From: David Hildenbrand Date: Fri, 12 Dec 2014 11:26:40 +0000 (+0100) Subject: KVM: s390: prevent sleep duration underflows in handle_wait() X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=bda343ef149bc0ce01ec965c74d464849bde96d8;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git KVM: s390: prevent sleep duration underflows in handle_wait() We sometimes get an underflow for the sleep duration, which most likely won't result in the short sleep time we wanted. So let's check for sleep duration underflows and directly continue to run the guest if we get one. Acked-by: Christian Borntraeger Acked-by: Cornelia Huck Signed-off-by: David Hildenbrand Signed-off-by: Christian Borntraeger --- diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index a845e35f904f..5744303c1cde 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -804,14 +804,20 @@ int kvm_s390_handle_wait(struct kvm_vcpu *vcpu) return -EOPNOTSUPP; /* disabled wait */ } - __set_cpu_idle(vcpu); if (!ckc_interrupts_enabled(vcpu)) { VCPU_EVENT(vcpu, 3, "%s", "enabled wait w/o timer"); + __set_cpu_idle(vcpu); goto no_timer; } now = get_tod_clock_fast() + vcpu->arch.sie_block->epoch; sltime = tod_to_ns(vcpu->arch.sie_block->ckc - now); + + /* underflow */ + if (vcpu->arch.sie_block->ckc < now) + return 0; + + __set_cpu_idle(vcpu); hrtimer_start(&vcpu->arch.ckc_timer, ktime_set (0, sltime) , HRTIMER_MODE_REL); VCPU_EVENT(vcpu, 5, "enabled wait via clock comparator: %llx ns", sltime); no_timer: