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, 13 insertions, 7 deletions

diff --git a/arch/s390/include/asm/sysinfo.h b/arch/s390/include/asm/sysinfo.h
index f92428e..73f12d2 100644
--- a/arch/s390/include/asm/sysinfo.h
+++ b/arch/s390/include/asm/sysinfo.h
@@ -90,7 +90,11 @@ struct sysinfo_2_2_2 {
 	unsigned short cpus_reserved;
 	char name[8];
 	unsigned int caf;
-	char reserved_2[16];
+	char reserved_2[8];
+	unsigned char mt_installed;
+	unsigned char mt_general;
+	unsigned char mt_psmtid;
+	char reserved_3[5];
 	unsigned short cpus_dedicated;
 	unsigned short cpus_shared;
 };
@@ -120,26 +124,28 @@ struct sysinfo_3_2_2 {
 
 extern int topology_max_mnest;
 
-#define TOPOLOGY_CPU_BITS	64
+#define TOPOLOGY_CORE_BITS	64
 #define TOPOLOGY_NR_MAG		6
 
-struct topology_cpu {
-	unsigned char reserved0[4];
+struct topology_core {
+	unsigned char nl;
+	unsigned char reserved0[3];
 	unsigned char :6;
 	unsigned char pp:2;
 	unsigned char reserved1;
 	unsigned short origin;
-	unsigned long mask[TOPOLOGY_CPU_BITS / BITS_PER_LONG];
+	unsigned long mask[TOPOLOGY_CORE_BITS / BITS_PER_LONG];
 };
 
 struct topology_container {
-	unsigned char reserved[7];
+	unsigned char nl;
+	unsigned char reserved[6];
 	unsigned char id;
 };
 
 union topology_entry {
 	unsigned char nl;
-	struct topology_cpu cpu;
+	struct topology_core cpu;
 	struct topology_container container;
 };