Commit 83987ace authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Marcelo Tosatti

s390/kvm: Fix BUG in include/linux/kvm_host.h:745

commit b080935c
    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 8fa22068
    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: default avatarFrederic Weisbecker <fweisbec@gmail.com>
CC: Gleb Natapov <gleb@redhat.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent ecf02a60
......@@ -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,
......
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