From c185f13918b4a133ccdd80cb56c4c510dae4d247 Mon Sep 17 00:00:00 2001 From: Sven Schnelle Date: Tue, 8 Dec 2020 07:35:21 +0100 Subject: [PATCH] s390/smp: perform initial CPU reset also for SMT siblings commit b5e438ebd7e808d1d2435159ac4742e01a94b8da upstream. Not resetting the SMT siblings might leave them in unpredictable state. One of the observed problems was that the CPU timer wasn't reset and therefore large system time values where accounted during CPU bringup. Cc: # 4.0 Fixes: 10ad34bc76dfb ("s390: add SMT support") Reviewed-by: Heiko Carstens Signed-off-by: Sven Schnelle Signed-off-by: Heiko Carstens Signed-off-by: Greg Kroah-Hartman --- arch/s390/kernel/smp.c | 18 +++--------------- 1 file changed, 3 insertions(+), 15 deletions(-) diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index 66d7ba61803c..659d99af9156 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -885,24 +885,12 @@ static void __no_sanitize_address smp_start_secondary(void *cpuvoid) /* Upping and downing of CPUs */ int __cpu_up(unsigned int cpu, struct task_struct *tidle) { - struct pcpu *pcpu; - int base, i, rc; + struct pcpu *pcpu = pcpu_devices + cpu; + int rc; - pcpu = pcpu_devices + cpu; if (pcpu->state != CPU_STATE_CONFIGURED) return -EIO; - base = smp_get_base_cpu(cpu); - for (i = 0; i <= smp_cpu_mtid; i++) { - if (base + i < nr_cpu_ids) - if (cpu_online(base + i)) - break; - } - /* - * If this is the first CPU of the core to get online - * do an initial CPU reset. - */ - if (i > smp_cpu_mtid && - pcpu_sigp_retry(pcpu_devices + base, SIGP_INITIAL_CPU_RESET, 0) != + if (pcpu_sigp_retry(pcpu, SIGP_INITIAL_CPU_RESET, 0) != SIGP_CC_ORDER_CODE_ACCEPTED) return -EIO;