[PATCH v4 3/3] xen/sched: Make cpu_nr_siblings() architecture-specific

[Hirokazu Takahashi <taka@xxxxxxxxxxxxx>]

Make cpu_nr_siblings() an architecture-specific function.
This patch provides the implementation for x86 and a common
version for Device Tree-based architectures.

Signed-off-by: Hirokazu Takahashi <taka@xxxxxxxxxxxxx>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/include/asm/processor.h |  1 +
 xen/common/sched/credit2.c           | 22 +++-------------------
 xen/include/xen/cpu-topology.h       |  5 +++++
 3 files changed, 9 insertions(+), 19 deletions(-)

diff --git a/xen/arch/x86/include/asm/processor.h 
b/xen/arch/x86/include/asm/processor.h
index 8ca6799a81..9758060129 100644
--- a/xen/arch/x86/include/asm/processor.h
+++ b/xen/arch/x86/include/asm/processor.h
@@ -106,6 +106,7 @@ extern void intel_init_arat(void);
 
 #define cpu_to_core(_cpu)   (cpu_data[_cpu].cpu_core_id)
 #define cpu_to_socket(_cpu) (cpu_data[_cpu].phys_proc_id)
+#define cpu_nr_siblings(_cpu) (cpu_data[_cpu].x86_num_siblings)
 
 unsigned int apicid_to_socket(unsigned int apicid);
 
diff --git a/xen/common/sched/credit2.c b/xen/common/sched/credit2.c
index ada430f262..6c645f0e21 100644
--- a/xen/common/sched/credit2.c
+++ b/xen/common/sched/credit2.c
@@ -29,22 +29,6 @@
 /* #define d2printk printk */
 #define d2printk(x...)
 
-/*
- * TODO: Abstract this properly, and figure out what Credit2 wants to do with
- *       the fact that x86_num_siblings doesn't even have the same meaning
- *       between x86 vendors.
- */
-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_topology[cpu].num_siblings : 1;
-#else
-    return 1;
-#endif
-}
-
 /*
  * Credit2 tracing events ("only" 512 available!). Check
  * include/public/trace.h for more details.
@@ -882,9 +866,9 @@ cpu_runqueue_match(const struct csched2_runqueue_data *rqd, 
unsigned int cpu)
 
 /*
  * Additional checks, to avoid separating siblings in different runqueues.
- * This deals with both Intel's HTs and AMD's CUs. An arch that does not have
- * any similar concept will just have cpu_nr_siblings() always return 1, and
- * setup the cpu_sibling_mask-s acordingly (as currently does ARM), and things
+ * This deals with Intel's HTs, AMD's CUs and ARM's SMT. An arch that
+ * does not have similar concept will just have cpu_nr_siblings() always
+ * return 1, and setup the cpu_sibling_mask-s accordingly, and things
  * will just work as well.
  */
 static bool
diff --git a/xen/include/xen/cpu-topology.h b/xen/include/xen/cpu-topology.h
index ee34425680..646cd0ff04 100644
--- a/xen/include/xen/cpu-topology.h
+++ b/xen/include/xen/cpu-topology.h
@@ -41,6 +41,7 @@ static inline void init_cpu_sibling_map(unsigned int cpu)
 
 #define cpu_to_core(cpu) (cpu_topology ? cpu_topology[cpu].phys_core_id : 0)
 #define cpu_to_socket(cpu) (cpu_topology ? cpu_topology[cpu].phys_socket_id : 
0)
+#define cpu_nr_siblings(cpu) (cpu_topology ? cpu_topology[cpu].num_siblings : 
1)
 
 #else /* CONFIG_GENERIC_CPU_TOPOLOGY */
 
@@ -64,6 +65,10 @@ static inline void init_cpu_sibling_map(unsigned int cpu)
 #define cpu_to_socket(cpu) (0)
 #endif
 
+#ifndef cpu_nr_siblings
+#define cpu_nr_siblings(cpu) (1)
+#endif
+
 #endif /* CONFIG_GENERIC_CPU_TOPOLOGY */
 
 #endif /* XEN_CPU_TOPOLOGY_H */
-- 
2.43.0