Christian Borntraeger 83987ace22 s390/kvm: Fix BUG in include/linux/kvm_host.h:745 ...

commit b080935c86
    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 8fa2206821
    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 <fweisbec@gmail.com>
CC: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

2013-01-10 17:53:40 -02:00

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