s390/sclp: Initialize sclp subsystem via arch_cpu_finalize_init()

With the switch to GENERIC_CPU_DEVICES an early call to the sclp subsystem
was added to smp_prepare_cpus(). This will usually succeed since the sclp
subsystem is implicitly initialized early enough if an sclp based console
is present.

If no such console is present the initialization happens with an
arch_initcall(); in such cases calls to the sclp subsystem will fail.
For CPU detection this means that the fallback sigp loop will be used
permanently to detect CPUs instead of the preferred READ_CPU_INFO sclp
request.

Fix this by adding an explicit early sclp_init() call via
arch_cpu_finalize_init().

Reported-by: Sheshu Ramanandan <sheshu.ramanandan@ibm.com>
Fixes: 4a39f12e753d ("s390/smp: Switch to GENERIC_CPU_DEVICES")
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/s390/include/asm/sclp.h b/arch/s390/include/asm/sclp.h
index 4da3b2956285..18f37dff03c9 100644
--- a/arch/s390/include/asm/sclp.h
+++ b/arch/s390/include/asm/sclp.h
@@ -172,6 +172,7 @@ void sclp_early_printk(const char *s);
 void __sclp_early_printk(const char *s, unsigned int len);
 void sclp_emergency_printk(const char *s);
 
+int sclp_init(void);
 int sclp_early_get_memsize(unsigned long *mem);
 int sclp_early_get_hsa_size(unsigned long *hsa_size);
 int _sclp_get_core_info(struct sclp_core_info *info);