s390: add SMT support

The multi-threading facility is introduced with the z13 processor family.
This patch adds code to detect the multi-threading facility. With the
facility enabled each core will surface multiple hardware threads to the
system. Each hardware threads looks like a normal CPU to the operating
system with all its registers and properties.

The SCLP interface reports the SMT topology indirectly via the maximum
thread id. Each reported CPU in the result of a read-scp-information
is a core representing a number of hardware threads.

To reflect the reduced CPU capacity if two hardware threads run on a
single core the MT utilization counter set is used to normalize the
raw cputime obtained by the CPU timer deltas. This scaled cputime is
reported via the taskstats interface. The normal /proc/stat numbers
are based on the raw cputime and are not affected by the normalization.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/s390/include/asm/topology.h b/arch/s390/include/asm/topology.h
index 56af53093d24..c4fbb9527c5c 100644
--- a/arch/s390/include/asm/topology.h
+++ b/arch/s390/include/asm/topology.h
@@ -9,9 +9,11 @@ struct cpu;
 #ifdef CONFIG_SCHED_BOOK
 
 struct cpu_topology_s390 {
+	unsigned short thread_id;
 	unsigned short core_id;
 	unsigned short socket_id;
 	unsigned short book_id;
+	cpumask_t thread_mask;
 	cpumask_t core_mask;
 	cpumask_t book_mask;
 };
@@ -19,6 +21,8 @@ struct cpu_topology_s390 {
 extern struct cpu_topology_s390 cpu_topology[NR_CPUS];
 
 #define topology_physical_package_id(cpu)	(cpu_topology[cpu].socket_id)
+#define topology_thread_id(cpu)			(cpu_topology[cpu].thread_id)
+#define topology_thread_cpumask(cpu)		(&cpu_topology[cpu].thread_mask)
 #define topology_core_id(cpu)			(cpu_topology[cpu].core_id)
 #define topology_core_cpumask(cpu)		(&cpu_topology[cpu].core_mask)
 #define topology_book_id(cpu)			(cpu_topology[cpu].book_id)