From 07a75d08cfa1b883a6e1256666e5f0617ee99231 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 20 Oct 2025 16:17:54 +0200 Subject: [PATCH] s390/smp: Fix fallback CPU detection In case SCLP CPU detection does not work a fallback mechanism using SIGP is in place. Since a cleanup this does not work correctly anymore: new CPUs are only considered if their type matches the boot CPU. Before the cleanup the information if a CPU type should be considered was also part of a structure generated by the fallback mechanism and indicated that a CPU type should not be considered when adding CPUs. Since the rework a global SCLP state is used instead. If the global SCLP state indicates that the CPU type should be considered and the fallback mechanism is used, there may be a mismatch with CPU types if CPUs are added. This can lead to a system with only a single CPU even tough there are many more CPUs. Address this by simply copying the boot cpu type into the generated data structure from the fallback mechanism. Reported-by: Alexander Egorenkov Fixes: d08d94306e90 ("s390/smp: cleanup core vs. cpu in the SCLP interface") Reviewed-by: Mete Durlu Signed-off-by: Heiko Carstens --- arch/s390/kernel/smp.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index da84c0dc6b7e0..70df4ca5d4436 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -697,6 +697,7 @@ static void __ref smp_get_core_info(struct sclp_core_info *info, int early) continue; info->core[info->configured].core_id = address >> smp_cpu_mt_shift; + info->core[info->configured].type = boot_core_type; info->configured++; } info->combined = info->configured; -- 2.47.3