From 83987ace22f541964bd0dbf83a3f6b0014ba3e1e Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Tue, 8 Jan 2013 16:23:10 +0100 Subject: [PATCH] s390/kvm: Fix BUG in include/linux/kvm_host.h:745 commit b080935c8638e08134629d0a9ebdf35669bec14d kvm: Directly account vtime to system on guest switch also removed the irq_disable/enable around kvm guest switch, which is correct in itself. Unfortunately, there is a BUG ON that (correctly) checks for preemptible to cover the call to rcu later on. (Introduced with commit 8fa2206821953a50a3a02ea33fcfb3ced2fd9997 KVM: make guest mode entry to be rcu quiescent state) This check might trigger depending on the kernel config. Lets make sure that no preemption happens during kvm_guest_enter. We can enable preemption again after the call to rcu_virt_note_context_switch returns. Please note that we continue to run s390 guests with interrupts enabled. Acked-by: Frederic Weisbecker CC: Gleb Natapov Signed-off-by: Christian Borntraeger Signed-off-by: Marcelo Tosatti --- arch/s390/kvm/kvm-s390.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index c9011bfaabbe..f090e819bf71 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -613,7 +613,9 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) kvm_s390_deliver_pending_interrupts(vcpu); vcpu->arch.sie_block->icptcode = 0; + preempt_disable(); kvm_guest_enter(); + preempt_enable(); VCPU_EVENT(vcpu, 6, "entering sie flags %x", atomic_read(&vcpu->arch.sie_block->cpuflags)); trace_kvm_s390_sie_enter(vcpu, -- GitLab