644
--- a/xen/common/sysctl.c
+++ b/xen/common/sysctl.c
@@ -28,6 +28,7 @@
 #include <xen/pmstat.h>
 #include <xen/livepatch.h>
 #include <xen/coverage.h>
+#include <xen/cpu-topology.h>
 
 long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) u_sysctl)
 {
diff --git a/xen/drivers/acpi/topology.c b/xen/drivers/acpi/topology.c
index 7a7042c84e..301ee0dafa 100644
--- a/xen/drivers/acpi/topology.c
+++ b/xen/drivers/acpi/topology.c
@@ -22,6 +22,9 @@ void __init acpi_init_cpu_topology(void)
     {
         struct cpu_topology *topo = &cpu_topology[cpu];
 
+        topo->phys_core_id = cpu;
+        topo->num_siblings = 1U;
+
         cpumask_set_cpu(cpu, &topo->thread_sibling);
         cpumask_copy(&topo->core_sibling, &cpu_possible_map);
     }
diff --git a/xen/include/xen/cpu-topology.h b/xen/include/xen/cpu-topology.h
index 896eefb04f..3fdbc25e8e 100644
--- a/xen/include/xen/cpu-topology.h
+++ b/xen/include/xen/cpu-topology.h
@@ -10,6 +10,10 @@ struct cpu_topology {
     cpumask_t thread_sibling;
     cpumask_t core_sibling;
     cpumask_t cluster_sibling;
+    unsigned int phys_core_id;
+    unsigned int phys_cluster_id;
+    unsigned int phys_socket_id;
+    unsigned int num_siblings;
 };
 
 
@@ -18,10 +22,16 @@ struct cpu_topology {
 extern struct cpu_topology *cpu_topology;
 void init_cpu_topology(void);
 
+#define cpu_to_core(cpu)   (cpu_topology[cpu].phys_core_id)
+#define cpu_to_socket(cpu)   (cpu_topology[cpu].phys_socket_id)
+
 #else /* CONFIG_CPU_TOPOLOGY */
 
 static inline void init_cpu_topology(void) {}
 
+#define cpu_to_core(cpu)   (0U)
+#define cpu_to_socket(cpu) (0U)
+
 #endif /* CONFIG_CPU_TOPOLOGY */
 
 #endif /* XEN_CPU_TOPOLOGY_H */
-- 
2.43.0